Selective Attention & Spatial Attention
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
4/14/2015: Lecture 03-2
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Outline
• Selective attention where does it occur in the information processing stream?
• Early and late selection models
Lecture probably
ends here
• Spatial attention
♦
Neuropsychological evidence for spatial attention
• Pathologies of attention
Psych 355, Miyamoto, Spr '15
#
2
Humans Are Limited Capacity Information Processors
• Humans cannot encode and represent ALL of the perceptual
information available to them.
• Selective attention performs two cognitive functions:
♦
Selection of the information for thorough processing
♦
Neglecting or excluding other parts of the information.
• Where does selection occur?
♦
Does selection occur near the sensory periphery?
♦
Does selection occur after higher processes like meaning-extraction
and pattern recognition have begun to take place?
Psych 355, Miyamoto, Spr '15
Shadowing & Dichotic Listening
3
"Shadowing" During Dichotic Listening Study
• Dichotic Listening
Listening with 2 ears
Monotic Listening
Listening with 1 ear
• "Shadowing"
Subject is instructed to repeat out loud the message(s)
in one ear, e.g., left ear only.
Psych 355, Miyamoto, Spr '15
Results for Shadowing
4
Shadowing While Engaged in Dichotic Listening: Results
• Participants could not report the content of the message
in unattended ear
♦
Knew that there was a message, but had no idea what it was
♦
Knew the gender of the speaker
♦
Did not know that the same word was repeated 35 times
• Unattended ear is being processed at some level
♦
Cocktail party effect
♦
Change in gender is noticed
♦
Change to a tone is noticed
• How to explain the lack of awareness regarding information
in the unattended ear?
Psych 355, Miyamoto, Spr '15
Attentional Filter – What Is It?
5
Attentional Filter
• Filter Hypothesis: There is a cognitive mechanism called a "filter"
that allows some sensory inputs to pass to deeper levels of processing,
and blocks other inputs from continued processing.
• Where is the attentional filter in the
cognitive process?
Inputs
Filter
• Early selection model:
Broadbent’s filter model
• Intermediate selection model:
Treisman’s attenuation theory
• Late selection model:
McKay (1973)
Psych 355, Miyamoto, Spr '15
Broadbent's Filter Model: An Early Selection Theory
6
Broadbent's (1958) Filter Model (Early Selection Model)
• Messages:
• Sensory memory
• Filter:
• Detector:
Components to be explained
in following slides
• Short-Term Memory
Psych 355, Miyamoto, Spr '15
Broadbent's Filter Model – Messages & Sensory Memory
7
Broadbent's (1958) Filter Model
• Messages: Information coming in from the environment.
• Sensory memory: Temporary, high capacity information
storage. Information is transcient. Only physical properties of
stimulus are processed here.
♦
A.k.a. "sensory store," "iconic store" for vision; "echoic store" for
audition.
Psych 355, Miyamoto, Spr '15
Broadbent's Filter Model – Filter
8
Broadbent's (1958) Filter Model
• Messages: Information coming in from the environment.
• Sensory memory: Transient, high-capacity sensory storeage
• Filter: Lets one message pass through. All others are blocked.
Broadbent’s filter model assumes that:
a)
b)
The filter blocks unattended messages in terms of their physical
characteristics, not in terms of meaning.
It takes time to switch attention from one message to another.
Psych 355, Miyamoto, Spr '15
Broadbent's Filter Model – Detector & STM
9
Broadbent's (1958) Filter Model
• Messages: Information coming in from the environment.
• Sensory memory
• Filter: Blocks most input messages, but lets one pass through.
• Detector: High quality processor of the selected message. Detector
extracts meaning from message.
• Short-Term Memory
Psych 355, Miyamoto, Spr '15
Broadbent’s Split Scan Experiment
10
Broadbent's (1958) Split-Scan Experiment
M
H
Trials 1, 2 & 3 occur in rapid succession.
Cond 1: Report letters in any order.
