Transition zone: Influence of pause duration on temporal reproduction

In contrast to the concept of objective time being continuous as described in classical physics, in psychology and cognitive neuroscience it has been discussed and studied since a long time whether subjective time has to be understood as being continuous or discrete. It has been demonstrated on the basis of different experimental conditions and with different research paradigms that subjective time does not match directly objective time. Different mechanisms of temporal processing have been disclosed in studies on the question how subjective time relates to objective time. One such mechanism is reflected in a low-frequency “time window” of 2 to 3 seconds which has been confirmed in many studies; it can be understood as a pre-semantic and automatic integration mechanism. One experimental paradigm in such studies is the temporal reproduction task. Previous studies mostly focused on how standard durations influence cognitive processing; the influence of pause durations for reproduction of temporal intervals has been neglected. Some preliminary research suggests, however, that in fact pause durations between stimulus presentation and its reproduction may play an important role. In the research presented here, the influence of pause duration was systematically investigaed with a behavioral paradigm and an EEG study. Experiment 1 used pause durations from 1 to 16 seconds as independent variable and investigated how various pause durations may effect the reproduction of a 2 second standard interval. Results showed that when pause durations were below 4 seconds, the reproduced durations increased and then levelled off. To further explore whether this effect only applied to 2 second standard intervals, a 3 and 4.5 second was added as standard stimulus in the second experiment. It was observed that the reproductions for different standards showed the same pattern, i.e., a transition zone of reproductions up to 4 seconds was observed, before a “plateau” or subjective set point of constant reproductions was reached. Experiment 3 employed longer pause durations by excluding short pause durations, and in this case no transition zone was observed which confirmed the critical role of pause duration for cognitive processing, and substantiates the existence of a low frequency time window of 2 to 3 seconds. Different standard and reproduced auditory stimuli were applied in experiment 4 to test a potential dependence of reproduction on stimulus characteristics; no such effect was observed supporting the notion of a generalized temporal reproduction mechanism for a 2 to 3 second time window. Experiment 5 using measurements with EEG examined possible neural indicators for the pause duration effect. Precisely timed and intense low-beta activities in the EEG across the entire cortical mantle were observed in the reproduction phase only up to a 3 second pause duration. This observation suggests the neural entrainment of a very low frequency oscillation or temporal integration interval by the onset of the standard to be reproduced. Thus, the low-beta activity as a neural marker may indicate the representation of a temporal stimulus in working memory.