Attention: Object-Based Attention & Neuropsychology PDF

Attention VII. and VIII. Object-Based Attention (1980s,1990s) and the Cognitive Neuropsychology of Attention Goldstein, p. 106-107, 122-123 Styles, ch. 4. “The Nature of Visual Attention” pp. 73-83 Styles, ch. 5. “Visual Attention” pp. 78-84 ...

Attention VII. and VIII. Object-Based Attention (1980s,1990s) and the Cognitive Neuropsychology of Attention Goldstein, p. 106-107, 122-123 Styles, ch. 4. “The Nature of Visual Attention” pp. 73-83 Styles, ch. 5. “Visual Attention” pp. 78-84  Learning Objectives  Explain the difference between spaced-based and object-based theories of attention  Give four experimental findings that imply that attention is object-based rather than space-based  Explain what is mean by "visual neglect"  Explain why researchers believe that visual neglect is an attentional and not a visual deficit  Describe the phenomenon of "extinction" and explain its relationship to normal attentional functioning  Describe the phenomenon of object-based inhibition of return and its significance for our understanding of attentional control  Describe Behrmann and Tipper's evidence that neglect is an object-based phenomenon  What Does Attention Act Upon?  Spotlight theory, FIT etc. assume attention acts on a region of space – enhances processing in that region  Alternative: attention acts on objects in space, not space itself: object based theories  What is the evidence and is it possible to distinguish? Rock and Gutman (1981)  Overlapping figures: attend to one and rate aesthetic appeal; ignore other  Memory test: good memory for attended figure, none for unattended figure (cf. Cherry, 1953)  Objects occupy same region of space.  Maybe the object of attention is the object, not the space it occupies? What Happens to the Unattended Shape?  Maybe it’s not perceived or not fully perceived?  Maybe people quickly forget the stimulus they’re not attending to? – inattentional amnesia  (cf. early vs. late selection)  Tipper (1985, etc.)  Pairs of red-green figures: trumpet- kite, anchor-trumpet etc. Negative Priming  Ignore green name red (e.g., ignore trumpet name kite)  What happens when trumpet must be named?  RT to name trumpet is slower if ignored on previous trial  “Negative priming” (regular priming produces speed up)  Means ignored shape must have been perceived to produce effect on subsequent trial (cf. late selection)  Implications of Rock & Guttman, Negative Priming  Possible to attend to one object and ignore another when both occupy same region of space – how?  Maybe attention operates on the object, not the space… Evidence for Object-Based Attention  Duncan (1984): stimuli differing on four attributes: box size, gap side, line slant, dotted or dashed line  Flash briefly, ask to report two of the attributes (e.g., line slant, gap side) Evidence for Object-Based Attention  More accurate if the two attributes belonged to same object than different objects  Same: box size and gap side or line slant and line style (dotted/dashed)  Different: box size and line slant, etc.  Stimuli occupy same region of space  Evidence that attention operates on whole objects?  Cuing Object-Based Attention (Egly, Driver, & Rafal, 1994)  Miscued locations in same object or different object – same distance from cued location  Space-based theories says miscuing costs should be the same Cuing Object-Based Attention (Egly, Driver, & Rafal, 1994)  Same object advantage: Mean RTs faster to miscued stimuli if in same object  Evidence that cuing effect spreads to encompass cued objects  Effects of an Occluding Bar (Moore, Yantis, & Vaughan, 1998)  Occluding bar in stereo space: still find same object advantage  Not related to crossing edges or boundaries; agrees with percept of continuous objects. Neuroimaging Evidence For Object-Based Attention  Selective fMRI activation when viewing houses and faces  Fusiform face area – active when viewing faces  Parahippocampal place area – active when viewing houses  Superimpose: attend to face or house  Face: FFA up, PPA down; house PPA up, FFA down  Conclusion  Evidence that attention selects objects in space – possibly by enhancing representation of selected object; suppression of other object  Attention to part of an object benefits other parts  Attention VIII. The Cognitive Neuropsychology of