Control of Cognition

Question 1

How do modules link to the control of cognition?

Answer 1

• brain has many specialised/domain-specific modules available
• many processes don’t happen automatically/constantly/in same way/linked up in the same way
• control mechanisms select and activate a subset of processing modules and organise, link, and tune them to accomplish a task

Question 2

What is the selection/activation of a single task-set?

Answer 2

• each object we encounter affords many possible tasks
• task-set (appropriate organisation of perceptual, cognitive and motor resources to carry out task)
• to some extent we select at will which task-set to adopt according to current goals
• to some extent the environment triggers familiar task-sets automatically

Question 3

What are other functions attributed to executive control?

Answer 3

• inhibiting inappropriate actions
• updating (selecting info for maintenance in working memory)
• managing search of long-term memory
• monitoring performance, troubleshooting, adjusting the balance between accuracy and speed of performance
• coordinating aspects of multitasking
• sequencing and planning of multistep tasks especially where the actions required are non-habitual

Question 4

How does prefrontal cortex damage link to control problems?

Answer 4

• it’s suggested that it’s important for high-level organisation of behaviour
• neuropsychological testing has revealed several types of control problems

Question 5

What are examples of impairments due to prefrontal cortex damage?

Answer 5

• utilisation behaviour
• perseverance
• difficulty in evaluative decision making
• disordered planning

Question 6

How is the belief of a homunculus incorrect?

Answer 6

• that there’s one single executive center when there isn’t
• observed dissociations among impairments of executive control after brain damage argue against the unitary executive
• we have distributed network of control mechanisms instead

Question 7

What are errors of control in everyday life and what are the examples of these errors?

Answer 7

• systematic analysis of such errors comes from diary studies and accident inquiries
• capture errors: habitual or recently exercised action patterns seize control of behaviour
• cross-talk errors: failure to keep separate elements of concurrent tasks
• lost intention: failure to initiate intended action when trigger conditions set in prospective memory occur

Question 8

How is control captured in the lab?

Answer 8

• need to examine situations where they need to: suppress task-set, reset control parameters, inhibit actions/thoughts/memories/emotions, manage multiple information flows
• try to isolate the effects of these demands on performance from effects of task-specific processes, arousal, emotion

Question 9

What is the response conflict in Stroop’s colour naming test?

Answer 9

• we already have a task-set for colour naming and a task-set for reading (more practiced)
• we try to selectively apply the naming task-set but can’t suppress the reading task-set
• fastest when both task-sets afford same response, slower when word doesn’t help and slowest when we can read the word but it’s in a different colour

Question 10

What is the flanker effect?

Answer 10

• 5 letters appear and have to attend to the central one, left if S and right if H
• incongruent (HHSHH) has slower response than neutral (PPSPP) which has slower response than congruent (SSSSS)
• spread of attentional spotlight allows flankers to activate response
• lateralised readiness potential: electrical activity in the activation of the competing response is already quite large, activation of the response for incongruent is nearly as large as it is for congruent

Question 11

What is the comparison of task switches and repeats in a task-cueing experiment?

Answer 11

• on each trial 1 of 2 task cues appeared (letter/string or number/digit) followed by compound stimulus and need to classify letter as vowel/consonant or number as odd/even
• task was same/switched and congruent/incongruent
• response congruence effect indicates facilitation/conflict from activation of response appropriate for other task, effect is larger on the trial where the task switches
• the other task-set is still active, not completely disabled
• reaction times for task switch are much larger, preparation interval is higher

Question 12

What is the neuro-imaging of response conflict and task-set preparation?
(MacDonald et al, 2000)

Answer 12

• anterior cingulate cortex (ACC) activated more after incongruent than congruent stimuli
• left lateral dorso-lateral prefrontal cortex activated by preparation for word-naming: task-set maintenance/suppression of stronger task set

Question 13

What did imaging ‘task-set inertia’ with fMRI find?

Yeung et al, 2006

Answer 13

• stimulus was a word on a face and the task given would be either say how many syllables the word had/ decide which gender the face was
• classification tasks in runs of 4, the RT switch cost on the first trial of run
• in separate blocks ‘localiser’ tasks established word and face selective regions of activation
• switch-trial-related activation of face-specific area predicts RT cost of switching to word task and activation of word-specific area predicts RT cost of switching to face task

Question 14

How does stop-signal RT measure response inhibition?

Answer 14

• choice RT but on some trials a tone signals when not to respond, vary stop-signal delay to find time required to inhibit response
• right inferior frontal gyrus, pre-SMA and basal ganglia associated with stopping, when rTMS is applied to inferior frontal gyrus it imapirs stopping
• in ADHD adults stopping is impaired but go RT isn’t leading to impulsivity