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A new perceptual illusion reveals mechanisms of sensory decoding

Abstract

Perceptual illusions are usually thought to arise from the way sensory signals are encoded by the brain, and indeed are often used to infer the mechanisms of sensory encoding1. But perceptual illusions might also result from the way the brain decodes sensory information2, reflecting the strategies that optimize performance in particular tasks. In a fine discrimination task, the most accurate information comes from neurons tuned away from the discrimination boundary3,4, and observers seem to use signals from these ‘displaced’ neurons to optimize their performance5,6,7. We wondered whether using signals from these neurons might also bias perception. In a fine direction discrimination task using moving random-dot stimuli, we found that observers’ perception of the direction of motion is indeed biased away from the boundary. This misperception can be accurately described by a decoding model that preferentially weights signals from neurons whose responses best discriminate those directions. In a coarse discrimination task, to which a different decoding rule applies4, the same stimulus is not misperceived, suggesting that the illusion is a direct consequence of the decoding strategy that observers use to make fine perceptual judgments. The subjective experience of motion is therefore not mediated directly by the responses of sensory neurons, but is only developed after the responses of these neurons are decoded.

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Figure 1: The combined discrimination–estimation experiment.
Figure 2: Discrimination and estimation responses.
Figure 3: Summary data for all six subjects.
Figure 4: Subjective estimates in a coarse direction discrimination task.

References

  1. Eagleman, D. M. Visual illusions and neurobiology. Nature Rev. Neurosci. 2, 920–926 (2001)

    Article  CAS  Google Scholar 

  2. Gregory, R. L. Eye and Brain: The Psychology of Seeing 5th edn (Oxford Univ. Press, 1997)

    Google Scholar 

  3. Seung, H. S. & Sompolinsky, H. Simple models for reading neuronal population codes. Proc. Natl Acad. Sci. USA 90, 10749–10753 (1993)

    Article  ADS  CAS  Google Scholar 

  4. Jazayeri, M. & Movshon, J. A. Optimal representation of sensory information by neural populations. Nature Neurosci. 9, 690–696 (2006)

    Article  CAS  Google Scholar 

  5. Patterson, R. D. Auditory filter shapes derived with noise stimuli. J. Acoust. Soc. Am. 59, 640–654 (1976)

    Article  ADS  CAS  Google Scholar 

  6. Regan, D. & Beverley, K. I. Postadaptation orientation discrimination. J. Opt. Soc. Am. A 2, 147–155 (1985)

    Article  ADS  CAS  Google Scholar 

  7. Hol, K. & Treue, S. Different populations of neurons contribute to the detection and discrimination of visual motion. Vision Res. 41, 685–689 (2001)

    Article  CAS  Google Scholar 

  8. Parker, A. J. & Newsome, W. T. Sense and the single neuron: probing the physiology of perception. Annu. Rev. Neurosci. 21, 227–277 (1998)

    Article  CAS  Google Scholar 

  9. Dean, A. F. The variability of discharge of simple cells in the cat striate cortex. Exp. Brain Res. 44, 437–440 (1981)

    Article  CAS  Google Scholar 

  10. Tolhurst, D. J., Movshon, J. A. & Dean, A. F. The statistical reliability of signals in single neurons in cat and monkey visual cortex. Vision Res. 23, 775–785 (1983)

    Article  CAS  Google Scholar 

  11. Britten, K. H., Shadlen, M. N., Newsome, W. T. & Movshon, J. A. The analysis of visual motion: a comparison of neuronal and psychophysical performance. J. Neurosci. 12, 4745–4765 (1992)

    Article  CAS  Google Scholar 

  12. Huttenlocher, J., Hedges, L. V. & Duncan, S. Categories and particulars: Prototype effects in estimating spatial location. Psychol. Rev. 98, 352–376 (1991)

    Article  CAS  Google Scholar 

  13. Rauber, H. & Treue, S. Reference repulsion when judging the direction of visual motion. Perception 27, 393–402 (1998)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work was supported by a research grant from the NIH. We are grateful to B. Lau, E. Simoncelli, D. Heeger, M. Landy and N. Graham for advice and discussion.

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Correspondence to Mehrdad Jazayeri.

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Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

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Supplementary Information

This file contains Supplementary Methods, Supplementary Figures 1–3 with Legends and Supplementary Discussion. The Supplementary Information includes two Supplementary Figures detailing the fit of a more complete model to the data, a Supplementary Figure showing a breakdown of the data from Fig. 4, and a discussion of the possible role of response bias in the results reported. (PDF 622 kb)

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Jazayeri, M., Movshon, J. A new perceptual illusion reveals mechanisms of sensory decoding. Nature 446, 912–915 (2007). https://doi.org/10.1038/nature05739

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