Compulsory averaging of crowded orientation signals in human vision

Article metrics

Abstract

A shape can be more difficult to identify when other shapes are near it. For example, when several grating patches are viewed parafoveally, observers are unable to report the orientation of the central patch. This phenomenon, known as 'crowding,' has historically been confused with lateral masking, in which one stimulus attenuates signals generated by another stimulus. Here we show that despite their inability to report the orientation of an individual patch, observers can reliably estimate the average orientation, demonstrating that the local orientation signals are combined rather than lost. Our results imply that crowding is distinct from ordinary masking, and is perhaps related to texture perception. Under crowded conditions, the orientation signals in primary visual cortex are pooled before they reach consciousness.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Examples of experimental stimuli.
Figure 2: Orientation thresholds for classifying targets as clockwise or counterclockwise.
Figure 3: Results of foveal presentation (experiment 6).
Figure 4: Effect of distractor tilt.

References

  1. 1

    Bennett, A. & Rabbetts, R. Clinical Vision Optics (Butterworths, Frome, Somerset, UK, 1989).

  2. 2

    Bouma, H. Interaction effects in parafoveal letter recognition. Nature 226, 177–178 (1970).

  3. 3

    Westheimer, G. & Hauske, G. Temporal and spatial interference with vernier acuity. Vision Res. 15, 1137–1141 (1975).

  4. 4

    Levi, D., Klein, S. & Aitsabaomo, A. P. Vernier acuity, crowding and cortical magnification factor. Vision Res. 25, 963–967 (1985).

  5. 5

    Westheimer, G., Shimamura, K. & McKee, S. P. Interference with line-orientation sensitivity. J. Opt. Soc. Am. 66, 332–338 (1976).

  6. 6

    Andriessen, J. J. & Bouma, H. Eccentric vision: adverse interactions between line segments. Vision Res. 16, 71–78 (1976).

  7. 7

    Dakin, S. C. & Watt, R. J. The computation of orientation statistics from visual texture. Vision Res. 37, 3181–3192 (1997).

  8. 8

    Green, D. M. & Swets, J. A. Signal Detection Theory and Psychophysics (Wiley, New York, 1966).

  9. 9

    Palmer, J., Verghese, P. & Pavel, M. The psychophysics of visual search. Vision Res. 40, 1227–1268 (2000).

  10. 10

    Morgan, M., Castet, E. & Ward, R. Visual search for a tilted target: tests of the spatial uncertainty model. Q. J. Exp. Psychol. A 51, 347–370 (1998).

  11. 11

    Baldassi, S. & Burr, D. C. Feature-based integration of orientation signals in visual search. Vision Res. 40, 1293–1300 (2000).

  12. 12

    Hubel, D. H. & Wiesel, T. N. Receptive fields of single neurons in the cat's striate cortex. J. Physiol. (Lond.) 148, 574–591 (1959).

  13. 13

    Heeley, D. W. & Buchanan-Smith, H. M. Mechanisms specialized for the perception of image geometry. Vision Res. 36, 3607–3627 (1996).

  14. 14

    Morgan, M. J., Hole, G. J. & Ward, R. M. Evidence for positional coding in hyperacuity. J. Opt. Soc. Am. A 7, 297–304 (1990).

  15. 15

    He, S., Cavanagh, P. & Intriligator, J. Attentional resolution and the locus of visual awareness. Nature 383, 334–337 (1996).

  16. 16

    Wilkinson, F., Wilson, H. R. & Ellemberg, D. Lateral interactions in peripherally viewed texture arrays. J. Opt. Soc. Am. A 14, 2057–2068 (1997).

  17. 17

    Levi, D. M. & Klein, S. A. Hyperacuity and amblyopia. Nature 298, 268–270 (1982).

  18. 18

    Polat, U. & Sagi, D. The architecture of perceptual spatial interactions. Vision Res. 34, 73–78 (1994).

  19. 19

    Usher, M., Bonneh, Y., Sagi, D. & Herrmann, M. Mechanisms for spatial integration in visual detection: a model based on lateral interactions. Spat. Vis. 12, 187–209 (1999).

  20. 20

    Morgan, M. J. & Hotopf, N. Perceived diagonals in grids and lattices. Vision Res. 29, 1005–1015 (1989).

  21. 21

    Malik, J. & Perona, P. Preattentive texture discrimination with early visual mechanisms. J. Opt. Soc. Am. A 7, 923–932 (1990).

  22. 22

    Lin, L.-M. & Wilson, H. R. Fourier and non-Fourier pattern discrimination compared. Vision Res. 36, 1907–1918 (1996).

  23. 23

    Dakin, S. C. Orientation variance as a quantifier of structure in texture. Spat. Vis. 12, 1–30 (1999).

  24. 24

    Morgan, M. & Baldassi, S. How the human visual system encodes the orientation of a texture and why it makes mistakes. Curr. Biol. 7, 999–1002 (1997).

  25. 25

    Solomon, J. A., Watson, A. B. & Morgan, M. J. Transducer model produces facilitation from opposite-sign flanks. Vision Res. 39, 987–992 (1999).

  26. 26

    Solomon, J. A. & Morgan, M. J. Facilitation by collinear flanks is abolished by non-collinear flanks. Vision Res. 40, 279–286 (2000).

  27. 27

    Sagi, D. & Julesz, B. “Where” and “what” in vision. Science 228, 1217–1219 (1985).

  28. 28

    Solomon, J.A. & Morgan, M.J. Odd-men-out are poorly localised in brief exposures. J. Vision, http://journalofvision.org, 1, 9–17 (2001).

  29. 29

    Kolb, F. C. & Braun, J. Blindsight in normal observers. Nature 377, 336–338 (1995).

  30. 30

    Morgan, M. J., Mason, A. J. S. & Solomon, J. A. “Blindsight” in normal observers. Nature 385, 401–402 (1997).

  31. 31

    Crick, F. C. & Koch, C. Nature 375, 121–123 (1995).

  32. 32

    Efron, B. Bootstrap methods: another look at the jackknife. Ann. Statistics 7, 1–26 (1979).

  33. 33

    Pelli, D. G. & Zhang, L. Accurate control of contrast on microcomputer displays. Vision Res. 31, 1337–1350 (1991).

  34. 34

    Watson, A. B. & Solomon, J. A. Psychophysica: mathematica notebooks for psychophysical experiments (cinematica—psychometrica—quest). Spat. Vis. 10, 447–466 (1997).

Download references

Acknowledgements

This work was supported by a grant from the Engineering and Physical Sciences Research Council (EPSRC) of Great Britain. The experiments were carried out at the Institute of Cognitive Neuroscience, University College London.

Author information

Correspondence to Michael Morgan.

Rights and permissions

Reprints and Permissions

About this article

Further reading