psych 435 attention. issues capacity –we can’t respond to everything in the environment –too...
TRANSCRIPT
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
Green
Blue
Red
Green
Yellow
Blue
Green
Stroop Task
Yellow
Blue
Red
Blue
Green
Blue
Red
Yellow
Blue
Red
Yellow
Blue
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Red
Blue
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