Perceptual Processes:
Attention & Consciousness
Dr. Claudia J. Stanny
EXP 4507
Memory & Cognition
Spring 2009
What do we mean when we say we
are “paying attention?”
Focus on one task to exclusion of others
• Selectivity
• Inhibition of irrelevant information
• Ability to shift attention (disengage from one task
and engage with another task)
Maintaining focus
• Vigilance – sustained attention to one task
Division of effort across multiple tasks
• Multitasking
• Allocation of resources to multiple tasks
Claudia J. Stanny
2
Defining Attention
Vigilance (Sustained attention)
Selective Attention (Focus on one task)
Division of Attention (Multitasking)
Attention as processing capacity or mental effort
• Controlled Processing (Attentional Processing)
• Automatic Processing
Claudia J. Stanny
3
Vigilance
Sustained attention
Example: Radar screen operators
Problems with boredom and distractibility
Lapses
• Missed signals
• Observers periodically disengage from tasks to
monitor the environment
• Neurological aspects of periodicities in attention
(Aue, Arruda, Kass, & Stanny in review)
Claudia J. Stanny
4
Selective Attention Tasks
Ability to focus attention
• Dichotic Listening Task
• Shadowing Task
• Stroop Task
Selection of one stimulus source, task, or
response
Inhibition of other stimulus sources, tasks, or
responses
Claudia J. Stanny
5
Selective Attention:
Shadowing Tasks
Cocktail Party Phenomenon
Two distinct messages arrive at each ear
Task is to repeat (shadow) the message in one ear
Claudia J. Stanny
6
Selective Attention:
Dichotic Listening Tasks
Two sets of digits
• Report by time of arrival
• Report by location (left ear, right ear)
Relative cost of reporting by location or switching channels to
report by time of arrival
Claudia J. Stanny
7
Selective Attention:
Dichotic Listening Tasks
Sometimes the cost of switching from one channel to
another is less than predicted by an early selection
model
Claudia J. Stanny
8
Stroop Task
Stimulus activates competing responses
• Color name (generated by reading)
• Color name (generated by perception of color)
Two possible task demands:
• Read the word
• Name the ink color
Must inhibit one response to make the correct
response for the task demands
Claudia J. Stanny
9
Demonstration of the Stroop Task
Claudia J. Stanny
10
Divided Attention
Division of attention across multiple tasks
Questions:
To what extent can attention be divided without
loss in quality of performance on tasks?
To what extent does practice change our ability
to maintain task performance when attention
is divided?
Claudia J. Stanny
11
What is the effect of practice?
Automatic & Controlled Processing
Schneider & Shiffrin, 1977; Shiffrin & Schneider, 1977
Controlled Processing
• Attentional processing
• Sequential, slow, flexible, requires resources
• Bottlenecks likely to occur during multi-tasking
Automatic Processing
• Distributed processing
• Parallel, fast, inflexible, requires few resources
• May be able to multi-task automatic processes
Claudia J. Stanny
12
Demonstration of Automatic and
Controlled Processing in the
Shiffrin & Schneider Task
Claudia J. Stanny
13
Theories of Attention
Bottleneck theories
Resource theories
Feature integration theory
Claudia J. Stanny
14
Bottleneck Theories
Where in the stream of information processing
does the bottleneck (selectivity) occur?
• Filter Theory (Broadbent, 1958)
• Attenuation Theory (Treisman, 1960)
• Late Selection Theory (Deutsch & Deutsch,
1963)
Claudia J. Stanny
15
Attention as Processing Resource
Attention as an allocation
of capacity or resources
for processing information
Kahneman (1973)
Attention and Effort
Role of arousal
Effects of practice
Potential for multitasking
Claudia J. Stanny
16
Implications for Multitasking
Development of automaticity can reduce
demands on processing resource
Automatic processing can enable the division of
attention and multitasking
• Possible for simple, highly practiced tasks
• Errors appear when one or more tasks become
more demanding
Claudia J. Stanny
17
Costs of Automaticity
Costs of rapid switching between tasks
Task analysis : Evaluate the specific demands of
each task
Automatic processes are inflexible and lead to
errors when situation requires a new response
Example in the Schneider & Shiffrin task:
Attentional Capture
Example in the Stroop task:
Difficulty in inhibiting rapid but irrelevant responses
Claudia J. Stanny
18
Multitasking Application:
Driving while talking on a cell phone
Cole, Kass, & Stanny (2007)
Claudia J. Stanny
19
Consequences of Divided Attention:
Other Applications
Response times are slower when we are engaged in a
cell phone conversation
Distracting effects of advertising on web pages
• Web pages with ads take longer to read and comprehend
than those without ads
• Added effects of animated ads
Memory and understanding of main points in text is
worse when textbooks include irrelevant cartoons
and side bars to generate interest
• Relevant photos, cartoons, and other materials aid
learning; irrelevant materials just distract
Claudia J. Stanny
20
Visual Search
Feature present searches
• Target identified by a single feature
• Rapid, parallel searches (target “pops out”)
Feature absent searches
• Target identified by the absence of a single feature
• Slow, serial examination of each stimulus
We process positive information (feature
present) more rapidly than negative
information (feature absent)
Claudia J. Stanny
21
Demonstration:
Visual Search Tasks
Claudia J. Stanny
22
Conjunction Searches
Target is a combination of features
Non-targets have only one of the features
Slow, serial search process
Focused attention to a location required to
detect integrations of features
When attention is distracted, illusory
combinations of features might occur
Claudia J. Stanny
23
Demonstration:
Searches involving
Feature Conjunctions
Claudia J. Stanny
24
Feature Integration Theory
Treisman & Gelade (1980)
Distributed attention
• Process stimuli in parallel
• Processing is distributed across the spatial array
• Process dominated by feature detection
Focused attention
• Process stimuli serially
• Attention is allocated to a specific spatial location
to accurately integrate the features for that
stimulus
Claudia J. Stanny
25
Neurological Correlates of
Attention
Orienting attention network
• Parietal lobe; active during visual search tasks &
when attending to spatial locations
• Visual neglect when this area is damaged
Executive attention network
• Frontal lobe; inhibits automatic responses when
task produces conflicting responses (e.g., Stroop)
• Top-down control of attention
Alerting attention network
• Orienting responses to novel stimuli
Claudia J. Stanny
26
Unilateral Neglect
Lesions of posterior
parietal lobe
Some role of frontal lobe
• Hemineglect
• Usually seen with right
parietal lesions
Claudia J. Stanny
27
Visual Search in Unilateral Neglect
Visual search strategies are
biased to one side of the
visual field in neglect
Husain, M (2008). Scholarpedia, 3(2):3681.
Severity of neglect is
exaggerated with increased
visual clutter
Claudia J. Stanny
28
Attention and Consciousness
Role of subjective awareness
• Awareness of products of mental processing
• Level of awareness of mental processes
themselves
Rapidity of some processes (e.g., retrieval) make them
inaccessible to awareness or conscious examination
Role of self-report as valid data about some processes
(e.g., problem solving, metamemory, metacognition)
Claudia J. Stanny
29
Disorders of Attention
Obsessive-Compulsive Disorder
Attentional Deficit Disorder
Blindsight
• Damage to visual cortex, sub-cortical visual areas
intact
Claudia J. Stanny
30