Utente:Drow/Sandbox
Faccia di Boe (Face of Boe) è un essere antico e saggio che viene incontrato in alcuni episodi ambientati nel futuro (La fine del mondo, La vendetta di Cassandra, L'ingorgo). È formato dalla sola faccia di forma umanoide, contenuta in una teca di vetro. Si dice sia l'essere più antico dell'universo, e custodisce un segreto che rivela al Dottore solo alla sua morte. Nel tredicesimo episodio della terza stagione si allude che egli possa essere in realtà l'immortale Jack Harkness, sopravvissuto per miliardi di anni ma con ora un corpo in decadimento. Il produttore esecutivo Russell T. Davies ha tuttavia dichiarato in un'intervista che il collegamento tra i due personaggi, se davvero esiste, non verrà esplicitato.[1]
Mickey Smith, interpretato da Noel Clarke, è il fidanzato di Rose Tyler, è abbastanza geloso del Dottore per via del legame che c'è fra lui e Rose, infatti alla fine l'amore di Mickey non sarà più corrisposto per via del fatto che Rose si innamorerà del Dottore (sentimento da lui ricambiato). In seguito diventa un cacciatore di alieni, inoltre lui e Martha Jones, un'altra compagna di viaggio del Dottore, si sposano.
Wilfred Mott, interpretato da Bernard Cribbins, è il nonno di Donna Noble. Vuole molto bene a sua nipote, inoltre ha sempre avuto un buon rapporto con il Dottore. Cercando di salvare Wilfred il Dottore ha dovuto sacrificarsi, rigenerandosi per la dodicesima volta.
Strax (Dan Starkey) è un soldato clone dell'esercito Sontaran, in diverse occasioni ha aiutato il Dottore. Viene ucciso nell'episodio Un uomo buono va in guerra, ma viene riportato in vita da Madame Vastra e sua moglie Jenny nel periodo vittoriano, diventando loro compagno e maggiordomo.
Madame Vastra (Neve Mclntosh) è una siluriana che aiuta il Dottore in diverse avventure. Omosessuale, sposata con un'umana di nome Jenny, nel periodo vittoriano viene riconosciuta coma una grande investigatrice col nome di "Velata Detective". Secondo quanto detto dal Dottor Simeon in I pupazzi di neve, Arthur Conan Doyle ha creato Sherlock Holmes basandosi sulle avventure sue e di Jenny.
=== La Chiesa ===
Appare negli episodi Il tempo degli Angeli, Carne e pietra, Un uomo buono va in guerra e The Time of the Doctor. Si tratta di un'organizzazione religiosa e militare del 51esimo e 52esimo secolo, che secondo l'Undicesimo Dottore si è evoluta dalla Chiesa Cattolica terrestre (Il tempo degli Angeli). I suoi obiettivi sono la sicurezza interstellare e la protezione delle popolazioni umane, ed è dotata di tutte le più avanzate tecnologie del suo periodo (si tratta essenzialmente di un'organizzazione di intelligence). Il suo comando e i suoi capi si trovano sul Mainframe Papale, un enorme astronave-chiesa spaziale.
Parte della Chiesa sono i Silenti che sono semplicemente suoi confessori (The Time of the Doctor).
Una parte della Chiesa, scissasi e ribellatasi al suo comando
Animal cognition is the study of the mental capacities of animals. It has developed out of comparative psychology, including the study of animal conditioning and learning, but has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology. The alternative name cognitive ethology is therefore sometimes used; much of what used to be considered under the title of animal intelligence is now thought of under this heading.[2]
Research has examined animal cognition in mammals (especially primates, cetaceans, elephants, dogs, cats, horses,[3][4] raccoons and rodents), birds (including parrots, corvids and pigeons), reptiles (lizards and snakes), fish and invertebrates (including cephalopods, spiders and insects).[2]
Historical background
Animal cognition from anecdote to laboratory
The behavior of non-human animals has captivated human imagination from antiquity, and over the centuries many writers have speculated about the animal mind, or its absence, as Descartes would have it.[5] Speculation about animal intelligence gradually yielded to scientific study after Darwin placed humans and animals on a continuum, although Darwin’s largely anecdotal approach to the topic would not pass scientific muster later on.[6] Unsatisfied with the anecdotal method of Darwin and his protégé J. G. Romanes,[7] E. L. Thorndike brought animal behavior into the laboratory for objective scrutiny. Thorndike’s careful observations of the escape of cats, dogs, and chicks from puzzle boxes led him to conclude that intelligent behavior may be compounded of simple associations and that inference to animal reason, insight, or consciousness is unnecessary and misleading.[8] At about the same time, I. P. Pavlov began his seminal studies of conditioned reflexes in dogs. Pavlov quickly abandoned attempts to infer canine mental processes; such attempts, he said, led only to disagreement and confusion. He was, however, willing to propose unseen physiological processes that might explain his observations.[9]
The behavioristic half-century
The work of Thorndike, Pavlov and a little later of the outspoken behaviorist John B. Watson[10] set the direction of much research on animal behavior for more than half a century. During this time there was considerable progress in understanding simple associations; notably, around 1930 the differences between Thorndike's instrumental (or operant) conditioning and Pavlov's classical (or Pavlovian) conditioning were clarified, first by Miller and Kanorski, and then by B. F. Skinner.[11][12] Many experiments on conditioning followed; they generated some complex theories,[13] but they made little or no reference to intervening mental processes. Probably the most explicit dismissal of the idea that mental processes control behavior was the radical behaviorism of Skinner. This view seeks to explain behavior, including "private events" like mental images, solely by reference to the environmental contingencies impinging on the human or animal.[14]
Despite the predominantly behaviorist orientation of research before 1960, the rejection of mental processes in animals was not universal during those years. Influential exceptions included, for example, Wolfgang Köhler and his insightful chimpanzees[15] and Edward Tolman whose proposed cognitive map was a significant contribution to subsequent cognitive research in both humans and animals.[16]
The cognitive revolution
Beginning around 1960, a "cognitive revolution" in research on humans[17] gradually spurred a similar transformation of research with animals. Inference to processes not directly observable became acceptable and then commonplace. An important proponent of this shift in thinking was Donald O. Hebb, who argued that "mind" is simply a name for processes in the head that control complex behavior, and that it is both necessary and possible to infer those processes from behavior.[18] Animals came to be seen as "goal seeking agents that acquire, store, retrieve, and internally process information at many levels of cognitive complexity.".[19] However, it is interesting to note that many cognitive experiments with animals made, and still make, ingenious use of conditioning methods pioneered by Thorndike and Pavlov.[20]
The scientific status of "consciousness" in animals continues to be hotly debated. Serious consideration of conscious thought in animals has been advocated by some (e.g., Donald Griffin),[21] but the larger research community has been notably cool to such suggestions.[22]
Methods
The acceleration of research on animal cognition in the last 50 years has led to a rapid expansion in the variety of species studied and methods employed. The remarkable behavior of large-brained animals such as primates and cetacea has claimed special attention, but all sorts of mammals large and small, birds, fish, ants, bees, and others have been brought into the laboratory or observed in carefully controlled field studies. In the laboratory, animals push levers, pull strings, dig for food, swim in water mazes, or respond to images on computer screens in discrimination, attention, memory, and categorization experiments.[20] Careful field studies explore memory for food caches, navigation by stars,[senza fonte] communication, tool use, identification of conspecifics, and many other matters. Studies often focus on the behavior of animals in their natural environments and discuss the putative function of the behavior for the propagation and survival of the species. These developments reflect an increased cross-fertilization from related fields such as ethology and behavioral biology. Also, contributions from behavioral neuroscience are beginning to clarify the physiological substrate of some inferred mental process.
Several long term research projects have captured a good deal of attention. These include ape-language experiments such as the Washoe project and project Nim. Other animal projects include Irene Pepperberg's extended series of studies with the African Gray Parrot Alex, Louis Herman's work with bottlenosed dolphins, and studies of long-term memory in pigeons in which birds were shown to remember pictures for periods of several years.
Some researchers have made effective use of a Piagetian methodology, taking tasks which human children are known to master at different stages of development, and investigating which of them can be performed by particular species. Others have been inspired by concerns for animal welfare and the management of domestic species: for example Temple Grandin has harnessed her unique expertise in animal welfare and the ethical treatment of farm livestock to highlight underlying similarities between humans and other animals.[23] From a methodological point of view, one of the main risks in this sort of work is anthropomorphism, the tendency to interpret an animal's behavior in terms of human feelings, thoughts, and motivations.[2]
Research questions

Human and animal cognition have much in common, and this is reflected in the research summarized below; most of the headings found here might also appear in an article on human cognition. Of course, research in the two also differs in important respects. Notably, much research with humans either studies or involves language, and much research with animals is related directly or indirectly to behaviors important to survival in natural settings. Following are summaries of some of the major areas of research in animal cognition.
Perception
Like humans, non-human animals process information from eyes, ears, and other sensory organs to perceive the environment. Perceptual processes have been studied in many species, with results that are often similar to those in humans. Equally interesting are those perceptual processes that differ from, or go beyond those found in humans, such as echolocation in bats and dolphins, motion detection by skin receptors in fish, and extraordinary visual acuity, motion sensitivity and ability to see ultraviolet light in some birds.[24]
Attention
Much of what is happening in the world at any moment is irrelevant to current behavior. Attention refers to mental processes that select relevant information, inhibit irrelevant information, and switch among these as the situation demands.[25] Often the selective process is tuned before relevant information appears; such expectation makes for rapid selection of key stimuli when they become available. A large body of research has explored the way attention and expectation affect the behavior of non-human animals, and much of this work suggests that attention operates in birds, mammals and reptiles in much the same way that it does in humans.[26]
The following paragraphs contain brief accounts of several experiments. These are intended to give the reader a bit of the flavor of research on attention, but they barely scratch the surface, and readers should consult the references for descriptions of many other experiments. Also, one must interpret putative "attentional" effects with caution, because they can often be accounted for in several different ways. For example, lack of response to a current stimulus might reflect inattention, but it might also reflect lack of motivation, or result from past learning that suppresses response to that stimulus or promotes an alternative response. Most experiments include control conditions intended to exclude as many alternative interpretations as possible.
