1. Attention, Effort, and Resource Allocation
September 6, 2007

2. What Is Attention?
“Every one knows what attention is. It is the taking possession by the mind, in a clear and vivid form of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal with others…” (James, 1890, p. 403)

3. Attention is... An attitude of mind
Relative proportion of activated traces to all memory traces
Some form of energy or desire involving will or effort
A filter, a skill
An allocation of resources
A spotlight, a selective attenuator

4. Characteristics
General agreement regarding two characteristics outlined by James:
Sensory attention driven by environmental events (bottom-up; stimulus-driven; exogenous)
Volitional attention to both external and internal stimuli (top-down; goal-driven; endogenous)
May be thought of as automatic vs. controlled, respectively.

5. Automatic Vs. Controlled Processing Distinction
Automatic processes
no capacity limitation; fast
do not require attention, effort
difficult to modify once learned
Controlled processes
limited in capacity; slow
require attentional resources, effort
can be used flexibly in changing circumstances

6. The brain network involved in the stimulus-driven attentional system, based on findings from various brain-imaging studies in which participants detected low-frequency target stimuli. The full names of the brain areas are in the text. From Corbetta and Shulman (2002). Copyright © 2002 by Nature Publishing Group.

7. The brain network involved in the goal-directed attentional system, based on findings from various brain-imaging studies in which participants were expecting certain visual stimuli. The full names of the brain areas are in the text. From Corbetta and Shulman (2002). Copyright © 2002 by Nature Publishing Group.

8. Purposes of Attention Cope with inherent capacity limitation of brain
Facilitate stimulus detection
Facilitate stimulus perception
Facilitate thinking
Facilitate memory
Recruit relevant processors
Prepare for action
James

9. Varieties of Attention
Focused attention (processing only one input)
Orienting to sensory events
Detecting signals for focal (conscious) processing
Divided attention (processing multiple inputs according to nature of inputs and goals)
Maintaining a vigilant state

10. Varieties of Attention

11. Dimensions of Attention
Focality (detection vs. selective attention)
Duration (brief vs. sustained attention)
Input channel
Visual attention
Spatial
Object-based
Auditory attention
What, where
Cognitive effect (facilitation vs. inhibition)

12. Why have an attentional system?
-brain as a limited-capacity processor; that which is selected should be consistent with goals and expectations

13. Early Visual Attention
Interface between Attention and STM: Attentional blink

14. Early Visual Attention (Cont’d)
Interface between Attention and STM: Repetition blindness

15. Early Visual Attention
AB and RB can be doubly dissociated (Chun)
Making targets different from distractors alleviates AB but not RB
Enhancing episodic distinctiveness of the two targets eliminates RB but not AB
May represent different things
AB represents bottleneck in attentional processing,
RB reflects failure of token individuation

16. Selective Attention
Selective processing of some information but not others
Filter vs. capacity models
Important research paradigms
Dichotic listening
Shadowing

17. Dear Linguist: I am hoping you might be able to provide some information for me regarding dichotic listening. I work in a call center in Vancouver, Canada.  The position I work in requires that we monitor 2 separate phone lines at the same time with 2 headsets (one on each ear) for 8 hour shifts.  We monitor the content of messages being left by callers, and subsequently accept or refuse their recorded greeting/message. There is a fairly large staff (approx. 60 employees) here that monitors the phone lines 24 hours a day, 7 days a week. The content of the messages is often rude and unsavory - we monitor a singles meeting place chat connector and callers can get fairly explicit - but this is not the issue that concerns me.  The position did involve listening to single lines before a company expansion over a year ago when it changed to double-line monitoring.  It seems that this double listening is affecting people negatively. Having done this for 8 months now, I know that I have been experiencing psychological trauma (depression, confusion, irritability, chronic headaches etc.), as have a number of my co-workers. My question is this:  Is this type of dual listening harmful in any way,or furthermore, have any studies been done in regards to the effects this type of extended exposure to dual listening may have on the human brain or psyche? I have just started looking into this - your name came up in a web search for dichotic listening - and I would greatly appreciate any information or reference that you could pass on. Thanks. -Name, Occupation

19. Cherry (1953)
Interested in attentional “popout” of relevant information (“cocktail party effect”)
Two messages, same voice, both ears: subjects could invariably separate messages, but with difficulty; uses physical/source characteristics
Dichotic listening with shadowing
Recalls little if any content from other ear
Often doesn’t recall language
Can recognize it as speech/nonspeech, and can recognize male-female

20. Broadbent (1958)
Influential paper on focused (selective) attention; felt by many to be a critical ‘cornerstone’ paper in cognitive psychology
Influenced by Cherry’s shadowing results
Used dichotic listening, and found a strong tendency to report digits ‘by ear’, thus reflecting a tendency to select based on perceptual/physical characteristics of the input

21. Broadbent’s Filter Theory
Stimulus #1
Stimulus #2
Limited capacity
STM
Selection Filter
Sensory register/buffer

22. Problems with Broadbent’s Theory: Recall across ears can be organized (automatically?)

23. Problems With Broadbent’s Filter Model
Sometimes attention doesn’t follow input source: Gray & Wedderburn (1960)
fan out
rage tas
tic ous
Can demonstrate that “unattended” information is processed phonologically or semantically: Corteen & Wood (1972)
EDR’s to shock-associated words in an unattended channel – city name study

