Experiments for Cash
• We are recruiting people who are active frequent
gamblers for an experiment
• Contact Greg Christie at greg.christie@uleth.ca
• You will have the chance to win money $$$ (but not
course credit)
Next Tuesday
• Read article by Anne Treisman
Attention
What is “attention”
• attention is poorly defined - different people mean
different things by “attention”
What is “attention”
• attention is poorly defined - different people mean
different things by “attention”
– An aroused state: a state conducive to rapid perception and
cognition. As in “pay attention!”
What is “attention”
• attention is poorly defined - different people mean
different things by “attention”
– An aroused state: a state conducive to rapid perception and
cognition. As in “pay attention!”
– Vigilance: maintaining a state of engagement - “paying
attention in class”
What is “attention”
• attention is poorly defined - different people mean
different things by “attention”
– An aroused state: a state conducive to rapid perception and
cognition. As in “pay attention!”
– Vigilance: maintaining a state of engagement - “paying
attention in class”
– Selective Attention: focusing on one object or location to
optimally deal with the sensory information coming from it
What is “attention”
• “Everyone knows what attention is. It is the
taking possession by the mind in clear and
vivid form, of one out of what seem several
simultaneously possible objects or trains of
thought...It implies withdrawal from some
things in order to deal effectively with
others…”
- William James
What is “attention”
• James’ definition emphasizes two important aspects
of attention:
What is “attention”
• James’ definition emphasizes two important aspects
of attention:
1. That attention implies a suppression of
information at unattended locations
What is “attention”
• James’ definition emphasizes two important aspects
of attention:
1. That attention implies a suppression of
information at unattended locations
2. That attention is a selection of some
information for enhanced perception or
mental operations
What is “attention”
• Enhanced Perception or mental operations?
– Further identification
– Planning appropriate response
– Encoding (storing) into memory
– Entry into awareness
Learning About Attention by Pushing
the Limits
•
Ulrich Neisser
–
Tracking one moving object out of many
Learning About Attention by Pushing
the Limits
•
Ulrich Neisser
–
Tracking one moving object out of many
–
About 50% miss the gorilla
Learning About Attention by Pushing
the Limits
•
Ulrich Neisser
–
Tracking one moving object out of many
–
About 50% miss the gorilla
–
Demonstration that unattended information is dramatically
absent from consciousness/memory
Selective Attention
A tale of bottlenecks and basketballs
Two Distinct Processes
• There are two processes that get bundled into our
idea of attention:
– orienting - shifting attention (usually in space, but also to
non-spatial features such as pitch)
– selection - what attention does to perception
• These are often confused and used interchangeably
• We’ll switch back and forth between the two, but we’ll
try to keep them separate
• First: the consequences of selection
Information Theory:
• ~1950’s: Psychologists began to think of the human
perceptual mechanisms as “information processors”
Information Theory:
• ~1950’s: Psychologists began to think of the human
perceptual mechanisms as “information processors”
• Began asking questions such as “how much
information can the human mind handle at once?”
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
x x x
o o o
x o o
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
– when simultaneous questions were asked, subject
performed poorly on all questions
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
•First principle of human
information processing:
capacity is limited
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
– when simultaneous questions were asked from physically
separate speakers, and subject instructed in advance which
question to answer, performance was nearly perfect
Information Theory
• Donald Broadbent - earliest systematic investigations
of selective attention
Second principle of human
information processing:
information sources can be
selected
Stages of Selection
• Broadbent: Early Selection - a bottleneck
exists early in the course of sensory
processing that filters out all but the attended
channel
• Alternative theory: Late Selection - the
bottleneck exists not at the lowest stages, but
at the highest - such as response planning,
memory and consciousness
Stages of Selection
Stages of Selection
• Testing Early Selection Theory - what prediction can
be made?
Stages of Selection
• Testing Early Selection Theory - what prediction can
be made?
• Information (such as meaning of words) in
unattended channel shouldn’t be processed for
meaning
Stages of Selection
• Shadowing Task: ignore one
input, repeat back the other
• Subjects are largely unaware
of unshadowed message
but…
• Certain words such as their
name distract them!?
• Why is this puzzling?
Stages of Selection
• Testing Early Selection Theory - what is another
prediction that can be made?
• Should be able to find differences in brain activity in
primary sensory areas (A1, V1)
Stages of Selection
• Electrical activity recorded at scalp (EEG) shows
differences between attended and unattended stimuli
in A1 within 90 ms
Hansen & Hillyard (1980)
Stages of Selection
• Evidence exists for both early and late selection
mechanisms
– One interpretation: early reduction in “sensory gain”
followed by late suppression of unselected information