Selective learning
Animals trained to discriminate between two stimuli, say black versus white, can be said to attend to the "brightness dimension," but this says little about whether this dimension is selected in preference to others. More enlightenment comes from experiments that allow the animal to choose from several alternatives. For example, several studies have shown that performance is better on, for example, a color discrimination (e.g. blue vs green) after the animal has learned another color discrimination (e.g. red vs orange) than it is after training on a different dimension such as an X shape versus and O shape. The reverse effect happens after training on forms. Thus, the earlier learning appears to affect which dimension, color or form, the animal will attend to.[27]
Other experiments have shown that after animals have learned to respond to one aspect of the environment responsiveness to other aspects is suppressed. In "blocking", for example, an animal is conditioned to respond to one stimulus ("A") by pairing that stimulus with reward or punishment. After the animal responds consistently to A, a second stimulus ("B") accompanies A on additional training trials. Later tests with the B stimulus alone elicit little response, suggesting that learning about B has been blocked by prior learning about A .[28] This result supports the hypothesis that stimuli are neglected if they fail to provide new information. Thus, in the experiment just cited, the animal failed to attend to B because B added no information to that supplied by A. If true, this interpretation is an important insight into attentional processing, but this conclusion remains uncertain because blocking and several related phenomena can be explained by models of conditioning that do not invoke attention.[29]
Divided attention
Casual observation suggests that attention is a limited resource and is not all-or-none: the more attention is devoted to one aspect or dimension of the environment, the less is available for others.[30] In preparing a meal you may divide your attention among a number of things, but a sudden spill may distract you from a falling souffle. A number of experiments have studied this sort of thing in animals. For example, in one experiment, a tone and a light came on simultaneously. The pigeon subjects gained reward only by choosing the correct combination of the two dimensions (a high pitch together with a yellow light). The birds did fairly well at this task, presumably by dividing attention between the two dimensions. When only one of the stimulus dimensions varied, while the other was held at its rewarded value, discrimination improved on the variable stimulus, and later tests showed that discrimination had also gotten worse on the alternative stimulus dimension.[31] These outcomes are consistent with the idea that attention is a limited resource that can be more or less focused among incoming stimuli.
Visual search and attentional priming
As noted above, attention functions to select information that is of special use to the animal. Visual search typically calls for this sort of selection, and search tasks have been used extensively in both humans and animals to determine the characteristics of attentional selection and the factors that control it.
Experimental research on visual search in animals was initially prompted by field observations published by Luc Tinbergen (1960).[32] Tinbergen observed that birds are selective when foraging for insects. For example, he found that birds tended to catch the same type of insect repeatedly even though several types were available. Tinbergen suggested that this prey selection was caused by an attentional bias that improved detection of one type of insect while suppressing detection of others. This "attentional priming" is commonly said to result from a pretrial activation of a mental representation of the attended object, which Tinbergen called a "searching image."
Tinbergen’s field observations on priming have been supported by a number of experiments. For example, Pietrewicz and Kamil (1977, 1979)[33][34] presented blue jays with pictures of tree trunks upon which rested either a moth of species A, a moth of species B, or no moth at all. The birds were rewarded for pecks at a picture showing a moth. Crucially, the probability with which a particular species of moth was detected was higher after repeated trials with that species (e.g. A, A, A,...) than it was after a mixture of trials (e.g. A, B, B, A, B, A, A...). These results suggest again that sequential encounters with an object can establish an attentional predisposition to see the object.
Another way to produce attentional priming in search is to provide an advance signal that is associated with the target. For example, if you hear a song sparrow you may be predisposed to detect a song sparrow in a shrub, or among other birds. A number of experiments have reproduced this effect in animal subjects.[35][36]
Still other experiments have explored nature of stimulus factors that affect the speed and accuracy of visual search. For example, the time taken to find a single target increases as the number of items in the visual field increases. This rise in RT is steep if the distracters are similar to the target, less steep if they are dissimilar, and may not occur if the distracters are very different in from the target in form or color.[37]
Concepts and categories
Fundamental but difficult to define, the concept of "concept" was discussed for hundreds of years by philosophers before it became a focus of psychological study. Concepts enable humans and animals to organize the world into functional groups; the groups may be composed of perceptually similar objects or events, diverse things that have a common function, relationships such as same versus different, or relations among relations such as analogies.[38] Extensive discussions on these matters together with many references may be found in Shettleworth (2010)[2] Wasserman and Zentall (2006)[20] and in Zentall et al. (2008). The latter is freely available online[39]
Methods
Most work on animal concepts has been done with visual stimuli, which can easily be constructed and presented in great variety, but auditory and other stimuli have been used as well.[40] Pigeons have been widely used, for they have excellent vision and are readily conditioned to respond to visual targets; other birds and a number of other animals have been studied as well.[2] In a typical experiment, a bird or other animal confronts a computer monitor on which a large number of pictures appear one by one, and the subject gets a reward for pecking or touching a picture of a category item and no reward for non-category items. Alternatively, a subject may be offered a choice between two or more pictures. Many experiments end with the presentation of items never seen before; successful sorting of these items shows that the animal has not simply learned many specific stimulus-response associations. A related method, sometimes used to study relational concepts, is matching-to-sample. In this task an animal sees one stimulus and then chooses between two or more alternatives, one of which is the same as the first; the animal is then rewarded for choosing the matching stimulus.[2][20][39]
Perceptual categories
Perceptual categorization is said to occur when a person or animal responds in a similar way to a range of stimuli that share common features. For example, a squirrel climbs a tree when it sees Rex, Shep, or Trixie, which suggests that it categorizes all three as something to avoid. This sorting of instances into groups is crucial to survival. Among other things, an animal must categorize if it is to apply learning about one object (e.g. Rex bit me) to new instances of that category (dogs may bite).[2][20][39]
Natural categories
Many animals readily classify objects by perceived differences in form or color. For example, bees or pigeons quickly learn to choose any red object and reject any green object if red leads to reward and green does not. Seemingly much more difficult is an animal’s ability to categorize natural objects that vary a great deal in color and form even while belonging to the same group. In a classic study, Richard J. Herrnstein trained pigeons to respond to the presence or absence of human beings in photographs.[41] The birds readily learned to peck photos that contained partial or full views of humans and to avoid pecking photos with no human, despite great differences in the form, size, and color of both the humans displayed and in the non-human pictures. In follow-up studies, pigeons categorized other natural objects (e.g. trees) and after training they were able without reward to sort photos they had not seen before .[42][43] Similar work has been done with natural auditory categories, for example, bird songs [44]
Functional or associative categories
Perceptually unrelated stimuli may come to be responded to as members of a class if they have a common use or lead to common consequences. An oft-cited study by Vaughan (1988) provides an example.[45] Vaughan divided a large set of unrelated pictures into two arbitrary sets, A and B. Pigeons got food for pecking at pictures in set A but not for pecks at pictures in set B. After they had learned this task fairly well, the outcome was reversed: items in set B led to food and items in set A did not. Then the outcome was reversed again, and then again, and so on. Vaughan found that after 20 or more reversals, associating reward with a few pictures in one set caused the birds to respond to the other pictures in that set without further reward, as if they were thinking "if these pictures in set A bring food, the others in set A must also bring food." That is, the birds now categorized the pictures in each set as functionally equivalent. Several other procedures have yielded similar results.[2][39]
Relational or abstract categories
When tested in a simple stimulus matching-to-sample task (described above) many animals readily learn specific item combinations, such as "touch red if the sample is red, touch green if the sample is green." But this does not demonstrate that they distinguish between "same" and "different" as general concepts. Better evidence is provided if, after training, an animal successfully makes a choice that matches a novel sample that it has never seen before. Monkeys and chimpanzees do learn to do this, as do pigeons if they are given a great deal of practice with many different stimuli. However, because the sample is presented first, successful matching might mean that the animal is simply choosing the most recently seen "familiar" item rather than the conceptually "same" item. A number of studies have attempted to distinguish these possibilities, with mixed results.[2][39]
Rule learning
The use of rules has sometimes been considered an ability restricted to humans, but a number of experiments have shown evidence of simple rule learning in primates[46] and also in other animals. Much of the evidence has come from studies of sequence learning in which the "rule" consists of the order in which a series of events occurs. Rule use is shown if the animal learns to discriminate different orders of events and transfers this discrimination to new events arranged in the same order. For example, Murphy et al. (2008)[47] trained rats to discriminate between visual sequences. For one group ABA and BAB were rewarded, where A="bright light" and B="dim light." Other stimulus triplets were not rewarded. The rats learned the visual sequence, although both bright and dim lights were equally associated with reward. More importantly, in a second experiment with auditory stimuli, rats responded correctly to sequences of novel stimuli that were arranged in the same order as those previously learned. Similar sequence learning has been demonstrated in birds and other animals as well.[48]
Memory
The categories that have been developed to analyze human memory (short term memory, long term memory, working memory) have been applied to the study of animal memory, and some of the phenomena characteristic of human short term memory (e.g. the serial position effect) have been detected in animals, particularly monkeys.[49] However most progress has been made in the analysis of spatial memory; some of this work has sought to clarify the physiological basis of spatial memory and the role of the hippocampus; other work has explored the spatial memory of scatter-hoarder animals such as Clark's Nutcracker, certain jays, tits and certain squirrels, whose ecological niches require them to remember the locations of thousands of caches,[2][50] often following radical changes in the environment.
