Selective Attention, Cognitive Load,
Spatial Attention, Object-Based Attention
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
04/13/2016: Lecture 03-3
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Outline
• Why do experiments sometimes support early selection models of
attention, and sometimes support late selection models of attention?
• Cognitive load and selective attention.
• Spatial attention - what is it?
• Overt and covert spatial attention
Neuropsychological evidence for covert spatial attention
• Unilateral neglect (a.k.a. hemispatial neglect) a pathology of attention
Lecture probably
ends here
• Object-based attention
• Unilateral neglect is a pathology of both spatial attention
and of object-based attention.
Psych 355, Miyamoto, Spr ‘16
Why do some experiments support early selection; others support late selection?
2
Which is Correct, Early Selection or Late Selection?
• Evidence shows that the correct model depends on the nature
of the task.
♦
Some tasks force the human to filter information at an early stage of
information processing.
♦
Other tasks allow the human to filter information at later stages of
information processing.
• Next slide explains the idea that different cognitive tasks require
different amounts of available attention.
Psych 355, Miyamoto, Spr '16
Is Attention a Divisible Cognitive Resource?
3
Is Attention a Divisible Cognitive Resource?
• Hypothesis: Attention is like a finite
cognitive resource. We can use up
some of it, or all of it, on any given task.
Remaining cognitive
resources
No cognitive
resources remain
Figure 4.7 Left (low cognitive load):
♦
Low demand task leaves excess attention
to wander to irrelevant stimuli.
Figure 4.7 Right (high cognitive load):
♦
High demand task requires 100% of
attention. Irrelevant stimuli are ignored.
Psych 355, Miyamoto, Spr '16
Resources used by
low-load primary task
Resources used by
high-load primary task
Figure 4.7. Attention
as a Finite Cognitive Resource
Influence of Cognitive Load on Early vs Late Selection
4
Influence of Cognitive Load
on Early versus Late Selection
Figure 4.7 Left:
♦
Low demand task leaves excess attention
to process meaning of irrelevant stimuli.
♦
When subjects are affected by meaning
of irrelevant stimuli, results support
late selection models.
♦
Therefore low demand task should
produce results that support late
selection.
• Figure 4.7 Right:
Remaining cognitive
resources
Resources used by
low-load primary task
No cognitive
resources remain
Resources used by
high-load primary task
Figure 4.7. Attention as a
Finite Cognitive Resource
♦
High demand task requires 100% of
attention.
♦
There is no excess attention to process meaning of irrelevant stimuli.
♦
Therefore high demand task should produce results that support early
selection.
Psych 355, Miyamoto, Spr '16
Table Showing Experimental Design for Testing This Hypothesis
5
Fig. 4.7: [Easy or Hard] x [Distractor Present or Absent]
TASK:
• Say "N"
if "N" is
present.
EASY
HARD
Distractor ABSENT
EASY
HARD
Distractor PRESENT
• Say "Z"
if "Z" is
present.
Goldstein Figure 4.7. Detection task was EASY or HARD.
Distractor (dog face) was ABSENT (Panel a) or PRESENT (Panel b)
• EASY Condition: Distractor stimuli are "o".
HARD Condition: Distractor stimuli are similar to "N" and "Z".
• Distractor ABSENT (a): No dog face in the display
Distractor PRESENT (b): Irrelevant dog face in the display
Psych 355, Miyamoto, Spr '16
Display Experimental Results; Discuss
6
Fig. 4.7: [Easy or Hard] x [Distractor Present or Absent]
Panel (b) on right:
• Grey tops to bars
show how much
the distractor (dog
face) slowed
down the RT.
• Distractor had
greater influence
in EASY
condition.
Goldstein Figure 4.7. Detection task was EASY or HARD.
Distractor (dog face) was ABSENT (Panel a) or PRESENT (Panel b)
• Interpretation: Subjects had more excess attention to divert to
distractor when the task was EASY.
Psych 355, Miyamoto, Spr '16
Results Support Hypothesis: Attention is Divisible Resource
7
Results Support Hypothesis:
Attention a Divisible Cognitive Resource
Hypothesis: Attention is like a finite cognitive resource.
We can use up some of it, or all of it, on any given task.
Figure 4.7 Left (low cognitive load):
♦
Low demand task leaves excess attention
to wander to irrelevant stimuli.
Remaining cognitive
resources
No cognitive
resources remain
Figure 4.7 Right (high cognitive load):
♦
High demand task requires 100% of
attention. Irrelevant stimuli are ignored.
