The octave illusion revisited again.
ABSTRACT The octave illusion (D. Deutsch, 1974) occurs when 2 tones separated by an octave are alternated repeatedly, such that when the right ear receives the high tone, the left ear receives the low tone, and vice versa. Most subjects in the original study reported hearing a single tone that alternated from ear to ear, whose pitch also alternated from octave to octave, and D. Deutsch (1975a) proposed an explanation in terms of separate what and where auditory pathways. C. D. Chambers, J. B. Mattingley, and S. A. Moss (2002) argued that the perceived pitch difference generally corresponds more to a semitone and proposed an alternative explanation in terms of diplacusis. This article argues that Chambers et al. used problematic procedures and reports a new experiment on the octave illusion. The findings confirm that an octave difference is generally perceived, and they agree with the model of Deutsch (1975a) but are at variance with the diplacusis hypothesis.
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Article: The octave illusion revisited again.
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ABSTRACT: Most right-handers perceive an octave illusion when they are presented with a 400 Hz tone to one ear and with a 800 Hz tone to the other ear simultaneously, and when the tones continuously reverse between the ears: instead of the correct sound sequence, the subjects typically report a high tone in the right ear alternating with a low tone in the left. To study the neural basis of the illusion, we recorded neuromagnetic responses to binaural 400 and 800 Hz tones in different combinations. In the auditory cortex of each hemisphere, the 100 ms response (N100m) was stronger to pairs where the 800 Hz tone was presented to the contralateral ear and the 400 Hz tone to the ipsilateral ear than vice versa. The sustained fields tended to behave in an opposite manner. We suggest that the perceived locations of the sounds in the octave illusion follow the N100m lateralization, and the percept is contributed by streaming by the ear.Neuroreport 06/2000; 11(7):1469-72. DOI:10.1097/00001756-200005150-00021 · 1.64 Impact Factor
Chapter: 6 Grouping Mechanisms in Music01/2013;
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ABSTRACT: Artwork can often pique the interest of the viewer or listener as a result of the ambiguity or instability contained within it. Our engagement with uncertain sensory experiences might have its origins in early cortical responses, in that perceptually unstable stimuli might preclude neural habituation and maintain activity in early sensory areas. To assess this idea, participants engaged with an ambiguous visual stimulus wherein two squares alternated with one another, in terms of simultaneously opposing vertical and horizontal locations relative to fixation (i.e., stroboscopic alternating motion; von Schiller, 1933). At each trial, participants were invited to interpret the movement of the squares in one of five ways: traditional vertical or horizontal motion, novel clockwise or counter-clockwise motion, and, a free-view condition in which participants were encouraged to switch the direction of motion as often as possible. Behavioral reports of perceptual stability showed clockwise and counter-clockwise motion to possess an intermediate level of stability compared to relatively stable vertical and horizontal motion, and, relatively unstable motion perceived during free-view conditions. Early visual evoked components recorded at parietal-occipital sites such as C1, P1, and N1 modulated as a function of visual intention. Both at a group and individual level, increased perceptual instability was related to increased negativity in all three of these early visual neural responses. Engagement with increasingly ambiguous input may partly result from the underlying exaggerated neural response to it. The study underscores the utility of combining neuroelectric recording with the presentation of perceptually multi-stable yet physically identical stimuli, in revealing brain activity associated with the purely internal process of interpreting and appreciating the sensory world that surrounds us.Frontiers in Human Neuroscience 08/2011; 5:73. DOI:10.3389/fnhum.2011.00073 · 2.90 Impact Factor