Effects of auditory pattern structure on anticipatory and reactive attending.

In three experiments, participants listened for a target's pitch change within recurrent nine-tone patterns having largely isochronous rhythms. Patterns differed in pitch structure of initial (context) and final (target distance) pattern segments. Also varied were: probe timing (Experiments 2 and 3) and instructions about probe timing (Experiments 2 and 3). In all experiments, identification of a recurrent target was poorer in patterns with wider context pitch intervals (in semitones) than in others. Effects of probe timing also occurred, with better performance for temporally expected than unexpected probes. However, when listeners were explicitly told to focus upon a target's pitch and not its timing (Experiment 3), they performed selectively better in patterns with smaller target/probe pitch distances, especially for rhythmically expected probes. Five theoretical approaches to the respective roles of pitch and/or time structure were assessed. Although no single approach accounted for all results, a modification of one theory (a Pitch/Time Entrainment model) provided a reasonable description of findings.