PSL440Y1 Chapter Notes - Chapter 7: Switching Barriers, Temporal Lobe, Brodmann Area 10

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Published on 8 Jun 2012
Chapter 7 – Executive Processes
Executive attention is the kind of selective attention that typically acts on the contents
of working memory and directs further processing so as to achieve some goal.
Executive processes organize our mental lives just as a corporate executive co-
ordinates a business’s activities. Thus, the function is administrative.
Executive processes are processes that modulate the operation of other processes and
are responsible for the co-ordination of mental activity so that a particular goal is
Executive processes are known as meta-processes i.e. all executive processes are meta-
processes but not every meta-process is an executive one because it may or may not co-
ordinate and control mental activity
The Frontal Lobe Connection
Frontal brain damage often occurs because of a closed head injury which is an injury
caused by an external bump that does not pierce the skull. This frontal lobe area is most
likely to get damaged since brain’s most sharpest and protruding ridge is adjacent to the
frontal lobes so a blow on the skull cuts deepest in the frontal lobes
The first evidence that executive processes are controlled by frontal lobes comes from
the study of Phineas Gage who suffered damage to the frontal lobe and as a result of
that lost the ability of social restraint.
Frontal lobe patients perform relatively normal on an IQ test but are incapable of
leading a normal life. They have all their cognitive components intact but they lose the
ability to organize, co-ordinate and control these components.
Patients with damage to the frontal lobe are rigid, inflexible, lack the ability to initiate
action or the ability to plan. They are monotone, express little emotion and require
continuous instructions. The deficit suggests that they lack the ability to self-monitor
and have trouble in switching attention
Frontal-lobe syndrome refers to the inability to sequence activities to achieve a goal
The area primarily involved is the prefrontal cortex which is present directly in front
of the pre-motor cortex and at its most posterior end has the Broca’s speech area
Prefrontal cortex is responsible for some of the more complex activities that human
carry out such as mentally sequencing a list of activities
Prefrontal cortex also acts like a co-ordinating center where is receives input from all
perceptual and motor areas and sends signal back to exert a top-down influence
Frontal executive hypothesis is the idea that every executive process is primarily
mediated by the prefrontal cortex
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Frontal Damage and the Frontal Hypothesis
A test that is designed for the patients with frontal lobe damage is called Stroop task
where the participant is asked to name the color of ink and ignore the content of the
word. The word and the color of the ink may be compatible or incompatible. Normal
participant’s accuracy level was high even when the word and the ink was incompatible
although took longer to respond in the incompatible condition. Frontal lobe patients
with damage to the dorsolateral prefrontal cortex had a significantly lower level of
Stroop task requires two executive processes; selective attention and inhibition which
are controlled by the prefrontal cortex
The question raised is whether a common mechanism underlines both attention and
Wisconsin card sort task is a test of frontal-lobe damage where 4 stimulus cards are
presented in front of the participant and each has a distinct style. The participant is then
given a deck of cards and is asked to match each card with those 4 model cards, but
they are not told the criteria of matching. Participants start by guessing the critical
attribute and by feedback eventually find out the right one. Then, the critical attribute is
changed and the participants switch to the new attribute. No difference was observed
between the normal participants and the participants with frontal-lobe damage but a big
difference was observed in their ability to switch attributes. Normal participants
successfully switch to the new attribute upon receiving feedback but the patients with
frontal lobe damage keep on making mistakes and fail to switch attributes. Therefore,
process of switching attention is compromised by frontal lobe damage
Tower of Hanoi problem where only one disk can be moved at a time, a bigger disk
cannot be placed on top of a smaller one. This task involves arranging the configuration
of disks in the working memory, selectively attending some disks while selectively
inhibiting others – moreover, continuously updating the new configuration of the
disks in the working memory each time after moving a disk, and then switching
attention to the new disks that are to be moved. This task also involves decomposition
of a bigger goal into smaller subgoals and therefore requires sequencing of steps
Patients with damage to the dorsolateral prefrontal cortex perform poorly on the Tower
of Hanoi problem; they tend to make many moves than normal participants to come up
with a solution
Alzheimer’s patients perform poorly on the frontal-lobe tasks because their prefrontal
cortex area gets affect.
Executive dysfunction refers to marked disorganization and failure in career
Five major Executive Processes
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1. Executive Attention
Executive attention directs subsequent processing and is required when multiple
mental representations operate in the working memory or multiple processes
operating on the mental representations compete for the control of cognition and
Executive attention determines which mental representation or process will gain
control e.g. in stroop task, the ink of the writing is allowed to gain control rather than
the content of the word
Another task called stimulus-response compatibility task is a measure of the
degree to which the assignment of the correct response to a stimulus matches with the
way people act naturally i.e. to what degree is the correct response provided
Compatibility effect is obvious where people are presented with a stimulus and
are required to press a key to indicate its presence with the hand that is on the same
side as the stimulus in the compatible trial. And in the incompatible trial the hand
on the opposite side is required to press a key to indicate the stimulus’s presence.
Participants are relatively quicker when the stimulus is presented on the same side as
that of the hand making the response than when it is presented on the opposite side.
Exact position of the stimulus is irrelevant.
The reason behind this is that in the compatible task, there is an automatic
connection between stimuli and responses. Since this connection is automatic, little
executive attention is required. However, in the incompatible task attention and
inhibiting of information is required which requires conscious extra cognitive work
A Neural Network Model of Conflict in Processing
This neural network model explains the information flow. According to this model,
information flows through 3 layers; input layer, hidden layer and the output layer.
The nodes are representations and the connections between the nodes are called
associations may vary in strength – but the assumption made here is that all the
associations have equal strength
For example in stroop task, imagine BLUE
i. Input layer; picks up blue and white in colour and blue and white in word.
Blue has to carry the inhibitory signal while white has to carry the excitatory
ii. Hidden layer; competition occurs in the occipital cortex between color blue
and white. Competition also occurs in the superior temporal cortex between the
word blue and white. Again, both the colour and word blue has to carry the
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