Comparing solid-body with point-light animations

The movement of faces provides useful information for a variety of tasks and is now an active area of research. We compare here two ways of presenting face motion in experiments: as solid-body animations and as point-light displays. In the first experiment solid-body and point-light animations, based on the same motion-captured marker data, produced similar levels of performance on a sex-judgment task. The trend was for an advantage for the point-light displays, probably in part because of residual spatial cues available in such stimuli. In the second experiment we compared spatially normalised point-light displays of marker data with solid-body animations and pseudorandom point-light animations. Performance with solid-body animations and normalised point-light displays was similar and above chance, while performance with the pseudorandom point-light stimuli was not above chance. We conclude that both relatively few well-placed points and solid-body animations provide useful information about facial motion, but that a greater number of randomly placed points does not support above-chance performance. Solid-body animations have the methodological advantages of reducing the importance of marker placement and are more effective in isolating motion information, even if they are subsequently rendered as point-light displays.     

Exaggerating temporal differences enhances recognition of individuals from point light displays

Humans are very good at perceiving each other's movements. In this article, we investigate the role of time-based information in the recognition of individuals from point light biological motion sequences. We report an experiment in which we used an exaggeration technique that changes temporal properties while keeping spatial information constant; differences in the durations of motion segments are exaggerated relative to average values. Participants first learned to recognize six individuals on the basis of a simple, unexaggerated arm movement. Subsequently, they recognized positively exaggerated versions of those movements better than the originals. Absolute duration did not appear to be the critical cue. The results show that time-based cues are used for the recognition of movements and that exaggerating temporal differences improves performance. The results suggest that exaggeration may reflect general principles of how diagnostic information is encoded for recognition in different domains.     

Making message recipients "feel right": how nonverbal cues can increase persuasion

Nonverbal cues are an inherent component of most persuasive appeals. We use regulatory-fit theory as a framework for understanding the effect of nonverbal cues on a message's effectiveness, and as a foundation for developing a new persuasion technique. We propose that when the nonverbal cues of a message source sustain the motivational orientation of the recipient, the recipient experiences regulatory fit and feels right, and that this experience influences the message's effectiveness. Experimental results support these predictions. Participants experiencing regulatory fit (promotion-focus participants viewing messages delivered in an eager nonverbal style, prevention-focus participants viewing messages delivered in a vigilant nonverbal style) had more positive attitudes toward a message's topic and greater intentions to behave in accordance with its recommendation than did participants experiencing nonfit. Feeling right was also greater for participants experiencing fit than for those experiencing nonfit and was associated with greater message effectiveness. Regulatory-fit theory provides a framework for making precise predictions about when and for whom a nonverbal cue will affect persuasion.     

Communication Styles,Cultural Values,and Counseling Effectiveness With Asian Americans

This study examined counseling intervention designed for Asian Americans. Participants (N = 158) rated session effectiveness after viewing a videotape of a counselor using a culturally congruent or incongruent communication style. Analyses of variance showed that the incongruent style was viewed as more satisfying and credible than the congruent style. Factor analysis showed that participants perceived “being direct” and “maintaining harmony” styles, and multiple regression analyses revealed that these perceptions had a positive relationship with effectiveness.     

Visual search strategies of baseball batters: eye movements during the preparatory phase of batting

The aim of this study was to analyze visual search strategies of baseball batters during the viewing period of the pitcher's motion. The 18 subjects were 9 experts and 9 novices. While subjects viewed a videotape which, from a right-handed batter's perspective, showed a pitcher throwing a series of 10 types of pitches, their eye movements were measured and analyzed. Novices moved their eyes faster than experts, and the distribution area of viewing points was also wider than that of the experts. The viewing duration of experts of the pitching arm was longer than those of novices during the last two pitching phases. These results indicate that experts set their visual pivot on the pitcher's elbow and used peripheral vision properties to evaluate the pitcher's motion and the ball trajectory.     

Stereoillusory motion concomitant with lateral head movements

Stationary objects in a stereogram can appear to move when viewed with lateral head movements. This illusory motion can be explained by the motion-distance invariance hypothesis, which states that illusory motion covaries with perceived depth in accordance with the geometric relationship between the position of the stereo stimuli and the head. We examined two predictions based on the hypothesis. In Experiment 1, illusory motion was studied while varying the magnitude of binocular disparity and the magnitude of lateral head movement, holding viewing distance constant. In Experiment 2, illusory motion was studied while varying binocular disparity and viewing distance, holding magnitude of head movement constant. Ancillary measures of perceived depth, perceived viewing distance, and perceived magnitude of lateral head movement were also obtained. The results from the two experiments show that the extent of illusory motion varies as a function of perceived depth, supporting the motion-distance invariance hypothesis. The results also show that the extent of illusory motion is close to that predicted from the geometry in crossed disparity conditions, whereas it is greater than the predicted motion in uncrossed disparity conditions. Furthermore, predictions based on perceptual variables were no more accurate than predictions based on geometry.     

