Flashcards in Control of cognition Deck (24)
what are executive control mechanisms?
Mind/brain has many specialised/domain-specific ‘modules’ available (for categorising, analysing/generating language, calculating, choosing actions, rehearsing, mental rotation etc)
control mechanisms must select and activate subset of processing ‘modules’ and organise, link and tune them to accomplish task
what processes don't happen from executive control mechanisms
All the time
Always in same way
Linked up in same way
selection/activation of single 'task-set'
Each object encountered affords many possible tasks
Task-set = appropriate organisation of perceptual, cog and motor resources to carry out task
To some extent select ‘at will’ which task-set to adopt according to current goals
To some extent env triggers familiar task-sets automatically (e.g. reading, recognising emotion, avoiding obstacles)
what are some other functions attributed to executive control?
Inhibiting inappropriate actions
‘Updating’: Selecting info for maintenance (/suppression) in WM
Managing search of LTM
Monitoring perf, troubleshooting, adjusting balance between accuracy and speed of perf
Coordinating aspects of multitasking, e.g. keeping diff info streams as segregated as pos, prioritising tasks
Sequencing, planning of multistep tasks esp. where actions required nonhabitual
what is the lure of the control homunculus?
i.e. attribution of control to unitary inner agent
examples of the lure of the control homunculus
Baddeley and Hitch (1974)
Norman and Shallice (1980/1986) - habitual/attractive/primed action/task-set wins unless SAS overrides
Gilbert and Burgess (2008)
how can we investigate control processes?
‘Natural history’ of control: Observation of:
- Failures of control in everyday life (some ‘action errors’
- Pathological failures of control after brain damage
Behavioural exps: Engage control processes in such as way that can isolate and study contribution to perf – in normal subjects/patients – e.g.:
- Exps on response conflict, e.g. Stroop effect
- Exps on task-switching
- Stop-signal exps
- Dual task and multitasking exps
And we can measure brain activity correlated with the exercise of control functions in these paradigms
what does systematic analysis of errors come from?
examples of types of control error
‘Capture’ errors – habitual/recently-exercised action patterns seize control of behaviour
‘Cross-talk’ errors – failure to keep separate elements of concurrent tasks, e.g.
- Picking up banana and holding it to ear instead of phone
- Concurrent writing and speaking (phonological code --> speech)
‘Lost intentions’: Failure to initiate intended action when ‘trigger conditions’ set in prospective memory occur
what happens with damage to the prefrontal cortex?
Imp of PFC for high level ‘organisation’ of behaviour suggested initially by clinical descriptions of patients with pre-frontal damage (Luria)
Neuropsych testing revealed several types control problems
Not always associated: Dissociations suggest fractionation of executive functions
examples of impairments due to PFC damage
- Inability to suppress habitual action to familiar object
- E.g. Wisconsin card sorting test
Difficulty in evaluative decision making
- E.g. Damasio’s (1999) patient J (orbito-frontal PFC)
- E.g. Strategy application disorder
what is the strategy application disorder?
Shallice and Burgess’s (1991) ‘multiple errands’ test (in shopping mall)
- Normal P’s path through mall
- P given money and instruction sheet: List of items to buy, info to find out, rendezvous and time, and some rules
- Perf of P with frontal lobe damage
- Disorganised perf:
- Subtasks not completed, ignored, repeated, done in inefficient order
- Rules broken
- Violations of social convention
- But not through lack of motivation
alternative explanations - no single executive 'homunculus'
Observed dissociations among impairments of exec control after brain damage argue against unitary ‘central exec’
- Instead, have distributed network of control mechanisms (in diff parts of PFC, basal ganglia and parietal cortex)
- Maintaining and controlling temp storage buffers small part of what exec control mechanisms do
how do we capture control in the lab?
Need to examine situs where need to:
- Suppress task-set/
- Reset control parameters/
- Inhibit actions, thoughts, memories, emotions/
- Manage multiple info flows
And try to isolate effects of demands on perf/brain activity from effects of task-specific process, arousal, emotion etc
what is the response conflict in Stroop's colour naming test?
Already have (in brains)
- Task-set for colour-naming
- Task-set for reading (much more practiced, habitual, ‘automatic’
Try to selectively attend to colour and apply naming task-set
But cannot (completely) suppress the reading task-set.
The difference in response time between the two conditions measures response conflict – which indexes the incompleteness of control.
what are some Stroop type inferences from habitual affordances?
Classic Stroop effect:
- RT (congruent) < RT (neutral) < RT (incongruent) - Green , ΔσφӨ , blue
How many digits
- 666 4444
Etc (See slides for more)
what is the Flanker effect response conflict triggered by application of instructed task set to irrelevant objects
5 letters will appear: Attend to central one: Press left key if S and right if H
comparing task switched and repeats in task-cueing exp
E.g. Monsell, Summer and Waters, 2003)
On each trial, coloured shape )(task cue) appeared, then digit in centre, P responds with left/right hand
- Pink background odd/even
- Blue background low/high
Task changed predictably every 4 trials – cue-stimulus interval varied
why is there a reduction in switch cost with prep?
Interval available for prep between response/cue and next stimulus 50, 650/1250 ms.response
what brain activity is associated with task-set reconfiguration?
Stimulus is word with letter coloured
Cue specifies task:
- Categorise word semantically (living/non-living)
- Decide whether colour pattern symmetrical
what is the neuroimaging response conflict and task-set prep?
MacDonald et al (2000)
Anterior cingulate cortex (ACC) activated more after incongruent than congruent stimuli: ‘Conflict detector’
Left lateral dorso-lateral prefrontal cortex (L.DLPFC) activated by prep for (harder) colour-naming more than by prep for word-naming: Task-set maintenance/suppression of stronger task set
what is the task-switch imaging 'task-set inertia' with fMRI
Stimulus = word on face
Classification tasks in runs of 4
- Word by no. syllables
- Face by gender
RT switch cost on first trial of run
In separate blocks ‘localiser’ tasks established word- and face- selective regions of activation (left Inferior Temporal Gyrus and right Fusiform Gyrus respectively)
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
which processes are prolonged on task-switch trial?
Elchepp et al (2015) manipulated word freq: Effect shows up in ERP from 280ms
Onset of freq effect delayed on switch trials by substantial fraction of residual RT switch cost (50 +- 12ms)
Early processes prolonged on switch trials: Attentional inertia?