Cognitive Processes PSY 334

1. Cognitive ProcessesPSY 334 Chapter 4 – Perception-Based Knowledge Representation

2. Dual-Code Theory • The mind operates upon internal representations of knowledge. • How is visual information (imagery) represented in memory? • Paivio’s Dual-Code Theory – memory is better if we encode information visually and verbally. • Separate representations are maintained for verbal and visual information.

3. Evidence for Dual Codes • Santa compared linear and spatial arrays of: • Three geometric objects • Three names of geometric objects • Subjects were asked whether the arrays contained the same objects or names. • Subjects were faster when shapes were in the same spatial arrangement but faster when words were linear.

4. Evidence From Brain Imaging • Subjects were asked to mentally rehearse: • A word jingle • Navigating their neighborhood • Increased blood flow occurred in different areas of the brain, depending upon the task. • The same brain areas were active as when actually speaking or seeing.

5. No Homunculus • Homunculus -- the idea that there are “pictures in the head” implies someone to look at those pictures. • Both images and percepts are represented topographically in the brain, but there is no homunculus to view them. • Kosslyn -- the same processes are used to view mental images and external percepts.

6. Mental Rotation • Shepard – two-dimensional and three-dimensional mental images are rotated in the same way as actual objects. • The more an object is rotated, the longer it takes to respond in a same/different task. • Georgopoulos et al. – measured neurons firing in monkey brains when moving a handle. • Intermediate cells fire showing rotation.

7. Image Scanning • Brooks – subjects scanned imagined diagrams (like letter F) and noted outside corners, or sentences noting nouns. • Respond by saying “yes” or “no” • Tap left hand for “yes,” right hand for “no” • Point to Y or N on a sheet • Scanning a sheet for Y’s & N’s conflicted with scanning the mental image. • Conflict is spatial not visual.

8. Comparing Visual Quantities • Time to make a judgment decreases as the difference in size between objects increases. • The smaller the difference the longer it takes to make a judgment. • Which is larger: • moose or roach, wolf or lion? • The same pattern emerges when asked to judge actual differences, line lengths.

9. Two Types of Imagery • Images involving visual properties (what) -- impaired with temporal damage. • Images involving spatial properties (where) – impaired with parietal damage. • Bilateral temporal lobe damage: • Difficulty judging color, size, shape. • No deficit in mental rotation, image or letter scanning, judgment of relative positions.

10. Are Images Like Perception? • A series of experiments to compare perception and imagery: • Imagining transformations of mental images vs perceived stimuli. • Ponzo illusions occurs with imagery. • Difficulty with reversible figures – depends on instructions, harder. • MRI plots show same brain activity.

11. Cognitive Maps • Two kinds of maps: • Route map – indicates places and turns, but not all landmarks. • Survey map – shows all relevant portions of space, not just route. • Adults produce survey maps, kids produce route maps. • Survey maps more versatile.

12. Map Distortions • Which is farther east: San Diego or Reno? • People make wrong guesses because they reason from the positions of the states, not cities. • Relative positions of larger areas are compared, not details – hierarchical chunking.

13. Translating Verbal Descriptions • Subjects were asked to read passages, rotate themselves and make judgments: • Fastest when making above-below judgments, slower with right-left. • Verbal directions (survey or route) are as good as using actual maps.

14. Remembering Serial Position • Serial position – what comes first and what comes later in a list. • Anchoring – first items are better remembered in sequences. • Hierarchical encoding helps serial recall: • Alphabet song

15. Hierarchical Encoding of Serial Order Information • Long sequences are remembered using hierarchical chunks, just as maps are: • Alphabet song • Spacing of letters separates them into subsequences (chunks).

16. Baddeley’s Working Memory • Imagery is accomplished in working memory. • Two parts correspond to dual-codes: • Visuospatial sketchpad – visual info • Phonological loop – verbal info • Central executive – coordinates the slave systems (sketchpad & loop)

17. Parts of the Phonological Loop • Articulatory loop – inner voice that rehearses verbal information • Activates Broca’s area of the brain • Phonological store – an inner ear that stores the inner voice and stores it in phonological form. • Activates parietal-temporal areas of brain