Memory has been widely investigated in foraging honeybees, Apis mellifera, which use both transient short-term working memory that is non-feeder specific and a feeder specific long-term reference memory.[51][52][53] Memory induced in a free-flying honeybee by a single learning trial lasts for days and, by three learning trials, for a lifetime.[54] Slugs, Limax flavus, have a short-term memory of approximately 1 min and long-term memory of 1 month.[55]
Methods
As in humans, research with animals distinguishes between “working” or “short-term” memory from “reference” or long-term memory. Tests of working memory evaluate memory for events that happened in the recent past, usually within the last few seconds or minutes. Tests of reference memory evaluate memory for regularities such as “pressing a lever brings food” or “children give me peanuts.”
Habituation
This is one of the simplest tests for memory spanning a short time interval. The test compares an animal’s response to a stimulus or event on one occasion to its response on a previous occasion. If the second response differs consistently from the first, the animal must have remembered something about the first, unless some other factor such as motivation, sensory sensitivity, or the test stimulus has changed.
Delayed response
Delayed response tasks are among the most useful methods used to study short-term memory in animals. Dating from research by Hunter (1913), the animal was shown a stimulus, such as a picture or a colored light, and a few seconds or minutes later the animal had to choose among alternative stimuli. In Hunter's studies, for example, a light appeared briefly in one of three goal boxes and then later the animal was allowed to choose among the boxes, finding food behind the one that had been lighted.[56] Most research has been done with some variation of the "delayed matching-to-sample" task. For example, in the initial study with this task, a pigeon was presented with a flickering or steady light. Then, a few seconds later, two pecking keys were illuminated, one with a steady light and one with a flickering light. The bird got food if it pecked the key that matched the original stimulus.[57]
A commonly-used variation of the matching-to-sample task requires the animal to use the initial stimulus to control a later choice between different stimuli. For example, if the initial stimulus is a black circle, the animal learns to choose "red" after the delay; if it is a black square, the correct choice is "green". Ingenious variations of this method have been used to explore many aspects of memory, including forgetting due to interference and memory for multiple items.[2]
Radial arm maze
The radial arm maze is used to test memory for spatial ___location and to determine the mental processes by which ___location is determined. In a radial maze test, an animal is placed on a small platform from which paths lead in various directions to goal boxes; the animal finds food in one or more goal boxes. Having found food in a box, the animal must return to the central platform. The maze may be used to test both reference and working memory. Suppose, for example, that over a number of sessions the same 4 arms of an 8-arm maze always lead to food. If in a later test session the animal goes to a box that has never been baited, this indicates a failure of reference memory. On the other hand, if the animal goes to a box that it has already emptied during the same test session, this indicates a failure of working memory. Various confounding factors, such as odor cues, are carefully controlled in such experiments.[58]
Water maze
The water maze is used to test an animal's memory for spatial ___location and to discover how an animal is able to determine locations. Typically the maze is circular tank filled with water that has been made milky so that it is opaque. Located somewhere in the maze is small platform placed just below the surface of the water. When placed in the tank, the animal swims around until it finds and climbs up on the platform. With practice the animal finds the platform more and more quickly. Reference memory is assessed by removing the platform and observing the relative amount of time the animal spends swimming in the area where the platform had been located. Visual and other cues in and around the tank may be varied to assess the animal's reliance on landmarks and the geometric relations among them.[59]
Spatial cognition
Whether an animal ranges over a territory of measured in square kilometers or square meters, its survival typically depends on its ability to do such things as find a food source and then return to its nest. Sometimes such a task can be performed rather simply, for example by following a chemical trail. Typically, however, the animal must somehow acquire and use information about locations, directions, and distances. Following paragraphs outline some of the ways that animals do this.[2][60]
- Beacons Animals often learn what their nest or other goal looks like, and if it is within sight they may simply move toward it; it is said to serve as a "beacon".
- Landmarks When an animal is unable to see its goal, it may learn the appearance of nearby objects and use these landmarks as guides. Researchers working with birds and bees have demonstrated this by moving prominent objects in the vicinity of nest sites, causing returning foragers to hunt for their nest in a new ___location.[2]
- Dead reckoning Dead reckoning, also known as "path integration," is the process of computing one's position by starting from a known ___location and keeping track of the distances and directions subsequently traveled. Classic experiments have shown that the desert ant keeps track of its position in this way as it wanders for many meters searching for food. Though it travels in a randomly twisted path, it heads straight home when it finds food. However, if the ant is picked up and released some meters to the east, for example, it heads for a ___location displaced by the same amount to the east of its home nest.
- Cognitive maps Some animals appear to construct a cognitive map of their surroundings, meaning that they acquire and use information that enables them to compute how far and in what direction to go to get from one ___location to another. Such a map-like representation is thought to be used, for example, when an animal goes directly from one food source to another even though its previous experience has involved only travel between each source and home.[2][61] Research in this area [60] has also explored such topics as the use of geometric properties of the environment by rats and pigeons, and the ability of rats to represent a spatial pattern in either radial arm mazes or water mazes. Spatial cognition is sometimes explored in visual search experiments in which a human or animal searches the environment for a particular object.[senza fonte]
Long-distance navigation; homing
Many animals travel hundreds or thousands of miles in seasonal migrations or returns to breeding grounds. They may be guided by the sun, the stars, the polarization of light, magnetic cues, olfactory cues, winds, or a combination of these.
It has been hypothesized that animals such as apes and wolves are good at spatial cognition because this skill is necessary for survival. This ability may have eroded somewhat in dogs because humans have provided necessities such as food and shelter during some 15,000 years of domestication.[62][63][64]
Timing
Time of day: Circadian rhythms
The behavior of most animals is synchronized with the earth's daily light-dark cycle. Thus, many animals are active during the day, others are active at night, still others near dawn and dusk. Though one might think that these "circadian rhythms" are controlled simply by the presence or absence of light, nearly every animal that has been studied has been shown to have a "biological clock" that yields cycles of activity even when the animal is in constant illumination or darkness.[2] Circadian rhythms are so automatic and fundamental to living things — they occur even in plants[65] - that they are usually discussed separately from cognitive processes, and the reader is referred to the main article (Circadian rhythms) for further information.
Interval timing
Survival often depends on an animal's ability to time intervals. For example, rufous hummingbirds feed on the nectar of flowers, and they often return to the same flower, but only after the flower had had enough time to replenish its supply of nectar. In one experiment hummingbirds fed on artificial flowers that quickly emptied of nectar but were refilled at some fixed time (e.g. twenty minutes) later. The birds learned to come back to the flowers at about the right time, learning the refill rates of up to eight separate flowers and remembering how long ago they had visited each one.[66]
The details of interval timing have been studied in a number of species. One of the most common methods is the "peak procedure". In a typical experiment, a rat in an operant chamber presses a lever for food. A light comes on, a lever-press brings a food pellet at a fixed later time, say 10 seconds, and then the light goes off. Timing is measured during occasional test trials on which no food is presented and the light stays on. On these test trials the rat presses the lever more and more until about 10 sec and then, when no food comes, gradually stops pressing. The time at which the rat presses most on these test trials is taken to be its estimate of the payoff time.
Experiments using the peak procedure and other methods have shown that animals can time short intervals quite exactly, can time more than one event at once, and can integrate time with spatial and other cues. Such tests have also been used for quantitative tests of theories of animal timing, though no one theory has yet gained unanimous agreement.[2]
Tool and weapon use
Because tool use is traditionally assumed to be a uniquely human trait, discussion of the cognitive underpinnings of animal tool use very often includes consideration of insight and comparisons of the overall intelligence and brain size. There is also considerable debate about what constitutes a "tool". A wide range of animals is considered to use tools including mammals, birds, fish, cephalopods and insects.
Mammals
Tool use has been reported many times in both wild and captive primates, particularly the great apes. The use of tools by primates is varied and includes hunting (mammals, invertebrates, fish), collecting honey, processing food (nuts, fruits, vegetables and seeds), collecting water, weapons and shelter. Research in 2007 shows that chimpanzees in the Fongoli savannah sharpen sticks to use as spears when hunting, considered the first evidence of systematic use of weapons in a species other than humans.[67] Other mammals that spontaneously use tools in the wild and captive include elephants, bears, cetaceans, sea otters and mongooses.
