Cognitive Processes PSY 334 Chapter 4 PerceptionBased Knowledge

Cognitive Processes PSY 334 Chapter 4 – Perception-Based Knowledge Representation

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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