24. Early Vs. Late Selection
“Early” theories (Broadbent, Treisman)
selection takes place well before extensive (e.g., semantic) analysis takes place
contradicted by studies showing semantic effects in unattended ear
“Late” theories (Deutsch & Deutsch)
extensive analysis of stimuli takes place before selection
raises issue of benefits of selective attention
shadowing delayed by presentation of a synonym in the other ear; recall biased by semantic interpretation (e.g., bank-river, vs. bank-money)

25. Broadbent Treisman Deutsch & Deutsch STM Sensory register
Selection Filter
Stim#1
Stim#2
Treisman
Sensory register
Attenuator
STM
Stim#1
Stim#2
Deutsch & Deutsch
STM
Sensory register
Stim#1
Stim#2

26. Perceptual Load Theory
Everyone has limited attentional capacity
The amount of attentional capacity allocated to the main task depends on its perceptual load, which is determined by “the number of units in the display and the nature of processing required for each unit” (Lavie & Tsal, 1994, p. 185)
“Any spare capacity beyond that taken by the high-priority relevant stimuli is automatically allocated to the irrelevant stimuli” (Lavie, 1995, p. 452). Thus, the total available attentional capacity is always allocated to processing

27. Evidence r t x p q k _ _ x _ _ _
Mean target identification time as a function of distractor type (neutral [N] vs. incompatible [Z]) and perceptual load (low vs. high). Based on data in Lavie (1995).

28. A Capacity Model Kahneman (1973)
Supplements previous bottom-up analysis with a consideration of top-down influences
Emphasizes concept of processing resources
Attention and mental effort are strongly correlated
Arousal can work to increase processing resources

29. Kahneman’s Model

30. Understanding the Effects of Attention is Important When there are Limitations on Processing
Resource-limited processes
Processes dependent on the availability of resources that can be devoted to task solution
Applying more effort or processing resources increases task performance
If output not available until task is finished, then devoting more resources decreases RT
If output continuously available, then performance level increases
Data-limited processes
Processes dependent upon the quality of data input, rather than upon resource allocation
Applying more resources may have little effect on performance
Most processes have both resource- and data-limited components

32. Basic Signal Detection Framework
Present
Absent
“Yes”
True Positive
False Positive
True Negative
False Negative
“No”
Basic Signal Detection Framework

33. Focused Visual Attention
The Attentional “Spotlight” model
items within a small portion of the field can be seen clearly
Posner’s ‘covert’ shifting of the spotlight
Problem: proximity not always facilitative –e.g. Driver & Baylis, 1989 – common movement
Zoom-lens model (Eriksen & Yeh, 1985)
Magnification inversely proportional to FOV
‘magnification’ can be increased or decreased
Grouping processes affect spatial extent of attention
Problem: attention can be object-based; objects outside the zoom can be processed or even inhibited

35. Evidence for Spotlight
Location-specific facilitation of attention
RT’s faster when object appears in cued location
search for target letter and report orientation of “U”; done better when two letters are close together T
vs. T  

36. Focused Visual Attention
The Attentional “Spotlight” model
items within a small portion of the field can be seen clearly
Posner’s ‘covert’ shifting of the spotlight
Problem: proximity not always facilitative –e.g. Driver & Baylis, 1989 – common movement overrides proximity
Zoom-lens model (Eriksen & Yeh, 1985)
Magnification inversely proportional to FOV
‘magnification’ can be increased or decreased
Grouping processes affect spatial extent of attention
Split attention (Awh & Pashler)
Problem: attention can be object-based

37. Experiments Demonstrating Split Attention (a problem for the zoom-lens model)
Awh and Pashler (2000).
(a) Shaded areas indicate the cued locations and the near and far locations are not cued; (b) probability of target detection at valid (left or right) and invalid (near or far) locations.
Based on information in Awh and Pashler (2000).
Array consists of 23 letters and 2 numbers. Before each trial, subject receives two cues (shaded) indicating the likely (80%) location of the digit targets, which they were asked to report. If the zoom lens model is correct, a digit appearing between the two cued locations should be reported accurately, but if split attention is possible, accuracy should be low. The graph shows a 60% reduction in accuracy of target detection in the near condition, indicating that split attention is possible. Still, there is a small effect of “zoom-lens” since the accuracy of “far” detections is 20% worse still.