Tracking hand movements captures the response dynamics of the evaluative priming effect

We tested the response dynamics of the evaluative priming effect (i.e. facilitation of target responses following evaluatively congruent compared with evaluatively incongruent primes) using a mouse tracking procedure that records hand movements during the execution of categorisation tasks. In Experiment 1, when participants performed the evaluative categorisation task but not the non-evaluative semantic categorisation task, their mouse trajectories for evaluatively incongruent trials curved more toward the opposite response than those for evaluatively congruent trials, indicating the emergence of evaluative priming effects based on response competition. In Experiment 2, implementing a task-switching procedure in which evaluative and non-evaluative categorisation tasks were intermixed, we obtained reliable evaluative priming effects in the non-evaluative semantic categorisation task as well as in the evaluative categorisation task when participants assigned attention to the evaluative stimulus dimension. Analyses of hand movements revealed that the evaluative priming effects in the evaluative categorisation task were reflected in the mouse trajectories, while evaluative priming effects in the non-evaluative categorisation tasks were reflected in initiation times (i.e. the time elapsed between target onset and first mouse movement). Based on these findings, we discuss the methodological benefits of the mouse tracking procedure and the underlying processes of evaluative priming effects.     

Gaze stability of observers watching Op Art pictures

It has been the matter of some debate why we can experience vivid dynamic illusions when looking at static pictures composed from simple black and white patterns. The impression of illusory motion is particularly strong when viewing some of the works of 'Op Artists, such as Bridget Riley's painting Fall. Explanations of the illusory motion have ranged from retinal to cortical mechanisms, and an important role has been attributed to eye movements. To assess the possible contribution of eye movements to the illusory-motion percept we studied the strength of the illusion under different viewing conditions, and analysed the gaze stability of observers viewing the Riley painting and control patterns that do not produce the illusion. Whereas the illusion was reduced, but not abolished, when watching the painting through a pinhole, which reduces the effects of accommodation, it was not perceived in flash afterimages, suggesting an important role for eye movements in generating the illusion for this image. Recordings of eye movements revealed an abundance of small involuntary saccades when looking at the Riley pattern, despite the fact that gaze was kept within the dedicated fixation region. The frequency and particular characteristics of these rapid eye movements can vary considerably between different observers, but, although there was a tendency for gaze stability to deteriorate while viewing a Riley painting, there was no significant difference in saccade frequency between the stimulus and control patterns. Theoretical considerations indicate that such small image displacements can generate patterns of motion signals in a motion-detector network, which may serve as a simple and sufficient, but not necessarily exclusive, explanation for the illusion. Why such image displacements lead to perceptual results with a group of Op Art and similar patterns, but remain invisible for other stimuli, is discussed.     

Relative motion and the adjacency principle

The perception of motion of physically moving points of light was investigated in terms of the distinction between absolute and relative motion cues and the change in the effectiveness of the latter as a function of the frontoparallel separation between the points. In situations in which two competing relative motion cues were available to determine the perceived path of motion of a point of light, it was found that the relative motion cue between more adjacent points was more effective than the relative motion cue between more separated points. In situations in which only one relative motion cue was available to determine the perceived motion of a point it was found that the effectiveness of this cue as compared with the absolute motion cue decreased with increased separation. These results are predictable from the adjacency principle which states that the effectiveness of cues between objects is an inverse function of object separation. Some consequences of the study for the theory of motion perception are discussed.     

Motion as a cue for viewpoint invariance

Natural face and head movements were mapped onto a computer rendered three-dimensional average of 100 laser-scanned heads in order to isolate movement information from spatial cues and nonrigid movements from rigid head movements (Hill & Johnston, 2001). Experiment 1 investigated whether subjects could recognize, from a rotated view, facial motion that had previously been presented at a full-face view using a delayed match to sample experimental paradigm. Experiment 2 compared recognition for views that were either between or outside initially presented views. Experiment 3 compared discrimination at full face, three-quarters, and profile after learning at each of these views. A significant face inversion effect in Experiments 1 and 2 indicated subjects were using face-based information rather than more general motion or temporal cues for optimal performance. In each experiment recognition performance only ever declined with a change in viewpoint between sample and test views when rigid motion was present. Nonrigid, face-based motion appears to be encoded in a viewpoint invariant, object-centred manner, whereas rigid head movement is encoded in a more view specific manner.     

