Perceived intensity effects in the octave illusion.

We showed that there is an intensity aspect to the octave illusion in addition to the pitch and location aspects originally reported by Deutsch (1974). In Experiment 1, we asked participants to directly compare the stimulus giving rise to the illusion (ILLU) with one mimicking its most commonly reported percept (illusion consistent; IC) and showed that they were easily able to distinguish between the two. In Experiment 2, we demonstrated a clear difference between the perceived loudness of ILLU and IC when IC follows ILLU, but not when IC precedes ILLU. In Experiments 3 and 4, we showed that this effect depends on the alternation of high and low tones between the ears in an extended pattern. In Experiment 5, we showed that this difference in perceived loudness disappears if the interval between the ILLU and IC stimuli is sufficiently large.