1 Chapter 8: Visual Imagery & Spatial Cognition Intro Memory Empirical Studies Interf MR Scan LTM Codes DCT Imagery & Spatial Cognition Rel Org Principles ImplEnc SpatEq Neuro Imaging Critique StruEq Prop PercEq TransEq IndDiff & Apps 2 Spatial Cognition Introduction Early History Imageless thought controversy during era of Introspection Behaviourism: minimized role of internal representations, including imagery (but Tolman s cognitive maps) Cognitive Era Debate about format of information in Semantic Memory Highly abstract, conceptual, and idea -like? Verbal and word-like? Concrete and object-like? Analogue representation? Most theories assume abstract concepts Object and Word representations in models are for convenience, rather than reflecting how storage is stored Much debate about need for imaginal representations No role in some models of Semantic Memory Imagery epiphenomenon in other models: i.e., cognitive event incidental to actual mechanisms and processes Imagery central in other models (e.g., Paivio s DCT) 3 Empirical Evidence Diverse tasks designed to determine whether mental representations have percept-like (i.e., imaginal) properties Word Concreteness & Imagery Effects Brooks: Selective Interference Mental Rotation Studies Mental Scanning Studies Image Generation and Property Studies Mental / Symbolic Comparisons Neuroscience and Mental Imagery Imagery in Animals? Individual Differences 4 Concreteness and Memory (see Ch. 6 LTM) Concrete words > Abstract words Pictures > Words Imagery instructions > No Imagery instructions Interactive imagery > Separate imagery Reports of spontaneous use of imagery (below) 5 Brooks: Selective Interference tasks (below) Pointing slower than Verbal Verbal slower for sentence task Slower if encoding & reporting formats same Segal & Fusella Detection of Visual or Auditory stimuli selectively interfered with by Visual or Auditory imagery 6 1
Mental Rotation Studies 7 General Paradigm Stimuli (e.g., block figures, letters) at different orientations Tasks may involve rotation: Same or Different, Name, Measure RT and relate to degree of rotation Representative Findings Shepard & Metzler (1971) (below +1) Cooper & Shepard (1973, 1975) (+2) Rotation of natural objects (+6) RT correlates with angle 8 Plane Depth Cooper & Shepard Stimulus Cue [delay] Test Stimulus Rotation RT decreases with increased delay 9 Other findings for Mental Rotation Rotation independent of complexity (below left) Mixed results for natural objects (below right) 10 Scanning Studies Scanning Objects (Kosslyn, 1973 F8.8 below left) Answer questions about objects starting at certain point e.g., focus on front of boat, asked Does boat have a motor? RT increases with distance between original focus and detail needed to answer question Scanning memorized maps (F8.9 below right) RT varied with distance between 7 locations (+1) 11 Kosslyn (1978) Results 12 2
Image Generation & Property Studies (Kosslyn, 1975) Do generated images have percept-like properties? Properties and Size of Image Larger images have more detail, produce faster RT 13 Mental Comparison Task Moyer (1973), Paivio (1975, 1976) Symbolic judgments about objects (e.g., which larger, ) Faster for pictures than words if symbolic comparison involves concrete dimensions RT varies with size discrepancy, faster for larger differences 14 15 Images not always accurate representations Distorted by heuristics (Tversky, F8.10 & below left) e.g., Reno thought to be east of San Diego Images do not show all same effects as objects Ambiguous figures failed to reverse when imaginal, but did when drawn (Chambers & Reisberg, 1985) Imagery & LTM Codes Explanations for concreteness effects in recall Concrete remembered better than Abstract Interactive images better than Separate images Dual Coding (+1, according to text) Memory best when we use both Verbal & Imaginal codes Concrete nouns better recalled because they allow both codes, Abstract words only Verbal Relational-Organizational Hypothesis Imagery produces more & richer associations between items Forming image of two items interacting better than two separate mental images But DCT also hypothesizes special redintegrative properties for interaction images 16 Paivio s Dual Coding 17 Principles of Visual Imagery (Finke) Implicit encoding: not intentional Brook s task: inner and outer edges of F () Perceptual equivalence: viewing mental image similar to looking at real object Perky (1910): images interfered with detection Farah (1985): imaging letter facilitated detection Spatial equivalence: images retain spatial relations Kerr (1983): scanning effects with blind participants Transformational equivalence: images can be rotated and transformed Mental rotation studies Structural equivalence: images retain structure of real object Time to generate image increases with complexity (F8.12 ) 18 3
