Interactions between perception and action in a reaction task with overlapping S-R assignments

 We have used a novel task to study relationships between perception and action. Four experiments studied stimulus-response (S-R) relationships under conditions in which stimuli and responses were functionally unrelated (i.e., not assigned to each other by instruction) and merely overlapped in time. On each trial, participants carried out movements on a graphic tablet while observing motions displayed on a computer screen. The movement on trial n was specified by the motion observed on the previous trial n-1, whereas the motion observed on trial n specified the movement to be performed on trial n+1. Results showed that stimulus motion had a contrast-like impact on response movement. Watching a small motion while performing a medium-sized movement increased movement size, whereas watching a large motion led to a decrease (Experiment 1). Further experiments showed that the contrast pattern was not affected by the mode of motion presentation (Experiment 2), or by the interval between motion and movement execution (Experiment 3). Contrast was also observed in the reverse direction, i.e., from action to perception (Experiment 4). We propose that the contrast effect is due to a mechanism for selective code modification. This mechanism acts to increase the distinctiveness of simultaneously activated perception and action codes in a common representational domain. Received: 11 July 2000 / Accepted: 4 March 2001     

Stimulus complexity and prospective timing: clues for a parallel process model of time perception

Whereas many studies have considered the role of attention in prospective timing, fewer have established relations between movement complexity and prospective timing. The present study aims at assessing to what extent motion complexity interferes with prospective timing and at delineating a neuropsychophysical plausible model. We have thus designed a visual paradigm presenting stimuli in sequential pairs (reference comparison interval). Stimuli are motionless or moving according to different complexities, and stimulus complexities are intermixed within each pair. To prevent a possible attention-sharing effect, no concurrent task was required. Our study suggests that movement complexity is a key component of duration perception, and that the relative judgement of durations depends on spatio-temporal features of stimuli. In particular, it shows that movement complexity can bias subjects’ perception and performance, and that subjects detect that comparison intervals are longer than reference before their end. In the discussion, we advocate that the classical internal clock model cannot easily account for our results. Consequently, we propose a model for time perception, based on a parallel processing between comparison interval perception and the reconstruction of the reference duration.     

Observations on stroboscopic induced motion

Subject-relative explanations of motion induction state that induced motion is the result of a misperceived shift of the median plane of the visual field of the subject. This theory does not require relative motion of the spot and frame, in the classical spot-and-frame condition, only asymmetrical stimulation. Three experiments are reported in which stroboscopic induced motion was investigated. The experimental arrangement was unconventional in that the induced object (spot) was presented only during the interstimulus interval between the exposures of the inducing object (frame). This allowed differentiation of the duration of the induced movement and that of the inducing one. In the first experiment it was demonstrated that perception of induced motion depends upon the duration of the interstimulus interval between the presentations of the inducing frame. In the second experiment it was shown that the perceived velocity of the induced movement can be different from that of the inducing one and depends on the duration of exposure of the induced object. In the third experiment a stimulus display was created in which the apparent displacement of an object and its induced motion are incongruous. The results are incompatible with subject-relative displacement as the sole determining factor of motion induction and they present some difficulties for the hypothesis that induced motion is the result of the apportionment of the objective displacement of the frame.     

Temporal restriction in apparent motion of two objects by presenting multipartite subframes

Two experiments tested whether proper perception of motion can be realized with a multipartite subframe stimulus. In order to elucidate the constructive processes of visual motion, two motion stimuli were used which differed according to their hierarchical levels of reference. It was found that: (a) stable motion was perceived so long as the temporal interval between the neighboring frames comprising several subframes was held between 30 and 120 ms; (b) visual unification of subframes was properly achieved independently of the number of subframes insofar as the temporal constraint mentioned above was satisfied; (c) when stimuli consisted of two motions of different hierarchical level of reference, perception of the higher-level motion required the prior perception of the lower-level motion.     

