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PubMed1997

Second-order motion perception in the peripheral visual field.

In motion perception, luminance-defined stimuli (first-order motion) are distinguished from stimuli defined by more complex attributes (second-order motion), because they differ in their processing requirements. For instance, a two-layer model with the output of an array of elementary motion detectors (EMD's) feeding into a second array of EMD's has been proposed to account for seeing the movement of motion-defined objects. The question is raised whether this processing scheme is operating across the whole visual field or whether second-order motion perception is restricted to the fovea. The detection, orientation discrimination, and motion direction discrimination of oblique, vertically moving bars was tested at horizontal eccentricities between 0 degree and 16 degrees. Bars were defined on a dynamic noise background by an area of static dots (drift-balanced motion) or by coherent dot motion either in the direction of the bar motion (Fourier motion) or in the orthogonal direction (theta motion). Coherence thresholds for direction discrimination are severely impaired in the periphery for both types of second-order motion but not for Fourier motion, whereas orientation discrimination and detection marginally decline for all three bar types when the stimuli are presented further out in the periphery. In a control experiment it is shown that this result cannot be due entirely to the changes in spatial scale of the peripheral visual system. The facts that motion-defined objects can be detected in the periphery and that their orientation can be detected, but not their direction of motion, supports the view that the two-layer system suggested for the processing of theta motion is restricted to the central region of the visual field.

Adult↗
PubMed1996

The shape of self-motion perception--II. framework and principles for simple and complex motion.

There have been numerous experimental studies on human perception and misperception of self-motion and orientation relative to the earth, each focusing on one or a few types of motion. We present a formal framework encompassing many types of motion and including all angular and linear components of velocity and acceleration. Using a mathematically rigorous presentation, the framework defines the space of all possible motions, the map from motion to sensor status, the space containing each possible status of the sensors, and the map from sensor status to perceived motion. The shape of the full perceptual map from actual motion to perceived motion is investigated with the framework, using formal theory and a number of published experimental results. Two principles of simple motion perception and four principles of complex motion perception are presented. The framework also distinguishes the roles of physics and the nervous system in the process of self-motion perception for both simple and complex motions. The present rigorous development of the self-motion perception framework allows the scientist to compare and contrast results from many studies with differing types of motion. The six principles formalized here comprise a foundation with which to explain and predict perceptual phenomena, both those observed in the past and those to be encountered in the future. The framework is especially aimed to expand our capacity to investigate complex motions such as those encountered in everyday life or in unusual motion environments.

Humans↗
PubMed1990

Effects of element orientation on apparent motion perception.

We present an ambiguous motion paradigm that allows us to quantify the influence of aspects of form relevant to the perception of apparent motion. We report on the role of bar element orientation in motion paths. The effect of orientation differences between bar elements in a motion path is small with respect to the crucial role of the orientation of bar elements relative to motion direction. Motion perception between elements oriented along the motion direction dominates motion perception between elements oriented perpendicularly to motion direction. The perception of apparent motion is affected by bar length and width and is anisotropic.

Attention↗
PubMed1977

Quantitation of motion perception in the digits: a psychophysical study in normal human subjects.

Threshold perception of motion of the digits was obtained in 14 normal subjects. The metacarpophalangeal joint of the index and the fifth finger of each hand and the metatarsophalangeal joint of the hallux of each foot were passively moved up and down with respect to a horizontal plane defined by the palmar or plantar surface. The motion was sinusoidal at frequencies of 0.5 and 5.0 Hz. A mpdified von Békésy paradigm similar to that used in audiometry was utilized to yield threshold levels of motion sensation. There was little difference in the thresholds obtained for the different joints. The difference between high- and low-frequency stimulation, however, was significant (p less than 0.001): the 0.5 Hz threshold was found to range from 0.8 to 1.0 degree, whereas the 5.0 Hz threshold varied from 0.4 to 0.6 degree. It is thought that motion sense is largely dependent on joint receptor contributions, but muscle and cutaneous receptors may also contribute to this proprioceptive sensation.

Adolescent↗
PubMed1985

Studies of some new phenomena of motion perception.

Contrast modulation of a set of features in a Glass pattern invokes, under certain circumstances, the perception of motion in the absence of any physical displacements. The illusion is spatially limited to within about 10' and is governed by contrast relationships. We find that the detected motion in these situations is due to local computations the results of which can be integrated over retinal areas of more than 1 degree. The possible motion detection mechanisms are discussed within the framework of the Reichardt/Hassenstein and Marr/Ullman type of motion detectors.

