Psychophysiology
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Studies investigating the feedback-related negativity (FRN) and the P300 following near misses, full misses, and wins have yielded inconsistent results. Furthermore, the P300 results were likely confounded by an oddball effect due to the probabilities of the different outcomes. We introduced a fourth outcome (narrow win), which allows for balanced outcome probabilities and thus rules out potential oddball effects. ⋯ The FRN was larger following misses compared to wins and larger following near compared to full outcomes. For the P300, we observed a larger positivity following wins compared to misses and full compared to near outcomes. These findings further corroborate that near and full outcomes are processed as distinct events even though they result in the same monetary outcomes.
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Current research suggests that we can watch visual working memory surrender the control of attention early in the process of learning to search for a specific object. This inference is based on the observation that the contralateral delay activity (CDA) rapidly decreases in amplitude across trials when subjects search for the same target object. ⋯ We show that the decline in CDA amplitude occurred even when the target objects were consistently lateralized to a single visual hemifield. Our findings demonstrate that reductions in the amplitude of the CDA during learning are not simply due to the dilution of the CDA from interhemispheric cancellation.
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We studied the temporal stability of individual differences in the acquisition and generalization of fear. Seventy-one participants were tested in two almost identical fear-acquisition and fear-generalization sessions (separated by 8 months). Acquisition and generalization were measured by the fear-potentiated startle, the skin conductance response, and online expectancies of the unconditioned stimulus. ⋯ Acquisition and generalization did not differ across sessions or as a function of the stimuli used in Session 2, and a significant proportion of individual differences in these processes was stable over time (generalizability coefficients ranged from 0.17 to 0.38). When the same stimuli were used, acquisition measures showed compromised stability. The results are discussed in terms of their theoretical and applied implications.
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Pain sensitivity decreases with exercise. The mechanisms that underlie this exercise-induced hypoalgesia (EIH) are unclear. Our purpose was to investigate conditioned pain modulation (CPM) as a potential mechanism of EIH. ⋯ Effect size calculations showed that the size of the hypoalgesic response was greater following painful exercise than nonpainful exercise. Our results suggest that exercise-induced muscle pain may contribute to the magnitude of EIH. However, as pain sensitivity also decreased following nonpainful exercise, CPM is not likely the primary mechanism of EIH.
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We recorded ERPs to investigate whether the visual memory load can bias visual selective attention. Participants memorized one or four letters and then responded to memory-matching letters presented in a relevant color while ignoring distractor letters or letters in an irrelevant color. Stimuli in the relevant color elicited larger frontal selection positivities (FSP) and occipital selection negativities (OSN) compared to irrelevant color stimuli. ⋯ Response mapping complexity was also modulated but did not affect the FSP and OSN. Together, the FSP data suggest that high memory load increased distractability. The OSN data suggest that memory load sustained attention to letters in a relevant color until working memory processing was completed, independently of whether the letters were in working memory or not.