Abstract

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

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References

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    [Crossref] [PubMed]
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    [Crossref] [PubMed]
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    [Crossref]
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    [Crossref] [PubMed]
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    [Crossref]
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    [Crossref] [PubMed]
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    [Crossref]
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1998 (1)

W. A. Simpson, A. Newman, “Motion detection and directional tuning,” Vision Res. 38, 1593–1604 (1998).
[Crossref] [PubMed]

1995 (1)

1994 (1)

W. A. Simpson, “Temporal summation of visual motion,” Vision Res. 34, 2547–2559 (1994).
[Crossref] [PubMed]

1993 (1)

1986 (1)

D. Regan, “Form from motion parallax and form from luminance contrast: Vernier discrimination,” Spatial Vision 1, 305–318 (1986).
[Crossref] [PubMed]

1985 (2)

1981 (3)

S. P. McKee, “A local mechanism for differential velocity detection,” Vision Res. 21, 491–500 (1981).
[Crossref] [PubMed]

R. P. Scobey, C. A. Johnson, “Displacement thresholds for unidirectional and oscillatory movement,” Vision Res. 21, 1297–1302 (1981).
[Crossref] [PubMed]

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]

1974 (1)

O. Braddick, “A short-range process in apparent motion,” Vision Res. 14, 519–527 (1974).
[Crossref] [PubMed]

1965 (1)

1964 (1)

1958 (1)

W. P. Tanner, T. G. Birdsall, “Definitions of d′ and η as psychophysical measures,” J. Acoust. Soc. Am. 30, 922–928 (1958).
[Crossref]

Adelson, E. H.

Barlow, H. B.

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]

Bergen, J. R.

Birdsall, T. G.

W. P. Tanner, T. G. Birdsall, “Definitions of d′ and η as psychophysical measures,” J. Acoust. Soc. Am. 30, 922–928 (1958).
[Crossref]

Braddick, O.

O. Braddick, “A short-range process in apparent motion,” Vision Res. 14, 519–527 (1974).
[Crossref] [PubMed]

Burgess, A. E.

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]

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]

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.

Finley, G.

G. Finley, “A high-speed plotter for vision research,” Vision Res. 25, 1993–1997 (1985).
[Crossref]

Jennings, R. J.

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]

Johnson, C. A.

R. P. Scobey, C. A. Johnson, “Displacement thresholds for unidirectional and oscillatory movement,” Vision Res. 21, 1297–1302 (1981).
[Crossref] [PubMed]

McKee, S. P.

S. P. McKee, “A local mechanism for differential velocity detection,” Vision Res. 21, 491–500 (1981).
[Crossref] [PubMed]

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.

Nagaraja, N. S.

Newman, A.

W. A. Simpson, A. Newman, “Motion detection and directional tuning,” Vision Res. 38, 1593–1604 (1998).
[Crossref] [PubMed]

Pelli, D. G.

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.

Regan, D.

D. Regan, “Form from motion parallax and form from luminance contrast: Vernier discrimination,” Spatial Vision 1, 305–318 (1986).
[Crossref] [PubMed]

Reichardt, W.

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.

Scobey, R. P.

R. P. Scobey, C. A. Johnson, “Displacement thresholds for unidirectional and oscillatory movement,” Vision Res. 21, 1297–1302 (1981).
[Crossref] [PubMed]

Siebert, W. M.

W. M. Siebert, Circuits, Signals, and Systems (McGraw-Hill, New York, 1986).

Simpson, W. A.

W. A. Simpson, A. Newman, “Motion detection and directional tuning,” Vision Res. 38, 1593–1604 (1998).
[Crossref] [PubMed]

W. A. Simpson, “Pedestal effect in visual motion discrimination,” J. Opt. Soc. Am. A 12, 2555–2563 (1995).
[Crossref]

W. A. Simpson, “Temporal summation of visual motion,” Vision Res. 34, 2547–2559 (1994).
[Crossref] [PubMed]

Steinman, R. M.

Tanner, W. P.

W. P. Tanner, T. G. Birdsall, “Definitions of d′ and η as psychophysical measures,” J. Acoust. Soc. Am. 30, 922–928 (1958).
[Crossref]

Wagner, R. F.

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]

Watamaniuk, S. N. J.

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]

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.

