| Abstract | Jones et al. in Journal of Experimental Psychology
Human Perception and Performance 21:293–307,
1995, showed that a temporal perturbation is easier to
detect in a 3:2 polyrhythm than in a single-stream isochronous
baseline condition if the two isochronous pulse
streams forming the polyrhythm are perceptually integrated:
integration creates shorter inter-onset interval (IOI)
durations that facilitate perturbation detection. The present
study examined whether this benefit of integration outweighs
the potential costs imposed by the greater IOI heterogeneity
and memory demands of more complex
polyrhythms. In “Experiment 1”, musically trained participants
tried to detect perturbations in 3:5, 4:5, 6:5, and 7:5
polyrhythms having one of two different pitch separations
between pulse streams, as well as in an isochronous baseline
condition. “Experiment 2” included an additional 2:5
polyrhythm, additional pitch separations, and instructions
to integrate or segregate the two pulse streams. In both
experiments, perturbation detection scores for polyrhythms
were below baseline, decreased as polyrhythm complexity
increased, and tended to be lower at a smaller pitch separation,
with little effect of instructions. Clearly, polyrhythm
complexity was the main determinant of detection performance,
which is attributed to the interval heterogeneity and/
or memory demands of the pattern formed by the integrated
pulse streams. In this task, perceptual integration was disadvantageous,
but apparently could not be avoided. |