Perceptual organization of apparent motion in the Ternus display

A typical Ternus display has three sequentially presented frames, in which frame 1 consists of three motion tokens, frame 2 (blank) defines the interstimulus interval, and frame 3 has similar motion tokens with their relative positions shifted to the right. Interestingly, what appears to be a seemingly simple arrangement of stimuli can induce one of two distinct apparent-motion percepts in the observer. The first is an element-motion perception where the left-end token is seen to jump over its two neighboring tokens (inner tokens) to the right end of the display. The second is a group-motion perception where the entire display of the three tokens is seen to move to the right. How does the visual system choose between these two apparent-motion perceptions? It is hypothesized that the choice of motion perception is determined in part by the perceptual organization of the motion tokens. Specifically, a group-motion perception is experienced when a strong grouping tendency exists among the motion tokens belonging to the same frame. Conversely, an element-motion perception is experienced when a strong grouping tendency exists between the inner motion tokens in frames 1 and 3 (i.e. the two tokens that overlap in space between frames). We tested this hypothesis by varying the perceptual organization of the motion tokens. Both spatial (form similarity, 3-D proximity, common surface/common region, and occlusion) and temporal (motion priming) factors of perceptual organization were tested. We found that the apparent-motion perception of the Ternus display can be predictably affected, in a manner consistent with the perceptual organization hypothesis.     

Occluded motion alters event perception

We employed audiovisual stream/bounce displays, in which two moving objects with crossing trajectories are more likely to be perceived as bouncing off, rather than streaming through, each other when a brief sound is presented at the coincidence of the two objects. However, Kawachi and Gyoba (Perception 35:1289–1294, 2006b) reported that the presence of an additional moving object near the two objects altered the perception of a bouncing event to that of a streaming event. In this study, we extended this finding and examined whether alteration of the event perception could be induced by the visual context, such as by occluded object motion near the stream/bounce display. The results demonstrated that even when the sound was presented, the continuous occluded motion strongly biased observers’ percepts toward the streaming percept during a short occlusion interval (approximately 100 ms). In contrast, when the continuous occluded motion was disrupted by introducing a spatiotemporal gap in the motion trajectory or by removing occlusion cues such as deletion/accretion, the bias toward the streaming percept declined. Thus, we suggest that a representation of object motion generated under a limited occlusion interval interferes with audiovisual event perception.     

Visual onset expands subjective time

We report a distortion of subjective time perception in which the duration of a first interval is perceived to be longer than the succeeding interval of the same duration. The amount of time expansion depends on the onset type defining the first interval. When a stimulus appears abruptly, its duration is perceived to be longer than when it appears following a stationary array. The difference in the processing time for the stimulus onset and motion onset, measured as reaction times, agrees with the difference in time expansion. Our results suggest that initial transient responses for a visual onset serve as a temporal marker for time estimation, and a systematic change in the processing time for onsets affects perceived time.     

Ideomotor effects of pitch on continuation tapping

The ideomotor principle predicts that perception will modulate action where overlap exists between perceptual and motor representations of action. This effect is demonstrated with auditory stimuli. Previous perceptual evidence suggests that pitch contour and pitch distance in tone sequences may elicit tonal motion effects consistent with listeners' implicit awareness of the lawful dynamics of locomotive bodies. To examine modulating effects of perception on action, participants in a continuation tapping task produced a steady tempo. Auditory tones were triggered by each tap. Pitch contour randomly and persistently varied within trials. Pitch distance between successive tones varied between trials. Although participants were instructed to ignore them, tones systematically affected finger dynamics and timing. Where pitch contour implied positive acceleration, the following tap and the intertap interval (ITI) that it completed were faster. Where pitch contour implied negative acceleration, the following tap and the ITI that it completed were slower. Tempo was faster with greater pitch distance. Musical training did not predict the magnitude of these effects. There were no generalized effects on timing variability. Pitch contour findings demonstrate how tonal motion may elicit the spontaneous production of accents found in expressive music performance.     

Tracking without perceiving: a dissociation between eye movements and motion perception

Can people react to objects in their visual field that they do not consciously perceive? We investigated how visual perception and motor action respond to moving objects whose visibility is reduced, and we found a dissociation between motion processing for perception and for action. We compared motion perception and eye movements evoked by two orthogonally drifting gratings, each presented separately to a different eye. The strength of each monocular grating was manipulated by inducing adaptation to one grating prior to the presentation of both gratings. Reflexive eye movements tracked the vector average of both gratings (pattern motion) even though perceptual responses followed one motion direction exclusively (component motion). Observers almost never perceived pattern motion. This dissociation implies the existence of visual-motion signals that guide eye movements in the absence of a corresponding conscious percept.     