Whalen, A. D.

A. D. Whalen, Detection of Signals in Noise (Academic, New York, 1971).

J. Acoust. Soc. Am. (1)

W. P. Tanner, T. G. Birdsall, “Definitions of d′ and η as psychophysical measures,” J. Acoust. Soc. Am. 30, 922–928 (1958).
[Crossref]

J. Opt. Soc. Am. (2)

J. Opt. Soc. Am. A (3)

Science (1)

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]

Spatial Vision (1)

D. Regan, “Form from motion parallax and form from luminance contrast: Vernier discrimination,” Spatial Vision 1, 305–318 (1986).
[Crossref] [PubMed]

Vision Res. (6)

W. A. Simpson, A. Newman, “Motion detection and directional tuning,” Vision Res. 38, 1593–1604 (1998).
[Crossref] [PubMed]

R. P. Scobey, C. A. Johnson, “Displacement thresholds for unidirectional and oscillatory movement,” Vision Res. 21, 1297–1302 (1981).
[Crossref] [PubMed]

W. A. Simpson, “Temporal summation of visual motion,” Vision Res. 34, 2547–2559 (1994).
[Crossref] [PubMed]

S. P. McKee, “A local mechanism for differential velocity detection,” Vision Res. 21, 491–500 (1981).
[Crossref] [PubMed]

O. Braddick, “A short-range process in apparent motion,” Vision Res. 14, 519–527 (1974).
[Crossref] [PubMed]

G. Finley, “A high-speed plotter for vision research,” Vision Res. 25, 1993–1997 (1985).
[Crossref]

Other (7)

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.

A. D. Whalen, Detection of Signals in Noise (Academic, New York, 1971).

W. M. Siebert, Circuits, Signals, and Systems (McGraw-Hill, New York, 1986).

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.

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]

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.

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.

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Figures (8)

Fig. 1
Fig. 1

Each cell in the diagram shows an experimental condition: a pair of standard and comparison displacements to be discriminated, in arbitrary units. Detectability d for discriminating each pair was measured.

Fig. 2
Fig. 2

Detectability d of the difference between the standard and comparison displacements (arcmin) for observers MM and WS. The display is noiseless.

Fig. 3
Fig. 3

Error—difference between observed and best-fitting values of d with use of Eq. (4)—as a function of the standard and comparison displacements (arcmin) for observers MM and WS and a device that obeys Weber’s law. The display is noiseless. In this and subsequent figures the region where the surface was not measured is given a height of zero to serve as a visual reference.

Fig. 4
Fig. 4

Time-averaging mechanism giving an output like that of a long-exposure photograph. This mechanism can perform motion detection by comparing the output for static random dots (top) with the streaks obtained for moving random dots (bottom).

Fig. 5
Fig. 5

Detectability d of the difference between the standard and the comparison displacements (arcmin) for observers MM, VM, and WS. The display has motion noise. Note the different d scale on each observer’s plot.

Fig. 6
Fig. 6

Error (difference between observed and fitted d) as a function of the standard and the comparison displacements (arcmin) for observers MM, VM, and WS. The display has motion noise. Note the different error scale on each observer’s plot.

Fig. 7
Fig. 7

Output of an energy detection mechanism as a function of the standard (a0) and comparison (a1) displacements. This model seems to explain the residual plots for VM and WS in Fig. 6.

Fig. 8
Fig. 8

Efficiency (F, the squared ratio of observed to ideal d) as a function of the standard and comparison displacements (arcmin) for observers MM, VM, and WS. The display has motion noise. Note the different efficiency scale on each observer’s plot.  

Equations (10)

Equations on this page are rendered with MathJax. Learn more.

d=k=1m(s1k-s0k)1/2σ.
s0k=a0δk-T=a0ifk=T0ifkT,
s1k=a1δk-T=a1ifk=T0ifkT.
d=[(a1-a0)2]1/2σ=|a1-a0|σ.
|a0-a1|=σ+|a0|σ1,
|a0-a1|=σ+|a1|σ1.
|a0-a1|=(σ+|a0|σ1)(σ+|a1|σ1).
d=|a0-a1|(σ+|a0|σ1)(σ+|a1|σ1).
de=|a12-a02|(2ν+2a02+2a12)1/2.
F=dobserveddideal2

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