The temporal course of the relationship between retinal disparity and the equidistance tendency in the determination of perceived depth

Changes in perceived depth as a function of exposure duration were compared for two stimulus conditions. In one. a depth interval between two points of light was produced by the retinal disparity cue, and in the other condition, otherwise identical to the first, the light points were connected by a thin luminous line. The principle finding was that the perceived depth interval between the light points increased as a function of exposure durations greater than 1 sec, while no change in the perceived depth interval between the end points of the line occurred. The results were interpreted in terms of a greater equidistance tendency (ET) operating for the line than for the point condition. It was concluded that both the ET and the retinal disparity cue increase in strength as a function of exposure duration.     

Exposure-time and spatial-frequency effects in the tilt illusion

The exposure durations of a vertical test line and a tilted inducing grating were varied and the tilt illusion thus generated was found to change as a function of this variation. Significant direct effects (acute-angle expansion) and indirect effects (acute-angle contraction) were found to occur at times consistent with Andrew's estimate of the time course of inhibition in the visual system when the inducing grating had a spatial frequency of 10 cycles deg-1. However, a 2.71 cycles deg-1 grating gave significant effects at exposure durations of 10 as well as 1000 ms, while in a further experiment a 10.91 cycles deg-1 grating gave significant effects at 1000 ms only. These results seem to suggest that orientation interactions thought to be due to inhibition (direct effect) and disinhibition (indirect effect) may occur within both sustained and transient channels with concomitant differences in time constants.     

Global interference: the effect of exposure duration that is substituted for spatial frequency

In this study, participants were required to identify hierarchically structured patterns that appeared at either global or local level. Paquet and Merikle (1984 Canadian Journal of Psychology 381 45-53) showed that global interference is affected by exposure duration in the processing of a hierarchical structure. They showed that only global-to-local interference occurred at short exposure durations. In contrast, global-to-local as well as local-to-global interference was observed at long exposure durations. They suggested that the effect of exposure duration with global interference depends on the high-spatial-frequency versus low-spatial-frequency channel. In the present study, exposure duration (short or long) was varied randomly from trial to trial (experiment 1), or held constant (experiment 2). In experiment 1, global-to-local interference occurred at both short and long exposure durations, even though the same physical properties existed as in experiment 2. In experiment 2, both global-to-local and local-to-global interference occurred at only long exposure durations, in line with the results reported by Paquet and Merikle. This suggests that the effect of exposure duration on global interference is explained not only by spatial-frequency channels, but also by attentional shift.     

The role of spatial integration in the perception of surface orientation with active touch

Vision research has shown that perception of line orientation, in the fovea area, improves with line length (Westheimer & Ley, 1997). This suggests that the visual system may use spatial integration to improve perception of orientation. In the present experiments, we investigated the role of spatial integration in the perception of surface orientation using kinesthetic and proprioceptive information from shoulder and elbow. With their left index fingers, participants actively explored virtual slanted surfaces of different lengths and orientations, and were asked to reproduce an orientation or discriminate between two orientations. Results showed that reproduction errors and discrimination thresholds improve with surface length. This suggests that the proprioceptive shoulder-elbow system may integrate redundant spatial information resulting from extended arm movements to improve orientation judgments.     

短时距估计中的标量特性

使用单任务研究程序,采用预期式研究范式和再现时距的研究方法,从心理物理学的视角,通过三个实验系统地考查了人类短时距估计的标量特性、变异源、时距估计中的转换点和韦伯函数的形态等问题。结果表明,刺激物的运动、变化、速度和物理时距是被试进行短时距估计的重要变异源;被试在实验中表现出高估较短时距和低估较长时距的倾向,时距估计的转换点为11.1s;计时过程中得到的韦伯函数是个分段连续函数, 韦伯函数的拐点有两个12s和21s,这两点与本研究得到的时距估计转换点具有部分一致性     

Stabilized images: Dependent variable specificity of pattern-specific effects with prolonged viewing

Two studies report results of viewing lines in different orientations in stabilized Maxwellian view. The first study examined the time course of four dependent variables-whole- and partial-fade frequencies and whole- and partial-fade durations. Whole-fade frequencies increased systematically throughout 10 min of the 15-min viewing session and were sensitive to line orientations. Partial-fade frequencies increased for 3–5 min during which orientation specificity occurred. Thereafter, partial-fade rate was constant and pattern-specific effects disappeared. Mean fade duration, which increased throughout the 15-min session for whole fades but for only 5 min for partial fades, was not pattern-specific. The second study demonstrated that the pattern specificity of whole fades could not be accounted for in terms of time-dependent extraneous variables. It was concluded that partial and whole fades may reflect the operation of different visual processes. The complete fading of images was attributed to the operation of supraretinal pattern processing units.     

