ON THE RELATIVITY OF PERCEIVED MOTION AH ... - CiteSeerX
When an eye movement is made over a stationary visual field, the image of that field shifts ..... 18 male and female students of the University of. Utrecht, aged ...
Acta Psychologica 48 (1981) 97-i IO North-Holland Publishing Company
ON THE RELATIVITY A.H. WERTHEIM Instiiute for Perception
OF PERCEIVED
MOTION
* TNO, The Netherlunds
Perceived stability of the visual world during eye movements is traditionally explained as due to the presence of extraretinal signals, equal in magnitude to retinal signals. Motion is perceived when the two signals differ. An experiment is reported in which motion thresholds were measured during smooth pursuit eye movements. The results show that the traditional view is incomplete. Motion is only perceived when the two signals differ by at least a just nottceahle dfference (JND), the magnitude of which depends on ocular velocity and is independent of the direction of stimulus motion relative to the eyes, The data lead to the rejection of theories according to which ocular velocity is under-represented in extraretinal signals. In addition they show that retinal image motion carries no information about stimulus motion. Perceived motion, direction and velocity are relative concepts. They depend on the JND and therefore they are relative to extraretinal signals. This principle explains the Filehne illusion and even predicts the Aubert-Fleischl phenomenon. A similar analysis can be applied to understand vestibular effects on motion perception.
Introduction When an eye movement is made over a stationary visual field, the image of that field shifts over the retina. If the eye movement is the result of the intention to move the eyes (and is not induced or affected by the application of an external force to the eyeball) motion of the visual field is not perceived. Apparently, the visual system ‘knows’ that the image shift was due to the (intended) eye movement. Such knowledge cannot be obtained from what happens on .the retina itself. The logical necessity that an extraretinal signal, carrying such information (sometimes termed a ‘corollary discharge’ or an ‘efference copy’) is needed for the establishment of a perceptually stable world during eye movements, was recognized long ago (see for some discussions Helmholz 1962; Holst 1954; Gyr 1972; Jeannerod et al. 1979). Nevertheless, the precise nature and function of such extraretinal signals remain controversial because of some anomalous experimental findings. First, the visual world is not always perceived as stationary during eye movements. When a stationary stimulus is briefly presented during a saccadic * Author’s Soesterberg,
movement indicates that the target is moving physically in the world. Because motion ... In A. F. Fuchs & W. Becker (Eds.), Progress in oculomotor research: Proceedings of ... Purkinje cells of the cerebellar dorsal vermis: simple-spike activity.
motion cycle in about 8 sec. A small shutter ..... divided into two groups, one of which was presented with ... ments varied from 20° to 60° with a median of 40°.
It is often denned as the set of "apparent mo- tions" of stationary objects ... parallax is so defined as to require ...... might go and how stable they might become.
you make a perfect response, you, theo- retically, should be able to reach into the ..... E. G. Boring (Eds.), A source book in the history of psychology. Cambridge: ...
inal size of 0.4 arc min and a luminance of 2 log units ( 14 cd/m2) above the detection ... distance between the moving test spot and the fixation target reached a ... and length of perceived smear for each acceptable trial (see below). 2.3. .... hal
Detection of a moving target depends not only upon the physical character of the target but also upon the observer's recent perceptual history. Experimental.
between the variables MD, SD, and MSD. A two-way ANOVA (stimulus ...... that modeled any possible physical configuration since the perception of change in ...
right in the frontal parallel plane behind an aperture. The line ... is given by: (i) the identity of line elements (i.e., points or line segments) in the two images; .... the line is proportional to the displacement of the line AB along its terminat
Statistical analysis was performed using a two-factor, repeated-measures analysis of ... 200 ms). Statistical values were defined as significant when P < 0.05, after ...... British Journal of Psychology, 1, 78â113. ... of explaining by modelling.
Apr 27, 2005 - constant for various stimulus motion directions. Wal- lach et al. (1985) presented observers with a vertically moving stimulus during vertical ...
scribed a scheme where objects trajectories can be com- puted on the basis of the motion coefficients provided by the wavelet transform, the so-called MTSTWT, ...
Apr 27, 2005 - The single free parameter that was varied to attain an optimal fit was the ..... tion h¢ to flip its direction from 0 to 180° or vice versa. One possible ...
motion estimation applied either to video compression or to scene analysis. We show in this paper some ..... WSEAS Multi Conference on Applied Mathematics.
Apr 27, 2005 - non-collinear motion, the visual system has to correct for this effect of the .... Seventeen students (6 males, 11 females) from Utrecht. University and the ... presentation and response registration were controlled by custom-made ...
16 sectors jump clockwise through a whole sector width, a spoke edge makes a tiny jump ... In conclusion, the apparent motion that we observed in our spoked wheel ... single black bar had a long TTB (about 15 s at an alternation rate of 3.75. Hz). ..
would appear light gray; so would a .... on the basis of their actual size, the ..... Results. The results shown in Table. 2 were quite clear. The 5"s were able.
In the fixation condition, the bright dot moved right or left at 50, 100, or 200° sâ1 .... Schematic illustration of the sequence of events during trials in the saccade (top panel) and fixation ..... Journal of the Optical Society of America A, 2,
the center of a surface such as a sheet of textured cardboard. .... In this terminology, slant must not be confused with what ... prefer to call tilt. This is a third and.
atic empirical basis for understanding individuals' systems of interpretation for ...... Johnson, K. O. (1983). Neural mechanisms of tactual form and texture.
We study the complexity of a coordinated play when allowing for a ..... construction is the existence of a map between the index of the subsequences rt to Q, as ..... Modeling economic interaction of agents with diverse abilities to recognize.
(Os). The motion of the humerus on the glenoid can be de- scribed in terms of the center of rotation. The method for determining it is shown in Figure. 3. For each.
we show that the latter is the case. ... experiment, observers (N = 7) stood in a completely dark ... mental method, including data analysis, see Methodological .... Eleven observers (age between 19-26 years) participated in the experiment of ...
sual angle on a black background (luminance: 1.68 cd/ m2), and the .... observed (300 ms), the blue curve shows that in control trials, where no initial stimulus ...
We now report a phenomenon that can probe. § College of Letters this high-level aspect of motion and visual attention. Ritsumeikan University. One hallmark of ...
