Chapter 4
Lecture Outline
Paying Attention
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Chapter 4: Paying Attention

Lecture Outline
 Selective Attention
 Divided Attention
 Practice
© 2010 by W. W. Norton & Co., Inc.
Selective Attention

Selective attention refers to the skill through
which one focuses on one input or one task
while ignoring other stimuli.
© 2010 by W. W. Norton & Co., Inc.
Selective Attention

Attention studies sometimes employ a task
known as shadowing.
 Using
headphones, different information is
presented to each ear. This is known as
dichotic listening.
 The participant pays attention to the
information presented to one ear (the
attended channel) while ignoring information
presented to the other (the unattended
channel).
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Selective Attention
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Results from these studies suggest that unusual
characteristics of the unattended channel go unnoticed.
Similar effects happen in visual studies, e.g., in a classic
study, participants asked to count the number of
basketball passes failed to notice a person in a gorilla
suit enter the scene.
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Selective Attention

There are some important exceptions, where
certain pieces of information will be noticed even
if presented to the unattended channel.
 The
participants own name, or any words of high
personal significance, will be noticed even in the
unattended channel.

This pattern is observed in real-life situations
and sometimes called the cocktail party effect.
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Selective Attention
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Sometimes effects of attention are so strong that
we fail to see stimuli that are directly in front of
our eyes.
For instance, if participants are asked to look at
a fixation target while attending to another part
of the screen, they may fail to notice changes in
shape to the fixation target. This phenomenon is
known as inattentional blindness.
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Selective Attention

A phenomenon similar to inattentional blindness occurs
when a distracted person cannot find something in the
refrigerator, even if it is directly in front of the eyes.
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Selective Attention
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From studies of inattentional blindness, one
might be tempted to conclude that there is “no
perception without attention.”
However, other studies demonstrate that
unconscious perception still occurs in the
absence of attention.
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Selective Attention

For example, participants’ judgments of line
length are influenced by the presence of “fins”
that cause the Müller-Lyer illusion, even if they
do not consciously see the fins.
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
Other studies of attention focus on a
phenomenon known as change
blindness, the inability of observers to
detect changes in scenes they are looking
directly at.
 See if you can detect the differences
between the following pairs of pictures:

© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
Similar effects of change blindness occur
when people fail to notice continuity errors
in films.
 In a particularly striking example,
participants failed to notice when the
person asking them for directions changed
identity (following a brief interruption by
two people carrying a door).

© 2010 by W. W. Norton & Co., Inc.
Selective Attention
Early studies of attention focused on when
the perceiver selects the desired input.
 According to the early-selection
hypothesis, the unattended input receives
little to no analysis.
 According to the late-selection
hypothesis, all input receives analysis but
only the attended input reaches
consciousness or is remembered.

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Selective Attention

Both the early- and late-selection
hypotheses capture part of the truth.
 For
instance, the study discussed earlier
showing that unattended stimuli have effects
on perception seems to be a case of late
selection.
 However, the electrical activity of the brain for
attended versus unattended inputs differs
within 70 ms of stimulus presentation,
suggesting early selection.
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Selective Attention
An experiment by Posner and Snyder
(1975) illustrates that there are two kinds
of priming related to attention.
 One kind of priming is stimulus-based, the
other is expectation-based.
 For this type of study, the dependent
variable is the response time to make a
decision about the stimuli.

© 2010 by W. W. Norton & Co., Inc.
Selective Attention
© 2010 by W. W. Norton & Co., Inc.
Selective Attention

Posner and Snyder (1975) found in the
low-validity condition that the primed
condition was faster than neutral.
 This
demonstrates an effect of repetition
priming; the receptors were “warmed up.”

But, the misled condition was not any
slower than neutral.
 Warming
up the “wrong” detector does not
take activation away from the correct one.
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Selective Attention

Posner and Snyder (1975) found in the
high-validity condition that the primed
condition was much faster than neutral.
 This
demonstrates an additional effect of
expectation in addition to repetition priming.