TIMING AND APPARENT MOTION PATH CHOICE WITH HUMAN BODY PHOTOGRAPHS

Abstract— In demonstrations of apparent motion, observers typically report seeing motion along the shortest possible path between two sequentially presented objects. Recent work has demonstrated that violations of this shortest path rule occur with realistic photographs of a human body displayed for sufficiently long temporal intervals when a longer path is more anatomically plausible than the shortest path. The current set of experiments investigated the mechanisms by which information about biomechanical motion constrains apparent motion perception. In Experiment 1, we demonstrated, first, that the availability of extra processing time does not simply—in and of itself—result in the perception of longer paths of apparent motion. Second, we rejected the hypothesis that the perception of biomechanically correct paths of apparent motion depends on biologically appropriate velocities. In Experiment 2, we discovered that the longer the motion path required to satisfy the biomechanical movement limitations of the stimulus, the longer the time needed to construct and therefore perceive that path. These findings together suggest that additional processing time is necessary, but not sufficient, for interpolations of longer paths.     

The temporal dynamics of global-to-local feedback in the formation of hierarchical motion patterns: psychophysics and computational simulations

Four motion quartets, each ambiguous with respect to the perception of parallel-path horizontal or vertical motion, were arranged in a diamond configuration. Both global parallel-path motion (the same motion axis for all the quartets), which is typical for multiquartet stimuli, and global rotational rocking are perceived. Experiment 1 indicated that rotational rocking is established at different levels of processing. Globally, larger displacements of each quartet's elements increase the angle of rotation and, thereby, the perception of rotational rocking. Locally, larger displacements have the opposite effect, weakening motion percepts. Experiment 2 showed that global-to-local feedback affects the local perception of rotation-consistent versus rotation-inconsistent motion directions. Experiment 3 provided evidence for hysteresis effects indicative of competition between global rotational rocking and parallel-path motion. The experimental results were simulated by a two-level dynamical model incorporating global-to-local feedback, with recurrent feedforward/feedback loops creating detection instabilities that amplify activation at both global and local levels of the rotational-rocking pattern.     

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.     

Learning of timing patterns and the development of temporal expectations

The present study investigated the learning of a culturally unfamiliar musical rhythm, leading to the development of temporal expectations, and it explored the potential for generalization across tempi and tasks. With that aim, we adapted the serial reaction time task to examine the learning of temporal structures by an indirect method. The temporal pattern employed was based on a complex interval ratio (2:3) and compared to one based on a simple interval ratio (1:2). In the exposure phase, non-musician participants performed a two-choice speeded discrimination task that required responding by key press to each event of the simple or complex auditory pattern. Participants were not informed about the temporal regularities; their task solely concerned the discrimination task. During exposure (Experiments 1–3), response times decreased over time for both temporal patterns, but particularly for the events following the longer interval of the more complex 2:3 pattern. Exposure further influenced performance in subsequent testing phases, notably the precision of tap timing in a production task (Experiment 2) and temporal expectations in a perception task (Experiment 3). Our findings promote the new paradigm introduced here as a method to investigate the learning of temporal structures.     

生物运动及其在社会认知障碍研究中的应用

人类对生物运动具有较强的视觉敏感性,即使在视觉线索有限的情况下,仍能提取其中的社会性信息。本研究系统梳理了当前生物运动视知觉实验研究涉及的各类社会性信息,并归纳分析社会认知缺陷与生物运动视知觉加工之间的内在联系,以期促进对生物运动视知觉加工心理机制问题的深入探讨     

音乐知觉的神经基础：脑成像研究的元分析

本研究根据音乐加工的层级结构, 对现有的脑成像研究进行了元分析, 探讨了音乐知觉的神经基础。具体而言, 对特异于音乐知觉加工的两个层级, 音程分析和结构分析的神经基础进行了分析, 并在此基础上对比了参与两个层级加工的脑区。结果发现, 音程分析主要的激活分布在双侧颞上回和右侧额下回, 在中央前回、角回和脑岛等脑区也有分布。音程分析在颞上回激活最多, 可能表明颞上回为音程分析的核心区域。结构分析激活分布较广, 主要激活颞上回、颞横回和前额叶区域, 此外, 还激活了下顶叶、缘上回和舌回等顶枕区域。结构分析在前额叶激活最多, 可能表明前额叶为结构分析的核心区域。最后, 对比两层级激活的脑区发现, 二者仅在后侧颞上回存在着重合, 而在绝大部分脑区则表现出分离, 这暗示了音程分析和结构分析通过颞上回进行交流, 并负责音乐不同层面的加工。     