The Effect of Nontemporal Information Processing on Time Estimation in Pigeons

Pigeons' ability to time a stimulus while simultaneously engaged in another information-processing task was examined in three experiments using a matching-to-sample procedure. Pigeons were trained to match temporal samples of 2 and 10 s and were tested with durations of 2, 3, 4.5, 6.7, or 10 s while simultaneously processing information from another dimension. Experiment 1 revealed that the psychophysical curve for long judgments taken when pigeons also had to evaluate line orientation was shifted to the right of a control curve taken from trials on which only time had to be judged. In Experiment 2, results from probe duration tests showed that processing the spatial location of a stimulus while attending to duration caused a more general loss of timing ability across the probe durations (shorter durations were judged as longer and longer durations were judged as shorter). In Experiment 3, a distracter light was illuminated on some probe trials to determine how such a perceptual distraction would affect time judgments on the probe trials. Results showed a general loss of timing ability similar to that found in Experiment 2. It is proposed that the data might best be explained by a divided-attention effect rather than by a systematic effect on the timing mechanism.     

Effects of component length and of the transitions among components in multiple schedules

Pigeons received equal variable-interval reinforcement during presentations of two line-orientation stimuli while five other orientations appeared in extinction. Component duration was 30 seconds for all orientations and the sequence was arranged so that each orientation preceded itself and each other orientation equally often. The duration of one component (0°) was shortened to 10 seconds and the other (90°) was lengthened to 50 seconds. All animals showed large increases in response rate in the shortened component and this increase was recoverable after an interpolated condition in which all components were again 30 seconds in duration. This effect was replicated in a second experiment in which component duration was changed from 150 seconds to 50 seconds and 250 seconds. An examination of local contrast effects during the first experiment showed that the shortened component produced local contrast during subsequent presentations of the lengthened component, just as would a component associated with more frequent reinforcement. When the presentation sequence was changed so that the lengthened component was always followed by the shortened component, response rates generally increased during the lengthened component. When the sequence was arranged so that the shortened component always preceded the longer component, response rate decreased in the former. These effects, as well as the increases in response rate following change in component length, seem not to be the product of local contrast effects among components.     

Temporal characteristics of line orientation identification

The hypothesis that identification of line orientation is based on different mechanisms--a detector mechanism at large orientation differences and a computational one at small orientation differences--was tested in three experiments. The first two experiments compared reaction time and time of complete temporal summation (tc) in two tasks, line detection and line orientation identification. Identification at orientation differences 15 degrees or more was similar to detection in several respects, suggesting that it was accomplished according to the principle of "labeled lines." In agreement with the initial hypothesis, identification at differences smaller than 15 degrees had a slower time course and could not be explained by the "labeled lines" principle. Experiment 3 explored the orientation acuity as a function of exposure duration and stimulus energy. Energy could not completely substitute for time in providing high orientation acuity, a result suggesting the involvement of neurophysiological mechanisms of large time constants.     

Attachment and information seeking in romantic relationships

Testing predictions derived from attachment theory, this research investigated how adult attachment orientations are associated with selective exposure to information about the self, one's partner, and one's relationship. The results of two studies revealed that (a) more avoidantly attached individuals have limited interest in knowing their partner's intimate thoughts and feelings, (b) more anxiously attached individuals selectively prefer information on intimate topics pertaining to their partner and relationship and focus on information that highlights their own as well as their partner's shortcomings, and (c) regardless of attachment orientation, individuals express interest in learning about the negative relationship behaviors and characteristics of their insecurely attached partners. These findings suggest that selective information seeking may have important effects on relationships and may help explain how attachment orientations affect important relationship outcomes.     

