Page 82-112, 30 pages Page 1 of9
Chapter 4: Attention
• Attention: The ability to focus on specific stimuli or locations.
• Selective Attention: The focusing of attention on one specific location, object, or message.
• Overt Attention: Shifting attention by moving the eyes, as the movements provide observable signals
of how attention is changing over time.
• Covert Attention: Attention is shifted without eye movement
• Divided Attention: Attending to two or more things at once; can be overt, covert, or a combination
• “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,” according to William James.
• Selective attention not only highlights whatever is being attended, but keeps us from perceiving
whatever is not being attended to. This can occur with any of our senses – vision, hearing, smell, touch,
• Attention is a relatively distributed, rather than modular, process occurring over several brain areas
Selective Attention as Filtering
• Dichotic Listening (Cherry, 1953): Different messages are presented to the two ears. Participants are
instructed to pay attention to the message presented to one ear, repeating it out loud by shadowing [to
confirm their attention], and ignore the message presented to the other ear.
• The content of the unattended message is not processed or remembered, although the voice gender
could be identified.
• Early Selection Model (Broadbent): Sensory memory holds all incoming information for a fraction of a
o The filter then identifies the attended message based on physical characteristics (tone, pitch,
speed, accent), and lets only this message pass through while all others are filtered out – acts like
o The detector processes information to determine higher-level characteristics such as meaning.
o Short-term memory receives the output and holds the information for 10-15 seconds; may
transfer it into long-
• Cocktail Party Effect
(Moray, 1959): Disproves
Broadbent’s model since
certain information in the unattended message can still be accessible to the consciousness. This
information includes: the individual’s name, distinctive or emotional messages such as “Fire!”, taboo
words, and sexually explcit information.
• “Dear Aunt Jane” experiment with dichotic shadowing, where the attended ear received “Dear 7
Jane” and the unattended “9 Aunt 6”. However, rather than reporting “Dear 7 Jane”, participants report
hearing “Dear Aunt Jane”. This means the participant’s attention had jumped from one ear to the other,
taking meaning of the words into account with top-down processing.
• Attenuation Theory of Attention (Treisman 1964): Attenuator analyzes incoming message not only
in terms of its physical characteristics, but its language (grouping into syllables or words) and its
meaning. This analysis only proceeds so far as is necessary to identify the attended message. Page 82-112, 30 pages Page 2 of9
• Once identified, both are let through
the attenuator – but the attended at full
strength and the unattended at low
levels (still present but weak due to
• The message is analyzed by the
dictionary unit, which contains stored
words with differing thresholds of activation. Words which are common or especially important, such as
one’s name, have a low threshold – and can be detected even if obscured by other stimuli. Uncommon
words have higher thresholds and take a stronger signal to be activated, such as nonsense word
• Signal Detection Theory: A signal is a relevant stimulus that we detect after it passes the threshold of
activation. E.g. Brightness can be perceived after passed threshold for the number of photons activating
photoreceptors. In the attenuation theory above, different signals have different thresholds.
• These are examples of early selection theories, proposing a filter at an early stage in the flow of
• Late selection models propose that the incoming information is processed to the level of meaning
before the message to be processed is selected. Based on ambiguous sentences such as “They were
throwing stones at the bank” heard by the attended ear being influenced by biasing words presented to
the unattended ear – the unattended biasing word must have been processed to the level of meaning.
• The “early-late” controversy is not yet solved
Composite Face Effect
• Task is to look at the TOP halves of two sets of faces
while ignoring the bottom halves, and to determine
whether the tops are the same or different. The tops
and bottoms may either be aligned or misaligned.
• Showed that participants were unable to ignore the
bottom half of the face, with accuracy for whether the
tops are same or different being around 60% while
misaligned was close to 90%.
• Similarly, aligned condition had lower reaction time as
participants had to actively try to ignore the bottom half of the face, at 800ms versus 600ms for
misaligned. Supports idea that we process faces holistically (Gestalt).
Cognitive Resources, Cognitive Load, and Task-Irrelevant Stimuli
• Cognitive Resources: Cognitive capacity to be used for carrying out various cognitive tasks.
Cognitive load is the amount of a person’s cognitive resources needed to carry out a particular task.
• Low-load tasks are easy and well-practiced, using a small amount of cognitive resources, while high-
load tasks are difficult and require more.
• The amount of cognitive resources that is used up as a person is carrying out a primary task
determines how much remains, and therefore their ability to attend to another, task-irrelevant stimuli.
Flanker Compatibility Task
• Flanker Compatibility Task (Eriksen & Eriksen, 1974):
Task is to selectively attend to the target in the center
position, and to press the “z” key if either A or B are
presented in the center and the “m” key if either C or D is in
the center. They are told to ignore the “flanker” stimuli on
either side of the central letter which are task-irrelevant –
this may be A, B, C, D, or X. Page 82-112, 30 pages Page 3 of 9
• Compatible flankers are associated with the same response as the target, e.g. B is compatible to A
because “z” key is the response for both. Incompatible flankers are associated with a different
response, e.g. C requires pressing “m”. X is a neutral flanker since it is not associated with any
• The target activity of pushing a key is easy and wouldn’t use all of a person’s cognitive resources, so
the flanker stimuli should be processed even if
unintended. Indeed, this results in slower response
time with incompatible flankers than compatible or
neutral flankers – the incompatible stimulus and the
response it would elicit compete with the response
needed for the target stimulus.
