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The intradimensional/extradimensional set shift task, (also called the attentional set shifting paradigm) was originally designed to test primates and is an analogue to the human Wisconsin Card Sorting Task, which assess frontal lobe functioning. These tasks all have in common a primary measure which gauges a subject’s ability to shift attention between the perceptual features of complex stimuli.
For example, a human may sort a deck of cards according to the color of the cards (receiving feedback that she was correct with each sort). Unbeknownst to the subject, the sorting rule changes (perhaps switching to sorting by suit). Feedback that the old sorting rule (color) is now incorrect prompts the subject to figure out the new rule. Normal subject eventually learn the new rule (sorting by suit) and can readily make the switch to the new rule. Interestingly, humans with frontal lobe damage find it difficult to switch to the new rule (even after they learn it) and tend to perseverate on the old rule.
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The rodent version capitalizes on the rodent’s rather pronounced olfactory abilities. In this version of the task following the correct rule is followed by a small food reward. This set-shifting task involves a series of discrimination problems using a compound stimulus which differs along two dimensions: digging medium and odor. Each discrimination problem involves a pair of terracotta pots; one deemed the “correct” choice, based on either digging medium or odor. Animals progress through a series of food-rewarded discriminations which includes a simple discrimination, a compound discrimination, an intradimensional shift (IDS), and an extradimensional shift (EDS), as well as tests of reversal learning.For the IDS, animals have to maintain their attention to the same dimension when confronted with new pairs of stimuli. The EDS requires animals to shift attention away from the previously reinforced perceptual dimension (e.g., digging medium) to the previously irrelevant dimension (e.g., odor). |
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