Critiques Tasks create demand characteristics Experimenters may cue participants about how to behave (Experimenter Expectancy effects) Are mental images REALLY like pictures? Or are they something else? Propositional Mental images do not have distinct memory code All forms of information represented as abstract propositions (units of meaning) Name Effects Labels on pictures can cause them to be represented, and later redrawn, in very different ways (+1) Real pictures couldn t be modified by labels (??) 19 Names affect image retrieved from memory Pictures in centre shown with labels to left or right Reproductions changed in direction of labelled objects Poor memory for familiar images (+1) Coins, Logos, 20 21 People s mental images for familiar stimuli often imperfect, not a faithful representation (copy) of external stimulus Brain Imaging Neuro- PET scans indicate that Psychology & different parts of brain are activated for mental arithmetic Imagery and visualizing walk through familiar neighborhood Occipital lobe for visualization, including Mental Rotation () Temporal lobe for imagining songs, 22 Faces activate fusiform face area, and places activate parohippocampal place area Such findings not subject to demand characteristics and expectancy effects More findings (+1) Neuroscience and Mental Imagery fmri = functional magnetic resonance imaging Scan people s brains while they perform imagery task V1 (area dedicated to vision) activated during visualization TMS = transcranial magnetic stimulation Disrupting V1 disrupts vision and visual imagery Measures of blood flow to different areas of brain Vivid imagers more blood flow to visual areas of brain Brain-damaged patients Some patients with perceptual problems have parallel problems in imagery: e.g., Cannot recognize or visualize faces A patient with unilateral neglect neglected side of his images Conclusion: much overlap between brain areas for imagery and perception 23 Spatial Cognition Kinds of Space (Tversky) Space of body: where parts of your body are located at any particular time Space around body: area immediately around you Space of navigation: larger spaces that we walk through, travel to, and explore (F8.15 F8.16 +1) Mental representations of these spaces May be distorted, made neater, and more regular 24 4
25 Individual Differences and Imagery 26 People vary in reported use of imagery Galton (1883): 3% people claimed no imagery Variety of questionnaires and paper & pencil tasks Dental Admissions Test (below) Rod and Frame task (+1) Rod & Frame Test 27 Gender and Imagery Gender and Visual-spatial Abilities Females somewhat lower average than males on some imagery tasks d =.40 (meta-analysis, effect size) (+1) But imagery not a unitary ability (+2) E.g., Linn & Peterson (1985) Spatial Perception d =.44 Spatial relations relative to self Mental Rotation d =.73 Spatial Visualization d =.13 Find shape in complex pattern Explanations Strategies Neurological findings (female brains less lateralized) Hormonal explanations: Kimura s work 28 Overlapping Normal Distributions (d=.5) 29 Dimensions of Imagery Ability 30 5
Imagery & Education Mayer s research on role of imagery & adjunct pictures on learning from scientific text Instructing students to generate mental image produces better memory and transfer (below) 31 32 Adjunct pictures () produced better memory and transfer Benefits of Image & Spatial Ability 33 Pictures integrated with text (vs separate) produced better transfer, but only for subjects with high spatial ability () Sport Psychology 34 Mental Rehearsal Repeated imaging of performance of some skill results in benefits, sometimes as good as actual practice () Visualization often used just prior to some performance Motivation Imaging winning Review Images seem to function in some ways like real pictures: They can be scanned, rotated, and transformed as real pictures can. But images do not always behave like pictures. Neuropsychological findings do suggest that visual images activate different parts of the brain than other cognitive tasks. 35 Review Visual images are mental representations of visual experiences. The dual-coding hypothesis states that there are separate codes for visual and verbal information, and two code are better than one. Not all psychologists believe in the existence of two separate codes. 36 6