Animals↗
PubMed1976

Stimulus length and orientation variables interact in peripheral motion perception.

To determine the effects of stimulus length and orientation on the perception of motion, 5 experienced subjects responded with a simple reaction to accelerating lines in peripheral vision while fixating on a reference cross at the center of a cathode-ray tube. Three experimental variables were involved: (a) line length, (b) direction of motion, and (c) orientation of the line with respect to the motion. Simple reaction time (RT) was significantly longer for vertical than for horizontal motion and for lines oriented in-line with the direction of motion than for lines oriented perpendicular to the direction of motion. A significant interaction was found between line length and orientation. The results show that the generalization that RT is shorter for small objects than for large objects must be modified in terms of the orientation of the object.

Adult↗
PubMed1989

Motion perception prominence alters anticipatory slow eye movements.

Perceived motion may be a stimulus for anticipatory slow eye movements. To test this possibility, the production of anticipatory slow eye movements in humans was studied using apparent motion stimuli. Short range apparent motion was produced with random dot stimuli and the anticipatory slow eye movements were isolated from the smooth pursuit responses by occasionally including trials in which the random dot stimulus did not appear. Long range apparent motion was produced with subjective contour stimuli. Both short range and long range apparent motion were found to be effective stimuli for anticipatory slow eye movements. The prominence of perceived motion was altered by changing the spatiotemporal displacement intervals in the short range apparent motion stimuli. Changing the subjective contours also changed the motion percepts of the long range apparent motion stimuli. With both stimuli, the peak anticipatory slow eye velocities that were achieved decreased as the prominence of the motion percepts decreased, while the time-course of the anticipatory responses were similar under the different conditions. These findings indicate that the expectation of perceived motion is necessary for anticipatory slow eye movements.

Adult↗
PubMed1997

Human brain potentials observed using the line-motion method: the neurophysiological correlates of visual illusory motion perception.

This study shows the temporal dynamics of neurophysiological activities in illusory motion perception. Event-related brain potentials were recorded from 12 healthy subjects while they performed a two-alternative (motion/no motion), forced-choice task using the line motion method. Amplitudes of a late positive component at Fz, Cz, Pz, O1 and O2 increased as cue lead time (CLT) increased. At a CLT of 50 ms, the amplitudes of the late positive component (the peak latency at O1, O2: 310 ms; Fz, Cz, Pz: 360-390 ms) observed during illusory motion perception was larger than that observed during no motion perception, even though the physical stimuli were the same. These results suggest that the perception of illusory motion correlates to a relatively late stage of visual information processing.

Adult↗
PubMed1996

The spatial grain of motion perception in human peripheral vision.

Motion reversal effects (the apparent reversal of the direction of motion of a high frequency sinusoidal grating) have been attributed to aliasing by the cone mosaic [Coletta et al. (1990). Vision Research, 30, 1631-1648] and postreceptoral layers [Anderson & Hess (1990). Vision Research, 30, 1507-1515] in human observers. We present data and a new model which suggest that at least two sampling arrays of different densities affect direction discrimination out to 30 degrees eccentricity. The first sampling layer matches anatomical estimates of the cone density. The second sampling layer is too dense to be the parasol cells alone; midget ganglion cells certainly contribute to this task. This is further evidence that motion perception is not mediated exclusively by the magnocellular stream.

Discrimination, Psychological↗
PubMed1991

Motion perception in the peripheral visual field.

Thresholds were determined for the perception of the motion of a single bar moving at different positions in the field of view. Performance in the temporal hemified was slightly superior to that in the nasal hemifield and depended on the orientation as well as on the direction of the motion. The perception of horizontal motion was better than that of vertical motion. In spite of large variations, centrifugal motion was significantly more readily perceived than centripetal motion.

Humans↗
PubMed1998

Chronic motion perception deficits from midline cerebellar lesions in human.

