Putting the tritone paradox into context: Insights from neural population decoding and human psychophysics

Bernhard Englitz, S. Akram, S. V. David, C. Chambers, Daniel Pressnitzer, D. Depireux, J. B. Fritz, Shihab A. Shamma

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations


The context in which a stimulus occurs can influence its perception. We study contextual effects in audition using the tritone paradox, where a pair of complex (Shepard) tones separated by half an octave can be perceived as ascending or descending. While ambiguous in isolation, they are heard with a clear upward or downward change in pitch, when preceded by spectrally matched biasing sequences. We presented these biased Shepard pairs to awake ferrets and obtained neuronal responses from primary auditory cortex. Using dimensionality reduction from the neural population response, we decode the perceived pitch for each tone. The bias sequence is found to reliably shift the perceived pitch of the tones away from its central frequency. Using human psychophysics, we provide evidence that this shift in pitch is present in active human perception as well. These results are incompatible with the standard absolute distance decoder for Shepard tones, which would have predicted the bias to attract the tones. We propose a relative decoder that takes the stimulus history into account and is consistent with the present and other data sets.

Original languageEnglish (US)
Title of host publicationBasic Aspects of Hearing
Subtitle of host publicationPhysiology and Perception
PublisherSpringer Science and Business Media, LLC
Number of pages8
ISBN (Print)9781461415893
StatePublished - 2013

Publication series

NameAdvances in Experimental Medicine and Biology
ISSN (Print)0065-2598

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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