Attention Goldstein, p. 111, 288 Visual Neglect  Control of attention involves balance of top-down and bottom-up systems  Reflexive system orients to new stimuli, voluntary system provides sustained attentional focus  Failure to focus and failure to disengage and reorient both found in clinical cases  Damage to right parietal lobe Attention and Visual Pathways  Two pathways for processing visual information  Ventral pathway, temporal lobe: form, colour – what pathway  Dorsal pathway, parietal lobe: direction of motion, spatial location – where pathway  Parietal lobe damage disrupts “where” pathway  Neuropsychology of Neglect  Deficit in processing spatial information  Not blind, but difficulty in making left side of space accessible to conscious awareness  Right parietal lobe damage leads to left visual field neglect  Neuropsychology of Neglect  Cancellation test  Behavioural manifestations: failure to dress left side of body, shave left side of face, etc. Cuing Deficits with Right Parietal Damage (Posner)  Compare intact and damaged hemispheres, use intact hemisphere as a control  Posner: normal attention involves engagement, disengagement, and shift (reorienting) of attention  Ability to voluntarily engage attention not impaired; difficulties in disengaging and shifting in response to new information Symptoms of Neglect: Extinction  Simultaneous identification of two stimuli  Unimpaired with only one stimulus  left visual field deficit with two simultaneous stimuli  Perceptual response to one stimulus “extinguishes” response to the other Why Does Extinction Occur?  cf. Moray (1970): Normals poor in identifying two weak, simultaneous signals  Late selection theory: Only one signal can get through filter to consciousness at a time  Extinction: Two competing perceptual representations can't co-exist Why Does Extinction Occur?  Recognition, identification require activation of neural structures  Damaged hemisphere chronically underactive, stimuli don't provide activation they should  Effects strongest with activity in other hemisphere (invalid cue, competing stimulus)  Balint’s Syndrome (Patient RM)  Bilateral lesions in parietal and/or occipital cortex  Inability to focus on individual objects and to see more than one object at a time (Simultanagnosia) – prone to illusory conjunctions  Occurs even when objects overlap (Object based!)  Space-Based and Object-Based Attention  Attention seems mainly associated with “where” pathway  Spotlight view: movement of attention through space; neglect associated with left of perceptual space  Object-based view: attention keeps track of objects “(can ignore,” “shouldn't ignore”)  Inhibition of return: cued spatial location tagged as uninteresting, so slower RT there  Tagging associated with objects, not just they space they occupy Object-Based Inhibition of Return (Tipper, 1991)  Standard IOR: peripheral cue, wait long SOA, flash target, slower RT at cued location  Object-based IOR: peripheral cue, then rotate display Object-Based Inhibition of Return (Tipper, 1991)  Markers move to new locations (visible on screen) Object-Based Inhibition of Return (Tipper, 1991)  Measure RT to target in previously cued or miscued marker circle  Find slower RT at previously cued marker  Inhibition of return tracks cued marker to new location!  IOR follows the cued object, not confined to one region of space Object-Based Neglect (Behrmann & Tipper, 1994)  Neglect: left visual field deficit with right parietal damage  Neglect of space, or neglect of left side of object?  Barbell stimulus: two location markers + connector, combine into one perceptual object  Longer detection RT on left Object-Based Neglect (Behrmann & Tipper, 1994)  Behrmann and Tipper's display: present barbell, rotate 180 deg., present target to be detected  Longer RTs on right  Neglect tracks marker to opposite visual field!  Neglect of left side of objects, not just left side of space  Allows space-based and object- based effects to be distinguished  Attention: The Take-Home Message  Haven't answered all the questions about attention  Shown how cognitive psychology thinks about attention  Main trends in attention from 1950s to the present  Important interplay between theory and experiments: experimental findings suggest new theories to explain them; theories suggest new experiments to test them