The differential effects of brief exposures and surrounding contours on direct and indirect tilt illusions

Four experiments in which logarithmic intervals between 25 and 1600 ms were used for stimulus duration in tests for the tilt illusion are reported. It is demonstrated that the direct and the indirect tilt illusions both increase in magnitude inversely with length of stimulus presentation. The data suggest that whereas the direct effect peaks with a value of about +7 degrees at the shortest flash duration used (25 ms), peak indirect effects (of about +2 degrees) do not occur at this duration. In addition, whereas direct effects level out after 100 ms stimulus exposure times, to the usual magnitude obtained with long presentations (about +2 degrees), indirect effects reach their standard magnitude (-0.5 degrees to -1.0 degrees) later, at exposures of about 400 ms. Even at very short flash durations, a luminance square frame surrounding the illusion display reduces the indirect effect by two thirds of its magnitude but has no effect at all on the direct effect. It is suggested that direct effects arise early in visual processing, in area V1, where there are transient mechanisms and where corruption of orientation analysis by the inducing grating would occur prior to later, extrastriate, global analysis of the surrounding peripheral frame. Indirect effects, on the other hand, may arise later, along the sustained parvocellular colour-form pathway, where more global processing occurs and susceptibility to surrounding fields might be expected.     

Effect of short and long exposure duration and dual-tasking on a global-local task

Past research has demonstrated a global advantage in responses to visually presented hierarchical stimuli such that, on incongruent trials, the global form interferes with responses to the local level [Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112, 24-38]. In Experiment 1, 32 adults performed alternating blocks of global or local identification of hierarchical letter stimuli in which the global and local letters were congruent, incongruent, or neutral, and were presented at either a short (17 ms) or long (100 ms) exposure duration. A global advantage was demonstrated at both durations. In the local-directed task, interference on incongruent, relative to neutral, trials was observed at both exposure durations, but facilitation on congruent trials, relative to neutral trials, was present only when stimuli were presented at the long exposure duration. In Experiment 2, global or local identification was performed by another group of 24 adults at either a long or short exposure duration, and also under conditions of full attention (FA) or dual-task (DT) conditions with a digit-monitoring task. Under FA, we again found significant interference at both exposure durations, but facilitation only at the long exposure duration. Under DT conditions, the pattern of facilitation and interference at the short duration remained unchanged. At the long duration, however, dual-tasking eliminated interference in the RT but not error data, while facilitation was present in both sets of data. Results are in line with a perceptual account of the global advantage, and suggest that facilitation requires consciously-mediated processes, whereas interference does not.     

光栅朝向分辨学习中存在关于45°对角线对称的镜像迁

采用光栅朝向分辨任务来探讨视知觉学习中是否存在关于45°对角线对称的镜像迁移现象。训练被试分辨15°或75°朝向3或5天,每天约1小时,训练前后测量15°、75°、45°朝向的分辨阈值。通过训练,训练朝向（15°或75°）的阈值下降,该学习效应没有迁移至45°朝向,但基本迁移到关于45°对称的朝向（75°或15°）上。这提示,视知觉学习可能发生在中间视皮层,该皮层同时具有一定的朝向特异性和关于45°对角线对称的镜像迁移性     

Pattern and orientation effects on afterimage duration

Patterns composed of a pair of lines: vertical + horizontal, vertical + oblique, horizontal + oblique, and oblique + oblique, either centrally-aligned or edge-aligned, were shown at two positions of rotation. After a 1-s exposure to the pattern observers timed the duration of afterimages consisting of individual lines (fragmentary state) and the pattern as a whole (unitary state) for the ensuring 60 s. Summing unitary and fragmentary afterimage durations yielded the total afterimage duration for each pattern. Three hypotheses were confirmed by the results: (i) total afterimage duration is constant for all patterns when integrated spatiotemporal luminances are equal; (ii) unitary afterimage duration is also constant; (iii) fragmentary afterimages of vertically oriented lines have longer durations than either their horizontal or oblique pair members, regardless of alignment and, with one exception, rotation. For all patterns, the durations of the unitary and the fragmentary state represent a fixed portion of the total afterimage duration. The difference between afterimage duration for differently oriented lines in patterns which include a vertical is discussed in relation to the vertical-horizontal illusion, the function and structure of cortical orientation processes, and perceptual development.     

Is target movement as well as target displacement a stimulus for saccadic eye movements?

The effects of visual movement on saccadic eye movement have been examined. In a classic apparent-movement demonstration with two successively exposed line-segment targets the quality of the movement is dependent on the relative orientation of the line segments. If saccadic eye movements are elicited between the targets in this situation, the configuration leading to optimal apparent movement also leads to the shortest-latency saccades. When a single line segment is succeeded by two line segments flanking it on opposite sides, and if one of these has the same orientation as the initial one and the other a different orientation, then apparent motion is seen between the two lines with the same orientation. However, the direction of saccades elicited in this configuration is not influenced by the relative orientations of the line segments. The two results together suggest that the effect of visual movement on saccadic eye movement is nonspecific.     