Birds
Several species of birds have been recorded as using tools in the wild including Warblers, Parrots, Egyptian Vultures, Brown-headed Nuthatches, Gulls and Owls. One species examined extensively under laboratory conditions is the New Caledonian crow. One individual called “Betty”, spontaneously made a wire tool to solve a novel problem in the laboratory and attracted considerable attention. She was being tested to see whether she would select a wire hook rather than a straight wire to pull a little bucket of meat out of a well. Betty tried poking the straight wire at the meat. After a series of failures with this direct approach, she withdrew the wire and began directing it at the bottom of the well, which was secured to its base with duct tape. The wire soon became stuck, whereupon Betty pulled it sideways, bending it and unsticking it. She then inserted the hook into the well and extracted the meat. In all but one of 10 subsequent trials with only straight wire provided, she also made and used a hook in the same manner, but not before trying the straight wire first.[68][69] Some other species of birds, such as the Woodpecker Finch of the Galapagos Islands, use particular tools as an essential part of their foraging behavior. However, these behaviors are often quite inflexible and cannot be applied effectively in new situations. Several species of corvids have also been trained to use tools in controlled experiments, or use bread crumbs for bait-fishing.[70]Template:Verify credibility
Fish
Several species of wrasses have been observed using rocks as anvils to crack bivalve (scallops, urchins and clams) shells. It was first filmed [3] in an orange-dotted tuskfish (Choerodon anchorago) in 2009 by Giacomo Bernardi. The fish fans sand to unearth the bivalve, takes it into its mouth, swims several metres to a rock which it uses as an anvil by smashing the mollusc apart with sideward thrashes of the head. This behaviour has been recorded in a blackspot tuskfish (Choerodon schoenleinii) on Australia's Great Barrier Reef, yellowhead wrasse (Halichoeres garnoti) in Florida and a six-bar wrasse (Thalassoma hardwicke) in an aquarium setting. These species are at opposite ends of the phylogenetic tree in this family, so this behaviour may be a deep-seated trait in all wrasses.[71]
Invertebrates
Some cephalopods are known to use coconut shells for protection or camouflage.[72]
Ants of the species Conomyrma bicolor pick up stones and other small objects with their mandibles and drop them down the vertical entrances of rival colonies, allowing workers to forage for food without competition.[73]
Reasoning and problem solving
Closely related to tool use is the study of reasoning and problem solving. It has been observed that the manner in which chimpanzees solve problems, such as that of retrieving bananas positioned out of reach, is not through trial-and-error. Instead, they were observed to proceed in a manner that was "unwaveringly purposeful."[74]
It is clear that animals of quite a range of species are capable of solving a range of problems that are argued to involve abstract reasoning;[75] modern research has tended to show that the performances of Wolfgang Köhler's chimpanzees, who could achieve spontaneous solutions to problems without training, were by no means unique to that species, and that apparently similar behavior can be found in animals usually thought of as much less intelligent, if appropriate training is given.[76] Causal reasoning has also been observed in rooks and New Caledonian crows.[77][78]
Language
The modeling of human language in animals is known as animal language research. In addition to the ape-language experiments mentioned above, there have also been more or less successful attempts to teach language or language-like behavior to some non-primate species, including parrots and Great Spotted Woodpeckers. Arguing from his own results with the animal Nim Chimpsky and his analysis of others results, Herbert Terrace criticized the idea that chimps can produce new sentences.[79] Shortly thereafter Louis Herman published research on artificial language comprehension in the bottlenosed dolphin. (Herman, Richards, & Wolz, 1984). Though this sort of research has been controversial, especially among cognitive linguists, many researchers agree that many animals can understand the meaning of individual words, and some may understand simple sentences and syntactic variations, but there is little evidence that any animal can produce new strings of symbols that correspond to new sentences.[2]
Consciousness
The sense in which animals can be said to have consciousness or a self-concept has been hotly debated; it is often referred to as the debate over animal minds. The best known research technique in this area is the mirror test devised by Gordon G. Gallup, in which an animal's skin is marked in some way while it is asleep or sedated, and it is then allowed to see its reflection in a mirror; if the animal spontaneously directs grooming behavior towards the mark, that is taken as an indication that it is aware of itself. Self-awareness, by this criterion, has been reported for chimpanzees and also for other great apes, the European Magpie,[80] some cetaceans and a solitary elephant, but not for monkeys. The mirror test has attracted controversy among some researchers because it is entirely focused on vision, the primary sense in humans, while other species rely more heavily on other senses such as the olfactory sense in dogs.[senza fonte]
It has been suggested that metacognition in some animals provides some evidence for cognitive self-awareness.[81] The great apes, dolphins, and rhesus monkeys have demonstrated the ability to monitor their own mental states and use an "I don't know" response to avoid answering difficult questions. These species might also be aware of the strength of their memories. Unlike the mirror test, which relies primarily on body images and bodily self-awareness, uncertainty monitoring paradigms are focused on the kinds of mental states that might be linked to mental self-awareness.[senza fonte]
A different approach to determine whether a non-human animal is conscious derives from passive speech research with a macaw (see Arielle). Some researchers propose that by passively listening to an animal's voluntary speech, it is possible to learn about the thoughts of another creature and to determine that the speaker is conscious. This type of research was originally used to investigate a child's crib speech by Weir (1962) and in investigations of early speech in children by Greenfield and others (1976). With speech-capable birds, the methods of passive-speech research open a new avenue for investigation.[senza fonte]
In July, 2012 during the "Consciousness in Human and Nonhuman Animals" conference in Cambridge a group of scientists announced and signed a declaration with the following conclusions: Template:Quotation
Animal insight
Along with consciousness comes insight. Do animals have that “outside-the-box” or the “Aha! experience", sometimes called the Eureka effect? That thinking process that helps them solve everyday problems and help them to adapt in the outside world. Some may argue that this is called instinct, but insight is different. Wolfgang Köhler is usually credited with introducing the concept of insight into the psychological world.[69] Köhler worked with apes that became masters of solving puzzles he gave them. Köhler followed Edward Thorndike’s theory that animals solve problems gradually, first finding success through a process of trial and error and slowly becoming more skillful. Köhler came to disagree with this theory saying, “Thorndike’s animals could only escape by chance at first because their structure did not permit other kinds of situations.”[69] More recently, it has been shown that Asian elephants (Elephas maximus) may exhibit insightful problem solving. A male was observed moving a box to a position where it could be stood upon to reach food that had been deliberately hung out of reach.[82]
Contemporary studies of human insight address the cognitive and neural mechanisms underlying problem-solving behavior that fit this definition. In the case of animals, this usually means associative learning. Because we cannot simply ask animals about their “aha” experiences we should define insightful behavior in terms of processes such as mental trial and error or casual understanding.[69]
Numeracy
Some animals are capable of distinguishing between different amounts and rudimentary counting. Elephants have been known to perform simple arithmetic, and rhesus monkeys and pigeons, in some sense, can count.[83][84][85] Ants are able to use quantitative values and transmit this information.[86][87] For instance, ants of several species are able to estimate quite precisely numbers of encounters with members of other colonies on their feeding territories.[88][89] Numeracy has been described in the yellow mealworm beetle, Tenebrio molitor,[90] and the honeybee.[91]
Western lowland gorillas given the choice between two food trays demonstrated the ability to choose the tray with more food items at a rate higher than chance after training.[92] In a similar task, chimpanzees chose the option with larger amount of food.[93] Salamanders given a choice between two displays with differing amounts of fruit flies, used as a food reward, reliably choose the display with more flies, as shown in a particular experiment.[94]
Other experiments have been conducted that show animals’ abilities to differentiate between non-food quantities. American black bears demonstrated quantity differentiation abilities in a task with a computer screen. The bears were trained to touch a computer monitor with a paw or nose to choose a quantity of dots in one of two boxes on the screen. Each bear was trained with reinforcement to pick a larger or smaller amount. During training, the bears were rewarded with food for a correct response. All bears performed better than what random error predicted on the trials with static, non-moving dots, indicating that they could differentiate between the two quantities. The bears choosing correctly in congruent (number of dots coincided with area of the dots) and incongruent (number of dots did not coincide with area of the dots) trials suggests that they were indeed choosing between quantities that appeared on the screen, not just a larger or smaller retinal image, which would indicate they are only judging size.[95]
Bottlenose dolphins have shown the ability to choose an array with fewer dots compared to one with more dots. Experimenters set up two boards showing various numbers of dots in a poolside setup. The dolphins were initially trained to choose the board with the fewer number of dots. This was done by rewarding the dolphin when it chose the board with the fewer number of dots. In the experimental trials, two boards were set up, and the dolphin would emerge from the water and point to one board. The dolphins chose the arrays with fewer dots at a rate much larger than chance, indicating they can differentiate between quantities.[96] A particular grey parrot, after training, has shown the ability to differentiate between the numbers zero through six using vocalizations. After number and vocalization training, this was done by asking the parrot how many objects there were in a display. The parrot was able to identify the correct amount at a rate higher than chance.[97] Angelfish, when put in an unfamiliar environment will group together with conspecifics, an action named shoaling. Given the choice between two groups of differing size, the angelfish will choose the larger of the two groups. This can be seen with a discrimination ratio of 2:1 or greater, such that, as long as one group has at least twice the fish as another group, it will join the larger one.[98]
Monitor lizards have been shown to be capable of numeracy, and some species can distinguish among numbers up to six.[99]
Biological constraints

Instinctive tendencies should be considered during interpretation of results from experiments on animal cognition. For example, dogs and rats easily learn to avoid an electric shock from the floor by moving to another part of the experimental chamber when they hear a tone preceding the shock. However, hedgehogs fail to learn this avoidance behavior. Whilst this might seem to show an inability to learn, the hedgehog's instinctive reaction to a threat is to curl up into a ball, a response that interferes with possible escape behavior in this situation.
Instinctive drift is another biological constraint that can influence interpretation of animal cognition studies. Instinctive drift is the tendency of an animal to revert to instinctive behaviors that can interfere with learned responses. The concept originated with Keller and Marian Breland when they taught a raccoon to put coins into a box. The raccoon drifted to its instinctive behavior of rubbing the coins with its paws, as it would do when forging for food.[100]
Cognitive faculty by species
A common image is the scala naturae, the ladder of nature on which animals of different species occupy successively higher rungs, with humans typically at the top.[101]
A more fruitful approach has been to recognize that different animals may have different kinds of cognitive processes, which are better understood in terms of the ways in which they are cognitively adapted to their different ecological niches, than by positing any kind of hierarchy. (See Shettleworth (1998), Reznikova (2007).)