Smiling when distressed: when a smile is a frown turned upside down

This research tested self-regulation and self-presentation as psychological mechanisms that motivate smiling when distressed. In Study 1, participants viewed moderately and intensely distressing, amusing, and neutral videos in social or nonsocial conditions. Smiling when distressed was most prevalent in conditions in which participants reported the greatest emotional distress. Specifically, while viewing distressing videos, men reported experiencing greater overall distress and also smiled more than women, especially in social conditions and while viewing intensely (as opposed to moderately) distressing stimuli. In general, smiling was related to more negative affect while viewing distressing videos but to more positive affect after viewing such stimuli. Study 2 explored raters' social perceptions of participants from Study 1, confirming that people judge distressed smilers as less socially appropriate and less likable than nonsmilers. Findings suggest that although distressed smiling serves a probable self-regulatory function, it may also bear some negative social consequences.     

Brain activity for visual judgment of lifted weight

It is well established that humans can recognize high-level aspects from point-light biological motion, such as gender and mood. If the task is to judge the manipulated weight we expected that sensorimotor regions should be recruited in the brain. Moreover, we have recently shown that chronic pain in a limb that is involved in the presented movement disturbs the weight judgment. We therefore hypothesized that some cortical regions usually activated during the processing of pain will also be activated while viewing point-light biological motion with the instruction to judge the manipulated weights. We investigated point-light biological motion of two types of movements performed with different weights in a blocked fMRI experiment in healthy subjects. In line with our a priori hypothesis, we found strong activity in the regions known as the neuromatrix of pain, such as the anterior cingulate (ACC), insula, as well as primary and secondary somatosensory regions. We also found activation in the occipital and temporal regions that are typical for biological motion, as well as regions in the cerebellum and prefrontal cortex. The activation of the somatosensory regions probably serves the judgment of the biological motion stimuli. Activation of the anterior cingulate and the insula might be explained by their role in the integration of behaviorally relevant information. Alternatively, these structures are known to be involved in the processing of nociceptive information and pain. So it seems possible that the interference between judgment of weights and perception of pain in chronic pain patients occurs in the somatosensory areas, anterior cingulate and/or insula. This finding provides important information as to the underlying mechanisms used for the weight judgment task, but also why chronic pain interferes with this task.     

Object categorisation,object naming,and viewpoint independence in visual remembering: Evidence from young children's drawings of a novel object

A simple object-drawing task confirms a three-way association between object categorisation, viewpoint independence, and longer-term visual remembering. Young children (5- to 7-year-olds) drew a familiar object or a novel object, immediately after it had been hidden from view or on the following day. Both objects were shown from a full range of viewpoints or from just two viewpoints, from neither of which would either object normally be drawn after unrestricted viewing. When drawing from short-term memory after restricted viewing, both objects were most likely to be depicted from a seen viewpoint. When drawing from longer-term memory after restricted viewing, the novel object continued to be drawn from a seen viewpoint, but the mug was now most likely to be drawn from a preferred viewpoint from which it had not been seen. Naming the novel object with a novel count noun (“Look at this. This is a dax”), to signal that it belonged to an object category, resulted in it being drawn in the same way as the familiar object. The results concur with other evidence indicating that short-term and longer-term visual remembering are differentially associated with viewpoint-dependent representations of individual objects and viewpoint independent representations of object categories, respectively.     

Object categorisation, object naming, and viewpoint independence in visual remembering: evidence from young children's drawings of a novel object

A simple object-drawing task confirms a three-way association between object categorisation, viewpoint independence, and longer-term visual remembering. Young children (5- to 7-year-olds) drew a familiar object or a novel object, immediately after it had been hidden from view or on the following day. Both objects were shown from a full range of viewpoints or from just two viewpoints, from neither of which would either object normally be drawn after unrestricted viewing. When drawing from short-term memory after restricted viewing, both objects were most likely to be depicted from a seen viewpoint. When drawing from longer-term memory after restricted viewing, the novel object continued to be drawn from a seen viewpoint, but the mug was now most likely to be drawn from a preferred viewpoint from which it had not been seen. Naming the novel object with a novel count noun ("Look at this. This is a dax"), to signal that it belonged to an object category, resulted in it being drawn in the same way as the familiar object. The results concur with other evidence indicating that short-term and longer-term visual remembering are differentially associated with viewpoint-dependent representations of individual objects and viewpoint independent representations of object categories, respectively.     

Detection and discrimination of coherent motion

When viewing a pair of bars defined by the difference of spatial Gaussian functions (DOGs), human observers can discriminate accurately the relative movements of the bars, even when they differ in spatial frequency. On each trial, observers viewed two brief presentation intervals in which a pair of vertically oriented DOGs moved randomly back and forth within a restricted range. During one interval, both bars moved in the same horizontal direction and by the same magnitude (correlated movements); in the other interval, their movements were uncorrelated. When discrimination accuracy is related to the simultaneous detection of two independent movements, it was found that, if observers can detect the movements of spatially separated bars, they can tell whether their relative movements are correlated. Performance remained remarkably accurate even when the two bars differed in spatial frequency by more than two octaves or were presented separately to the two eyes. Apparently, the accurate discrimination of coherent motion involves an efficient spatial integration of optical motion information over multiple spatial locations and multiple spatial scales.     