Further, the misled condition was slower
than the neutral condition.
 Expectation
is limited in capacity; the
“wrong” expectation interferes with activating
the correct detectors.
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Selective Attention

Studies of spatial attention examine the ability
to focus on a particular position in space and to
be prepared for stimuli appearing in that
position.
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Selective Attention
For example, when detecting a stimulus
on the right or left side of the screen,
participants benefit if an arrow provides a
cue indicating on which side the stimulus
is about to appear (Posner et al., 1980).
 Note that directing spatial attention is
different than moving the eyes.

© 2010 by W. W. Norton & Co., Inc.
Selective Attention

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Spatial attention is
sometimes thought of
as a “searchlight.”
We can move this
searchlight in space,
as well as adjust the
size of the “beam.”
© 2010 by W. W. Norton & Co., Inc.
Selective Attention
Do we attend to positions in space or to
objects?
 Evidence from unilateral neglect
syndrome, caused by damage to the right
parietal lobe, could be argued to support a
space-based view. These individuals
cannot attend to the left side of space.
 However, some experiments suggest that
the deficit is also object-based.

© 2010 by W. W. Norton & Co., Inc.
Selective Attention

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Unilateral-neglect
patients attended to
the red circle, initially
presented on the
right, even after it
rotated to the left side
of the object.
Healthy participants
also show a mixture
of spatial and objectbased attention.
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Selective Attention

Summary of selective attention:
 Attention
involves both facilitating the
processing of desired input and inhibiting the
processing of unwanted input.
 Attention can be directed to both what the
object is as well at where it is in space.
 There is some flexibility in when the effects of
attention will take place (early or late).
 What we think of as attention is not a single
process or a particular mechanism.
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Divided Attention
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Divided attention
refers to the skill of
performing multiple
tasks simultaneously.
This is only possible
when the sum of the
tasks’ demands is
within the “cognitive
budget.”
Julius Caesar was
praised for his ability
to multitask.
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Divided Attention

Some cognitive resources are specialized.
 For
instance, verbal and spatial tasks can sometimes
be performed spatially because each draws upon
different resources.
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Divided Attention

Other cognitive resources are general.
 For
instance, speaking on a cell phone (even with a
hands-free device) interferes with the ability to drive,
even though the two tasks are seemingly very
different.
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Divided Attention

Several task-general cognitive resources
have been proposed, such as:
 A response
selector that is required for
selecting and initiating responses, both
physical and mental.
 A central executive that sets goals and
priorities, chooses strategies, and directs the
function of many cognitive processes.
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Divided Attention
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Executive control is strongly connected with
working memory.
It is also believed to inhibit automatic or habitual
responses when a situation requires a novel
response.
Kane et al. (2001) found that individual
differences in working memory did not predict
the ability to move the eyes towards a cue (the
automatic response), but did predict the ability to
move the eyes away from a cue (a novel
response).
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Practice

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As a task becomes
more practiced, it
requires fewer
cognitive resources.
As the ability
becomes more
automatic, executive
control and the
response selector are
needed less and less.
© 2010 by W. W. Norton & Co., Inc.
Practice

Why does practice improve performance?
tasks – like playing tennis, playing
the piano, or driving a car – can by
themselves create problems in divided
attention.
 With practice, components of the task change
from being a controlled process to being an
automatic one.
 Complex
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Practice

Controlled tasks are novel and require
flexibility in one’s approach.
 These
tasks require attention and cannot be
carried out if the person is busy with another
task.

Automatic tasks are well practiced and
do not require flexibility.
 These
tasks require little or no attention and
can be carried out if the person is also busy
with another task.
© 2010 by W. W. Norton & Co., Inc.
Practice
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The downside of
automaticity is seen
in tasks that require
the participant to
override an automatic
response.
The Stroop task
illustrates the high
automaticity of
reading.
Try to name the ink
color and do not read
the word.
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Practice


In this variant of the
Stroop task, try to
identify how many
symbols are present
in each row.
This also illustrates
the automaticity of
reading the numbers.
© 2010 by W. W. Norton & Co., Inc.
Practice

Summary of divided attention and practice:
 Tasks
require resources, and you cannot
“spend” more resources than you have.
 Some resources are task-specific, and others
are task-general.
 If two tasks make demands upon the same
resources, the result will be interference.
 Practice increases the automaticity of a task,
resulting in the need for fewer cognitive
resources.
© 2010 by W. W. Norton & Co., Inc.