We examined how impression (such as safety, pleasantness, and impact), as well as emotional arousal and valence, evoked by viewing a picture affects temporal resolution of visual processing and perceived picture duration. In the first experiment as an index of temporal resolution of visual processing, we measured the noticeable duration of a monochrome picture after presenting a color picture. In the second experiment, we measured the duration of the picture presentation, which was equivalent to the duration of the presentation of a gray rectangle that should not evoke specifically safe or pleasant impressions. We found that the minimum duration in which an observer could notice a monochrome image in viewing a dangerous picture was shorter than that in viewing safe pictures. We also found that observers overestimated the duration of the picture presentation in viewing dangerous pictures. However, there was no significant correlation between the results of the two experiments. These results suggest that the basis for improvement of the temporal resolution in visual processing differs from that for the elongation of the perceived duration.

We examined the effects of emotional response, with different levels of valence and arousal, on the temporal resolution of visual processing by using photos of various facial expressions. As an index of the temporal resolution of visual processing, we measured the minimum lengths of the noticeable durations for desaturated photographs using the method of constant stimuli by switching colorful facial expression photographs to desaturated versions of the same photographs. Experiments 1 and 2 used facial photographs that evoke various degrees of arousal and valence. Those photographs were prepared not only in an upright orientation but also in an inverted orientation to reduce emotional response without changing the photographs’ image properties. Results showed that the minimum duration to notice monochrome photographs for anger, fear, and joy was shorter than that for a neutral face when viewing upright face photographs but not when viewing inverted face photographs. For Experiment 3, we used facial expression photographs to evoke various degrees of arousal. Results showed that the temporal resolution of visual processing increased with the degree of arousal. These results suggest that the arousal of emotional responses evoked by viewing facial expressions might increase the temporal resolution of visual processing.

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