Resources used by
low-load primary task
Resources used by
high-load primary task
Goldstein’s Figure 4.8. Attention
as a Finite Cognitive Resource
Psych 355, Miyamoto, Spr '16
Video Game Study
8
Study of Novice & Expert Video Game Players
• Low Load (easy game): Both novices and experts are
affected by irrelevant stimuli.
• High Load (difficult game): Experts are affected by irrelevant stimuli;
novices are not affected.
• Cognitive load has to be defined in terms of the difficulty
of the task for a particular individual (it can vary from
one person to the next).
• Conjecture (Invisible Gorilla Experiment):
If subjects were trained to count passes and bounces (became
"experts"), then they would notice the gorilla.
Psych 355, Miyamoto, Spr '16
Conclusions: Early vs Late Selection Depends on Available Excess Attention
9
Conclusions: Early versus Late Selection Models
• Main Question: Where in the cognitive process does attentional
selection occur? Early? Late? In between?
♦
(Remember the issue in early versus late selection is the question
whether attentional selection occurs before or after the assignment of
meanings to stimuli.)
♦
There is evidence that early selection occurs with hard tasks;
Late selection occurs with easy tasks.
• Results also suggest that we can treat attention like it is a divisible
cognitive resource.
Psych 355, Miyamoto, Spr '16
Define Spatial Attention; Overt & Covert Spatial Attention
10
Overt Attention & Covert Attention
• Overt visual attention - controlling visual information acquisition
with eye movements and movements of the head and body.
• Covert visual attention - controlling visual information acquisition
without changing the direction of the gaze.
• Spatial attention is attention to different locations in visual space.
♦
Overt spatial attention - attention to locations is achieved
through eye movements, and head and body movements.
♦
Covert spatial attention - a person can shift attention to different locations
in the visual field without moving the eyes.
Psych 355, Miyamoto, Spr '16
Diagram Explaining What is Spatial Attention
11
Spatial Attention – What Is It?
█
+
▲
Fixation Point
• It is possible to attend to either the red rectangle or the blue triangle
while maintaining eye fixation at the +.
• Spatial attention is attention to different locations in visual space.
• Behavioral evidence for covert spatial attention is provided by
experiments with precueing.
♦
Covert spatial attention is demonstrated by the superior performance when the
precue is valid than when it is invalid. See Posner study on pp. 99-100 of Goldstein's textbook.
Psych 355, Miyamoto, Spr '16
Monkey Experiment - Neuropsych Evidence for Spatial Attention
12
Monkey Attention Experiment
(Colby, Duhamel, Goldberg, 1995)
Fixation
Point
Peripheral
Stimulus
BOTH CONDITIONS: Monkey holds down a bar while fixating the
fixation point. Monkey is rewarded if he releases the bar at the “right”
moment.
FIXATION ONLY CONDITION:
When the fixation point dims, the monkey must release the bar.
FIXATION & ATTENTION CONDITION:
When the peripheral stimulus dims, the monkey must release the bar.
Psych 355, Miyamoto, Spr '16
Single-Cell Recording in Monkey Parietal Cortex
13
Single-Cell Recording in Monkey Parietal Cortex
FIXATION & ATTENTION
Firing Rate
Firing Rate
FIXATION ONLY
• Recording is made during the period while monkey is waiting for the signal
to respond.
• The stimulus is the same for the left & right graph, but the monkey is attending
to the peripheral location on the right.
• Results constitute neuropsychological evidence for spatial attention
(attention to the location of the peripheral stimulus).
Psych 355, Miyamoto, Spr '16
Unilateral Neglect & Spatial Attention
14
This slide is based on instructional material that was downloaded from the Pearson Publishers
website (http://vig.prenhall.com) for Smith & Kosslyn (2006; ISBN 9780131825086).
Unilateral Neglect – A Pathology of Attention
Unilateral Neglect:
A deficit of attention in which one
entire half of a visual scene is
simply ignored.
(Discussed in Goldstein Chapter 10)
The cause of unilateral neglect is
often a stroke that has interrupted
the flow of blood to the right
parietal lobe.
Figure to the right: Patient’s copy
of an image (model) shows
systematic deficits.
Psych 355, Miyamoto, Spr '16
The patient’s copy in the right
column neglects the left side of
the visual field (opposite to the
side of brain damage).
Brain Diagram - Locate Parietal Lobe
15
Left Hemisphere: Note Location of Parietal Cortex
Head is
facing
LEFT
• Unilateral neglect is associated with injury to the left or right
parietal cortex.
Psych 355, Miyamoto, Spr '16
Behavioral Differences Between Left & Right Parietal Injuries
16
More Examples of Unilateral Neglect
a) Brain scan of patient showing
right parietal damage
(head faces up)
b) Drawings made by patient.
c) Patient instructed to put a
crossing line through every line.
