Toads (Bufo bufo) are able to distinguish small stripes with axis orientation in the direction of motion (worm-like stripes) from those with axis orientation perpendicular to the direction of motion (anti-worm-like stripes). The configurational discrimination ability of the toad is, thus far investigated, largely invariant for (1) movement direction in ...

This paper reports studies on the mechanisms underlying seaward orientation in hatchling turtles. The particular aim was to investigate whether activity in different regions of the retina and associated tectal areas, as assessed by some comparator mechanism, results in turning in different directions. Hatchling green turtles (Chelonia mydas) were tested ...

The findings obtained in neurophysiological and psychophysical investigations using tactile stimuli that move at constant velocity across the skin are reviewed. For certain neurons in the postcentral gyrus of the cerebral cortex (S-I) of macaque monkeys, direction of stimulus motion is a "trigger feature"" i.e., moving tactile stimuli evoke vigorous ...

Foveal images fade much faster than peripheral images, at light-on as well as at light-off. An opposite result can be obtained, however, in case of unsatisfactory stabilization. The amount and extension of the brightness spreading before the fading depend on the stimulus brightness and its location on the retina. The ...

Two experiments recorded the simple RT of 13 and 10 airline pilots, respectively, to accelerating lines and dots on a cathode-ray tube. In Exp. 1, dotted lines of six lengths moved in-line or frontally, and downward or to the right. Exp. 2 compared seven different in-line-moving solid lines with dot ...

1. On psychophysical grounds, Beverley & Regan suggested that in man different neural mechanisms mediate the binocular perception of movement in depth and the binocular perception of positional (static) depth. They proposed that the human visual pathway contains several neural mechanisms, each sensitive to a different direction of motion in ...

The aim of the present research was to study illusory dilatation of surfaces isolating some factors contributing to this phenomenon. A series of displays (8.5 cm x 8.5 cm) was prepared: a white square card and five square cards with a uniform pattern of black dots, increasing gradually. The displays ...

The Boyden chamber system has been used to study the motile response of rabbit peritoneal neutrophils to partially purified casein cytotaxin. The results of these in vitro experiments indicate that neutrophils respond in two distinct ways to cytotaxin. Firstly, they increase their innate random mobility. Secondly, they respond to the ...

The visual perception of velocity was studied in three experiments. The stimulus used in the first experiment was an endless striped belt moving behind a stable fixation line. In the second experiment a vertical moving line was presented in front of a stable striped background. In the third experiment the ...

1. Several statistical analyses were performed on 205 S-type and CX-type cells which had been completely analyzed on 12 response variables: orientation tuning, end stopping, spontaneous activity, response variability, direction selectivity, contrast selectivity for flashed or moving stimuli, selectivity for interaction of contrast and direction of stimulus movement, spatial-frequency selectivity, ...

Trajectories of polymorphonuclear leukocytes which are responding to a chemical gradient are analyzed in order to deduce probability distributions of the angles between successive path segments. The turn angle probability distributions thus obtained are seen to be strongly dependent on the direction of locomotion prior to a turn, in that ...

Recent interest in the neural processing of complex cutaneous stimuli such as moving stimuli has necessitated more versatile stimulating devices. This article describes the construction and application of a relatively inexpensive instrument, utilizing equipment readily available in most neurophysiological laboratories, which provides a variety of moving cutaneous stimuli of selected ...

Most simple cells in the striate cortex of the cat are direction selective, firing to broadside movement of an optimally oriented edge or bar in one direction of motion and not the other. The smallest stimulus displacement for which a direction-selective discrimination can be made cannot be smaller than the ...

1. Binocular discrimination of the direction of a target's motion in depth was measured in terms of the smallest angular difference in direction that could be detected with a probability 50% better than chance. Directional discrimination was measured for targets moving along 16 different trajectories directed to the left and ...

1. The properties of the receptive fields of simple cells in the cat striate cortex have been studied by preparing average response histograms both to moving slits of light of different width and to single light-dark edges or contours.2. The movement of a narrow (< 0.3 degrees ) slit across ...

Direct vision prisms are useful for quick examination of any spectrum. Most of the commercial direct vision instruments utilize the cemented type Amici prism consisting of both crown and flint prisms. In this paper a type of direct vision prism made of single glass is discussed. It utilizes two refractions ...

Single-molecule tracking of membrane proteins has become an important tool for investigating dynamic processes in live cells, such as cell signaling, membrane compartmentation or trafficking. The extraction of relevant parameters, such as interaction times between molecular partners or confinement-zone sizes, from the trajectories of single molecules requires appropriate statistical methods. ...

In the introduction to Chapter II of his work L'Int?grale de Fourier et ses Applications ? l'Optique, Duffieux reduces Dirichlet's Theorem to a "specific summary." Developed by a convolution where the functions of influence apply [Rev. Opt. 34, 351 (1960)], Dirichlet's Theorem immediately gives data on the form of two ...

These units responded vigorously to stimuli moving entirely across their receptive field centers in one direction (preferred) and not at all when the direction of motion was reversed (null). The directional selectivity was the result of an inhibitory mechanism which prevented responses to null movements. Surrounding each field center was ...

Two pairs of horizontal lines of equal length, with different configurations of dots above and below, are presented stereoscopically. Upon fusion, the two lines are perceived as tilting in space in directions opposite to the depth effects of the dots.

There are ganglion cells in the pigeon retina that respond selectively, some to any edge moving in a particcular direction only, others to any vertically moving horizontal edge. This selective response to a specific stimulus arises from the selective sensitivity of each neuron to a particular spatiotemporal configuration in its ...

Among the ganglion cells in the rabbit's retina there is a class that responds to movement of a stimulus in one direction, and does not respond to movement in the opposite direction. The same directional selectivity holds over the whole receptive field of one such cell, but the selected direction ...

As an approximation based on various experiments reported in the literature, the least detectable difference in speed (delta w) varies in direct proportion to the speed (w) over a range from 0.1 to 20 degrees of visual angle per second. The constancy of the Weber ratio (deltaw/w) aids in understanding ...