One question that can be asked coherently is how far different species are intelligent in the same ways as humans are, i.e., are their cognitive processes similar to ours. Not surprisingly, our closest biological relatives, the great apes, tend to do best on such an assessment. Among the birds, corvids and parrots have typically been found to perform well. Octopodes have also been shown to exhibit a number of higher-level skills such as tool use,[102] but the amount of research on cephalopod intelligence is still limited.[senza fonte]
Baboons have been shown to be capable of recognizing words.[103][104][105]
See also
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- ^ Baboons can learn to recognize words; Monkeys' ability suggests that reading taps into general systems of pattern recognition 12 April 2012 Nature
- ^ Baboons can recognize written words, study finds; The monkeys don't assign meaning to them, but learn what letter combinations are common to real words, the study authors say April 12, 2012 Los Angeles Times
- ^ Baboons show their word skills; Reading may stem from a visual aptitude shared by all primates May 5, 2012
Further reading
- Brown, M.F., & Cook, R.G. (Eds.). (2006). Animal Spatial Cognition: Comparative, Neural, and Computational Approaches. [On-line]. Available: www.pigeon.psy.tufts.edu/asc/
- Goodall, J. (1991). Through a window. London: Penguin.
- Griffin, D. R. (1992). Animal minds. Chicago: University of Chicago Press.
- Hilgard, E. R. (1958). Theories of learning, 2nd edn. London: Methuen.
- Neisser, U. (1967). Cognitive psychology. New York, Appleton-Century-Crofts.
- Romanes, G. J. (1886). Animal intelligence, 4th edn. London: Kegan Paul, Trench.
- Shettleworth, S. J. (1998) (2010,2nd ed). Cognition, evolution and behavior. New York: Oxford University Press.
- Skinner, B. F. (1969). Contingencies of reinforcement: a theoretical analysis. New York: Appleton-Century-Crofts.
- Narby, Jeremy. (2005) Intelligence In Nature. New York: Penguin.
- Lurz, Robert W. (2009) Mindreading Animals: The Debate over What Animals Know about Other Minds. The MIT Press.
External links
- The limits of intelligence Douglas Fox, Scientific American, 14 June 2011.
- Template:Sep entry
- Template:Sep entry
- Animal Cognition Network
- Template:IEP
- Center for Avian Cognition University of Nebraska (Alan Kamil, Alan Bond)
Template:Animal cognition Template:Animal communication Template:Great ape language
Gastric acid is a digestive fluid, formed in the stomach. It has a pH of 1-2 and is composed of hydrochloric acid (HCl) (around 0.5%, or 5000 parts per million) as high as 0.1 M,[1] potassium chloride (KCl) and sodium chloride (NaCl). The acid plays a key role in digestion of proteins, by activating digestive enzymes, and making ingested proteins unravel so that digestive enzymes break down the long chains of amino acids.
Gastric acid is produced by cells lining the stomach, which are coupled to systems to increase acid production when needed. Other cells in the stomach produce bicarbonate, a base, to buffer the fluid, ensuring that it does not become too acidic. These cells also produce mucus, which forms a viscous physical barrier to prevent gastric acid from damaging the stomach. Cells in the beginning of the small intestine, or duodenum, further produce large amounts of bicarbonate to completely neutralize any gastric acid that passes further down into the digestive tract.
Gastric acid is produced by parietal cells (also called oxyntic cells) in the stomach. Its secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the gastric acid is secreted into the lumen of the stomach. These cells are part of epithelial fundic glands in the gastric mucosa. The pH of gastric acid is 1.5 to 3.5 [2] in the human stomach lumen, the acidity being maintained by the proton pump H+/K+ ATPase. The parietal cell releases bicarbonate into the blood stream in the process, which causes a temporary rise of pH in the blood, known as alkaline tide.
The resulting highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein's peptide bonds. The chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen and rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis. In addition, many microorganisms have their growth inhibited by such an acidic environment, which is helpful to prevent infection.
Secretion
Gastric acid secretion happens in several steps. Chloride and hydrogen ions are secreted separately from the cytoplasm of parietal cells and mixed in the canaliculi. Gastric acid is then secreted into the lumen of the oxyntic gland and gradually reaches the main stomach lumen. The exact manner in which the secreted acid reaches the stomach lumen is controversial, as acid must first cross the relatively pH neutral gastric mucus layer.
Chloride and sodium ions are secreted actively from the cytoplasm of the parietal cell into the lumen of the canaliculus. This creates a negative potential of -40 mV to -70 mV across the parietal cell membrane that causes potassium ions and a small number of sodium ions to diffuse from the cytoplasm into the parietal cell canaliculi.
The enzyme carbonic anhydrase catalyses the reaction between carbon dioxide and water to form carbonic acid. This acid immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ions leave the cell through H+/K+ ATPase antiporter pumps.
At the same time sodium ions are actively reabsorbed. This means that the majority of secreted K+ and Na+ ions return to the cytoplasm. In the canaliculus, secreted hydrogen and chloride ions mix and are secreted into the lumen of the oxyntic gland.
The highest concentration that gastric acid reaches in the stomach is 160 mM in the canaliculi. This is about 3 million times that of arterial blood, but almost exactly isotonic with other bodily fluids. The lowest pH of the secreted acid is 0.8,[3] but the acid is diluted in the stomach lumen to a pH between 1 and 3.
There is a small continuous basal secretion of gastric acid between meals of usually less than 10 mEq/hour.[4]
There are three phases in the secretion of gastric acid which increase the secretion rate in order to digest a meal:
- The cephalic phase: Thirty percent of the total gastric acid secretions to be produced is stimulated by anticipation of eating and the smell or taste of food. This signalling occurs from higher centres in the brain through the Vagus Nerve. It activates parietal cells to release acid and ECL cells to release histamine. The Vagus nerve also releases Gastrin Releasing Peptide onto G cells. Finally, it also inhibits somatostatin release from D cells.[5]
- The gastric phase: About fifty percent of the total acid for a meal is secreted in this phase. Acid secretion is stimulated by distension of the stomach and by amino acids present in the food.
- The intestinal phase: The remaining 10% of acid is secreted when chyme enters the small intestine, and is stimulated by small intestine distension and by amino acids. The duodenal cells release entero-oxyntin which acts on parietal cells without affecting gastrin.[5]
Regulation of secretion

Gastric acid production is regulated by both the autonomic nervous system and several hormones. The parasympathetic nervous system, via the vagus nerve, and the hormone gastrin stimulate the parietal cell to produce gastric acid, both directly acting on parietal cells and indirectly, through the stimulation of the secretion of the hormone histamine from enterochromaffine-like cells (ECL). Vasoactive intestinal peptide, cholecystokinin, and secretin all inhibit production.
The production of gastric acid in the stomach is tightly regulated by positive regulators and negative feedback mechanisms. Four types of cells are involved in this process: parietal cells, G cells, D cells and enterochromaffine-like cells. Besides this, the endings of the vagus nerve (CN X) and the intramural nervous plexus in the digestive tract influence the secretion significantly.
Nerve endings in the stomach secrete two stimulatory neurotransmitters: acetylcholine and gastrin-releasing peptide. Their action is both direct on parietal cells and mediated through the secretion of gastrin from G cells and histamine from enterochromaffine-like cells. Gastrin acts on parietal cells directly and indirectly too, by stimulating the release of histamine.
The release of histamine is the most important positive regulation mechanism of the secretion of gastric acid in the stomach. Its release is stimulated by gastrin and acetylcholine and inhibited by somatostatin.
Neutralization
In the duodenum, gastric acid is neutralized by sodium bicarbonate. This also blocks gastric enzymes that have their optima in the acid range of pH. The secretion of sodium bicarbonate from the pancreas is stimulated by secretin. This polypeptide hormone gets activated and secreted from so-called S cells in the mucosa of the duodenum and jejunum when the pH in duodenum falls below 4.5 to 5.0. The neutralization is described by the equation:
- HCl + NaHCO3 → NaCl + H2CO3
The carbonic acid rapidly equilibrates with carbon dioxide and water through catalysis by carbonic anhydrase enzymes bound to the gut epithelial lining,[6] leading to a net release of carbon dioxide gas within the lumen associated with neutralisation. In the absorptive upper intestine, such as the duodenum, both the dissolved carbon dioxide and carbonic acid will tend to equilibrate with the blood, leading to most of the gas produced on neutralisation being exhaled through the lungs.
Role in disease
In hypochlorhydria and achlorhydria, there is low or no gastric acid in the stomach, potentially leading to problems as the disinfectant properties of the gastric lumen are decreased. In such conditions, there is greater risk of infections of the digestive tract (such as infection with Vibrio or Helicobacter bacteria).
In Zollinger–Ellison syndrome and hypercalcemia, there are increased gastrin levels, leading to excess gastric acid production, which can cause gastric ulcers.
In diseases featuring excess vomiting, patients develop hypochloremic metabolic alkalosis (decreased blood acidity by H+ and chlorine depletion).
Pharmacology
The proton pump enzyme is the target of proton pump inhibitors, used to increase gastric pH (and hence decrease stomach acidity) in diseases that feature excess acid. H2 antagonists indirectly decrease gastric acid production. Antacids neutralize existing acid.
History
The role of gastric acid in digestion was established in the 1820s and 1830s by William Beaumont on Alexis St. Martin, who, as a result of an accident, had a fistula (hole) in his stomach, which allowed Beaumont to observe the process of digestion and to extract gastric acid, verifying that acid played a crucial role in digestion.[7]
See also
- Stomach
- Digestion
- Gastroesophageal reflux disease
- Discovery and development of proton pump inhibitors
- Acidic Mouth
Notes
- ^ http://www.acidbase.org/index.php?show=sb&action=explode&id=31&sid=42
- ^ Marieb EN, Hoehn K, Human anatomy & physiology, San Francisco, Benjamin Cummings, 2010, ISBN 0-8053-9591-1.
