Week 8: Object-Based Attention and Cogitive Neuropsychology of attention

Question 1

What does attention Act Upon? (2)

Answer 1

Spotlight theory, 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

Question 2

object based theories:
Study 1
Rock and Gutman (1981)
Description (S3)

Answer 2

Overlapping figures (abstract)

Participants attend to one and rate aesthetic appeal; ignore other

Then given memory test:
Either on the red or green shapes without the colour, then asked did you study tt

Question 3

object based theories:
Study 1
Rock and Gutman (1981)
Results (S3)

Answer 3

Good mem for attended figure (cf. Cherry, 1953 -> audio)

Objects occupy same region of space (unlike left right ear)
=> contradict the spotlight of attention, maybe pay attention for object, not space.

Question 4

What happens to the Unattended Shape in Rock and Gutman (1981)?
Tipper (1985, etc.)

Answer 4

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)

Question 5

What happens to the Unattended Shape in Rock and Gutman (1981)?
Tipper (1985, etc.)
Negative priming

Answer 5

Pairs of red-green figures: trumpet-kite, anchor-trumpet etc (similar to Rock and Gutman just non-abstract figures)

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 (recognised and cognitively registered to be ignored) to produce effect on subsequent trial (cf. late selection)

Maybe operating on object, not space

Question 6

Implications of Rock & Guttman, Negative Priming

Answer 6

Possible to attend to one object and ignore another when both occupy same region of space

Maybe attention operates on the object, not the space

Question 7

Evidence for Object-Based Attention
Duncan (1984) (s7)
Description

Answer 7

stimuli differing on four attributes: box size (big/small), gap side(right/left), line slant(right/left), style of the line(dotted/dashed)

Flash briefly, ask to report two of the attributes (e.g., line slant, gap side)

two groups:

1) Report 2 from same object (box/line)
2) Report 1 from each object

Question 8

Evidence for Object-Based Attention
Duncan (1984)
Results

Answer 8

More accurate if the two attributes belonged to same object than different objects
Existence of benefit if belong to same object.

Stimuli occupy same region of space

Evidence that attention operates on the perceptual object, not the space.

Question 9

Cuing Object-Based Attention
(Egly, Driver, & Rafal, 1994)
(S9)
Description and results

Answer 9

Conditions:

1) cued
2) Miscued same object
3) Miscued different object

the predictions:
Space Theory:
Faster for condition (1). the others would be similar as only space matter.
Object theory:
1) Faster for condition 1 and 2 as they belong to the same object compared to 3.

Question 10

Cuing Object-Based Attention
(Egly, Driver, & Rafal, 1994)
(S10)
Results

Answer 10

Same object advantage: Mean RTs faster to miscued stimuli if in same object

Evidence that cuing effect spreads to encompass cued objects

Question 11

Cuing Object-Based Attention with …
Effects of an Occluding Bar (Moore, Yantis, & Vaughan, 1998)
Description and results

Answer 11

Same as (Egly, Driver, & Rafal, 1994)
with an  Occluding Bar across the the 2 objects

Occluding bar in stereo space: still find same object advantage

Not related to crossing edges or boundaries; agrees with percept of continuous objects.

Question 12

Neuroimaging Evidence For Object-Based Attention

Answer 12

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

Viewing Face: FFA up, PPA down;
Viewing House: PPA up, FFA down

Question 13

Evidence that attention selects objects in space

Answer 13

possibly by enhancing representation of selected object; suppression of other object

Attention to part of an object benefits other parts

Question 14

Neuropsychology of Attention:

Visual Neglect

Answer 14

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 -> deficits is lateralised

Question 15

Attention and Visual Pathways

2 main streams (in the brain)

Answer 15

1) Ventral pathway, temporal lobe: form, colour – what pathway
2) Dorsal pathway, parietal lobe: direction of motion, spatial location – where pathway

Parietal lobe damage disrupts “where” pathway

Question 16

Neuropsychology of Neglect

Answer 16

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

usually the results of stroke

Behavioural manifestations: failure to dress left side of body, shave left side of face, etc.

Question 17

Neuropsychology of Neglect

Manifestations and tests

Answer 17

(drawing test - missing left side; Cancellation test)

Behavioural manifestations: failure to dress left side of body, shave left side of face, etc.

Question 18

Neuropsychology of Neglect

Cuing Deficits with Right Parietal Damage (Posner)

Answer 18

 Compare intact and damaged hemispheres, use intact hemisphere as a control

 Posner: normal attention involves engagement, disengagement, and shift (reorienting) of attention

Mean RT:

1) Similar for valid cues
2) lot slower for INVALID Left visual field (Damaged) Vs Right visual field (Intact)

 Ability to voluntarily engage attention not impaired; difficulties in disengaging and shifting in response to new information

==> also suggest that this is an attentional deficits not a visual one as it can be overcame by appropriately shifting attention.

Question 19

Symptoms of Neglect: Extinction - definition

s20

Answer 19

perceptual response of to one stimulus “extinguishes” response to the other

Extinction: Two competing perceptual representations can’t co-exist

Question 20

Symptoms of Neglect: Extinction

When does it occur?

Answer 20

Simultaneous identification of two stimuli

Unimpaired with only one stimulus

left visual field deficit with two simultaneous stimuli

Question 21

Symptoms of Neglect: Extinction
Where else was it shown in;
Relevant to which theories

Answer 21

cf. Moray (1970): Normals poor in identifying two weak, simultaneous signals (audio)
John Dunken (Vision) -> however need very hard stimuli to get it.

Late selection theory: Only one signal can get through filter to consciousness at a time

Question 22

Symptoms of Neglect: Extinction

Why Does Extinction Occur

Answer 22

Recognition, identification require activation of neural structures

Damaged hemisphere chronically under-active, stimuli don’t provide activation they should

Effects strongest with activity in other hemisphere (invalid cue, competing stimulus)

Question 23

Balint’s Syndrome (Patient RM)
where and symptoms
Edv for object based attention

Answer 23

Bilateral lesions in parietal and/or occipital cortex

Inability to focus on individual objects and to see > 1 object at a time (Simultanagnosia) – prone to illusory conjunctions (combining them 2gether S23)

Occurs even when objects overlap (Object based!)

Question 24

Space-Based and Object-Based Attention:

Maybe it is a combination of both…

Linking both to Neuropsychology of Neglect

Answer 24

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 (can this be shown for objects?)

Tagging associated with objects, not just they space they occupy

Question 25

Object-Based Inhibition of Return (Tipper, 1991)
S25 to 29
Description

Answer 25

Standard IOR: peripheral cue, wait long SOA, flash target, slower RT at cued location

Object-based IOR: peripheral cue => then rotate display => Markers move to new locations

Measure RT to target in previously cued or miscued marker circle

Question 26

Object-Based Inhibition of Return (Tipper, 1991)
S25 to 27
Results

Answer 26

Found 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

Question 27

Object-Based Neglect (Behrmann & Tipper, 1994)
Modified form Tipper 1991
S28 to 29
Rationale and methods

Answer 27

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
(Control)

Behrmann and Tipper’s display: present barbell, rotate 180 deg., present target to be detected

Question 28

Object-Based Neglect (Behrmann & Tipper, 1994)
Modified form Tipper 1991
S28 to 29
Results

Answer 28

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

Question 29

Attention: The Take-Home Messages

Answer 29

Important interplay between theory and experiments: experimental findings suggest new theories to explain them; theories suggest new experiments to test them

Haven’t answered all the questions about attention