Letter | Published:

Stereoillusion based on visual persistence

Naturevolume 256pages639640 (1975) | Download Citation



IF a moving vertical line is stroboscopically lit, it seems to undergo a multiplication, so that at any instant of time it is perceived as a series of lines, spread out in the direction of motion1–3. If the illumination going to the eye is reduced, the apparent multiplication increases3, suggesting possibly that the effect is a function of sensory integration time or “persistence” as it is affected by adaptation state of the eye2. Since the adaptation conditions of the two eyes are substantially independent4, it is interesting to ask what we should see if a stroboscopically moving target were viewed with a filter over one eye only, and the different numbers of apparent bars stereoscopically fused. In these conditions more bars should be signalled by the filtered than by the unfiltered eye, and it is not obvious what the fused percept will be.

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  1. 1

    Crawford, A., Bull. Br. Psychol. Soc., 17, 2A–3A (1964).

  2. 2

    Allport, D. A., Br. J. Psychol., 59, 395–406 (1968).

  3. 3

    Mollon, J., thesis, Univ. Oxford.

  4. 4

    Crawford, B. H., Proc. R. Soc., B 128, 552 (1940).

  5. 5

    Morgan, M. J., and Thompson, P., Perception (in the press).

  6. 6

    Edmund, C., Acta Ophthal., 6, 414–424 (1928).

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  1. The Psychological Laboratory, University of Cambridge, Cambridge, UK



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