Lange, K.
Heinrich Heine Universität Düsseldorf, Düsseldorf, Germany
Temporal expectations can induce an orienting of attention to the expected point in time. On a behavioral level, it has been consistently shown that this temporal orienting leads to faster responding to attended compared to unattended stimuli. Regardless of how exactly temporal expectations were induced, these behavioral effects have been accompanied by an enhancement of the P300 wave of the auditory event-related potential. This suggests that temporal orienting affects processes localized relatively late in the auditory processing stream. By contrast, effects of temporal orienting on early auditory processing (as measured by the auditory N1) are more diverse. Early effects depend on the underlying temporal expectations and on whether or not the timing of the stimuli can be anticipated reliably. In the talk, I will present data of three experiments in which temporal expectations were based on different experimental manipulations, leading to distinct effects of temporal orienting on the auditory N1. When temporal expectations were based solely on statistical properties of the stimulation, no effects of temporal orienting on the auditory N1 were observed. When temporal expectations were rhythmical, based on a regular (vs. an irregular) stimulus sequence prior to the critical tone, the effect of temporal orienting on the N1 depended on whether the sequence reliably predicted the tone’s onset or not. Reliable predictions of the tone’s onset were associated with a reduced N1. By contrast, rhythmic expectations lead to an enhancement of the auditory N1 when participants could not be certain about the timing of the tone. Thus, the present data suggest that effects of temporal orienting on early sensory processing steps depend crucially on the involved temporal expectations, whereas temporal orienting effects in later, response-related processing stages are independent of how exactly the underlying temporal expectations are achieved.