Intra-Extra Dimensional Set Shift (IED)
Overview
Intra-Extra Dimensional Set Shift is a test of rule acquisition and reversal. It features: visual discrimination and attentional set formation maintenance, shifting and flexibility of attention
This test is primarily sensitive to changes to the fronto-striatal areas of the brain.
This test is a computerised analogue of the Wisconsin Card Sorting test, and is sensitive to cognitive changes associated with schizophrenia, Parkinson's Disease, and dopaminergic dependent processes.
Administration Time
Around 7 minutes, depending on level of impairment.
Task
Two artificial dimensions are used in the test:
- colour-filled shapes
- white lines
Simple stimuli are made up of just one of these dimensions, whereas compound stimuli are made up of both, namely white lines overlying colour-filled shapes. The participant starts by seeing two simple colour-filled shapes, and must learn which one is correct by touching it.
Feedback teaches the participant which stimulus is correct, and after six correct responses, the stimuli and/or rules are changed. These shifts are initially intra-dimensional (e.g. colour filled shapes remain the only relevant dimension), then later extra-dimensional (white lines become the only relevant dimension).
Participants progress through the test by satisfying a set criterion of learning at each stage (6 consecutive correct responses). If at any stage the participant fails to reach this criterion after 50 trials, the test terminates
Outcome Measures
This test has eighteen outcome measures, assessing errors, and numbers of trials and stages completed.
Test
Clinical mode (for testing once); seven parallel modes (for repeated testing).
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