Aftereffects in binocular rivalry

Five experiments are reported in which the aftereffect paradigm was applied to binocular rivalry. In the first three experiments rivalry was between a vertical grating presented to the left eye and a horizontal grating presented to the right eye. In the fourth experiment the rivalry stimuli consisted of a rotating sectored disc presented to the left eye and a static concentric circular pattern presented to the right. In experiment 5 rivalry was between static radiating and circular patterns. The predominance durations were systematically influenced by direct (same eye) and indirect (interocular) adaptation in a manner similar to that seen for spatial aftereffects. Binocular adaptation produced an aftereffect that was significantly smaller than the direct aftereffect, but not significantly different from the indirect one. A model is developed to account for the results; it involves two levels of binocular interaction in addition to monocular channels. It is suggested that the site of spatial aftereffects is the same as that for binocular rivalry, rather than sequentially prior.     

Selective adaptation of monocular and binocular neurons in human vision

Psychophysical techniques were used to examine how subpopulations of visual neurons varying in their ocular dominance interacted in determining performance on a visual task. Using an asymmetric alternating adaptation of the left and right eyes, we manipulated the sensitivity of monocularly driven neurons while keeping the sensitivity of binocularly driven neurons constant. Relative threshold elevations were measured in the left eye, right eye, and both eyes of five observers following different ratios of alternating adaptation. It was found that whereas monocularly measured aftereffects varied monotonically as a function of the adaptation duration of the measured eye, the magnitude of the binocularly measured aftereffect remained constant regardless of how the adaptation was divided between the two eyes. This suggests that neurons differing in their ocular dominance pool their activity in determining sensitivity to a test target.     

Visual orientation during and after lateral head,body, and trunk tilt

Visual judgments of orientation were investigated during (effect) and after (aftereffect) different body postures. In Experiment 1 four trained Ss made apparent verticality (AV) judgments before and after 2 min in each of seven orientations: head tilt left and right, body tilt left and right, trunk tilt left and right and a control condition with head ’and body upright. The aftereffect was significant for all postures excepting trunk tilt left and the control. The aftereffect from head tilt was greater than that from the same degree of body tilt, and that in the trunk tilt condition was in the same direction as’ predicted from neck stimulation. In Experiment 2, 30 Ss made AV judgments during tilt in the same seven postures. The E-phenomenon resulted from both head and body tilts, and an effect was found for trunk tilt in the direction predicted from neck stimulation. The results are discussed in terms of the otolith, neck, and trunk receptor systems.     

Eye direction aftereffect

Three experiments using computer-generated human figures showed that after a prolonged observation of eyes looking to the left (or right), eyes looking directly toward the viewer appeared directed to the right (or left). Observation of an arrow pointing left or right did not induce this aftereffect on the perceived eye direction. Happy faces produced the aftereffect more effectively than surprised faces, even though the image features of the eyes were identical for both the happy and the surprised faces. These results suggest that the eye direction aftereffect may reflect the adaptation of relatively higher-level mechanisms analyzing the others eye direction.     

Motion aftereffect with subjective contours

Stationary lines appear to move from left to right following exposure to lines moving from right to left. This aftereffect, which normally is generated by exposure to moving edges that are defined in terms of local luminance discontinuity, can also be induced by adaptation to displays containing subjective contours. In both cases, stereodeficient observers demonstrated reduced interocular transfer of the aftereffect relative to stereonormal observers. Since interocular transfer of the motion aftereffect entails binocular function within the visual system, these results suggest that the perception of subjective contours depends on excitation of neural feature detectors rather than simply on cognitive inference.     

Slant perception and binocular brightness differences: Some aftereffects of viewing apparent and objective surface slants

Placing a neutral-density filter in front of one eye produces two kinds of distortion in the perceived slant of a binocularly viewed rotating disk: (1) the top or the bottom of a disk rotating in a frontoparallel plane appears displaced toward or away from the observer, depending on the direction of rotation and whether the left or right eye is filtered; and (2) the left or right side of such disk—rotating or stationary—appears closer, depending on whether the left or right eye is filtered. The Pulfrich phenomenon accounts for the first variety of apparent slant, and the Venetian blind effect accounts for the second. Viewing the apparent slant of the rotating disk produces an aftereffect of slant in the third dimension which is greater than the aftereffect of viewing an objective slant of the same direction and magnitude.     

视时距知觉适应后效的空间选择性

时距知觉适应后效是指长时间适应于某一特定时距会导致个体对后续时距产生知觉偏差。其中对视时距知觉适应后效空间选择性的探讨存在争议,有研究支持位置不变性,也有研究支持位置特异性。这类研究能有效揭示时距编码的认知神经机制,位置不变性可能意味着时距编码位于较高级的脑区,而位置特异性则可能意味着时距编码位于初级视觉皮层。未来还可以探究时距知觉适应后效的视觉坐标表征方式,开展多通道研究以及相应的神经基础研究。     

Attentional modulation of the visual motion aftereffect has a central cognitive locus: evidence of interference by the postcategorical on the precategorical

An attentionally demanding task undertaken during adaptation to motion reduces the duration of the subsequent motion aftereffect (A. Chaudhuri, 1990). Previous studies have suggested that this effect is intramodal in character, reflecting the selective deployment of visual attention. The present study demonstrates that nonvisual tasks, performed concurrently with motion adaptation, can significantly reduce the duration of the ensuing aftereffect. Three experiments converge on the conclusionthat postcategorical processes can influence otherwise unrelated concurrent precategorical processes. The experiments also show that neither perceptual input nor motor output components of the attentional task are responsible for the subsequent reduction in motion of aftereffect. The results suggest a reappraisal of findings in this area and of the general distinction between perception and cognition.     

