A simple scheme for deriving relative depth (time-to-collision, or TTC) from optic flow is developed in which the total flow is first sensed by unconnected motion (imperfect filter) sensors and then the rotational component is subtracted to yield the translational component. Only the latter component yields depth information. This scheme is contrasted with one where the TTC sensors respond only to the translational component at the initial registration of the flow (perfect filter sensors or looming detectors). The simple scheme predicts the results of three experiments on discrimination of TTC: discrimination thresholds are elevated if the objects withdraw from rather than approach the observer, thresholds are elevated if a rotational component is added to the flow, and the amount of threshold elevation resulting from the addition of a rotational component is reduced by prior adaptation to a pure rotational flow. These results confirm the simple model and disconfirm predictions based on the looming detector scheme.
BeverleyK IReganD, 1979“Visual perception of changing size: The effect of object size”Vision Research191093–1104.
3.
CampbellF WNachmiasJJukesJ, 1970“Spatial frequency discrimination in human vision”Journal of the Optical Society of America60555–559.
4.
CarpenterR H S, 1977Movements of the Eyes (London: Pion).
5.
CuttingJ E, 1983“Perceiving and recovering structure from events” in Motion: Representation and Perception Eds BadlerN ITsotsosJ K, (New York: North Holland) pp 264–270.
6.
CuttingJ E, 1986Perception with an Eye for Motion (Cambridge, MA: MIT Press).
7.
van DoornA JKoenderinkJ Jvan de GrindW A, 1985“Perception of movement and correlation in stroboscopically presented noise patterns”Perception14209–224.
8.
GeorgesonM AHarrisM G, 1978“Apparent foveofugal drift of counterphase gratings”Perception7527–536.
9.
GibsonJ J, 1950The Perception of the Visual World (Boston, MA: Houghton Mifflin).
10.
GibsonJ JOlumPRosenblattF, 1955“Parallax and perspective during aircraft landings”American Journal of Psychology68372–385.
11.
JohnstonI RWhiteG RCummingR W, 1973“The role of optical expansion patterns in locomotor control”American Journal of Psychology86311–324.
12.
KoenderinkJ J, 1985“Space, form and optical deformations” in Brain Mechanisms and Spatial Vision Eds IngleD JJeannerodMLeeD N, (Boston, MA: Martinus Nijhoff) pp 31–58.
LeeD N, 1980“The optic flow field: The foundation of vision”Philosophical Transactions of the Royal Society of London, Series B290169–179.
15.
LiebermanH RPentlandA, 1982“Microcomputer-based estimation of psychophysical thresholds: The best PEST”Behavior Research Methods and Instrumentation1421–25.
16.
LlewellynK R, 1971“Visual guidance of locomotion”Journal of Experimental Psychology91245–261.
17.
Longuet-HigginsH C, 1984“The visual ambiguity of a moving plane”Proceedings of the Royal Society of London, Series B223165–175.
18.
Longuet-HigginsH CPrazdnyK, 1980“The interpretation of a moving retinal image”Proceedings of the Royal Society of London, Series B208385–397.
19.
MatinE, 1974“Saccadic suppression: A review and an analysis”Psychological Bulletin81899–917.
20.
McKeeS P, 1981“A local mechanism for differential velocity detection”Vision Research21491–500.
21.
PerroneJ A, 1986“Anisotropic responses to motion toward and away from the eye”Perception & Psychophysics391–8.
22.
PrazdnyK, 1983“On the information in optical flows”Computer Vision, Graphics, and Vision Processing22239–259.
23.
RatkowskyD A, 1983Nonlinear Regression Modelling (New York: Dekker).
24.
ReganD, 1986“Visual processing of four kinds of relative motion”Vision Research26127–145.
25.
ReganDBeverleyK I, 1978“Looming detectors in the human visual pathway”Vision Research18415–421.
26.
ReganDBeverleyK I, 1979“Binocular and monocular stimuli for motion in depth: Changing-disparity and changing-size feed the same motion-in-depth stage”Vision Research191331–1342.
27.
ReganDBeverleyK I, 1982“How do we avoid confounding the direction we are looking and the direction we are moving?”Science215194–196.
28.
ReganDBeverleyK I, 1985“Visual responses to vorticity and the neural analysis of optic flow”Journal of the Optical Society of America, Series A2280–283.
29.
RiegerJ HLawtonD T, 1985“Processing differential image motion”Journal of the Optical Society of America, Series A2354–360.
30.
RiegerJ HToetL, 1985“Human visual navigation in the presence of 3-D rotations”Biological Cybernetics52377–381.
SekulerR, 1975“Visual motion perception” in Handbook of PerceptionVolume 5, Eds CarteretteE CFriedmanM P, (New York: Academic Press) pp 387–430.
33.
SekulerRPantleALevinsonE, 1978“Physiological basis of motion perception” in Handbook of Sensory PhysiologyVolume 8, Eds HeldRLeibowitzH WTeuberH L, (New York: Springer) pp 67–96.
34.
SimpsonJ ISoodakR EHessR, 1979“The accessory optic system and its relation to the vestibulocerebellum”Progress in Brain Research50715–724.
35.
SimpsonW A, 1987Depth Discrimination from Optic Flow: A Model Based on Simple Motion DetectorsPhD thesis, University of Toronto, Canada.
36.
ThompsonP, 1981“Velocity after-effects: The effects of adaptation to moving stimuli on the perception of subsequently seen moving stimuli”Vision Research21337–345.
37.
ToddJ T, 1981“Visual information about moving objects”Journal of Experimental Psychology: Human Perception and Performance7795–810.
38.
TreismanM, 1963“Temporal discrimination and the indifference interval: Implications for a model of the ‘internal clock’”Psychological Monographs771–31.
39.
WaxmanA MWohnK, 1988“Image flow theory: A framework for 3-D inference from time-varying imagery” in Advances in Computer VisionVolume 1 Ed. BrownC, (Hillsdale, NJ: Lawrence Erlbaum Associates) pp 165–224.
