Can a regular context induce temporal orienting to a target sound?

It has been shown recently (Lange, 2009) that the N1 of the auditory event related potential (ERP) is attenuated when the eliciting stimulus predictably follows a regular vs. an irregular sequence. This may be a sign of temporal orienting induced by the regular sequence. Alternatively, the attenuated N1 may have been due to sensory predictability of target timing. The present study investigated whether presenting a regular sequence still attenuates target N1 when target timing is unpredictable. A regular (vs. irregular) tone sequence was presented prior to a target tone, which appeared unpredictably at one of three different time points after the sequence. For the regular sequence, targets either continued regularity (on-time targets) or were early or late with respect to this regular time point. ERPs to on-time targets were compared as a function of sequence regularity. Consistent with the assumption that N1 attenuation reflects sensory predictability of target timing, an attenuated N1 was not observed in the present study, where target timing was uncertain.