Discontinuity of seen motion reduces the visual motion aftereffect

Would a motion-picture film of a rotating spiral induce a spiral aftereffect? This question was studied in two experiments in which Ss viewed an animated film of circles collapsing to a point. The rate of apparent motion of the collapsing circles and the discontinuity of motion—the length of jump between successively projected circles—were varied independently. A visual aftereffect like the spiral aftereffect was created. The aftereffect increased in strength and duration with the rate of motion, but at all rates of motion it declined as discontinuity of motion increased. The results are taken as evidence that motion aftereffects are caused by selective fatigue of small, directionally sensitive motion-receptive fields.     

Auditory motion aftereffects

Observers were adapted to simulated auditory movement produced by dynamically varying the interaural time and intensity differences of tones (500 or 2,000 Hz) presented through headphones. At lO-sec intervals during adaptation, various probe tones were presented for 1 sec (the frequency of the probe was always the same as that of the adaptation stimulus). Observers judged the direction of apparent movement (“left” or “right”) of each probe tone. At 500 Hz, with a 200-deg/sec adaptation velocity, “stationary” probe tones were consistently judged to move in the direction opposite to that of the adaptation stimulus. We call this result an auditory motion aftereffect. In slower velocity adaptation conditions, progressively less aftereffect was demonstrated. In the higher frequency condition (2,000 Hz, 200-deg/sec adaptation velocity), we found no evidence of motion aftereffect. The data are discussed in relation to the well-known visual analog-the “waterfall effect.” Although the auditory aftereffect is weaker than the visual analog, the data suggest that auditory motion perception might be mediated, as is generally believed for the visual system, by direction-specific movement analyzers.     

Simple and contingent aftereffects of perceived duration in vision and audition

After repeated presentations of a long inspection tone (800 or 1,000 msec), a test tone of intermediate duration (600 msec) appeared shorter than it would otherwise appear. A short inspection tone (200 or 400 msec) tended to increase the apparent length of the intermediate test tone. Thus, a negative aftereffect of perceived auditory duration occurred, and a similar aftereffect occurred in the visual modality. These aftereffects, each involving a single sensory dimension, aresimple aftereffects. The following procedures producedcontingent aftereffects of perceived duration. A pair of lights, the first short and the second long, was presented repeatedly during an inspection period. When a pair of test lights of intermediate duration was then presented, the first member of the pair appeared longer in relation to the second. A similar aftereffect occurred in the auditory modality. In these latter aftereffects, the perceived duration of a test light or tone is contingent—dependent—on its temporal order, first or second, within a pair of test stimuli. An experiment designed to test the possibility of cross-modal transfer of contingent aftereffects between audition and vision found no significant cross-modal aftereffects.     

The interaction of postural systems in visual orientation

Visual orientation judgments were made during right head tilt, left body tilt, and left trunk tilt, each of 30 deg. In these postures the otolith, neck, and trunk systems are stimulated in pairs. The hypothesis that the visual vertical during trunk tilt is equal to the algebraic sum ofthose in the same direction ofbody tilt and the opposite head tilt was tested and accepted. This result demonstrates the interaction of these postural systems in visual orientation, and complements the confirmation of the same hypothesis for the visual aftereffect following prolonged tilt.     

Modifying an underlying component of perceived arm length: adaptation of tactile location induced by spatial discordance

In four experiments we examined the adaptation and aftereffect that resulted from a treatment yielding tactile/kinesthetic length discordance between the arms. Perceived discordance diminished with trials and tended to zero. Subsequent visual/tactile cross-modal judgments of distance showed the aftereffect to be a change in the perceived location of an unseen probed spot on each hand with respect to the location of a truly coincident visual marker. This occurred toward the body for the probed spot on one arm and away from the body on the other. There were three other main findings: (a) Arm movement was not a necessary condition for adaptation or aftereffect; (b) with intrinsic length information about the right arm present, but touch information from the right index finger absent during treatment, adaptation and aftereffect were abolished; (c) aftereffects of tactile location that were manifest at the hand and wrist tended to zero when a point close to the elbow was tested with a cross-modal procedure. The experiments provide evidence that the mapping of the tactile sheet onto an internal length domain had been modified by the treatment. The sensory consequences of the treatment led many subjects to report spontaneously that their arms felt to be of different lengths.     