Audiovisual influences on the perception of visual apparent motion: exploring the effect of a single sound

Previous research has shown that irrelevant sounds can facilitate the perception of visual apparent motion. Here the effectiveness of a single sound to facilitate motion perception was investigated in three experiments. Observers were presented with two discrete lights temporally separated by stimulus onset asynchronies from 0 to 350 ms. After each trial, observers classified their impression of the stimuli using a categorisation system. A short sound presented temporally (and spatially) midway between the lights facilitated the impression of motion relative to baseline (lights without sound), whereas a sound presented either before the first or after the second light or simultaneously with the lights did not affect motion impression. The facilitation effect also occurred with sound presented far from the visual display, as well as with continuous-sound that was started with the first light and terminated with the second light. No facilitation of visual motion perception occurred if the sound was part of a tone sequence that allowed for intramodal perceptual grouping of the auditory stimuli prior to the critical audiovisual stimuli. Taken together, the findings are consistent with a low-level audiovisual integration approach in which the perceptual system merges temporally proximate sound and light stimuli, thereby provoking the impression of a single multimodal moving object.     

Perception of American sign language in dynamic point-light displays

Perception of dynamic events of American Sign Language (ASL) was studied by isolating information about motion in the language from information about form. Four experiments utilized Johansson's technique for presenting biological motion as moving points of light. In the first, deaf signers were highly accurate in matching movements of lexical signs presented in point-light displays to those normally presented. Both discrimination accuracy and the pattern of errors were similar in this matching task to that obtained in a control condition in which the same signs were always represented normally. The second experiment showed that these results held for discrimination of morphological operations presented in point-light displays as well. In the third experiment, signers were able to accurately identify signs of a constant handshape and morphological operations acting on signs presented in point-light displays. Finally, in Experiment 4, we evaluated what aspects of the motion patterns carried most of the information for sign identifiability. We presented signs in point-light displays with certain lights removed and found that the movement of the fingertips, but not of any other pair of points, is necessary for sign identification and that, in general, the more distal the joint, the more information its movement carries.     

Evidence for frames of reference based on pursuit eye movements

Lighted points that moved as if located on the rim of a rolling wheel were displayed to subjects whose task was to describe the pattern they perceived. The perceived patterns could be classified into one of four categories ranging from cycloidal to circular motion. Pursuit eye movements were controlled by having subjects track a fixation point that moved in the direction of the rolling wheel on a path just above the wheel’s rim. With respect to the translatory velocity of the rolling wheel, the velocity of the fixation point was 100%, 67%, 33%, or 0% (i.e., stationary). The patterns traced out by the points on the wheel were perceived to become increasingly circular as pursuit eye movements more closely matched the translatory speed of the rolling wheel. This is taken to support Stoper’s hypothesis that pursuit eye movements can establish a frame of reference for motion analysis.     

Male more than female infants imitate propulsive motion

Few experimental studies investigate the mechanisms by which young children develop sex-typed activity preferences. Gender self-labeling followed by selective imitation of same-sex models currently is considered a primary socialization mechanism. Research with prenatally androgenized girls and non-human primates also suggests an innate male preference for activities that involve propulsive movement. Here we show that before children can label themselves by gender, 6- to 9-month-old male infants are more likely than female infants to imitate propulsive movements. Further, male infants’ increase in propulsive movement was linearly related to proportion of time viewing a male model’s propulsive movements. We propose that male sex-typed behavior develops from socialization mechanisms that build on a male predisposition to imitate propulsive motion.     

Affect-congruent approach and withdrawal movements of happy and angry faces facilitate affective categorisation

Increasing evidence indicates that evaluation of affective stimuli facilitates the execution of affect-congruent approach and avoidance responses, and vice versa. These effects are proposed to be mediated by increases or decreases in the relative distance to the stimulus, due to the participant's action. In a series of experiments we investigated whether stimulus categorisation is similarly influenced when changes in this relative distance are due to movement of the stimulus instead of movements by the participant. Participants responded to happy and angry faces that appeared to approach (move towards) or withdraw (move away) from them. In line with previous findings, affective categorisation was facilitated when the movement was congruent with stimulus valence, resulting in faster and more correct responses to approaching happy and withdrawing angry faces. These findings suggest that relative distance indeed plays a crucial role in approach–avoidance congruency effects, and that these effects do not depend on the execution of movements by the participant.