1. 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?

2. 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

3. Image switching: perception vs. imagery
Subjects report image switching in perception, not imagery

4. 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

5. Mental rotation and mental scanning studies

6. 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.

7. Combination of conceptual and imagery system
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?)

8. Conceptual distortions of survey knowledge