Pattern Of Vertical Stripes Research Articles

Chapter 16 Open-loop and closed-loop optokinetic nystagmus in Squirrel monkeys (Saimiri sciureus) and in man

Horizontal optokinetic nystagmus (OKN) was measured in 3 normal Squirrel monkeys by means of the electromagnetic search coil technique. Binocular and monocular stimulation of each eye to the left and right by moving vertical stripe patterns of 2.37 or 15 degree period were applied at angular velocities of 0.5 to 400 deg/s. After measurement of horizontal OKN under normal conditions, open-loop OKN gain was determined by monocular stimulation of an eyeball immobilized by means of retrobulbar injections of 11 units botulinum toxin (BoTx type A) and compared with the pre-injection data or with monocular stimulation of the other eye, which remained mobile. In normal Squirrel monkeys gain of optokinetic nystagmus reached values between 0.8 and 0.97 at angular velocities below 1.5 deg/s. Gain under these conditions was related to stimulus angular velocities Vs, i.e. Ge = Ve/Vs. A slightly higher gain was found for binocular than for monocular stimulation. No significant differences were found in OKN when monocular stimulation in the naso-temporal and in the temporo-nasal direction was applied. The upper cut-off angular velocity (-3 dB-point) reached values of 180-230 deg/s, significantly above those observed in man under similar stimulus conditions. Monocular optokinetic stimulation of an immobilized eye led to vigorous optokinetic nystagmus and OKAN of the other eye, whereby maximum gain (Gi = Ve/Vr) was found to be between 20 and 30 at lower retinal stimulus velocities (2-5 deg/s). Gain was related to retinal stimulus velocity Vr. Increase in Vr above 10 deg/s led to a decrease in gain with a slope of about 20 dB per decade. Measurement of gain of closed-loop OKN related to retinal stimulus velocity Vr (which was determined by the difference between Vs and Ve) led to a similar dependence of OKN as in closed-loop stimulus conditions. Differences in sensitivity between the temporal and the nasal visual hemifield stimulation evoking horizontal open-loop OKN are described. Directional selectivity appeared in these experiments. Open-loop OKN data from a human subject are reported. With highly attentive horizontal optokinetic gaze nystagmus, Ve depended on the duration of the pursuit phases of OKN. Ve accelerated with the duration of the individual slow phase of OKN and was reset by each backward saccade (of the covered mobile eye). OKN gain was considerably smaller when the subject intentionally pursued as many stripes as possible of the 1.15 degree period stripe pattern (gain related to Vr about 1.5-3).(ABSTRACT TRUNCATED AT 400 WORDS)

Landing responses of the tsetse fly Glossina morsitans morsitans Westwood and the stable fly Stomoxys calcitrans (L.) (Diptera: Glossinidae & Muscidae) to black-and-white patterns: a laboratory study

AbstractThe landing preferences of fed males of Glossina morsitans morsitans Westwood and Stomoxys calcitrans (L.) were measured under constant conditions in a two-choice situation. Pairs of black-and-white landing targets were presented on the grey walls of an arena ca 60 cm in diameter. In a simple choice of blackness vs whiteness, G. m. morsitans showed a ninefold greater preference for black; S. calcitrans displayed no preference. G. m. morsitans landed twice as frequently on a 15×30-cm vertical black stripe as on a horizontal one, but S. calcitrans preferred the horizontal one. Comparisons between a vertical stripe (or a horizontal one) and similar stripes sloping at various angles indicated that at about 50° G. m. morsitans distinguished the sloping stripe from the vertical (or the horizontal), but did not well distinguish slopes closer to the vertical (or horizontal). Tests with multiple vertical stripe patterns indicated that G. m. morsitans did not significantly distinguish between a single 15-cm stripe and two- or three-striped targets of the same total black area, but landed significantly less frequently on targets of four or five stripes, implying an angular, behavioural visual ‘resolution' of roughly 17°; S. calcitrans responded similarly. Both species showed a marked preference for landing near the edge of the black on all targets, with G. m. morsitans strongly biassed to the black side of an interface.

Comparison between the movement detection systems underlying the optomotor and the landing response in the housefly