• In original experiment, 5 conditions: 1 with noise
same as target had fastest reaction time, followed by 2 noise with a compatible response. Then,
conditions 5 (heterogenous noise that looks distinct from H) and 4 (heterogenous noise that looks
similar to H). The longest response time was noise with incompatible response in condition 3.
Increased Load Flanker Task
• The target stimulus “X” appears somewhere in a ring of 6 stimuli, and the flanker stimulus “N” is
presented off to the side. The target is told to press a different key for X and N; sometimes N is the target
and X is the flanker – in both cases, since they are associated with different responses, they are
• Sometimes the flanker presented is compatible: target is X and flanker is also X
• When “X” is embedded in a circle of “O”s, the task of responding to X is low-load. When “X” is
embedded in other letters that are more linear and similar, the task is high-load.
• The incompatible flanker
causes a slower response in
the low-load condition
(compared to the compatible low-
load condition), but has no effect
in the high-load condition
(compared to the compatible high-
• Because cognitive resources are
available in low-load, the
incompatible flanker intrudes to
cause slower responding; in high-
load, no cognitive resources are
available for the incompatible
flankers to affect response.
• Thus the ability to ignore task-
irrelevant stimuli is a function of both the load of the target task, and of how powerful the task-irrelevant
The Strop Effect
• Strop Effect: Difficult to name each stimulus by the colour of its ink instead of its meaning/content
(“White” printed in purple ink). Participants have automatized the process of reading, so the color names
of the words are always processed very quickly. On the other hand, identifying colors is not a task that
participants have to report on very often and, because it is not automatized, it is slower. The fast and
automatic processing of the color name of the word interferes with the desired reporting of the ink color.
• This allows researchers to test the behind-the-scenes properties of automatized behaviors by noting
their influence on more easily measured behaviors. Page 82-112, 30 pages Page 4 of9
• On each trial you are shown a word (RED, GREEN, or BLUE) that was printed in either red, green, or
blue font color. Your task was to classify, as quickly as possible, the font color, regardless of the word
• The independent variable in this experiment was whether the word name and font color were the same
or different. The dependent variable was the response time between the appearance of the stimulus and
• Word and Font Color Mean RT (ms)
Different 826.375 much slower due to conflict
Divided Attention with Practice: Automatic Processing
• Schneider & Shiffrin (1977): Divided attention to simultaneously hold memory info about a target
stimulus, and pay attention to a series of “distractor” stimuli to determine if the target is somewhere in
• First shown a memory set with target stimuli, such as “3”. Then rapid presentation of test frames that
contain distractors, which may or may not contain the “3” from the memory set.
• Consistent mapping condition where the targets and
distractors were from different categories, with target as a
number and distractor as a letter. Even if the memory set
target changes from trial to trial, this distinction is clear.
• At first, participants must repeat the target items in each
memory set to remember them. However, after 600 trials the
task became automatic and reached 90% accuracy –
attention could be divided successfully to deal with the target
and test items simultaneously
• Automatic Processing: Processing that occurs without intention, and at a low cost to cognitive
resources. These include everyday actions such as walking,
driving, or typing.
Divided Attention with Harder Tasks: Controlled Processing
• Now, varied mapping condition with rules that change from trial
to trial since the targets in the memory set and the distractors are
both letters. This means a target on one trial can be a distractor on
the next, and vice versa (target P on trial 1 is a distractor on trial 2,
while target T on trial 2 was distractor on trial 1).
• Performance on the consistent mapping condition reaches 90%
accuracy when the test frame duration is only 80s, while for varied
mapping condition performance needs 400ms presentation for
• Controlled Processing: Automaticity is never reached,
participants must pay close attention at all times, searching for the
target among distractors in a much more focused and controlled
Distractions while Driving Page 82-112, 30 pages Page 5 of 9
• There is a proven connection between cellphone use and traffic accidents. In a laboratory experiment,
participants did a simulated driving task where they had to apply brakes as quickly as possible to a red
• Participants who talked on a cellphone in this task missed 2x as many red lights, and had 100ms
slower reaction time in applying the brakes. This occurred regardless of whether the cellphone was
handheld or hands-free.
• Talking on the cellphone uses cognitive resources needed for driving, decreasing attention and
• Other distracting elements include GPS systems and menu screens, food, reading email, makeup, etc.
ATTENTION & VISUAL PERCEPTION
• Inattentional Blindness: Failure to notice an obvious unexpected object in the environment because
our attention is focused on something else – bottom-up since we do not notice a stimulus
• Mack & Rock (1998): Task to indicate which arm
of the cross was longer, the horizontal or vertical.
Then, on one trial, a small test object in the field of
vision was added to the display. In a subsequent
recognition test, the subject is told to pick out the
object that was presented – unable to because
paying attention to the cross had made them “blind”
to the unattended test object.
• Simons (1999): Film with two teams of basketball players. Observer told to count the number of passes
by the white team, and