Psych 355, Miyamoto, Spr '16
Large Diagram of the Lobes of the Brain
17
Other Examples of Unilateral Neglect
• Reported examples:
♦
Patient (male) shaves only half of his face.
♦
Patient (female) puts make up on only half of her face.
♦
Patient only eats food on half of her plate.
• Bisiach & Luzzatti (1978) tested Italian man with left
unilateral neglect.
♦
If asked to describe a current scene, the man fails to describe what
is on the left side of the scene.
♦
If asked to describe a familiar place from memory from the perspective
of a particular position, he fails to describe what can be seen on the left
from that position.
Unilateral (unilateral) neglect is not discussed in the Goldstein's attention chapter
(Ch 4); it is briefly discussed in the mental imagery chapter (ch 10, p. 288).
Psych 355, Miyamoto, Spr '16
Is Unilateral Neglect a Pathology of Spatial Attention?
18
Left versus Right Parietal Injury
Right: Figure 3.16 from Anderson (2005).
• Patients with left or right
parietal injuries were asked
to copy the figure in column
A.
• Right injury: Small parts
were correct – general form
was not.
• Left injury: General form
was correct – small parts
were not.
A: Model
to be
Copied
Psych 355, Miyamoto, Spr '16
B: Right
Parietal
Injury
C: Left
Parietal
Injury
Same Slide Without the Red Emphasis Rectangles
19
Left versus Right Parietal Injury
Right: Figure 3.16 from Anderson (2005).
• Patients with left or right
parietal injuries were asked
to copy the figure in column
A.
• Right injury: Small parts
were correct – general form
was not.
• Left injury: General form
was correct – small parts
were not.
A: Model
to be
Copied
Psych 355, Miyamoto, Spr '16
B: Right
Parietal
Injury
C: Left
Parietal
Injury
Other Examples of Unilateral Neglect
20
Is Unilateral Neglect a Pathology of Spatial Attention?
• Unilateral neglect (unilateral neglect) seems to involve
a problem focusing on particular spatial locations (relative
to the viewpoint of an individual).
• Is visual attention equivalent to attention to locations?
Results from object based attention show that the answer
it “NO”!
Psych 355, Miyamoto, Spr '16
Location-Based Attention vs Object-Based Attention – What Are They?
21
Wednesday, April 13, 2016: The Lecture Ended Here
Psych 355,, Miyamoto, Spr '16
22
Location-Based versus Object-Based Attention
• Attention is location-based when it
is organized around spatial
locations in the visual field.
Spotlight Metaphor
Location-based
• Attention is object-based when it
is organized around the structure
of objects rather than spatial
locations.
Psych 355, Miyamoto, Spr '16
Same Slide without the Red Emphasis Rectangles
23
Location-Based versus Object-Based Attention
• Attention is location-based when it
is organized around spatial
locations in the visual field.
Spotlight Metaphor
Location-based
• Attention is object-based when it
is organized around the structure
of objects rather than spatial
locations.
Psych 355, Miyamoto, Spr '16
Experimental Demonstration of Object-Based Attention
24
Demonstration of Object-Based Attention
Egly, R., Driver, J., & Rafal, R. D.
(1994).
• Targets can appear
at any of the 4 ends
of the rectangles.
• Cue appears at
the location where
the target is most
likely to appear.
o
o
+
o
o
• The RT is fastest at the location of the cue (no surprise),
but it is faster at the other location within the object than
at an equally close location on a different object.
Psych 355, Miyamoto, Spr '16
Same Slide Without the Emphasis Ovals
25
Demonstration of Object-Based Attention
Egly, R., Driver, J., & Rafal, R. D.
(1994).
• Targets can appear
at any of the 4 ends
of the rectangles.
• Cue appears at
the location where
the target is most
likely to appear.
o
o
+
o
o
• The RT is fastest at the location of the cue (no surprise),
but it is faster at the other location within the object than
at an equally close location on a different object.
Psych 355, Miyamoto, Spr '16
Horizontal Occlusion Does Not Affect Object-Based Effect
26
Occluding Part of the Object
Does Not Affect Object-Based Effect
• Same finding occurs
even if a horizontal
bar occludes (hides
part of) the vertical
“objects.”
• The greater speed at
shifting within an
object is not due to
the avoidance of
object boundaries!
Standard Display
o
o
+
o
o
Altered Display
C
A
B
Psych 355, Miyamoto, Spr '16
Tipper & Behrman - Unilateral Neglect & Object-Based Attention
27
Object-Based Attention & Unilateral Neglect
• Person with left unilateral neglect (right parietal injury) seems to suffer
from a deficit to spatial attention.