- ^ Arthur C. Guyton, John E. Hall, Textbook of Medical Physiology, 11ª ed., Philadelphia, Elsevier Saunders, 2006, p. 797, ISBN 0-7216-0240-1.
- ^ Page 192 in: Elizabeth D Agabegi; Agabegi, Steven S., Step-Up to Medicine (Step-Up Series), Hagerstwon, MD, Lippincott Williams & Wilkins, 2008, ISBN 0-7817-7153-6.
- ^ a b Lecture, "Function of the Stomach and Small Intestine" Deakin University School of Medicine - October 15, 2012
- ^ PMID 2506730
- ^ R. Harré, Great Scientific Experiments, Phaidon (Oxford), 1981, pp. 39–47, ISBN 0-7148-2096-2.
External links
- The Parietal Cell: Mechanism of Acid Secretion at vivo.colostate.edu
- First Principles of Gastroenterology. Chapter 6. Salena B. J., Hunt R. H. The Stomach and Duodenum
Comparazioni con la neurobiologia
Il sistema sensoriale e di risposta di una pianta è stato comparato con i processi neurobiologici degli Animali. La neurobiologia delle piante riguarda soprattutto il comportamento adattativo sensoriale dell'elettrofisiologia di piante e vegetali. Lo scienziato indiano J. C. Bose è accreditato come la prima persona ad aver parlato di neurobiologia delle piante. Molti scienziati dei vegetali e neuroscienziati, tuttavia, ritengono che questo termine sia inesatto, in quanto le piante non hanno neuroni.[1]
Le idee dietro la neurobiologia vegetale sono state criticate in un articolo del 2007[1] pubblicato in Trends in Plant Science da Amedeo Alpi e 35 altri scienziati, comprendenti eminenti biologi delle piante come Gerd Jürgens, Ben Scheres, e Chris Sommerville. L'ampiezza dei campi della scienza delle piante rappresentata da questi ricercatori riflette il fatto che la stragrande maggioranza della comunità scientifica di ricerca sulle piante rifiuta la neurobiologia vegetale. I loro argomenti principali sono[1]:
- "La neurobiologia vegetale non aggiunge nulla alla nostra comprensione della fisiologia vegetale, della biologia cellulare vegetale o della segnalazione".
- "Nelle piante non c'è evidenza di strutture assimilabili a neuroni, sinapsi o cervelli".
- Il verificarsi comune di plasmodesmata nelle piante, che "pone un problema per la segnalazione da un punto di vista elettrofisiologico" dato l'ampio accoppiamento elettrico precluderebbe la necessità di qualsiasi trasporto cellula-cellula di composti simili a neurotrasmettitori.
Se il concetto di "neurobiologia delle piante" è a beneficio della comunità di ricerca gli autori chiedono la fine di "analogie superficiali e estrapolazioni discutibili".[1]
Ci sono state diverse risposte alla critica per chiarire che il termine "neurobiologia vegetale" è una metafora e che le metafore si sono rivelate utili in diverse occasioni.[2][3]
Viene detta intelligenza la capacità cognitiva che permette ad un soggetto (individuo o animale) di comprendere l'ambiente e la propria interiorità, di adattarsi e di fronteggiare con successo nuove situazioni. In altre parole l'intelligenza è la capacità psichica e mentale che permette - sulla base di informazioni e di ricordi già posseduti - di formulare autonomamente le informazioni e le idee necessarie per raggiungere i propri obiettivi (i quali non dovranno essere necessariamente consci o esplicitati) o prevenire/evitare il verificarsi di situazioni future negative, quando le informazioni e le idee in questione sono nuove per il soggetto.
Attualmente non vi sono definizioni accademiche, ovvero prodotte dalla comunità dei ricercatori, di intelligenza che godano dell'accordo universale della comunità scientifica stessa. Tra i molti enunciati proposti si segnala quello riportato in una dichiarazione editoriale del 1994 firmata da cinquantadue ricercatori, Mainstream Science on Intelligence:
L'intelligenza è l'insieme di tutte le funzioni psichiche/mentali che permettono ad un soggetto (individuo o animale) di capire cose ed eventi, scoprendo le relazioni che intercorrono tra di essi ed arrivando ad una conoscenza concettuale e razionale (ovvero non percettiva o intuitiva). Essa si percepisce nella capacità di comprendere, adattarsi e fronteggiare con successo nuove situazioni e può dunque essere concepita come una capacità di adattamento all'ambiente.
In particolare, l'intelligenza permette di rilevare o cogliere relazioni problematiche, contrasti e di risolvere autonomamente i problemi nuovi (effettivi, potenziali); comporta inoltre la capacità di prevedere e scongiurare il verificarsi di situazioni future negative, o di evitarlo (non necessariamente in maniera conscia), per merito delle proprie elaborazioni di informazioni, ricordi e/o dati percettivi, invece che unicamente per merito di un richiamo/riapplicazione automatico/a di informazioni o comportamenti pregressi.
L'Uomo è dotato di intelligenza concettuale: la comprensione per Homo Sapiens passa attraverso l'uso dei concetti, ovvero di parole a cui associare dei significati. La capacità di linguaggio è dunque un aspetto fondamentale dell'intelligenza umana, che permette tra l'altro il ragionamento complesso e astratto.[4]
Comportamenti assimilabili a quelli indotti dall'intelligenza animale sono riscontrabili anche nelle piante, mentre i settori di ricerca legati al campo dell'intelligenza artificiale tentano di creare delle macchine in grado di riprodurre tali comportamenti.
La varietà dei comportamenti umani e animali cosiddetti "intelligenti" è estremamente ampia; ciò rende problematico il raggiungimento di una definizione accademica di intelligenza che risulti sintetica, onnicomprensiva e al contempo universalmente condivisa. Si riscontra pertanto all'interno della comunità scientifica degli psicologi una diversità di definizioni, ciascuna delle quali risente dell'orientamento di pensiero di chi l'ha formulata.
La varietà dei comportamenti umani e animali "intelligenti" è estremamente ampia; ciò, rende problematico il raggiungimento di una definizione accademica di intelligenza che risulti al contempo sintetica, onnicomprensiva e universalmente condivisa. Si riscontrano pertanto all'interno della comunità scientifica degli psicologi definizioni diverse, ciascuna delle quali risentente dell'orientamento di pensiero di chi l'ha formulata.
La varietà dei comportamenti umani e animali "intelligenti" è estremamente ampia; ciò, rende problematico il raggiungimento di una definizione accademica di intelligenza che possa essere sintetica, onnicomprensiva e al contempo universalmente condivisa. All'interno della comunità scientifica degli psicologi vi è pertanto una pluralità di definizioni.
La definizione di intelligenza è in realtà controversa: la varietà delle manifestazioni comportamentali umane e animali ad essa associabili è difatti estremamente ampia, rendendo problematico il raggiungimento di una definizione di intelligenza che risulti sintetica, completa, universalmente condivisa dalla comunità scientifica in primo luogo.
Le definizioni date sono pertanto plurime, dipendenti dall'orientamento di pensiero di chi le ha formulate. Tra le più importanti si segnala quella fornita in una dichiarazione editoriale del 1994, Mainstream Science on Intelligence, firmato da cinquantadue ricercatori:
Una definizione di intelligenza dotata delle qualità di sintesi, completezza e condivisione universale da parte della comunità scientifica è in verità ancora lontana dall'essere raggiungibile: la varietà delle manifestazioni comportamentali umane e animali associabili all'intelligenza è infatti estremamente ampia, dando adito, piuttosto, ad una pluralità di definizioni anche in seno accademico.
Tra i molti enunciati forniti, si segnala per importanza quello pubblicato su Mainstream Science on Intelligence, una dichiarazione editoriale del 1994 firmata da cinquantadue ricercatori:
Il raggiungimento di una definizione di intelligenza singola e universalmente condivisa dalla comunità scientifica è da sempre questione estremamente complessa: l'intelligenza si manifesta in una varietà pressoché infinita di aspetti e comportamenti umani e animali, varietà che risulta ardua da sintetizzare in un enunciato breve e al contempo rigoroso.
Le proposte di definizione per l'intelligenza sono pertanto molteplici. Tra esse si segnala quella riportata su Mainstream Science on Intelligence, una dichiarazione editoriale firmata da cinquantadue ricercatori:
«[Dicesi intelligenza] Una generale funzione mentale che, tra l'altro, comporta la capacità di ragionare, pianificare, risolvere problemi, pensare in maniera astratta, comprendere idee complesse, apprendere rapidamente e apprendere dall'esperienza. Non riguarda solo l'apprendimento dai libri, un'abilità accademica limitata, o l'astuzia nei test. Piuttosto, riflette una capacità più ampia e profonda di capire ciò che ci circonda – "afferrare" le cose, attribuirgli un significato, o "scoprire" il da farsi.»
Altre definizioni comprendono: "la capacità o disposizione ad utilizzare in modo adeguato allo scopo tutti gli elementi del pensiero necessari per riconoscere, impostare e risolvere nuovi problemi" (William L. Stern)[6]; "la capacità generale di adattare il proprio pensiero e condotta di fronte a condizioni e situazioni nuove" (Daniel N. Stern)[7]; "... l'anticipazione utile [...] si misura a posteriori dal grado di soddisfazione raggiunto dal soggetto".
