Auditory stimuli follow conventional levels-of-processing rules, although are somewhat weaker in general [[Recollection|recall]] value when compared with vision. Some studies suggest that auditory weakness is only present for [[explicit memory]] (direct recall), rather than [[implicit memory]].<ref>{{Cite journal|doi=10.3758/BF03210786 |volume=4 |issue=1 |pages=130–133 |last=Habib |first=R |author2=Nyberg L |title=Incidental retrieval processes influence explicit test performance with data-limited cues |journal=Psychonomic Bulletin & Review |year=1997 |url=http://www.psychonomic.org/search/view.cgi?id=821 |format=pdf |doi-access=free }}{{dead link|date=May 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> When test subjects are presented with auditory versus visual word cues, they only perform worse on directed recall of a spoken word versus a seen word, and perform about equally on implicit free-association tests. Within auditory stimuli, semantic analysis produces the highest levels of recall ability for stimuli. Experiments suggest that levels-of-processing on the auditory level is directly correlated with neural activation.<ref name = Fletcher>{{Cite journal | doi = 10.1093/brain/121.7.1239 | volume = 121 | issue = 7 | pages = 1239–1248 | last = Fletcher | first = PC |author2=Shallice T |author3=Dolan RJ | title = The functional roles of prefrontal cortex in episodic memory. I. Encoding | journal = Brain | year = 1998 | url = http://brain.oxfordjournals.org/cgi/reprint/121/7/1239 | format = pdf
}}{{dead link|date=May 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> In this study, subjects were presented with an object in both visual and tactile form (a subject is shown a sphere but cannot touch it, and later is given a similar sphere to only hold and not view). Subjects had more trouble identifying size difference in visual fields than using tactile feedback. A suggestion for the lower level of size processing in visual fields is that it results from the high variance in viewed object size due to perspective and distance.