Flies evaluate movement within their visual field in order to control the course of flight and to elicit landing manoeuvres. Although the motor output of the two types of responses is quite different, both systems can be compared with respect to the underlying movement detection systems. For a quantitative comparison, both responses were measured during tethered flight under identical conditions. The stimulus was a sinusoidal periodic pattern of vertical stripes presented bilaterally in the fronto-lateral eye region of the fly. To release the landing response, the pattern was moved on either side from front to back. The latency of the response depends on the stimulus conditions and was measured by means of an infrared light-beam that was interrupted whenever the fly lifted its forelegs to assume a preprogrammed landing posture (Borst and Bahde 1986). As an optomotor stimulus the pattern moved on one side from front to back and on the other side in the opposite direction. The induced turning tendency was measured by a torque meter (Gotz 1964). The response values which will be compared are the inverse latencies of the landing response and the amplitude of the yaw torque. 1. Optomotor course-control is more sensitive to pattern movement at small spatial wavelengths (10° and 20°) than the landing response (Fig. 1a and b). This suggests that elementary movement detectors (EMDs, Buchner 1976) with large detection base (the distance between interacting visual elements) contribute more strongly to the landing than to the optomotor system. 2. The optimum contrast frequencies of the different responses obtained at a comparatively high pattern contrast of about 0.6 was found to be between 1 and 10 Hz for the optomotor response, and around 20 Hz for the landing response (Fig. 2a and b). This discrepancy can be explained by the fact that the optomotor response was tested under stationary conditions (several seconds of stimulation) while for the landing response transient response characteristics of the movement detectors have to be taken into account (landing occurs under these conditions within less than 100 ms after onset of the movement stimulus). To test the landing system under more stationary conditions, the pattern contrast had to be reduced to low values. This led to latencies of several seconds. Then the optimum of the landing response is around 4 Hz. This is in the optimum range of the optomotor course-control response. The result suggests the same filter time constants for the movement detectors of both systems. 3. The dependence of both responses on the position and the size of the pattern was examined. The landing response has its optimum sensitivity more ventrally than the optomotor response (Fig. 3a and b). Both response amplitudes increase with the size of the pattern in a similar progression (Fig. 3c and d).

フラクタル理論による縞パターンとその心理効果

Most of the configurations of natural phenomena such as crystal of snow, outline of clouds, structure of trees have common patterns between the whole structure and the substructures. This theory built on the system of self-similarity is developed by Benoit Mandelbrot and is called to be fractal theory. This theory can explain the configurations of natural phenomena because of its origin. In the field of Computer Graphics, this theory is often be used for simulating the natural phenomena. The objects of the present study are the following ; (1) The application of the fractal theory to vertical stripe patterns, available to the design of the interior walls and the exterior ones. (2) The ascertainment of how the fractal stripe patterns make people feel natural. (3) The visual comparison of the fractal stripe patterns with stripes of which spectra are reciprocal of frequency, with an equi-spaced stripe and with random stripe patterns.

Colour-contingent after-effects are really wavelength-contingent.

McCollough reported that following adaptation to (say) a red and black pattern of vertical stripes, alternating every few seconds with a green and black pattern of horizontal stripes, an orientation-contingent colour after-effect is observed when black and white gratings are viewed. Vertical gratings are tinged with green and horizontal gratings with pink. We have exploited colour constancy, the tendency for objects to appear constant in hue despite large changes in the spectral composition of the illuminant, to examine whether the colours observed on the McCollough effect test gratings are determined by the wavelength composition of the adaptation patterns or by their perceived colour. The key to this approach can be illustrated by Edwin Land's elegant demonstrations of colour constancy using 'Mondrian' displays. By embedding the adapting grating that is used to induce the McCollough effect within a Mondrian we show that the effect depends upon the wavelength of light coming from the grating, rather than the perceived colour.

Perception at the blind spot and similarity grouping

Perceptual completion at the blind spot was investigated by using patterns with a vertical blank stripe. The perceptual completion occurred across the vertical blank stripe in the test pattern, which was presented at the blind spot when a similarity grouping based on differences in the property of elements constituting the vertical blank stripe pattern was formed. There was no interaction between similarity groups in the filling-in process. The results obtained here indicate that perceptual completion is generated after similarity grouping, and that similarity groups are independent of each other in perceptual completion. The results seem to suggest that filling-in is closely related to a segregative process based on stimulus differences.

Head movements of the mealworm beetle Tenebrio molitor

Tethered walking imagines of the mealworm beetle Tenebrio molitor wave their heads in random fashion. If a periodic pattern of vertical black and white stripes is rotated around the animal a regular nystagmic head movement is superimposed upon the random waving, the frequency of the latter equals the contrast frequency within large ranges of the angular velocity of the pattern. The nystagmus is inverted: After a short period of tracking, during which the angular velocity of the head is the same as that of the panorama, the head returns slowly toward its normal position according to an exponential-like function. Resting animals do not wave their heads. However, if the above panorama is rotated, the beetle turns its head in the direction of the movement of the panorama and holds it in a side-way position, as long as the rotation is maintained. The angular position reached depends in the same manner on the angular velocity of the panorama as the turning tendency of walking animals established in open loop experiments using the spherical Y-maze method.

