OSA's Digital Library

Journal of the Optical Society of America A

Journal of the Optical Society of America A


  • Vol. 16, Iss. 12 — Dec. 1, 1999
  • pp: 2836–2844

Is motion processing unitary?

William A. Simpson, Velitchko Manahilov, and Melissa S. Mair  »View Author Affiliations

JOSA A, Vol. 16, Issue 12, pp. 2836-2844 (1999)

View Full Text Article

Enhanced HTML    Acrobat PDF (442 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



Motion discrimination space is conventionally categorized into motion detection, speed discrimination, and direction discrimination tasks. But an ideal observer uses a unitary motion mechanism that is affected only by the noise level and the difference in speed (or displacement) between two stimuli. We tested whether human performance in the various motion tasks showed the working of a unitary mechanism or the combined outputs of more than one mechanism. We examined the whole motion discrimination space, using random dots that underwent a sudden jump or displacement. The discriminability was measured as a function of the standard and comparison displacements. Both the ideal observer model and a nonideal observer model that contains additive internal noise predict a planar response surface. When the dot motion was noiseless, the planar surface fitted well except for much higher than expected sensitivity for motion detection. This is consistent with a purely temporal mechanism that uses flicker or a purely spatial mechanism that uses the length of time-averaged streaks. It is also consistent with a Weber’s law device. When motion noise was added to the displays, the planar response surface again fitted well, although the residuals showed the presence of a speed energy mechanism. We conclude that a unitary motion mechanism exists (nonideal observer model), although its performance may be supplemented by other mechanisms whose main impact is on discrimination of speeds near zero.

© 1999 Optical Society of America

OCIS Codes
(330.4060) Vision, color, and visual optics : Vision modeling
(330.4150) Vision, color, and visual optics : Motion detection
(330.5510) Vision, color, and visual optics : Psychophysics

Original Manuscript: March 9, 1999
Revised Manuscript: July 21, 1999
Manuscript Accepted: July 21, 1999
Published: December 1, 1999

William A. Simpson, Velitchko Manahilov, and Melissa S. Mair, "Is motion processing unitary?," J. Opt. Soc. Am. A 16, 2836-2844 (1999)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. W. A. Simpson, “Temporal summation of visual motion,” Vision Res. 34, 2547–2559 (1994). [CrossRef] [PubMed]
  2. S. P. McKee, “A local mechanism for differential velocity detection,” Vision Res. 21, 491–500 (1981). [CrossRef] [PubMed]
  3. O. Braddick, “A short-range process in apparent motion,” Vision Res. 14, 519–527 (1974). [CrossRef] [PubMed]
  4. S. P. McKee, S. N. J. Watamaniuk, “The psychophysics of motion perception,” in Visual Detection of Motion, A. T. Smith, R. J. Snowden, eds. (Academic, New York, 1994), pp. 85–114.
  5. A. D. Whalen, Detection of Signals in Noise (Academic, New York, 1971).
  6. W. M. Siebert, Circuits, Signals, and Systems (McGraw-Hill, New York, 1986).
  7. G. Finley, “A high-speed plotter for vision research,” Vision Res. 25, 1993–1997 (1985). [CrossRef]
  8. R. M. Steinman, “Effect of target size, luminance, and color on monocular fixation,” J. Opt. Soc. Am. 55, 1158–1165 (1965). [CrossRef]
  9. R. P. Scobey, C. A. Johnson, “Displacement thresholds for unidirectional and oscillatory movement,” Vision Res. 21, 1297–1302 (1981). [CrossRef] [PubMed]
  10. E. H. Adelson, J. R. Bergen, “Spatiotemporal energy models for the perception of motion,” J. Opt. Soc. Am. A 2, 284–299 (1985). [CrossRef] [PubMed]
  11. W. Reichardt, “Autocorrelation, a principle for the evaluation of sensory information by the central nervous system,” in Sensory Communication, W. A. Rosenblith, ed. (MIT Press, Cambridge, Mass., 1961), pp. 303–317.
  12. D. Regan, “Form from motion parallax and form from luminance contrast: Vernier discrimination,” Spatial Vision 1, 305–318 (1986). [CrossRef] [PubMed]
  13. A. E. Burgess, “On observer internal noise,” in Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems (PACS IV) for Medical Applications, R. H. Scheider, S. J. Dwyer, eds., Proc. SPIE626, 208–213 (1986). [CrossRef]
  14. S. N. J. Watamaniuk, “Ideal observer for discrimination of the global direction of dynamic random-dot stimuli,” J. Opt. Soc. Am. A 10, 16–28 (1993). [CrossRef] [PubMed]
  15. W. A. Simpson, “Pedestal effect in visual motion discrimination,” J. Opt. Soc. Am. A 12, 2555–2563 (1995). [CrossRef]
  16. W. A. Simpson, A. Newman, “Motion detection and directional tuning,” Vision Res. 38, 1593–1604 (1998). [CrossRef] [PubMed]
  17. A. E. Burgess, R. F. Wagner, R. J. Jennings, H. B. Barlow, “Efficiency of human visual signal discrimination,” Science 214, 93–94 (1981). [CrossRef] [PubMed]
  18. W. P. Tanner, T. G. Birdsall, “Definitions of d′ and η as psychophysical measures,” J. Acoust. Soc. Am. 30, 922–928 (1958). [CrossRef]
  19. N. S. Nagaraja, “Effect of luminance noise on contrast thresholds,” J. Opt. Soc. Am. 54, 950–955 (1964). [CrossRef]
  20. D. G. Pelli, “The quantum efficiency of vision,” in Vision: Coding and Efficiency, C. Blakemore, ed. (Cambridge U. Press, New York, 1990), pp. 3–24.
  21. A. E. Burgess, “High level visual decision efficiencies,” in Vision: Coding and Efficiency, C. Blakemore, ed. (Cambridge U. Press, New York, 1990), pp. 431–440.

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited