Grouping distinct, temporally separated sounds is assumed to follow Gestalt principles, such as similarity or proximity. In the auditory streaming paradigm, the probability of perceiving all sounds as part of the same repeating pattern (the integrated percept) increases when the interstimulus interval (ISI) is increased from medium to long intervals. However, ISIs shorter than 50 ms have not been systematically explored. Here we show that below ca. 60-ms intervals the direction of the effect of ISI on perception is reversed compared to longer ISIs: Decreasing the ISI increases the probability of the integrated percept. This suggests that temporal proximity plays a different role in auditory stream segregation at very short than at longer ISIs. As the effect of temporal proximity may vary among individuals, we tested whether the proportion of the integrated reports with short ISIs could be associated with individual differences in the temporal resolution of the central auditory system. We found that individual differences in the temporal integration threshold (as measured by a temporal order judgment task) correlated with the percentage of integrated percept reports in some of the short-ISI regions. Although this result cannot be regarded as strong evidence, it is compatible with the notion that temporal integration plays a role in auditory stream segregation at short ISIs. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Fatigue is a core symptom in many psychological disorders and it can strongly influence everyday productivity. As fatigue effects have been typically demonstrated after long hours of time on task, it was surprising that in a previous study, we accidentally found a decline of temporal order judgment (TOJ) performance within 5-8 min. After replicating prior relevant findings we tested whether pauses and/or feedback relating the participant's performance to some "standard" can eliminate or reduce this short-term performance decline. We also assessed whether the performance decline is specific to the processes evoked by the TOJ task or it is a product of either general inattentiveness or the lack of willingness to thoroughly follow the task instructions. We found that both feedback and introducing pauses between successive measurements can largely reduce the performance decline, and that these two manipulations likely mobilize overlapping capacities. Performance decline was not present in a similar task when controlling for the TOJ threshold and it was not a result of uncooperative behavior. Therefore, we conclude that the TOJ threshold decline is either specific to temporal processing in general or to the TOJ task employed in the study. Overall, the results are compatible with the notion that the decline of TOJ threshold with repeated measures represents a short-term cognitive fatigue effect. This objective fatigue measure did not correlate with subjective fatigue. The latter was rather related to perceived difficulty/effort, the reduction of positive affectivity, heightened sensitivity to criticism, and the best TOJ threshold.

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