Abstract
Human observers can simultaneously encode direction information at two different scales, one local (an individual dot) and one global (the coherent motion of a field of dots distrisbuted over a 10°-diameter display). We assessed whether encoding global motion would preclude the encoding of a local trajectory component and vice versa. In the present experiments, a large number (100–150) of dots were randomly assigned directions in each frame from a uniform distribution of directions spanning a range of 160° to create global motion in a single direction (Williams & Sekuler, 1984). Amidst these background dots, 1 dot moved in a consistent direction (trajectory) for the duration of the display. The direction of this “trajectory dot” was similar to the mean direction of the distribution of directions determining the movement of the background dots. Direction discrimination for both the global motion and the trajectory was measured, using the method of constant stimuli, under precued and postcued partial report conditions. A low- or high-frequency 85-msec tone signaled which motion the subject was to judge. In the precue condition, the tone was presented 200 msecbefore the onset of the stimulus, whereas in the postcue condition, the tone was presented immediatelyafter the offset of the stimulus. Direction discrimination thresholds for both global and local motion in the postcued condition were not significantly different from those obtained in the precued condition. These results suggest that direction information for both global and local motion is encoded simultaneously and that the observer has access to either motion signal after the presentation of a stimulus.
Article PDF
Similar content being viewed by others
References
Campbell, F. W., &Robson, J. G. (1968). Application of Fourier analysis to the visibility of gratings.Journal of Physiology,197, 551–566.
Farell, B., &Pelli, D. G. (1993). Can we attend to large and small at the same time?Vision Research,33, 2757–2772.
Finney, D. J. (1971).Probit analysis. Cambridge: Cambridge University Press.
Gattass, R., &Gross, C. G. (1981). Visual topography of striate projection zone (MT) in posterior superior temporal sulcus of the macaque.Journal of Neurophysiology,46, 621–638.
Gibson, J. J. (1966).The senses considered as perceptual systems. Boston: Houghton Muffin.
Graham, N. (1985). Detection and identification of near-threshold visual patterns.Journal of the Optical Society of America A,2, 1468–1482.
Grzywacz, N. M., Watamaniuk.S. N. J., &McKee, S. P. (1995). Temporal coherence theory for the detection and measurement of visual motion.Vision Research,35, 3183–3203.
Henning, G. B., Hertz, B. G., &Broadbent.D. E. (1975). Some experiments bearing on the hypothesis that the visual system analyses spatial frequency.Vision Research,15, 887–897.
Hirsch, J., Hylton, R., &Graham, N. (1982). Simultaneous recognition of two spatial frequency components.Vision Research,22, 365–375.
Hoffman, J. E. (1980). Interaction between global and local levels of a form.Journal of Experimental Psychology: Human Perception & Performance,6, 222–234.
Hughes, H. C., Layton, W. M., Baird, J. C., &Lester, L. S. (1984). Global precedence in visual pattern recognition.Perception & Psychophysics,35, 361–371.
LaGasse, L. L. (1993). Effects of good form and spatial frequency on global precedence.Perception & Psychophysics,53, 89–105.
Martin, M. (1979). Local and global processing: The role of sparsity.Memory & Cognition,7, 476–484.
Miller, J. (1981). Global precedence in attention and decision.Journal of Experimental Psychology: Human Perception & Performance,7, 1161–1174.
Morgan, M. I., &Fahle, M. (1992). Effects of pattern element density upon displacement limits for motion detection in random binary luminance patterns.Proceedings of the Royal Society of London: Series B,248, 189–198.
Nakayama, K. (1990). The iconic bottleneck and the tenuous link between early visual processing and perception. In C. Blakemore (Ed.),Vision coding and efficiency (pp. 411–422). Cambridge: Cambridge University Press.
Navon, D. (1977). Forest before trees: The precedence of global features in visual perception.Cognitive Psychology,9, 353–383.