Stream/bounce perception and the effect of depth cues in chimpanzees (Pan troglodytes)

The stream/bounce display represents an ambiguous motion event in which two identical visual objects move toward one another and the objects overlap completely before they pass each another. In our perception, they can be interpreted as either streaming past one another or bouncing off each other. Previous studies have shown that the streaming percept of the display is generic for humans, suggesting the inertial nature of the motion integration process. In this study, chimpanzees took part in behavioral experiments using an object-tracking task to reveal the characteristics of their stream/bounce perception. Chimpanzees did not show a tendency toward a dominant "stream" perception of the stream/bounce stimulus. However, depth cues, such as X-junctions and local motion coherence, did promote the stream percept in chimpanzees. These results suggest both similarities and differences between chimpanzees and humans with respect to motion integration and object individuation processes.     

Microgenesis of the length perception of paired lines

The changes in perception associated with exposure time are probably continuous in the microgenetic process, as is demonstrated by such phenomena as intensity change in illusions, adaptation and normalization, practice effect, aftereffects, etc. The simultaneous contrast and assimilation in the perception of length of paired lines were measured by controlling the exposure duration or repetition. In the tachistoscopic experiment, the greatest contrast appeared at an early stage of microgenesis. In the repeated presentation experiment, the perception changed from contrast to assimilation on the expanded stage of microgenesis. These changes in perception are assumed to be the results of the differentiation of set that progresses in the microgenetic process. In the fixed-set experiment, the differentiation of set was reflected in the intensity of the aftereffect. The changes in the aftereffect and the transformation into the assimilation coincided with each other when the exposure time was varied. An expansion of the conception of perceptual microgenesis to a wider range of perceptual variability is accordingly proposed.     

Temporal factors in pattern vision

A sequence of uncorrelated randomly patterned visual stimuli (“visual noise”) is normally seen as a field of particles in “Brownian motion.” When each frame of the sequence is followed by a blank flash superimposed on the same region of the visual field, the apparent structure of the noise field is strikingly altered, its form varying with the time interval between frame and flash. At a critical interval, many dots seem to cohere, to form maggot-like objects.

Some of the factors determining this critical interval have been studied. They include the brightness, repetition frequency and exposure duration of the noise field, and the distance of its retinal image from the fovea.

The critical interval for “perceptual blanking” is quite different from that for the “maggot effect,” but the two show a suggestively similar dependence upon the duty cycle of the noise display.

It is of some neurological interest that the phenomenon is not appreciably visible with dichoptic mixing of noise and blank stimuli.     

海洛因戒断者的时间知觉特征

本研究采用时间二分任务来探讨海洛因戒断者的时间知觉特征。结果发现: (1)戒断组的长反应比例在中间时距上显著高于对照组; (2)戒断组的主观相等点低于对照组且差异显著, 韦伯比例与对照组相比差异不显著。结论: 海洛因戒断者更容易高估时间, 并且对时间的高估更多体现在中间时距上。     

Examining auditory kappa effects through manipulating intensity differences between sequential tones

The auditory kappa effect is a tendency to base the perceived duration of an inter-onset interval (IOI) separating two sequentially presented sounds on the degree of relative pitch distance separating them. Previous research has found that the degree of frequency discrepancy between tones extends the subjective duration of the IOI. In Experiment 1, auditory kappa effects for sound intensity were tested using a three-tone, AXB paradigm (where the intensity of tone X was shifted to be closer to either Tone A or B). Tones closer in intensity level were perceived as occurring closer in time, evidence of an auditory-intensity kappa effect. In Experiments 2 and 3, the auditory motion hypothesis was tested by preceding AXB patterns with null intensity and coherent intensity context sequences, respectively. The auditory motion hypothesis predicts that coherent sequences should enhance the perception of motion and increase the strength of kappa effects. In this study, the presence of context sequences reduced kappa effect strength regardless of the properties of the context tones.