The precision of velocity discrimination across spatial frequency

The precision of velocity coding for moving stimuli of different spatial frequencies was assessed by measuring velocity discrimination thresholds for a 1-c/deg grating paired with a grating whose spatial frequency ranged from 0.25 to 4 c/deg and for grating pairs of the same spatial frequency (0.25, 1, and 4 c/deg). The gratings always moved upward, with velocities ranging from 0.5 to 16 deg/sec, Velocity discrimination was as precise for stimuli that varied in spatial frequency by: ±2 octaves (0.25 vs. 1 c/deg and 4 vs. 1 c/deg) as for stimuli of the same spatial frequency, for specific ranges of velocity that depended on the spatial and, therefore, the temporal frequencies of the stimuli. Compared with a 1-c/deg grating, the perceived velocity of 4-c/deg gratings was about 1.3 times faster and that of 0.25-c/deg gratings was about 1.3 times slower. Although these perceived velocity biases imply variation of velocity-signal processing among spatial frequency channels, the discrimination results indicate that the motion-sensing system can compare signals across different spatial frequency channels to make fine velocity discrimination within appropriate temporal frequency limits.

[1]  A. T. Smith Velocity perception and discrimination: Relation to temporal mechanisms , 1987, Vision Research.

[2]  Hugh R. Wilson,et al.  Peripheral temporal frequency channels code frequency and speed inaccurately but allow accurate discrimination , 1993, Vision Research.

[3]  C Blakemore,et al.  On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images , 1969, The Journal of physiology.

[4]  D. H. Kelly Motion and vision. II. Stabilized spatio-temporal threshold surface. , 1979, Journal of the Optical Society of America.

[5]  M. Baggiolini,et al.  Ion channels in human neutrophils activated by a rise in free cytosolic calcium concentration , 1986, Nature.

[6]  E H Adelson,et al.  Spatiotemporal energy models for the perception of motion. , 1985, Journal of the Optical Society of America. A, Optics and image science.

[7]  D C Van Essen,et al.  Functional properties of neurons in middle temporal visual area of the macaque monkey. I. Selectivity for stimulus direction, speed, and orientation. , 1983, Journal of neurophysiology.

[8]  J. Movshon,et al.  Spatial and temporal contrast sensitivity of neurones in areas 17 and 18 of the cat's visual cortex. , 1978, The Journal of physiology.

[9]  G. Orban,et al.  Factors influencing velocity coding in the human visual system , 1984, Vision Research.

[10]  D. Levi,et al.  Stimulus uncertainty affects velocity discrimination , 1998, Vision Research.

[11]  D. G. Albrecht,et al.  Spatial frequency selectivity of cells in macaque visual cortex , 1982, Vision Research.

[12]  Thom Carney,et al.  Cortical processing of hyperacuity tasks , 1989, Vision Research.

[13]  B. Troost,et al.  The effects of age on normal saccadic characteristics and their variability , 1983, Vision Research.

[14]  Scott N. J. Watamaniuk,et al.  Dependence of speed and direction perception on cinematogram dot density , 1993, Vision Research.

[15]  H. Wilson,et al.  Spatial frequency tuning of orientation selective units estimated by oblique masking , 1983, Vision Research.

[16]  Steven C. Panish,et al.  Velocity discrimination at constant multiples of threshold contrast , 1988, Vision Research.

[17]  Vincent P. Ferrera,et al.  Perceived speed of moving two-dimensional patterns , 1991, Vision Research.

[18]  D J Heeger,et al.  Model for the extraction of image flow. , 1987, Journal of the Optical Society of America. A, Optics and image science.

[19]  Anthony J. Movshon,et al.  Visual Response Properties of Striate Cortical Neurons Projecting to Area MT in Macaque Monkeys , 1996, The Journal of Neuroscience.

[20]  J. Robson Spatial and Temporal Contrast-Sensitivity Functions of the Visual System , 1966 .

[21]  P. Thompson Discrimination of moving gratings at and above detection threshold , 1983, Vision Research.

[22]  Randolph Blake,et al.  Broad tuning for spatial frequency of neural mechanisms underlying visual perception of coherent motion , 1994, Nature.

[23]  Andrew T. Smith,et al.  Is global motion really based on spatial integration of local motion signals? , 1994, Vision Research.

[24]  A. T. Smith,et al.  The influence of spatial frequency on perceived temporal frequency and perceived speed , 1990, Vision Research.

[25]  K. Mullen,et al.  Red-green and achromatic temporal filters: a ratio model predicts contrast-dependent speed perception. , 1997, Journal of the Optical Society of America. A, Optics, image science, and vision.

[26]  S. McKee,et al.  Sequential recruitment in the discrimination of velocity. , 1985, Journal of the Optical Society of America. A, Optics and image science.

[27]  D. W. Heeley,et al.  Orientation acuity for sine-wave gratings with random variation of spatial frequency , 1993, Vision Research.

[28]  R. Reszelbach,et al.  35S-methionine incorporation in rat lenses in media simulating cataractogenic conditions. , 1983, Investigative ophthalmology & visual science.

[29]  S. McKee,et al.  Precise velocity discrimination despite random variations in temporal frequency and contrast , 1986, Vision Research.

[30]  Christopher W. Tyler,et al.  Binocular cross-correlation in time and space , 1978, Vision Research.

[31]  A. T. Smith,et al.  Antagonistic comparison of temporal frequency filter outputs as a basis for speed perception , 1994, Vision Research.

[32]  A. T. Smith,et al.  The separability of temporal frequency and velocity , 1991, Vision Research.

[33]  J. Robson,et al.  Discrimination at threshold: Labelled detectors in human vision , 1981, Vision Research.

[34]  A. Yuille,et al.  A model for the estimate of local image velocity by cells in the visual cortex , 1990, Proceedings of the Royal Society of London. B. Biological Sciences.