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Mental Imagery. Mental imagery : representation of nonpresent object or event that is subjectively experienced as the object or event itself. Note: visual imagery is just one form of mental imagery Three hypotheses:
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Mental Imagery Mental imagery: representation of nonpresent object or event that is subjectively experienced as the object or event itself. Note: visual imagery is just one form of mental imagery Three hypotheses: Dual code: (Allan Paivio) – info can be encoded into two possible system: verbal system or imagery system. Recall is best if represented in both rather than single system. Empirical evidence: Words high in imagery value (tornado) better recalled than words low in imagery value (reciprocal) Brooks study – selective interference – verbal task not affected if paired with spatial response; affected in paired with verbal response. *Important point – image systems seen as independent form of representation; but is this so?
Mental Imagery • Hypo 2: Conceptual/propositional hypo: all info is stored as conceptual/propositional information. When propositional info is especially elaborate it may be experienced as ‘image’ but this is illusion, does not reflect true nature of representation. • Pylyshyn’s arguments against imagery: • Pictures in head • Mind’s eye • Tacit knowledge • Epiphenomenalism: Images as ‘dependent’ on more basic form of representation • Empirical evidence • Mental rotation studies – shoes rotated more slowly than feathers? • Ambiguous figures: reversal as stimulus not as image
Image switching: perception vs. imagery • Subjects report image switching in perception, not imagery
Mental Imagery • Hypo 3: Functional equivalency – images formed in STM based on more basic (propositional) LTM representation, but posses independent features. • Kosslyn – mental scanning, mental image size studies; Shepard – mental rotation • Kosslyn – fMRI studies showing visual system/imagery system equivalency
Neuroscience of Imagery Important findings: • Same areas of brain important for imagery and visual perception: Occipital/temporal visual pathway • Damage to occip/temp visual pathway leads to visual not spatial deficits (case of LH) • Occipital parietal pathway important for spatial tasks – see below.
Mental imagery • Cognitive mapping: mental representation of spatial layout of navigatable space. • Combination of conceptual and imagery system • Route vs. Survey knowledge • Conceptual distortions of spatial representations (ex: which is farther west San Diego, CA or Reno, NV?)