38. Object-Based Attention
Subjects were asked to determine whether the two irregular ends in the display contained the same or different number of “bumps”. The ability to do that across a single, unoccluded object, should be fastest, and the authors were interested to know whether the data favored an object vs. a spatial framework. If object-based attention existed, the RT to perform the same-different judgment should be no different for the occluded than the unoccluded objects. What they found was that RT for occluded and unoccluded objects were not different, but both were slower than the RT to do the same-different judgment across two objects.
Behrmann, et al (1998) JEP: HPP, 24,

39. Inhibition in Attention

40. Inhibition in Attention (Cont’d) Negative Priming Paradigm
Attended repeat
Task = name red drawing
Unrelated
Unattended repeat
Prime
Probe

41. A B Attention as Facilitation Attention as Inhibition Stimulus 1
Preattentive Processing
Further Cognitive Processing
ATTENTION A
Attention as Inhibition
Stimulus 1
Stimulus 2
Preattentive Processing
Further Cognitive Processing
ATTENTION B

42. Inhibition of Return (IOR)
“A reduced perceptual priority for information in a region that recently enjoyed a higher priority” (Samuel & Kat, 2003, p. 897)
A bias favouring novel locations and objects
Posner and Cohen (1984)
IOR due to inhibition of perceptual and/or attentional processes
Taylor and Klein (1998)
IOR due to inhibition of motor processes
Prime and Ward (2004) ERP study
IOR is a perceptual phenomenon not in motor response

43. Models of Visual Search
Feature integration model
rapid initial parallel process not dependent on attention
subsequent attention-dependent serial processes in which features are combined to form objects
attention provides “glue” binding features together into an object; can only do this one object at a time
feature combination affected by stored knowledge
without focused attention, features combined randomly, producing ‘illusory conjunctions’

44. Display Size Effect Find the “T” L L L L L L L L L L L L L L L L T L L

45. Feature Search & Feature Singletons
L L L L L L L L L
L L L O L L L L L
O O O O O O O O
O O O O O T O O
Find the “T”
Find the “O”

46. Treisman & Gelade (1980) Find the “Green T” Find the “B lue Letter”
L L L T L L T L L
L T L L T L L T L
L L L L T L L L T
L L T L T L T L L
L T L L L T L L L
L L L L T L L T L
L T T L L L L L L
L L L T L L L L T
T T L T T L L L L
L L T L L L T L L
L T L T L T L T L
L T L T L L L T T
L L L T L T T L L
S L R M T N X A Y
W S B X N I F M I
Q W A S Z X L K P
M B E W E R U I N
U O W L X P D G H
Find the “Green T”
Find the “B lue Letter”

48. S S S S S S S Feature Conjunctions & Illusory Conjunctions
Find the triangle
Find the “$”

49. S S S S S S S Similarity vs. Feature Conjunctions Find the “R”
Q W E + T Y [ # S
@ ! & F ) W B X K
A M J + H F I O U
? * P Q A G D
B > / ( S T U K =
* Q A Z O Y K C V
% K C X S T P U *
E & # N B Z % \ )
P O ! * K J D A B
^ S W Q I C K M N
$ G + ( Y Z R L S
* B N T & Q C D >
@ W % K S { H X }
r s t + t y [ # s
@ y n k ) w l s i
a b r + l f R g u
? ! < q ( p e
c # ] “ t u v l +
* p b a p z l d w
x l d % t ^ q v +
f ! # m c a = } *
q s “ * l k e b c
^ t x s j % l n =
@ h ? ) z a s m \
# c o u / b d e <
@ p * j w + o t } S S S S S S S
It’s not just feature conjunctions, it’s item similarity that drives performance on visual search tasks.
Find the “R”

50. Key Takeaway Points
Generally agreed that two processes are involved in visual search (parallel & serial), though recent neuroimaging data suggests otherwise – substantial overlap in brain areas involved
Different visual features are processed independently
Speed of visual search depends on set size and similarity of targets to distractors
Perceptually grouped objects will be selected or rejected together; grouping probably takes place prior to attentional ‘enhancement’

51. Posner’s paradigm

52. Posner’s paradigm

53. Posner’s paradigm

54. Posner’s paradigm •

55. Posner’s paradigm

56. Posner’s paradigm

57. Posner’s paradigm

58. Posner’s paradigm •

59. Posner’s components of attention
Three components involved in visual attention:
Disengage attention from a given stimulus
Shift attention from one stimulus to another
Engage attention on a new stimulus

63. Dual Task Performance Relevant to processing capacity
Interference methodology a useful tool to determine whether two tasks share resources
What determines degree of interference?
Task similarity
Task difficulty
Practice/expertise

64. Sensitivity (d') to auditory and visual signals as a function of concurrent imagery modality (auditory vs. visual). Adapted from Segal and Fusella (1970).

65. Multiple-resource Theories
Wickens (1984). A proposed dimensional structure of human processing resources. From “Processing resources in attention” by Wickens, C.D. in Varieties of Attention edited by R. Parasuraman and D.R. Davies © 1984 by Academic Press. Reproduced by permission of Elsevier.

66. Automatic Vs. Controlled Processing Distinction
Automatic processes
no capacity limitation; fast
do not require attention
difficult to modify once learned
Controlled processes
limited in capacity; slow
require attentional resources
can be used flexibly in changing circumstances

68. Norman & Shallice Three levels of functioning:
Fully automatic processes, controlled by well-learned schemas
Partially automatic processing, controlled by contention scheduling
Deliberate control by a conscious, supervisory attentional system

69. Summary: Important Concepts
Limited-capacity for information-processing (information bottleneck) leads to selective attention
Attentional acts take time and effort
Attentional control re: goals and plans
Automatic vs. Controlled processing
Attention and consciousness