A selective motion perception deficit is seen in patients with acute midline cerebellar lesions. Patients with more lateralized acute cerebellar damage do not demonstrate such a deficit (Nawrot M, Rizzo M. Vis Res 1995;35:723-731). However, as these patients were tested only between 10 and 14 days post-ictus, the stability of this perceptual deficit into the chronic phase remained undetermined. The current study extends the previous findings by showing that the motion perception deficit caused by mid-line cerebellar lesions remains permanent at least 2 years into the chronic phase. The extent and longevity of this deficit resembles that of the well known motion-blind patient LM who has a large cerebellar lesion in addition to her extensive cortical damage. Again, we propose that the mid-line cerebellar damage may produce a severe motion perception deficit by disruption the visual-motor integration mechanisms involved in perceptual stabilization, even though cortical motion processing mechanisms are unaffected.

Cerebellum↗
PubMed1988

Drift-balanced random stimuli: a general basis for studying non-Fourier motion perception.

To some degree, all current models of visual motion-perception mechanisms depend on the power of the visual signal in various spatiotemporal-frequency bands. Here we show how to construct counterexamples: visual stimuli that are consistently perceived as obviously moving in a fixed direction yet for which Fourier-domain power analysis yields no systematic motion components in any given direction. We provide a general theoretical framework for investigating non-Fourier motion-perception mechanisms; central are the concepts of drift-balanced and microbalanced random stimuli. A random stimulus S is drift balanced if its expected power in the frequency domain is symmetric with respect to temporal frequency, that is, if the expected power in S of every drifting sinusoidal component is equal to the expected power of the sinusoid of the same spatial frequency, drifting at the same rate in the opposite direction. Additionally, S is microbalanced if the result WS of windowing S by any space-time-separable function W is drift balanced. We prove that (i) any space-time-separable random (or nonrandom) stimulus is microbalanced; (ii) any linear combination of pairwise independent microbalanced (respectively, drift-balanced) random stimuli is microbalanced and drift balanced if the expectation of each component is uniformly zero; (iii) the convolution of independent microbalanced and drift-balanced random stimuli is microbalanced and drift balanced; (iv) the product of independent microbalanced random stimuli is microbalanced; and (v) the expected response of any Reichardt detector to any microbalanced random stimulus is zero at every instant in time. Examples are provided of classes of microbalanced random stimuli that display consistent and compelling motion in one direction. All the results and examples from the domain of motion perception are transposable to the space-domain problem of detecting orientation in a texture pattern.

Fourier Analysis↗
PubMedDate not supplied

Motion perception tested with reversing grating in Duane's syndrome.

Many papers have reported that motion perception asymmetry (MPA) is replaced by motion perception symmetry (MPS) by the 4th to 5th month after birth, when stereopsis starts to occur in normal infants. Duane's syndrome is a congenital motor abnormality, it does, however, reportedly show good stereopsis. We confirmed the stereopsis in Duane's syndrome and checked the motion perception (MP) by using the Reversing Grating Test to investigate if the congenital motor abnormality affects the MP in patients whose binocular sensory system is well developed. Thirty-eight Duane's syndrome patients aged 3 to 45 years were included in the present study. They were divided into 24 cases of Duane I, 9 cases of Duane II, 5 cases of Duane III. The Titmus Stereo Tests, Lang Stereotest, and TV-Random Dot Stereo Test were used to examine the stereopsis. Thirty-four patients had good stereopsis, and 4 had poor stereopsis. None of them showed MPA in any spatial frequencies (1/ 4, 1/2, 1 cycles/degree) examined. The Reversing Grating Test is useful for examining MPA in strabismus patients with eye movement limitations.

Adolescent↗
PubMed1994

Contribution of colour to the motion aftereffect and motion perception.

The aim in this work was to assess the contribution which colour information makes to the perception of motion. Two dependent variables were measured: the reaction time to a sudden cessation of motion (motion-end RT) and the duration of the motion aftereffect (MAE). In each case, a baseline measure of performance was made with the aid of a monochrome stimulus with a given contrast and added luminance noise. This was compared with performance when red/green colour modulation was added to the luminance display. Any difference between these measures would reveal the extent of chromatic input. For motion-end RT the addition of colour had little effect under conditions where the stimulus had a strong luminance component and little added luminance noise. Increasing departures from these conditions revealed the contribution of a colour-sensitive mechanism. In general, the chromatic contribution to MAE duration was much smaller than was the equivalent contribution to motion-end RT, thus possibly indicating a neurological dissociation between the mechanisms subserving these effects. The results of an experiment in which the effect of different temporal frequencies of the added luminance noise was assessed supported this dissociation between MAE and motion-end RT. The findings are therefore consistent with there being two motion (sub)systems, which differ in the extent of chromatic input. The subsystem revealed by MAE measures is less affected by colour information.