A partire dal diffondersi di strumenti validi e attendibili per la misura dell'intelligenza, si è successivamente focalizzata l'attenzione sulle differenze individuali legate alla funzione intellettiva. L'intelligenza infatti è stato un significativo campo di discussione tra coloro che ne identificano le cause all'aspetto genetico e coloro che invece assegnano una maggiore importanza ai fattori ambientali. Alcuni studi mostrano come la presenza di alcune patologie psichiatriche, come la depressione, influisca sulla performance al test d'intelligenza WAIS-R: più è severa la patologia più la performance al test è deficitaria.[8] Il che non significa che chi soffre di depressione è meno intelligente di un soggetto non affetto, ma ci suggerisce che, durante l'episodio depressivo, le performance ai test d'intelligenza sono altamente inficiate.
Gli studi differenziali sull'intelligenza evidenziano una forte correlazione tra QI (quoziente intellettivo) di gemelli monovulari. Si evidenzia inoltre una fortissima incidenza dei fattori ambientali sullo sviluppo delle capacità cognitive (si pensi agli studi portati avanti sulla differenza di intelligenza tra bianchi e neri, ricondotti non a differenze cognitive, ma piuttosto al fattore interveniente del livello socio-demografico). La psicologia risolve la dialettica tra componenti innate e ambientali nello sviluppo dell'intelligenza evidenziando come la componente genetica sembra rappresentare una disponibilità, mentre la componente educativa rappresenta un fattore di innesco per tradurre un potenziale in una funzionalità effettiva. Per quanto riguarda l'avanzare dell'età, il rendimento su alcune scale del WAIS tende a diminuire, mentre su altre rimane stabile o aumenta. Riprendendo la distinzione proposta da Raymond Cattell tra intelligenza fluida e cristallizzata, caratteristiche legate all'intelligenza fluida (acquisizione di nuovi stimoli e autocorrezione) tendono a diminuire dopo i 60 anni, mentre l'intelligenza cristallizzata (uso ottimale del proprio patrimonio di strategie, conoscenze, competenze) aumenta in maniera costante per tutta la vita.
Con il termine intelligenza si fa riferimento all'insieme di tutte le funzioni psichiche/mentali che permettono ad un soggetto (individuo o animale) di capire cose ed eventi, scoprendo le relazioni che intercorrono tra di essi ed arrivando ad una conoscenza concettuale e razionale (ovvero non percettiva o intuitiva).
Essa si percepisce nella capacità di comprendere, adattarsi e fronteggiare con successo nuove situazioni e può dunque essere concepita come una capacità di adattamento all'ambiente. L'intelligenza permette in particolare di rilevare o cogliere relazioni problematiche e contrasti, di identificare i problemi nuovi, di risolverli autonomamente, e di risolverli nel modo più appropriato alle situazioni in cui sono immersi. Comporta inoltre la capacità del soggetto di prevedere e scongiurare, o di evitare (non necessariamente in maniera conscia), il verificarsi di situazioni future negative per merito delle proprie elaborazioni di informazioni, ricordi e/o dati percettivi (ovvero, non unicamente per merito di un/una richiamo/riapplicazione automatico/a di informazioni o comportamenti pregressi).
Comportamenti assimilabili a quelli indotti dall'intelligenza animale sono riscontrabili anche nelle piante, mentre i settori di ricerca legati al campo dell'intelligenza artificiale tentano di creare delle macchine in grado di produrre anch'esse comportamenti intelligenti.
== Etimologia ==
La parola intelligenza deriva dal sostantivo latino intelligenzĭa, a sua volta derivante dal verbo intelligĕre, "capire". La genesi di intelligĕre è incerta: secondo alcuni, sarebbe una contrazione del verbo legĕre (= "scegliere", "leggere") con l'avverbio intus (= "dentro"), mentre secondo altri lo sarebbe con l'avverbio inter (= "tra"). Nel primo caso, il termine latino significherebbe "leggere-dentro", suggerendo una capacità di "leggere oltre la superficie", di comprendere davvero, comprendere le reali intenzioni. Nel secondo, intelligĕre starebbe per "leggere-tra", suggerendo forse una capacità di "leggere tra le righe", di stabilire delle correlazioni tra elementi.
== Definizioni accademiche ==
La comunità scientifica non ha ad oggi raggiunto un accordo universale su una definizione universitaria unica e condivisa di intelligenza. Tra le molte definizioni proposte dai ricercatori si segnala quella riportata su Mainstream Science on Intelligence, una dichiarazione editoriale del 1994 firmata da cinquantadue di essi:
«[Dicesi intelligenza] Una generale funzione mentale che, tra l'altro, comporta la capacità di ragionare, pianificare, risolvere problemi, pensare in maniera astratta, comprendere idee complesse, apprendere rapidamente e apprendere dall'esperienza. Non riguarda solo l'apprendimento dai libri, un'abilità accademica limitata, o l'astuzia nei test. Piuttosto, riflette una capacità più ampia e profonda di capire ciò che ci circonda – "afferrare" le cose, attribuirgli un significato, o "scoprire" il da farsi.»
Altre definizioni date sono: "la capacità o disposizione ad utilizzare in modo adeguato allo scopo tutti gli elementi del pensiero necessari per riconoscere, impostare e risolvere nuovi problemi" (William L. Stern)[9]; "la capacità generale di adattare il proprio pensiero e condotta di fronte a condizioni e situazioni nuove" (Daniel N. Stern)[10]; "... l'anticipazione utile [...] si misura a posteriori dal grado di soddisfazione raggiunto dal soggetto".
Una definizione di intelligenza che risulti universalmente condivisibile dalla comunità scientifica, è difficile da raggiungere per via della varietà amplissima e dunque difficilmente sintetizzabile di manifestazioni comportamentali umane e animali in cui l'intelligenza si manifesta. Tra le numerose definizioni proposte si segnala quella pubblicata su una dichiarazione editoriale del 1994 firmata da cinquantadue ricercatori, Mainstream Science on Intelligence:
«[Dicesi intelligenza] Una generale funzione mentale che, tra l'altro, comporta la capacità di ragionare, pianificare, risolvere problemi, pensare in maniera astratta, comprendere idee complesse, apprendere rapidamente e apprendere dall'esperienza. Non riguarda solo l'apprendimento dai libri, un'abilità accademica limitata, o l'astuzia nei test. Piuttosto, riflette una capacità più ampia e profonda di capire ciò che ci circonda – "afferrare" le cose, attribuirgli un significato, o "scoprire" il da farsi.»
Altre definizioni comprendono: "la capacità o disposizione ad utilizzare in modo adeguato allo scopo tutti gli elementi del pensiero necessari per riconoscere, impostare e risolvere nuovi problemi" (William L. Stern)[11]; "la capacità generale di adattare il proprio pensiero e condotta di fronte a condizioni e situazioni nuove" (Daniel N. Stern)[12]; "... l'anticipazione utile [...] si misura a posteriori dal grado di soddisfazione raggiunto dal soggetto".
L'intelligenza è l'insieme di tutte le funzioni psichiche/mentali che permettono ad un soggetto (individuo o animale) di capire cose ed eventi, scoprendo le relazioni che intercorrono tra di essi ed arrivando ad una conoscenza concettuale e razionale (ovvero non percettiva o intuitiva). Essa si percepisce nella capacità di comprendere, adattarsi e fronteggiare con successo nuove situazioni e può dunque essere concepita come una capacità di adattamento all'ambiente. In particolare, l'intelligenza permette di rilevare o cogliere relazioni problematiche e contrasti, di identificare i problemi nuovi, di risolverli autonomamente e di risolverli nel modo più appropriato alle situazioni in cui sono immersi; da essa consegue inoltre la capacità di un soggetto di prevedere e scongiurare, o evitare (non necessariamente in maniera conscia), il verificarsi di situazioni future negative, per merito delle proprie elaborazioni di informazioni, ricordi e/o dati percettivi (ovvero, non unicamente per merito di un/una richiamo/riapplicazione automatico/a di informazioni o comportamenti pregressi).
Le piante presentano comportamenti che sono assimilabili a quelli indotti dall'intelligenza animale; i settori di ricerca legati al campo dell'intelligenza artificiale tentano di creare delle macchine in grado di produrre anch'esse comportamenti intelligenti.
Lintelligenza è l'insieme di tutte le funzioni e facoltà psichiche/mentali che permettono ad un soggetto (individuo o animale) di avere un rapporto ottimale con l'ambiente, ovvero di essere o di divenire adattato ad esso.
L'intelligenza si percepisce nella capacità di capire, scoprendo le relazioni intercorrenti tra elementi ed arrivando ad una conoscenza concettuale e razionale (ovvero non percettiva o intuitiva), consente di rilevare o cogliere relazioni problematiche e contrasti, di risolvere autonomamente i problemi nuovi e di risolverli nel modo più appropriato alle situazioni in cui sono immersi, e in base al suo grado di evoluzione può esprimersi anche nelle capacità di ragionare, di pensare in maniera astratta, di pianificare, di generare la previsione e prevenzione, o evitamento (non necessariamente conscio), del verificarsi di situazioni future negative sulla base di proprie elaborazioni di informazioni, ricordi e/o dati percettivi, piuttosto che unicamente tramite richiami/riapplicazioni automatici/automatiche di informazioni o comportamenti pregressi.
Si è riscontrato che anche le piante presentano comportamenti che sono assimilabili ad alcuni di quelli indotti dall'intelligenza animale, mentre i settori di ricerca legati al campo dell'intelligenza artificiale tentano di creare delle macchine in grado di produrre anch'esse comportamenti intelligenti.
L'intelligenza è in generale definibile come la capacità, caratterizzante individui e specie, e riconducibile unicamente a delle facoltà mentali, di adattarsi all'ambiente.
