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These errors are considered a measure of participants' ability to adapt to contingency changes, and they are the most commonly used indices of reversal learning performance across species. The errors made after the reversal are often termed "perseverative errors". After learning criterion has been reached (e.g., 8 consecutively correct responses), the probabilities of receiving positive feedback reverse such that the image that was previously correct 80% of the time is now only correct 20% of the time. Typically, one of the images is correct 80% of the time. Although there are several variants of the PRLT, the most commonly used involves choosing the correct image in a pair of simultaneously presented images given probabilistic feedback (Swainson et al., 2000). For example, in a concurrent discrimination task in which participants must choose between A or B and A is initially reinforced during acquisition, participants must learn that A is no longer reinforced during the reversal stage and choose B. The PRLT, like other reversal learning tasks, includes initial learning stages (acquisition) followed by a reversal stage in which stimulus-response contingencies change and participants must re-learn new associations. Evidence for genetic associations with this feedback sensitivity bias has also been found (Frank et al., 2007). When off dopamine agonist medications, PD patients are more likely to learn by avoiding negative feedback, but rely on positive feedback more when on medications. The tendency to choose A versus avoiding B is associated with several neuropsychiatric phenotypes, most notably observed in Parkinson's patients (Frank et al., 2004). E), and a bias towards learning from negative feedback is derived by the number times that the lowest probability card is avoided (B vs. A bias towards learning from positive feedback is determined by the number of times participants choose the highest probability card (the card receiving the most positive feedback) relative to the others (A vs. Participants are required to make a choice given these novel pairs without receiving feedback. After training, to assess whether participants learn more from positive or negative feedback, the cards are recombined in a "probe" phase, such that each card is paired with every other card.
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Learning may be achieved either by choosing the card associated with positive feedback or by avoiding the card associated with negative feedback. Over time, participants learn to choose the higher probability cards - choosing A, C, and E most of the time. For CD, choosing C leads to positive feedback 70% of the time, and E in EF 60% of the time. For pair AB, choosing A is associated with positive feedback 80% of the time (B 20% of the time).
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Each pair is associated with different probabilities. In the typical implementation of the PST (Frank et al., 2004), three pairs of cards are presented and participants must learn the "correct" card in each pair. Both tasks involve initial training periods in which participants must learn appropriate responses given probabilistic feedback ("noisy" feedback). The probabilistic reversal learning task, originally developed by Trevor Robbins and Robert Rogers (Lawrence et al, 1999 Swainson et al., 2000), examines participants' ability to adapt to changes in learned contingencies. Initially designed by Michael Frank, the probabilistic selection task is specifically used to determine participants' tendencies to learn either from positive or negative feedback (e.g., Frank et al., 2004). Both have been extensively used to determine reinforcement learning biases and behavioral flexibility in both healthy and patient populations. These tasks both involve reinforcement learning and were designed to assess feedback sensitivity and behavioral flexibility, respectively.
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The CNP "RL" task contains two tasks embedded in one - a probabilistic selection task (PST) and a probabilistic reversal learning task (PRLT).