This is not exactly true!!!
• Next:
How unilateral neglect interacts with object-based attention.
Object-based attention is discussed in the Goldstein textbook; see Goldstein p. 100
and Item 7 on p. 115. But the relationship between object-based attention and
unilateral neglect is not discussed.
Psych 355, Miyamoto, Spr '16
Tipper & Behrman Study of Patient with Unilateral Neglect
28
Object-Based Visual Attention & Unilateral Neglect
Tipper & Behrman (1996)
• Patient had left unilateral
neglect.
• Initial display – patient is slower
to respond to flash in left circle
than to flash in right circle.
Response to stimulus is slow.
Response to stimulus is fast.
Psych 355, Miyamoto, Spr '16
Same Slide without the Sequencing
29
Object-Based Visual Attention & Unilateral Neglect
Tipper & Behrman (1996)
• Patient had left unilateral
neglect.
• Initial display – patient is slower
to respond to flash in left circle
than to flash in right circle.
(I added the color and bars in
the circles to these displays to
make it easier to explain the
experiment – they were not
used in the actual experiment.)
Psych 355, Miyamoto, Spr '16
Response to stimulus is slow.
Response to stimulus is fast.
Demonstrate Flip Trials
30
Flip Trials
• Stimulus is presented like
this at the beginning of a
trial.
• The stimulus rotates
180 degrees while the
patient watches.
Psych 355, Miyamoto, Spr '16
Repeat This Slide With Label for Pre- & Post Left & Right
31
Flip Trials
• Stimulus is presented
like this at the beginning
of a trial.
• The stimulus rotates
180 degrees while the
patient watches.
This circle
started on the
RIGHT side.
Now it’s on
the LEFT
side.
Psych 355, Miyamoto, Spr '16
This circle
started on the
LEFT side.
Now it’s on
the RIGHT
side.
How Does Flip Affect Patient’s RT to Target?
32
Effect of Rotation on Patient’s RT to Target
BEFORE the stimulus rotates:
Patient is
slower here.
Patient is
faster here.
AFTER the stimulus rotates:
Patient is
faster here.
Patient is
slower here.
• In general, the patient is slow to respond to information on
the “left” side, but ....
• .... neglect of the "left side" was defined in terms of the object
as it was initially presented, not the current visual stimulation.
• Object-based attention!
Psych 355, Miyamoto, Spr '16
“No Bar” Condition – An Important Control Condition
33
Important Aspect of the Effect of Flipping the Object
• If the two circles are not
connected by a bar, then
flipping the circles has no
effect, i.e., ...
the patient continues to show
inferior performance with a
flash on the left.
Standard Version
with Bar
Alternate Version
NO Bar
Psych 355, Miyamoto, Spr '16
Flip Trials in the “No Bar” Condition
34
Flip Trials – No Bar Condition
• Stimulus is presented like this
at the beginning of a trial.
• As before, the stimulus flips
left to right and right to left
while the patient watches.
Psych 355, Miyamoto, Spr '16
Results for "No" Bar Condition
35
Results in “No Bar” Condition
BEFORE the stimulus rotates:
Patient is
slower here.
Patient is
faster here.
AFTER the stimulus rotates:
Patient is
slower here.
Patient is
faster here.
• Conclusion: For patient with left unilateral neglect, flipping the colored
circles only reverses the side with a faster response if the two circles
appear to be part of a single object.
Psych 355, Miyamoto, Spr '16
Summary re Object-Base Attention - END
36
Summary: Object-Based Attention
• Spatial Attention: Attention is directed to specific locations
in the visual field. (a.k.a. location-based attention)
• Object-Based Attention: Attention is organized around the structure of
objects.
♦
Easier to move attention within an object than between objects.
♦
Objects have a special status in attention and perception.
• Spatial attention and object-based attention are two aspects
of human attention.
• Unilateral neglect exhibits deficits in both spatial attention
and object-based attention.
Psych 355, Miyamoto, Spr '16
END
37
Summary So Far
• Pathologies of attention demonstrate multiple functional components to
attention.
♦
Attention to left or right visual field.
♦
Attention to global perceptual structure versus attention to smaller details
♦
Problems with attention switching – perseveration
♦
Problems with attending to objects (Balint's syndrome)
• Is visual attention always equivalent to attention to locations?
Results from object based attention show that the answer is “no”!
(later)
Psych 355, Miyamoto, Spr '16
END
38
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Psych 355, Miyamoto, Spr ‘16
39