Navon, D. (1981). The forest revisited: More on global precedence.Psychological Research,43, 1–32.
Navon, D. (1991). Testing a queue hypothesis for the processing of global and local information.Journal of Experimental Psychology: General,120, 173–189.
Navon, D., &Norman, J. (1983). Does global precedence really depend upon visual angle?Journal of Experimental Psychology: Human Perception & Performance,9, 955–965.
Olzak, L. (1981). Inhibition and stochastic interactions in spatial pattern perception.Dissertation Abstracts International,42, 1651B.
Olzak, L., &Thomas, J. P. (1986). Seeing spatial patterns. In K. R. Boff, L. Kaufman, & J. P. Thomas (Eds.),Handbook of perception and human performance: Vol. I. Sensory processes and performance (pp. 7.1–7.56). New York: Wiley.
Pantle, A., &Sekuler, R. (1968). Size-detecting mechanisms in human vision.Science,162, 1146–1148.
Paquet, L., &Merikle, P. M. (1984). Global precedence: The effect of exposure duration.Canadian Journal of Psychology,3, 45–53.
Pomerantz, J. R. (1983). Global and local precedence: Selective attention in form and motion perception.Journal of Experimental Psychology: General,112, 516–540.
Robertson, L. C., Egly, R., Lamb, M. R., &Kerth, L. (1993). Spatial attention and cuing to global and local levels of hierarchical structure.Journal of Experimental Psychology: Human Perception & Performance,19, 471–487.
Smith, A. T., Snowden, R. J., &Milne, A. B. (1994). Is global motion really based on spatial integration of local motion signals?Vision Research,34, 2425–2430.
Sperling, G. (1960). The information available in brief visual presentations.Psychological Monographs: General & Applied,74, 1–29.
Van Essen, D.C., Maunsell, J. H. R., &Bixby, J. L. (1981). The middle temporal visual area in macaque: Myeloarchitecture, connections, functional properties and topographic representation.Journal of Comparative Neurology,199, 293–326.
Ward, L. M. (1982). Determinants of attention to local and global features of visual forms.Journal of Experimental Psychology: Human Perception & Performance,8, 562–581.
Ward, L. M. (1983). On processing dominance: Comment on Pomerantz.Journal of Experimental Psychology: General,112, 541–546.
Watamaniuk, S. N. J. (1997). Speed tuning for detecting a trajectory in noise.Investigative Ophthalmology & Visual Science,38, S1167.
Watamaniuk, S. N. J., McKee, S. P., &Grzywacz, N. M. (1995). Detecting a trajectory embedded in random-direction motion noise.Vision Research,35, 65–77.
Watamaniuk, S. N. J., &Sekuler, R. (1992). Temporal and spatial integration in dynamic random-dot stimuli.Vision Research,32, 2341–2347.
Watamaniuk, S. N. J., Sekuler, R., &Williams, D. G. (1989). Direction perception in complex dynamic displays: The integration of direction information.Vision Research,29, 47–59.
Watson, A. B., &Robson, J. G. (1981). Discrimination at threshold: Labelled detectors in human vision.Vision Research,21, 1115–1122.
Westheimer, G., &Wehrhahn, C. (1994). Discrimination of direction of motion in human vision.Journal of Neurophysiology,71, 33–37.
Williams, D. G., &Sekuler, R. (1984). Coherent global motion percepts from stochastic local motions.Vision Research,24, 55–62.
Wilson, H. R., &Bergen, J. R. (1979). A four mechanism model for threshold spatial vision.Vision Research,19, 19–32.
Author information
Authors and Affiliations
Corresponding author
Additional information
This research was supported by AFOSR Grant F49620-95-1-0265.
Rights and permissions
About this article
Cite this article
Watamaniuk, S.N.J., McKee, S.P. Simultaneous encoding of direction at a local and global scale. Perception & Psychophysics 60, 191–200 (1998). https://doi.org/10.3758/BF03206028
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.3758/BF03206028