1.
R
S
Typical Result: Subjects says: "M, R, W",
then "H, S, P".
♦
2.
W
3.
Psych 355, Miyamoto, Spr '15
P
65% correct.
-----------------------------
Cond 2: Report letter pairs in presentation
order: trial 1, then trial 2, then trial 3
TypicalResult: Subjects says: "M, H",
"R, S", "W, P".
♦
20% correct.
♦
Subjects say Cond 2 is more difficult than Cond 1.
How does Broadbent's filter model explain this pattern of results? 11
How does Broadbent's (1958) filter model
explain this pattern of results?
• Switching attention requires a change
(retuning) of the filter. This takes time
and cognitive effort.
• Cond 1 requires 1 switch of attention;
• Cond 2 requires 5 switches of attention.
Therefore Cond 2 is harder
(more errors; feels more difficult).
Psych 355, Miyamoto, Spr '15
M
H
R
S
W
P
Problems with Broadbent's Filter Model
12
Problems with Broadbent's Filter Model
Problems with Broadbent’s filter model are due to the assumption
of early selection (selection precedes the extraction of meaning).
• Cocktail Party Phenomenon: People remember hearing their own
name even if it is presented in the unattended ear.
♦
Broadbent's filter model says that unattended messages are
completely blocked. Cocktail Party Phenomenon should not occur.
• Gray & Wedderburn's (1960): "Dear Aunt Jane" experiment
Psych 355, Miyamoto, Spr '15
Grey & Wedderburn – Dear Aunt Jane Experiment
13
Gray & Wedderburn's (1960) "Dear Aunt Jane" Experiment
9
Dear
• Subject is told to report what you hear
in your left ear.
Correct response: "Dear, 7, Jane"
Aunt
7
Typical response: "Dear Aunt Jane"
• If Broadbent's filter is all-or-none, then
subjects should give correct response.
6
Psych 355, Miyamoto, Spr '15
Jane
Conclusion: Subjects extract some
meaning from the message in the
unattended ear. Broadbent's filter must
leak!
Return to Problems with Broadbent's Filter Model
14
Problems with Broadbent's Filter Model
• Cocktail Party Phenomenon: People remember hearing their own
name even if it is presented in the unattended ear.
♦
Broadbent's filter model says that unattended messages are
completely blocked. Cocktail Party Phenomenon should not occur.
• Participants track meaningful messages that switch from one ear to
another even when they are not supposed to do this.
Gray & Wedderburn's (1960): "Dear Aunt Jane" experiment
• Effects of practice on detecting information in unattended ear
♦
You can be trained to detect information in the unattended ear
(based on the meaning of the message)
Psych 355, Miyamoto, Spr '15
Treisman’s Attenuator Model
15
Treisman's Attenuation Model
• The attenuator intensifies the attended message, and weakens
(attenuates) the unattended message.
♦
The attenuator analyzes information in terms of (a) physical characteristics and
(b) linguistic form, e.g., sentence structure.
• Dictionary Unit detects words according to importance,
♦
Words in the attended channel automatically get a boost in importance.
♦
Word in unattended channels can still get through if words in these channels
have sufficient importance.
Psych 355, Miyamoto, Spr '15
MacKay's Late Selection Model
16
Evidence for Late Selection (MacKay, 1973)
Instructed
to ignore
Money
Instructed
to ignore
River
Psych 355, Miyamoto, Spr '15
They threw
stones at the
bank
• Subjects told to attend to left ear.
• All sentences in left ear were
ambiguous.
• Word in right ear suggests one
of two interpretations for
ambiguous sentence.
They threw
stones at the
bank
Example of a Question Asked to the Subjects
17
Evidence for Late Selection (MacKay, 1973)
Instructed
to ignore
Money
They threw
stones at the
bank
Later, subjects were asked:
Which sentence is closer to the
meaning of a sentence that you
heard?
A. They threw stones at the
savings and loan association.
