Perceptual learning in temporal discrimination: asymmetric cross-modal transfer from audition to vision.

This study assessed possible cross-modal transfer effects of training in a temporal discrimination task from vision to audition as well as from audition to vision. We employed a pretest-training-post-test design including a control group that performed only the pretest and the post-test. Trained participants showed better discrimination performance with their trained interval than the control group. This training effect transferred to the other modality only for those participants who had been trained with auditory stimuli. The present study thus demonstrates for the first time that training on temporal discrimination within the auditory modality can transfer to the visual modality but not vice versa. This finding represents a novel illustration of auditory dominance in temporal processing and is consistent with the notion that time is primarily encoded in the auditory system.

Exogenous visual attention prolongs perceived duration.

Previous studies have shown that spatial attention prolongs the perceived duration of visual stimuli. Chen and O'Neill (Perception & Psychophysics, 63, 1229-1238, 2001) reported, however, the reversed result and thus challenged the generality of this attention effect. We therefore reinvestigated the influence of spatial attention on the perceived duration of visual stimuli in various experimental settings. In five experiments, perceived duration was longer for validly cued stimuli; thus, spatial attention was found to prolong perceived duration. In a further experiment, the specific conditions were such that neither the attention effect nor the reversed pattern, as found by Chen and O'Neill, emerged. Although we cannot provide a conclusive account of why Chen and O'Neill observed the reversed attention effect, the present results reinforce the generality of the spatial attention effect on perceived duration but also make advisable a systematic examination of the factors that might modulate this effect.

Temporal preparation decreases perceptual latency: evidence from a clock paradigm.

A clock paradigm was employed to assess whether temporal preparation decreases the time to detect the onset of a stimulus-that is, perceptual latency. In four experiments participants watched a revolving clock hand while listening to soft or loud target tones under high or low temporal preparation. At the end of each trial, participants reported the clock hand position at the onset of the target tone. The deviation of the reported clock hand position from the actual position indexed perceptual latency. As expected, perceptual latency decreased with target tone intensity. Most importantly, however, greater temporal preparation decreased perceptual latency in all four experiments, especially for soft tones, which supports rather directly the idea that temporal preparation diminishes the duration of perceptual processing.

Does the asymmetry effect inflate the temporal expansion of odd stimuli?

Tse et al. (Percept Psychophys 66:1171-1189, 2004) reported that participants tend to overestimate the duration of an oddball stimulus. The size of this effect was much larger than the one reported by Ulrich et al. (Psychol Res 70:77-87, 2006). More crucially, the effect in the study of Tse et al. already emerged at short standard durations, arguing against the arousal account proposed by Ulrich et al. This study investigated whether the oddball effect reported by Tse et al. was inflated by an asymmetry effect, that is, by an asymmetrical distribution of physical comparison durations around the duration of the standard. Experiment 1 demonstrated that an asymmetry effect could mimic an oddball effect. Therefore, we conducted Experiment 2 to replicate the results by Tse et al. employing not only their original procedure but also an adaptive procedure that rather avoids an asymmetry effect. Both psychophysical procedures in this experiment revealed an oddball effect, which, however, was of smaller size than the one reported by Tse et al. Furthermore, this effect emerged only at longer standard durations, which is in agreement with the arousal account as the underlying mechanism of this robust temporal illusion.