The Poggendorff illusion: Amputations,rotations, and other perturbations

Studies of the Poggendorff illusion (a transversal interrupted by parallel lines) showed that illusory effects increased linearly with increasing separation between the parallels, increased in inverse proportion to the tangent of the angle of intersection between transversal and parallels, decreased whenever line segments (other than a transversal segment) were omitted, decreasing to zero when the segment of a parallel forming the obtuse angle with the transversal was omitted, and varied systematically with the tilt of the whole display, approaching zero when the transversal was oriented in a horizontal or vertical position. Hypothesis: The Poggendorff illusion involves at least three kinds of effects on the perceived orientation of a segment: distortion by other segments (especially a segment intersecting at an obtuse angle), stability of vertical and Horizontal orientations, and assimilation towards vertical or horizontal.     

Adjusting fixed-ratio schedules in the squirrel monkey

On an adjusting schedule of reinforcement, a parameter of the schedule is varied as a function of some characteristic of the animal's performance. In Experiment I, the fixed-ratio response requirement was varied as a function of the time that elapsed before the animal started responding in each fixed-ratio (initial pause). When initial pauses were shorter than a specified duration, the response requirement was increased; when they were longer than the specified duration, the response requirement was decreased. Specified durations of 1, 2, 4, 8, and 15 min were studied. The average response requirement maintained by each monkey was directly related to the length of the specified duration of initial pause. In Experiment II, the fixed-ratio response requirement was constant, but reinforcement occurred only when the initial pause was longer than a specified duration. The average durations of initial pauses were directly related to the length of the specified duration and to the response requirement. Meprobamate consistently decreased the average durations of initial pauses.     

Figural effects in afterimage fragmentation

Afterimages consisting of between two and five lines were observed in five experiments. Measures were taken of both the duration and frequency of visibility of the lines comprising the configurations, and also of all line combinations. In Experiments I-III, lines forming angles, triangles, and a square were varied in orientation. Neither the absolute nor the relative orientation of the lines had any systematic effects on the measures. These results are compared with those that have been derived from steady fixation and optical stabilization, in which vertical-horizontal line pairs yield greater stability than other orientations. In Experiment IV, afterimages of the letters N and Z were found to be more stable than those of their mirror-image reversals, both in terms of the duration of visibility of the entire configurations and the obliques. This pattern was not produced using a complex configuration that could fragment into either a letter or a reversed letter (Experiment V). Similar effects have been found during steady fixation.     

An application of the optic sphere theory in discrimination of slant with minimal information

In Johansson and Börjesson (1989), a new theory of visual space perception—the optic sphere theory—was presented in which the hemispheric shape of the retina is utilized for determination of slant of plane surfaces in wide-angle perception. The process of the optic sphere mechanism can be described as the projection of a translating distal line on the optic sphere, and an extrapolation of this projection to a great circle. The determination of the 3-D slant of the distal line is made by identification of points of no change on the great circle during its rotation. The main objective of the present study was to investigate this process as applied to central stimulation of the retina with reduced and minimal information of slant or horizontal orientation. Each stimulus pattern consisted of either two continuous lines or two pairs of dots in motion presented on a computer screen. The pairwise lines and the pairs of dots defined simulated 3-D slants (or horizontal orientations) of different magnitude within each pair, and the subjects' task was to discriminate between these simulated slants. It was shown that the simulations evoke percepts of 3-D slants, and of horizontal orientations, and that it is possible to discriminate between them even from minimal information (pairs of dots). Further, the empirical findings of Börjesson (1994) indicated that longer extrapolations of the projected arc to a point of no change yield less accurate discriminations of slant. We failed to replicate this in Experiment 4, in which case stimulus variables that covaried with extrapolation length were eliminated or minimized. It is suggested that this raises some doubt about discrimination accuracy as dependent on extrapolation length per se. The overall conclusion, however, is that the optic sphere theory represents a possible explanation of, or analogy to, the process utilized by the visual system for determination of the simulated 3-D slants and horizontal orientations in the present study.     

Perceived common rotary motion of ambiguous stimuli as a criterion of perceptual grouping

Apparent common behavior of contours with respect to a property for which each contour is ambiguous (in this case direction of rotary motion in depth) was used as a criterion of the unitary processing of the contours or “grouping.” Grouping was found to decrease as a monotonic function of the difference in line orientation and, for fixed orientations, to decrease as a monotonic function of line separation. These results are tentatively attributed to the distribution of line detectors in the projection area.