Instructed
to ignore
River
Psych 355, Miyamoto, Spr '15
They threw
stones at the
bank
B. They threw stones towards
the side of the river.
Finding: Word in right ear biases
interpretation of sentence in left
ear.
Text: Contrast Btwn Early vs Late Selection Models & Attenuator Model
18
Contrast Between Early, Intermediate,
and Late Selection Models
This slide is pretty much the same as the preceding slide, except that the information is stated verbally.
• Early selection models:
♦
Attentional selection is based exclusively on physical characteristics of the
signal.
♦
Attentional selection cannot be based on meaning of signal
♦
Unattended signals (messages) are completely blocked
• Intermediate selection model (attenuation model)
♦
Attentional selection is based exclusively on physical characteristics of the
signal.
♦
Unattended signals (messages) are weakened (attenuated), not blocked
• Late selection models
♦
Attentional selection can be based on meaning as well as on physical
characteristics of the signal
♦
Unattended signals are only partially blocked
Psych 355, Miyamoto, Spr '15
Diagram of Early vs Late Selection Models & Attenuator Model
19
Contrast Between Early Selection, Attenuation,
and Late Selection Models
Before Extraction
of Meaning
Extraction
of Meaning
After Extraction
of Meaning
Early
Selection
Attenuation
Late
Selection
Psych 355, Miyamoto, Spr '15
Which Is Correct? Early or Late Selection?
20
Which is Correct, Early Selection or Late Selection?
• Evidence suggests 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.
• We need to introduce the idea that attention is a cognitive resource.
Psych 355, Miyamoto, Spr '15
Is Attention a Divisible Cognitive Resource?
21
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.
Figure 4.8 Left (low cognitive load):
♦
Remaining cognitive
resources
Low demand task leaves excess attention
to wander to irrelevant stimuli.
No cognitive
resources remain
Figure 4.8 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 '15
Predicted Influence of Cognitive Load on Early vs Late Selection
22
Predicted Influence of Cognitive Load
on Early versus Late Selection
Figure 4.8 Left:
♦
Low demand task leaves excess attention
to process meaning of irrelevant stimuli.
♦
When subject performs a low demand
task, response can be sensitive to
meaning of irrelevant stimulus.
♦
Therefore low demand task should
produce results that support late
selection.
• Figure 4.8 Right:
Remaining cognitive
resources
Resources used by
low-load primary task
No cognitive
resources remain
Resources used by
high-load primary task
Figure 4.8. Attention as a
Finite Cognitive Resource
♦
High demand task requires 100% of
attention. There is no excess attention
to process meaning of irrelevant stimuli.
♦
High demand task should produce results that support early selection
because response will be insensitive to meaning of irrelevant stimuli.
Psych 355, Miyamoto, Spr '15
Elementary Version of the Flanker Compatibility Task
23
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: Non-target stimuli are "o".
HARD Condition: Non-target 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 '15
24
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: Non-target stimuli are "o".
HARD Condition: Non-target 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 '15
25
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 '15
Results Support Hypothesis: Attention is Divisible Resource
26
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):
♦
Remaining cognitive
resources
Low demand task leaves excess attention
to wander to irrelevant stimuli.
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 '15
Video Game Study
27
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 '15
Conclusions: Early vs Late Selection Depends on Available Excess Attention
28
Conclusions: Early versus Late Selection Models
• Main Question: Where in the cognitive process does attentional
selection occur? Early? Late? In between?
♦
Some kinds of tasks provide evidence for early selection.
♦
Other tasks provide evidence for late selection.
♦
There is evidence that early selection occurs with hard tasks;
Late selection occurs with easy tasks.
♦
(Remember the issue in early versus late selection is the question
whether attentional selection occurs before or after the assignment of meanings
to stimuli.)
• Results suggest that we can treat attention like it is a divisible
cognitive resource.
Psych 355, Miyamoto, Spr '15
Define Spatial Attention
29