Post on 03-Jan-2016
Psych 435
Attention
Issues
• Capacity– We can’t respond to everything in the environment
– Too many pieces of information
– we can only actively respond to a subset of these
• Attention– The selection of relevant cues to respond to
– Cues may be externally or internally generated
Attention
• What is attention?– “The concentration of mental effort on sensory or mental
events”
• Phenomena– Switching vs. sharing attention
– Attention Capture
– Visual Search
– Selective attention- Stroop
Examples of Controlled vs. Automatic Processes
• Show 3 pairs of search demos
• Each member of each pair will have a few or a lot of items
• Search for a single target
Find the T:
TL
L
LL
L
L
L
• This was an automatic process: fast
Find the T:
TLL
L
L
L
L
L
L
L
L
L
LL
L
LL
L
L
L L
LL
L
L LL
LL
L
L
L
LL
• This was an automatic process: still fast even with more distractors
Find the T:
TL
L
LL L
L
• Slower without color
Find the T:
T
LL
L
L
L
L
L
L
L
L
L
LL
L
LL
L
L
L L
LL
L
L LL
LL
L
L
L
LL
• This was a controlled search- slower, look at each letter
• Much slower than with colored T
Find the Red L
L
LL
L
L
TT
T
T
T
• Slow: searching for a conjunction
Find the Red L
TLL
L
L
L
L
L
L
L
L
L
LL
L
LL
L
L
L L
LL
L
LLL
LL
L
L
L
LL
T
TT
TT
T
T
T
T
T T
T
T
T
T
T
T
T
TT
L
• Even slower- searching for a conjunction
Data from Display Set-Size Experiment
Fast search done with automatic (preattentive) mechanismsDone in parallel
Slow search done with controlled (attentive) mechanismsDone in serial
Applications of Attentional Seach
• List search situations and decide if fall into preattentive or attentive search requiring focal attention
• E.g.– Search computer screen for icon
– scan crowd for people
– scan crowd for americans
– look for airplane in sky
• What makes things preattentive?– probably the amount of difference between the objects
– L’s and T’s are similar
– Red and blue are quite different
– Looking for small differences requires focal attention
Models of attention
• Filter Models– Recognition after Filtering
» Broadbent-or-
– Recognition before Filtering
» Broadbent’s critics
• Attentuation Models– Treisman
• Automatic vs. Controlled Processes– Also called Preattentive vs. Attentive Processes.
– Neisser
– Schneider and Shiffrin
Filter Models
• What is a Filter?
• A description of the response properties of the system
• Describes what a system responds to, and what it doesn’t respond to.
Types of Filter Models
Detection RecognitionInput
DetectionInput
Filter
Recognition
DetectionInput
Filter
Recognition
Recognition Before Filtering:
Recognition After Filtering (Broadbent):
Broadbent’s Filter Model
• Channels carry different types of information
• E.g. color, spatial frequency, pitch, hot, etc.
• Apply mental effort: selectively process info coming from a small set of channels
• We must do this: limited capacity processing and memory system– We just can’t deal with all the information at once
• However, can switch between channels
Broadbent’s Filter Model cont.• On the basis of some aspect of the stimulus or
our memories, we can switch between channels
• This switching may be voluntary or involuntary
• Switching takes effort, reduces performance– Broadbent’s dichotic listening techinque- present two digits
at once, one to each ear
– 8, 3, 2 in left ear
– 9, 1, 5 in right ear
– recall by ear (left or right): subjects respond “8 3 2 9 1 5”
– or in order: subjects respond “8 9 3 1 2 5”
– performance for latter task is reduced (65% to 20%)
– In second task subjects had to switch more often- hurts.
Broadbent’s Filter Model cont.
• Problems: Gray and Wedderburn (1960)– Easy to switch if information in the to-be-switched-to ear
is relevant
– e.g.: Story continues in alternating ears
• Problems: GSR experiments– Associate word with shock- hearing word elicits a GSR
response.
– When that word is presented in unattended channel, produces GSR response.
– Semantically similar words also elicit response- some semantic processing takes place in unattended channel.
Attenuation Models-Treisman
• Info in unattended channels is still processed– but at a reduced rate
– info in unattended channels is attenuated.
Treisman’s Attention Model
Attention Capture
Failures of Selective Attention
• Attention is supposed to focus in on what you want to attend to
• Exclude irrelevant information
Stroop Task
Blue
Green
Yellow
Red
Yellow
Yellow
Green
Blue
Red
Green
Blue
Red
Green
Yellow
Blue
Green
Stroop Task
*****
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Stroop Task
Blue
Green
Yellow
Red
Yellow
Yellow
Green
Blue
Red
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Blue
Red
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Yellow
Blue
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Stroop Task
Yellow
Blue
Red
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Yellow
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Blue
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Yellow
Stroop
• Failure of selective attention
• Race model– Word name is processed automatically
– Color is not so automatic
– Both arrive at the same time, we have a hard time attending to the relevant stimulus attribute
– Doesn’t happen upside down
Stroop Task.
Failure of Attention: Failure to Disengage
• Mind Develops Brain clip– infant- failure to disengage
Spatial Attention: Posner Task
A
Attention switches to here(but eyes don’tmove)
Target mightappear here:
A
or here:
Time
Fixation Point
Cue75%accurate
Sharing Attention: Dual Tasks
• Do two things at once: can they be performed at the same time?
• Do they interfere?
• Experiment has 3 conditions
• Task A alone
• Task B alone
• Task A and B together at the same time
Sharing Attention: Dual Tasks
• Example:
• Pat head and rub belly
• Now speed up just your belly
• If you can’t do it, it suggest that they share the same processing capacity
• Same brain area?
Sharing Attention: Dual Tasks
words per minute
Example:Task A: Driving without an accidentTask B: Talking on cell phone
Can you talk on your cell phone at the normal rate while still drivingwithout getting into an accident?
Normal Save Driving Speed: 30 mphNormal speaking rate: 80 wpm
Safe DrivingSpeed
0 50 100
0
10
20
30 a
b
c40
Central Executive Interactions
Pet Evidence-Right Parietal
Lesion Data- Attending to Different Spatial Scales