Spiral aftereffect duration as a correlate of impulsiveness

In a correlational analysis impulsiveness (Imp), assessed by means of a questionnaire concerned with speed of judgment and decision making, was found to be negatively related to spiral aftereffect (SAE) duration. However, this relationship was present only in a sample of subjects with high neuroticism scores. In this group SAE duration was also positively related to debilitating anxiety. A parallel was seen between Imp and Heymans' “Secondary function,” a personality dimension which was similarly operationalized in a visual aftereffect experiment. Some other SAE correlates are also discussed.     

刺激呈现时间对汉字语义加工脑偏侧化的影响

以往关于汉字字词识别脑功能偏侧化的研究发现了左半球优势、右半球优势或者大脑两半球均势三种不同的结果。该研究采用一侧化Stroop范式(刺激分别只呈现于左视野、中央视野或右视野中),通过系统地改变刺激呈现时间以期探讨刺激呈现时间是可以解释这些不一致结果的可能因素之一。结果显示:对于右利手被试,在刺激呈现时间为60 ms时右半球出现了较强的Stroop效应,在刺激呈现200 ms时左右半球的Stroop效应没有表现出差异,在刺激呈现时间较长时左半球表现出较强的Stroop效应。该结果提示,随着刺激呈现时间的延长,语义优势发生了从右半球到左半球的转换。     

Psychophysical evidence for an extrastriate contribution to a pattern-selective motion aftereffect

A stationary vertical test grating appears to drift to the left after adaptation to an inducing grating drifting to the right, this being known as the motion aftereffect (MAE). Pattern-specific motion aftereffects (PSMAEs) induced by superimposed pairs of gratings in which the component gratings drift up and down but the observer sees a single coherent plaid drifting to the right have been investigated. Two experiments are reported in which it is demonstrated that the PSMAE is tuned more to the motion of the pattern than to the orientation and direction of motion of the component gratings. However, when subjects adapt to the component gratings in alternation, aftereffect magnitude is dependent upon the individual grating orientations and motion directions. These results can be interpreted in terms of extrastriate contributions to the PSMAE, possibly arising from the middle temporal area, where some cells, unlike those in striate cortex (V1), are tuned to pattern motion rather than to component motion.     

Hemisphere function and vigilance

A vigilance task in which successive signals were presented to one or other hemiretina, and therefore to one or other cerebral hemisphere, revealed no differences between the hemispheres in terms of detections, although detections declined overall during the experimental period. False positive responses also declined, but consistently more arose from the left hemisphere. There was also a difference in the detection of signals received through the nasal and temporal hemiretinae, the temporal hemiretina showing superiority in detection rate throughout the experiment. This finding may provide a new and more economical approach to the tunnel vision phenomenon.     

The influence of a secondary task and type of feedback on adaptation to lateral displacement of the visual array

Summary This experiment was designed to investigate the influence of a secondary attention-demanding force-production task on adaptation to prismatic displacement. Recent suggestions by Finke (1979) lead to the prediction that a secondary task executed during adaptation would interfere with the central component of adaptation (as measured by intermanual transfer), but not the peripheral component (adaptation specific to adapted limb). There were three secondary task conditions (no task, easy task, difficult task). Other factors investigated were: type of feedback (continuous, terminal), hand adapted (right, left) and prism orientation (base right, base left). While negative aftereffect was not influenced by the secondary task manipulation, intermanual transfer results provide partial support for Finke's model. Correlational analyses indicate the importance of task-specific parameters in determining the nature of perceptual-motor adaptation.     

Conflict between aftereffects of retinal sweep and looming motion

Summary Observers looked monocularly into a tunnel, with gratings on the left and right sides drifting toward the head. An exposure period was followed by a test with fixed gratings. With fixation points, left and right retinal fields could be stimulated selectively. When exposure and test were on the same retinal fields, but fixation was on opposite sides of the tunnel during exposure and test periods, aftereffects of retinal sweep and of perceived looming were in opposite directions. The two effects tended to cancel, yielding no perceived aftereffect. When they did occur, aftereffects in the retinal and the looming directions were equally likely. Cancellation was significantly more likely in the experimental conditions than in the control, when fixation always remained on the same side. When areas of retinal stimulation in the exposure and test periods did not overlap, cancellation was less frequent and aftereffects of looming were more frequent. Results were not significantly different for left and right visual fields, indicating that cortical vs. subcortical OKN pathways do not influence the illusion. Vection resulted for 16 of 20 observers under one or another of our conditions.     

Attention affects the stereoscopic depth aftereffect

'Preattentive' vision is typically considered to include several low-level processes, including the perception of depth from binocular disparity and motion parallax. However, doubt was cast on this model when it was shown that a secondary attentional task can modulate the motion aftereffect (Chaudhuri, 1990 Nature 344 60-62). Here we investigate whether attention can also affect the depth aftereffect (Blakemore and Julesz, 1971 Science 171 286-288). Subjects adapted to stationary or moving random-dot patterns segmented into depth planes while attention was manipulated with a secondary task (character processing at parametrically varied rates). We found that the duration of the depth aftereffect can be affected by attentional manipulations, and both its duration and that of the motion aftereffect varied with the difficulty of the secondary task. The results are discussed in the context of dynamic feedback models of vision, and support the penetrability of low-level sensory processes by attentional mechanisms.