La locuzione "adattarsi all'ambiente" è intesa in un senso ben preciso e peculiare: data una certa situazione, e un determinato insieme di circostanze esterne ed interiori, un individuo può reagire alle stesse in uno qualunque tra una varietà pressoché infinita di modi diversi (un esempio banale: se si è avuto un litigio con qualcuno a cui si tiene, per far finire le proprie sofferenze si può decidere di parlare con la persona amata per sistemare le cose ma anche, eventualmente, di buttarsi giù da un ponte). Il soggetto riconosciuto come più intelligente è quello che, mediante la sua peculiare risposta, meglio riesce nell'assicurare, nel presente e nel futuro, l'ottenimento e/o il mantenimento della propria sussistenza, del proprio equilibrio (biologico e mentale), della propria soddisfazione, in maniera diversa concordemente con la propria scala di priorità. Si parla quindi di "adattamento all'ambiente" come adozione (da parte di un soggetto) di comportamenti in primo luogo psichici/mentali, e conseguentemente fisici, comunicativi, operativi favorevoli nei propri confronti, in interazione con l'ambiente, ma anche in risposta al proprio stato interiore, alle proprie esigenze e ai propri desideri.
L'intelligenza quale è stata definita necessita delle capacità di comprensione della realtà, delle idee e del linguaggio, di ragionamento, di apprendimento, di apprendimento dall'esperienza, di pianificazione e di problem solving, al punto che in prima approssimazione (adottando un punto di vista cosiddetto "ingenuo") essa è identificabile con la capacità di esercitare le facoltà citate, in tutti gli ambiti e i campi conoscibili dal soggetto che sta esercitando l'intelligenza secondo le teorie che riconoscono un'intelligenza "unica", o di volta in volta in taluni ambiti specifici (come quello pratico, quello linguistico, quello sociale, quello logico-matematico...) secondo il costrutto delle intelligenze multiple.
Le capacità citate di comprensione ecc. sono quelle che vengono comunemente prese in considerazione nei test sull'intelligenza, sebbene con tutte le limitazioni del caso.
In ambito tecnico-accademico il termine "intelligenza" viene usato nel suo senso più intuitivo associandolo però a dei termini dal significato invece tecnico per designare varie facoltà che sottintendono (o sottinderebbero) all'esercizio dell'intelligenza vera e propria quale la si è definita.
L'intelligenza è l'insieme di tutte le funzioni e facoltà psichiche/mentali che permettono ad un soggetto (individuo o animale) di capire cose ed eventi, scoprendo le relazioni che intercorrono tra di essi ed arrivando ad una conoscenza concettuale e razionale (ovvero non percettiva o intuitiva).
Essa si percepisce nella capacità di comprendere, adattarsi e fronteggiare con successo nuove situazioni e può dunque essere concepita come una capacità di adattamento all'ambiente. In particolare, l'intelligenza permette di rilevare o cogliere relazioni problematiche e contrasti tra elementi, di identificare i problemi nuovi, di risolverli autonomamente e di risolverli nel modo più appropriato alle situazioni contingenti; comporta inoltre la capacità del soggetto di prevedere e scongiurare, o evitare (non necessariamente in maniera conscia) il verificarsi di situazioni future negative utilizzando le proprie elaborazioni di informazioni, ricordi e/o dati percettivi, andando così oltre l'uso di richiami o riapplicazioni automatici/automatiche di informazioni o comportamenti pregressi.
L'intelligenza come è stata definita e descritta è una caratteristica comune a esseri umani e animali. Comportamenti assimilabili ad alcuni di quelli generalmente ascrivibili all'intelligenza animale sono però riscontrabili anche nelle piante; alcuni studiosi credono perciò che si debba attribuire una forma di intelligenza anche ad alcuni membri del regno vegetale.
L'intelligenza artificiale è la capacità (attuale e parziale o teorica) di alcune macchine create dall'uomo (ad esempio computer e robot) di simulare l'intelligenza umana o animale.
Il concetto di intelligenza è un concetto che emerge, o è emerso nel corso della storia, per denotare ciò che "sta sotto" ad alcune classi di comportamenti umani, ovvero ad alcuni modi di comportarsi di individui specifici (si veda Etimologia). Con l'evolvere delle conoscenze scientifiche in primo luogo, e della filosofia e dell'etica in secondo, si è esteso l'utilizzo del concetto anche in riferimento a ciò che soggiace i comportamenti di altre specie animali, quelli di alcune macchine ipotetiche o reali (intelligenza artificiale), e, recentemente, quelli delle piante.
Il concetto di intelligenza è un concetto di utilizzo estremamente ampio, utilizzo difficile da sintetizzare in maniera rigorosa e al contempo sintetica; da ciò la pluralità delle definizioni di intelligenza esistenti (-->Definizioni). Nel caso di esseri umani e animali, si può asserire però che il concetto è afferente, e l'intelligenza soggiace a, tutte le attività del pensiero che implichino un "'lavorare' sulle informazioni che si possiede per 'andare oltre' ".[13] Esempi di queste attività possono essere "trarre delle conclusioni a partire da ciò che è noto, fare previsioni riguardo al futuro, esprimere un giudizio, risolvere un problema mai incontrato in precedenza, scoprire in una situazione aspetti prima non considerati, inventare qualcosa che non esiste ancora".[13] L'intelligenza umana e animale è allora una capacità, un insieme di facoltà psichiche e/o mentali, che permettono di compiere attività del pensiero come quelle menzionate, e di farlo bene[13].
In che senso è possibile estendere l'utilizzo del concetto di intelligenza anche in riferimento alle piante? è emerso che analizzando i comportamenti delle forme di vita principali del Regno vegetale sulle lunghe durate, essi sono spesso assimilabili ad alcuni di quelli tipicamente indotti dalla presenza di intelligenza animale. L'attribuzione di una forma di intelligenza anche alle piante è attualmente oggetto di dibattito all'interno della comunità scientifica (--> si veda sezione L'intelligenza nelle piante).
Si parla di intelligenza delle macchine, o intelligenza artificiale, quando esse, teoricamente o in pratica, sono in grado di imitare alcuni o tutti gli aspetti del pensiero intelligente umano o animale.
- ^ a b c d Plant neurobiology: no brain, no gain? Alpi A, Amrhein N, Bertl A, Blatt MR, Blumwald E, Cervone F, Dainty J, De Michelis MI, Epstein E, Galston AW, Goldsmith MH, Hawes C, Hell R, Hetherington A, Hofte H, Juergens G, Leaver CJ, Moroni A, Murphy A, Oparka K, Perata P, Quader H, Rausch T, Ritzenthaler C, Rivetta A, Robinson DG, Sanders D, Scheres B, Schumacher K, Sentenac H, Slayman CL, Soave C, Somerville C, Taiz L, Thiel G, Wagner R. (2007). Trends Plant Sci. Apr;12(4):135-6. PMID 17368081
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- ^ Sorgenti: ↑ : Dictionnaire Encyclopédique Alpha, dictionnaires Larousse et Robert. Pour le raisonnement, dictionnaire en ligne TLFI ↑ Prolégomènes, tome II, page 323 http://classiques.uqac.ca/classiques/Ibn_Khaldoun/Prolegomenes_t2/ibn_pro_II.pdf [archive] ↑ Jean Piaget, La Construction du Réel, 1936 ↑ A formal definition of intelligence based on an intensional variant of Kolmogorov complexity, Jose Hernandez-orallo, Proceedings of the International Symposium of Engineering of Intelligent Systems (EIS'98). ↑ Marcus Hutter, « A Theory of Universal Artificial Intelligence based on Algorithmic Complexity », dans cs/0004001, 2000-04-03 [texte intégral [archive] (page consultée le 2010-03-11)] ↑ (en) Marcus Hutter, Universal Artificial Intelligence: Sequential Decisions Based On Algorithmic Probability, Berlin, SpringerVerlag, 2005 (ISBN 978-3-540-22139-5) (LCCN 2004112980) [lire en ligne [archive] (page consultée le 2010-04-30)] ↑ R. J Solomonoff, « A Formal Theory of Inductive Inference. Part I », dans Information and Control, vol. 7, no 1, 1964, p. 1-22 ↑ J. Veness, « A Monte Carlo AIXI Approximation », dans Arxiv preprint arXiv:0909.0801, 2009 ↑ a et b Aljoscha Neubauer, Les mille facettes de l'intelligence, Pour la Science, Cerveau & psycho, n°1, page 49.
- ^ a b c Gottfredson, L.S., Foreword to "intelligence and social policy", in Intelligence,, volume 24, fascicolo 1, 1997, pp. pagine 1–12, DOI:10.1016/S0160-2896(97)90010-6. URL consultato il 18 marzo 2008.
- ^ Intelligenza
- ^ Psicologia e psicologi on line. Corsi di formazione, risorse gratuite e servizi per formare e promuovere la professione di psicologo
- ^ Mandelli Laura, Serretti Alessandro, Colombo Cristina, Marcello Florita, Alessia Santoro, David Rossini, Raffaella Zanardi, Enrico Smeraldi, (2006). "Improvement of cognitive functioning in mood disorder patients with depressive symptomatic recovery during treatment: an exploratory analysis". Psychiatry Clin. Neurosci. 60 (5): 598–604. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1440-1819.2006.01564.x
- ^ http://www.psicolife.com/index.php?option=com_content&view=article&id=188:intelligenza&catid=10009:saggie-e-articoli&Itemid=226
- ^ http://www.opsonline.it/printable-16916-intelligenza.html
- ^ Intelligenza
- ^ Psicologia e psicologi on line. Corsi di formazione, risorse gratuite e servizi per formare e promuovere la professione di psicologo
- ^ a b c Manuale di psicologia generale - Intelligenza e pensiero, pag. 215.