Feature integration theory: Difference between revisions

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According to Treisman, the first stage of the Feature Integration Theory is the preattentive stage. Perception occurs automatically, unconsciously, effortlessly, and early in the perceptual process. During this stage, the object is analyzed for details such as shape, color, orientation and movement, with each aspect being processed in different areas of the brain. The idea that features are automatically separated appears to be counterintuitive; however, we are not aware of this process because it occurs early in perceptual processing, before we become conscious of the object.

The second stage of the Feature Integration Theory is the focused attention stage, where the individual features of an object combine in order to perceive the whole object. In order to combine the individual features of an object, attention is required and selection of that object occurs within a "master map" of locations. The "master map" of locations contains all of the locations in which features have been detected, with each ___location in the "master map" having access to the multiple feature maps. When attention is focused at a particular ___location on the map, the features currently in that position are attended to and are stored in "object files". If the object is familiar, associations are made between the object and prior knowledge, inwhich orderresults toin aididentification inof recognitionthat object. In support of this stage, researchers often refer to patients suffering from [[Balint's syndrome]]. Due to damage in the parietal lobe, these people are unable to focus attention on individual objects. When given stimuli that requires combining features, sufferers from Balint's syndrome are unable to focus attention long enough to combine the features, providing support for this stage of the theory.

[[File:FITstages.png|alt=The stages of Feature Integration Theory.]]

It was widely speculated that the saliency map could be located in early visual cortical areas, e.g. the [[Primary Visual Cortex]] (V1), though this is controversial. Wolfe's popular Guided Search Model offers a more up to date theory of visual search but is also problematic.<ref>{{cite PMID|2527952}}</ref>

Treisman distinguishes between two kinds of visual search tasks, "feature search" and "conjunction search". Feature searches can be performed fast and pre-attentively for targets defined by only one primitive feature, such as color, shape, perceived direction of lighting, movement or orientation. ConjunctionFeatures searchesshould proceed"pop seriallyout" forduring targetssearch definedand byshould abe able to form illusory conjunctions. Conversely, conjunction (searches occur with the combination of two or more) offeatures primitiveand featuresare -identified itserially. Conjunction search is much slower than feature search and requires conscious attention. Sheand concludedeffort. fromIn manymultiple experiments, some listed in this article, Treisman concluded that [[color]], [[Orientation (geometry)|orientation]], and [[intensity (disambiguation)|intensity]] are primitive features, for which feature searches may be performed.

As a reaction to the Feature Integration Theory, Wolfe (1994) proposed the Guided Search Model 2.0. According to this model, attention is directed to an object or ___location through a preattentive process. The preattentive process, as Wolfe explains, directs attention in both a bottom-up and top-down way. Information acquired through both bottom-up and top-down processes is ranked according to priority, which ''guides'' visual search, as well as making the search more efficient. Whether the Guided Search Model or the Feature Integration Theory are "correct" is still a hotly debated topic.

==Experiments==