Color Perception↗
PubMed1993

The characteristics of residual motion perception in the hemifield contralateral to lateral occipital lesions in humans.

Unilateral damage to the lateral occipital region in humans can give rise to impaired motion perception in the contralateral visual field [Plant et al. (1993), Brain, 116, 1303-1335]. We report the following characteristics of the residual vision. (i) Spatial acuity and spatial frequency discrimination are not affected. (ii) Contrast thresholds for direction-of-motion (DOM) discrimination of luminance modulated (LMod) sine-wave gratings is unaffected regardless of drift temporal frequency and the effect of spatial and temporal frequency on drifting/counterphase sensitivity ratios is normal (providing further evidence that cortical directionally selective mechanisms are intact). (iii) Contrast thresholds for DOM discrimination of contrast modulated (CMod) gratings are elevated by a log unit across a range of drift velocities. (iv) The residual motion perception shows neither a directional nor a naso-temporal asymmetry. (v) Weber fractions for velocity discrimination are shown in one patient in whom this measurement was carried out, to be elevated by around a factor of three but the functions relating velocity discrimination to stimulus contrast and to the velocity of the standard are parallel in the affected and unaffected hemifields. (vi) Weber fractions for temporal frequency discrimination using counterphase modulated gratings are also elevated. We conclude that the degraded motion perception is mediated by mechanisms which have similar contrast and temporal properties to those subserving normal motion perception. Mechanisms subserving DOM discrimination of LMod gratings may be spared because they are more widely distributed in extra-striate cortex than mechanisms subserving non-Fourier (second-order) motion perception or velocity discrimination. The anomaly resembles that described in some recent animal studies of impaired motion perception after extra-striate cortical damage.

Adult↗
PubMed1991

Reversed rotary motion perception.

A stroboscopically presented revolving annulus composed of dots is used to elicit rotary motion perception. Observers judge the direction of rotary motion. We find sharp and gradual transitions in the probability for reversed motion perception as a function of the angle of rotation between successive frames. These transitions reveal that matches between nonsuccessive frames can dominate motion perception. The transitions are scale invariant. The strength of a match is discussed in terms of a motion strength function, which is a separable function of the angle of rotation between successive frames and the frame repetition rate. The dependence of motion strength on the frame repetition rate (time function) is computed from the transitions. The similarity of this time function for rotary motion with the time function for linear motion [Psychol. Rev. 88, 171 (1981)] suggests that mechanisms for the discrimination of rotary motion address local detectors of linear motion.

Humans↗
PubMed1990

On and off pathway contributions to apparent motion perception.

We studied the separability and/or interaction of the On and Off pathways in their role as inputs to visual motion perception. Using the long-range motion perception system, we asked if the motion system can use brightness polarity information, by testing whether correspondence is preferred between elements for which brightness polarity is preserved. We found such a preference, suggesting that brightness polarity information is indeed available to the motion system. However, under certain conditions motion is perceived even though the brightness polarity of apparent motion stimulus elements is reversed, indicating that the apparent motion system does integrate information from these two pathways. The source of the preference for maintaining polarity seems not to be the different brightnesses of the dark and bright stimulus elements, but the very fact that information must be integrated from different pathways. We relate the characteristics of the dependence of the motion perception on element contrast and contrast sign to those of previously reported visual evoked potential responses to brightness increments and decrements.

Contrast Sensitivity↗
PubMed1987

Object-motion detection affected by concurrent self-motion perception: applied aspects for vehicle guidance.

Thresholds and response times for object-motion detection are significantly raised during concurrent real or visually induced self-motion perception. This was demonstrated by standardized laboratory experiments in which subjects had to react to a suprathreshold visual stimulus (1 degree-light spot moving with 5 degrees/s speed) under different stimulus conditions of simultaneously perceived self-motion. Elevated response times (mean elevation factor: 3.27) were also obtained for the detection of changes in inter-vehicle distance (headway) under real road conditions with the simultaneous involvement of self- and object-motion perception compared to a corresponding (object-motion perception) simulation in the laboratory without any self-motion. With regard to vehicle guidance, existing concepts of safe stopping distances, which depend upon adequate detection of a collision course and the corresponding reaction times, have to be recalculated.

Adult↗