7-WorkingMemory Flashcards
What is a task set?;
Preparation to perform one task rather than another; involves selecting, linking, enabling “modules” for task components (e.g., perception, response selection)
When do switch costs arise?
In establishing the appropriate task set & disengaging an inappropriate set
What does a typical switching task procedure involve?;
How do you avoid confounding practice & fatigue?
Usually simple responses to digits & letters (e.g. AABB, etc, where A is one task & B is another);
These are matched over switch trials and same-task trials
When the task changes, even though the task changes are regular and thus predictable, what is usually observed?
A severe switch cost of up to several hundred ms
Jersild (1927) found there were small switch costs if both stimuli and responses were different (e.g., number task alternating with word task). When were major costs incurred?;
Do participants occasionally forget what task is next?
When participants change the task and thus the response selection rule for a common stimulus configuration (attaching 2 response demands to the same set of stimuli becomes tricky);
No. No evidence of occasional slow trials; instead a general slowing over the RT distribution
There is a large literature showing that repeated stimuli are processed more easily (through pre-activation of their memory representations). When is this not the case?
When these repetition effects are controlled (e.g. same stimulus on every trial but cued to do different things with them), resulting in switch costs
In Rogers & Monsell’s (1995) AABB paradigm, digit-letter pairs appeared in one of 4 boxes & participants pressed right or left buttons for odd or even digits; & right or left for consonants or vowels in the letter task. How did they perform in switch tasks compared to non-switch tasks?
There was a large switch cost (even though task switches were predictable); a large improvement on day 2, especially for switch trials; similar performance for letter and digit tasks (similar difficulty)
What occurs with practice of separate tasks & switching tasks?
Costs are reduced but not eliminated
In relation to task difficulty, what incurs the greater cost?;
What does this result suggest about the roles of relevant task engagement vs. irrelevant task disengagement in switch costs?
Switching TO the easier / dominant task (e.g., from colour naming to word naming in Stroop task);
The prior difficult task requires effort & concentration so it’s hard to disengage (counter-intuitive)
Rogers & Monsell (1995) conducted a study with an emphasis on Task Set Re-configuration (TSR) prior to the switched task (had to change task set to meet demands of the next task). What was found?
Can maintain 2 task sets for different tasks & stimuli. But with different responses for the same stimuli, need to change task set when task changes (applying to a common set is harder to maintain)
In a task-cuing paradigm by Sudevan & Taylor (1987), participants made different judgements about digits. They were cued before the trial as to which task to perform & the cue to digit interval was manipulated (400 to 4000 ms). What was found?;
What factors confounded with these results?
Switch cost decreased as the interval increased to 2-3 sec (more time given, the lower the switch cost);
Preparation time with delay from the previous trial
Meiran (1996) had participants give the position of a disk (up, down vs. left, right); they were given a pre-trial cue. They maniplated cue-to-next-stimulus interval and last-response-to-cue interval. What was found?;
What does this suggest?
A short cue-to-stimulus interval led to a large switch cost even if there was a long delay from the last trial;
That it’s an active preparation effect, not just decay of effects of prior trial (involves both disengaging the past task and engaging the coming task)
Can adequate preparation remove the switch cost?
No, there is always a residual cost (so task preparation is not the whole story)
What kind of effects are residual costs?
Exogenous effects - “stimulus driven” (no matter how prepared you are you can’t do any decision-making for the next trial until the stimulus has been presented and identified)
Meiran found that response selection on switch trials is subject to interference from the prior trial, & that deciding on the response for the current stimulus may be affected by what?
The response associated with the stimulus for the alternative task (e.g. pressing L in one trial then R in the next)
In Roger & Monsell’s Task congruity trial with letter-digit stimuli, what was the effect between congruent & incongruent trials?;
What does this reflect?
Incongruent (R for letter, L for vowel) produced a slower reaction time than congruent (R for both);
Participants’ learning of responses for certain stimuli
In what ways do theories of the switch cost differ?
The role of active preparation (endogenous factor); the role of interference effect from prior task & task set that dissipate passively (with the passage of time); whether exogenous factors play a role
Describe the Disengagement theory by Alport et al.
Proactive interference occurs from “task set inertia” (TSI) – we hang on to the prior task; this decays after several minutes; but impairs adoption of the alternative task set
Explain the Endogenous component described by Rogers & Monsell;
The residual cost that cannot be removed by adequate preparation is due to what?
Preparation by participant requires time; switch cost is reduced as preparation time increases.
An exogenous component of the task set that must be triggered by the arrival of a suitable stimulus
Describe the Endogenous Only theory by de Jong
The residual cost arises because participants do not prepare adequately on every trial
As proposed by Nieuwenhuis & Monsell, 2002, what can we conclude about switch costs?
That even when motivation, fatigue & practice addressed, and RTs decrease, a residual switch cost remains, so it’s necessary to consider both endogenous & exogenous control
What is Kahneman’s capacity theory in regards to automaticity?;
According to this theory, what does substantial practice lead to?
Over-learned tasks become automatic & consume few resources;
Improves performance, reduces task effort; facilitates re-structuring and co-ordination of concurrent tasks
Shiffrin & Schneider gave participants a memory set for targets to be searched for in the upcoming trial, they then had to press a key as soon as they saw a target, or another key for no target. What were the key IVs for automaticity?
Size of memory set (2 vs. 4 letters); categorical/consistent mapping (targets came from one set of letters, & distractors from another set); mixed/varied mapping (targets and distractors came from one item set)
In Shiffrin & Schneider’s study, what was found in the categorical condition?;
What about the mixed condition?
Accuracy cost for larger memory set (4 vs. 2) but after practice, there’s no effect of memory set size - evidence of automaticity;
It’s impossible to use a simple response rule & become automatic; there’s always a cost of having a larger memory set (even after nearly 10,000 trials)
