Psych 351B: Midterm 2 Review (Central Executive)

Central Executive

Involved in executive attention

Switching executive attention from one activity to another

Ignoring/inhibiting information that has already been perceived

Scheduling a sequence of activities

Monitoring performance

Executive attention

Selective attention that acts on the contents of working memory and directs subsequent processing so as to achieve some goal

What can we say about the central exectuive

That it has to do with cognitive control, cannot treat it like a theory because it is simply a list of phenomena

Stroop test

One is shown a colour and a word and asked to either respond with the colour or the word (e.g. word is red and one must respond with either green or red depending on what is asked)

Stroop effect

The difference between the neutral and incongruent trials

T or F: those with frontal lobe damage (i.e. phineas gage) will do equally as well as controls when asked to name the word in the stroop test

T, test is asymmetrical, there is only an effect when naming the colour, not the word 

What is the computational model that is used to explain the stroop test

There are 4 inputs for the stroop test, the two words and the two colours, activating one colour node will inhibit the other node and lead to a response (denoted using a barbell)

Why are some arrows thicker in the computational model

Because there is a stronger response for words than for colours

What is the problem with the computational model

Has nothing that allows for prefrontal control, therefore the word will always be selected due to its activation being stronger, thus we need some form of cognitive control

What is the reason for a hidden/intermediate layer in the model

Required so the model will work properly, allows the model to learn

How is cognitive control accomplished in the computational model

Reverberatory loop on goal information, has two parts:

Conflict monitor - tests if output is congruent with goal or not, if not attention controller is activated

Attention controller - connects back the colour nodes to increase activation

What is the problem found regarding brain activation during the stroop test using an fMRI

Expect that frontal lobe would be locally activated when engaged in cognitive control, in fact activation is scattered, not confined to any area

Why is the stroop effect so much smaller on congruent trials

Because one can respond incorrectly (read the word not the colour), but because the colour and the word are the same, their response is correct

Stimulus onset asynchrony

The interval between the onset of the word and the onset of the colour

What is found regarding SOA polarity when the results of the stroop test is graphed

If SOA is negative - task irrelevant dimension proceeds the relevant one

If SOA is positive - task relevant dimension proceeds the irrelevant one

Why can it be said that the stroop effect is asymmetrical

Words interfere with colour naming but colours do not interfere with word naming

Horse race theory of stroop results

Argues that there are two horses, one for words and one for colour. The word horse is much faster than the colour horse and that if they arrive at the same time then there will be conflict

According to the horse race theory why must words always be suppressed when trying to read colour

Because the word will always arrive to control first, thus if one wants to read colour they must suppress responding with the word

What is the problem with the horse race theory

Claims that if colour gets enough of a head start (about 10th of a second) then colour and word should arrive at the same time and thus conflict will arise when asked to read the word. This is not the case, as there is no interference

What do the fMRI results tell us with regard to the instructional phase of the stroop test

Anterior cingulate - there is no change regardless of goal (read colour or word)

Dorsolateral PFC - change that causes increased activation when asked to read colour

What do the fMRI results tell us with regard to the incompatible/compatible trials phase of the stroop test

Anterior cingulate - more active on incompatible trials then compatible trials

Dorsolateral PFC - No difference between incompatible and compatible trials, activation is equivalent

What do the fMRI results from the stroop test tell us with regard to the dorsolateral PFC and anterior cingulate

Anterior cingulate - engaged in dealing with conflict

Dorsolateral PFC - engaged in planning

Both work together and share the workload to complete tasks

Simon task

One is to respond with left sided keypress to a triangle and right sided keypress to a circle, the location of the shape is irrelevant

Simon effect

One will respond slower when shape and location are incompatible (e.g. triangle is on the right side of the screen), takes about 10 ms (compared to stroop effect 50ms)

Where does activation flow during the stroop test in the brain

Flows from the attentional PFC to teh fusiform gyrus (for processing colour)

Where does activation flow during the simon task in the brain

Flows from the attentional PFC to the premotor cortex (this is much simpler as the premotor cortex can be activated without concious awareness)