Psy 1

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Psy 1

• Today
• Attention
• Learning conditioning

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Psy 102

• Today
• Attention
• Visual Search
• Change Blindness

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Limited capacity processor
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One way to study attention is to
measureREACTION TIMES
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Stroop Effect
Fig. 8.29
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Stroop Spy Test
ROUGE VERT NOIR JAUNE VERT BLANC ROUGE VERT NOIR
JAUNE ROUGE
BLEIKT GULT SVART GULT BLEIKT HVITT SVART BLEIKT
SVART GULT HVITT
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What causes the Stroop effect?

• Response competition.
• Overlearned name that word reading response
  competes with unfamiliar name that ink task

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Attention andVisual Search
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Finding Laura Bush at a Jesse Jackson rally is
hard
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But your friend with the green scarf at Pamplona
jumps out at you
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Visual Search

• Looking for a target in a display containing
  distracting elements
• Target the goal of visual search
• Distractor any stimulus other than the target
• Set Size the number of items in a visual display

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Reaction times in visual search

• Fast, easy, parallel, pre-attentive search
• Slow, hard, serial, post-attentive search (must
  inspect each item in turn)

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Selection based on color is easy
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Selection based on upright vs upside down is not
easy
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Visual search experiments
One target present on half the trials Vary the
number of items in display Subject reports
whether target is present or absent Measure the
time from the appearance of the display to the
response
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Visual search experiments
If reaction time is unaffected by number of
distractors (slope0) Then target identity was
available preattentively and drew attention to
itself
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Visual search experiments
If reaction time increases with number of
distractors Then identity not available
preattentively, had to be determined by
selecting each item in turn and analyzing it for
match to target
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Visual Search (contd)
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But high-level properties may also be easy to
find, scene properties like surface curvature
from shading
Preattentive identification not not limited to
properties extracted by cells in striate cortex
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It is not just the features, the same pattern
with accentuated features is hard to find here
At either orientation. It is the shaded depth
that was the easily found surface, or scene
property.
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Preattentive to Attentive Stages
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How long does it take you to react when driving?
Reaction time

• Chronometry (Measuring reaction times) can tell
  us about brain processes
• Typical reaction times .01 sec to 1 sec
• Broomstick demonstration

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Reaction time

• Nerve conduction time
• Muscle movement time
• CHOICE DECISION TIME in brain

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To measure short reaction time

• Get an accurate timer
• OR
• Measure a series of reaction times and take the
  average Class demonstration
• Ankle vs. Shoulder measure neural conduction
  velocity!

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Why should attention move independently of
eyes?Useful for multiple targets, covert
surveillance
Tracking, individuationOnce captured, attention
tracks moving and/or changing targets
How many can you track?
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Pylyshyn Storm, 1988 Yantis, 1992
Intriligator Cavanagh, 2001.
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Spatial resolution of attention
You can shrink the area of selection to be
small But not as small as the smallest detail you
can see
While looking in the center, you can see the bars
but you cannot attend to individual bars try
counting them without moving your eyes
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Region of selection can zoom in or out but has a
minimum size that is surprisingly coarse
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Region of selection can zoom in or out but has a
minimum size that is surprisingly coarse
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5. Temporal Attention
individuate events at slow speed
vs a rush of undifferentiable flicker
Focused attention improves representation in time
as well
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Deficits in attention
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Right parietal damage leads to inattention to
objects on the left (Spatial Neglect)

• Clothes
• Medawar slides
• Dinner plate
• Draw a clock

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Artists self portraits as he recovers from
neglect
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Right-parietal patient shows spatial neglect of
left side
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Imagery and neglect
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• LEFT hemisphere sees the TREE

• RIGHT hemisphere sees the FOREST

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Balints syndrome

• Bilateral parietal damage
• Can only attend to one thing at a time

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Attentional Deficit Hyperactivity Disorder
Problems with attention span, concentration,
distractibility, impulsivity, and
hyperactivity Difficulty remaining seated, easily
distracted, fidgets, often interrupts, can't play
quietly, loses things, talks impulsively or
excessively, doesn't seem listen. Affects about
3 to 5 percent of all children, can continue to
adulthood. Different attentional style Moderated
by stimulants
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Change Blindness

• demonstrations
• Helicopter
• Boats

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Real-life change blindness

• Dan Simons DOOR experiment

Cav 21.rm
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Change blindness attention

• We dont see changes until we ATTEND to specific
  part of field where change is
• Suggests we do NOT see the detailed picture of
  the world that we think we do.

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Thank you.