Two independent motion-detecting systems underlie the optokinetic response of Carcinus maenas

Horridge [1] and Wiersma and Hirsh [2] suspected that two motion-detecting systems underlie the optokinetic response in crabs. Choosing adequate stimuli it was demonstrated that a fast and a slow system do indeed contribute to the response. The eye movement was recorded as described by Fleischer and Pflugradt [3]. During the experiment the crab is fixed in the center of a drum, which carries a vertical-stripe pattern on its inner surface and can be rotated around its vertical axis. The stimuli applied have been steplike displacements of the panorama, i.e., velocity pulses of duration less than 180 ms (a in Fig. 1). In the first series of experiments drum's rotation (see short arrows in the inset of Fig. 1). There is much evidence that the slow component is also a velocity rather than a position response. The biphasic response does not necessarily require two independent motion-detecting systems, unless it is possible to evoke phase I and phase II independently. This could be done by varying the presentation time of a striped pattern before the steplike rotation of the drum. In this experiment the pattern consisted of six groups of lamps, 7.5 ~ wide and 26 ~ high, each composed of three soffits. The angular distance of the groups, arranged upon a homogeneously illuminated background in front of

The aerial and aquatic visual acuity of the optomotor response in the crested newt (Triturus cristatus)

Behavioural and electrophysiological experiments using equidistant vertical stripe patterns were performed. The coherence between the visual acuity of the optomotor response and of the recordings from the accessory optic tract could be shown. The possibility of the existence as well of a background movement system as a tectal nearness system with a greater myopia in the newt is discussed.

Letter: Binocularly induced motion of flicker patterns.

A new apparent motion phenomenon is described. It occurs when two flashing screens are observed binocularly, one screen for each eye, and the temporal phase between the flashes is suddenly changed. It appears as a low-contrast pattern of vertical stripes that move either to the left or right, depending on the phase of the lights. Changing the relative intensity of the screens alters the effect in a manner consistent with previous measurements on visual time delays.

Relations between the amplitudes of spontaneous saccades and visual responses*

Electroretinograms and visually evoked cortical potentials, dependent on the occurence of spontaneous saccadic eye movements, were recorded from human observers. A computer system was used to isolate average-response waveforms that result from saccadic displacements of the retinal image. The responses were recorded as the observer fixed his eye on the center of a steady pattern of vertical stripes presented in maxwellian view. The responses depended on the spatial frequency of the pattern being viewed; in all cases, they were proportional to the extent of saccadic movement. The results are interpreted in terms of response additivity and the numbers of cones stimulated by the image displacement.

Orientation-sensitive after-effects or dichoptically presented colour and form.

MCCOLLOUGH1 discovered that if a grating pattern of (say) red vertical stripes is viewed alternately with one of green horizontal stripes for some minutes, an orientation-specific colour after-effect is observed when viewing a black-and-white test grating. White stripes in a given orientation appear tinted with the hue complementary to the hue presented at that orientation in the original stimulus. McCollough observed that if only one eye was exposed to the original sequence of stimuli, no after-effect was seen when the other eye was used to view the test grating. From this she concluded that the adaptation responsible for the after-effect must occur somewhere in the uniocular pathway before signals from left and right eyes are combined. She suggested as a possible explanation that orientation-sensitive channels in the uniocular nervous system (“edge-detectors”) may be colour-coded, so that strong adaptation with bars of red light in one orientation leads to a “minus-red” after-response from the adapted channels to similarly oriented colourless bars. Harris and Gibson2 have confirmed that the effect persists in conditions ruling out ordinary negative afterimages, which Murch and Hirsch3 have shown sufficient to induce it. Held and Shattuck4 have demonstrated a corresponding after-effect of colour upon the perceived orientation of test bars.

The McCollough Effect Created by Complementary Afterimages

McCollough (1965) was the first to observe the visual effect that a pattern of vertical stripes on a red ground, alternating with a pattern of horizontal stripes on a green ground, has upon the subsequent perception of a test pattern of vertical and horizontal lines on a white ground. Observers usually report an apparent reddish color on the horizontal and a greenish color on the vertical portions of the neutral test pattern. This is know as the McCollough effect. Based on Hubel and Wiesel's observation (1959, 1968) that the visual system of the vertebrate contains edge detectors sensitive to line orientation, McCollough's model (1965) to explain the effect assumed that these detectors were color sensitive and subject to fatigue after successive stimulation, responding with decreased sensitivity to those wavelengths with which they had been most recently stimulated. According to McCollough, the effect was the result of a fatiguing of the verticalline detectors sensitive to red, a fatiguing such that the test pattern's vertical lines were then processed by the nonadapted vertical receptors for green and blue. Similarly, prolonged viewing of the horizontal pattern on green fatigued the horizontal-line detectors sensitive to green, so that the test pattern's horizontal lines appeared reddish. Stromeyer (1969) further observed that alternating a single pattern on a colored background with another, orthogonally oriented pattern on a neutral ground would also produce the usual McCollough effect. An inspection pattern of vertical lines on a red ground ('red verticals') alternated with an inspection pattern of horizontal lines on a white ground produced a greenish aftereffect on the verticals and a reddish aftereffect on the horizontals of a test pattern. Stromeyer explained his

Same-different discrimination of horizontal and vertical stripe patterns in cats

Cats learned a discrimination task requiring comparison of the orientation of stripe patterns presented in same and different pairs. Horizontal and vertical patterns were back-projected on choice doors, and S received a food reward for selecting the alternative with differently oriented stripes. Controls ruled out response on a configurational basis or in terms of absolute characteristics of the individual patterns.