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The aim of this study was to compare the effect on interval discrimination of the presentation of disgusting mutilation images and the presentation of faces expressing disgust. In Experiments 1 and 2, participants had to say whether the second of two images was presented for a shorter or a longer duration than the first (intervals = 400 ms vs. 482 ms). Although the overall probability of responding "long" was not exactly the same in these two experiments, participants reported that duration was longer more often when disgusting mutilation images were presented than when neutral or disgusted faces were presented. In Experiment 3, in which a single-stimulus method was employed, mutilation images were once again reported to be presented for a longer duration than neutral or disgusted faces. The investigation also reveals that discrimination levels are not higher when mutilation images are presented. It is argued that the effect of mutilation images on perceived duration is not due to attention; it is rather attributed to the increased arousal caused by these images.

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The main objective of the present study was to determine whether event-related potentials (ERPs) predominant in prefrontal cortex (PFC) respond in a similar fashion to ERPs predominant in posterior parietal cortex (PPC) in duration and size discrimination tasks. The results indicate that contingent negative variation (CNV) and P300 components changed according to task demands. In the time-related task, amplitudes and duration of both components increased as a function of stimulus duration and easier discriminability. This was not the case in the size discrimination task. These results are in accordance with the hypothesis of a functional link between PFC and PPC in timing behavior. The later-appearing LPCt component was observed in both tasks, but its amplitude increased only as a function of stimulus duration.

Recently, a late positive component (LPCt) with prefrontal dominance was identified in a duration discrimination task as a marker of decision-making processes (Paul et al., 2003). In the present study, LPCt amplitudes and latencies were measured in visual and size discrimination tasks for the purpose of determining the selectivity of this phenomenon. LPCt amplitudes were larger and latencies shorter for longer stimulus pairs, at a time of maximal behavioral performances. Wave amplitudes were also larger for smaller stimuli, but were not directly related to behavioral performances. These results indicate that the LPCt is not specific to temporal discrimination but can reflect more general decision-making processes.