Infant sensitivity to trajectory forms

The authors investigated whether infants are sensitive to visual event trajectory forms, and whether they are sensitive to the underlying dynamics of trajectory forms. The authors habituated 8-month-old infants to a videotaped event run either forward or reversed in time and then switched them to the same event run in the opposite direction. Infants dishabituated when switched to the event with the novel direction in time, indicating sensitivity to the form of the trajectory. Infants exhibited equivalent habituation rates and looking times for forward and reversed events, thus failing to provide evidence that infants are sensitive to the underlying dynamics. In a partial replication of this first experiment, the same pattern of results was found. Both experiments revealed infant sensitivity to the trajectory forms, but not the underlying dynamics of events. The authors discuss implications for methods used in infant event perception studies.     

Visual perception of the relative phasing of human limb movements

Studies of bimanual coordination have found that only two stable relative phases (0 degree and 180 degrees) are produced when a participant rhythmically moves two joints in different limbs at the same frequency. Increasing the frequency of oscillation causes an increase in relative phase variability in both of these phase modes. However, relative phasing at 180 degrees is more variable than relative phasing at 0 degree, and when the frequency of oscillation reaches a critical frequency, a transition to 0 degree occurs. These results have been replicated when 2 people have coordinated their respective limb movements using vision. This inspired us to investigate the visual perception of relative phase. In Experiment 1, recordings of human interlimb oscillations exhibiting different frequencies, mean relative phases, and different amounts of phase variability were used to generate computer displays of spheres oscillating either side to side in a frontoparallel plane or in depth. Participants judged the stability of relative phase. Judgments covaried with phase variability only when the mean phase was 0 degree or 180 degrees. Otherwise, judgments covaried with mean relative phase, even after extensive instruction and demonstration. In Experiment 2, mean relative phase and phase variability were manipulated independently via simulations, and participants were trained to perceive phase variability in testing sessions in which mean phase was held constant. The results of Experiment 1 were replicated. The HKB model was fitted to mean judgment standard deviations.     

Mothers' voices: Coping with their children's initial disability diagnosis

For parents of infants and toddlers receiving a diagnosis of disability, a variety of responses may result. Yet, little is known about the specific ways families cope with the initial diagnosis. This qualitative study investigated 6 mothers' memories of their children's diagnoses. Mothers described their use of both palliative strategies (denying, questioning, and wishful thinking) and problem‐solving strategies (searching for information, seeking social support, reframing, and seeking spiritual support) to cope with their children's initial diagnoses. The results of this study may improve professionals' understanding of parents' need for information and support at the time of initial diagnosis.     

Seeing Where the Stone Is Thrown by Observing a Point-Light Thrower: Perceiving the Effect of Action Is Enabled by Information,Not Motor Experience

People are very adept at perceiving biological motion (e.g., Johansson, 1973 Johansson, G. (1973). Visual perception of biological motion and a model for its analysis. Perception & Psychophysics, 14(2), 201–211.[Crossref], [Web of Science ®] , [Google Scholar]). This ability has been an essential life skill to members of this social species. The human niche during the ice age was socially coordinated hunting for big game. Being able to judge the location targeted by the throw of a conspecific would be a valuable perceptual ability that we now study to investigate 2 competing theories of biological motion perception: Common Coding (CC; Prinz, 1997 Prinz, W. (1997). Perception and action planning. European Journal of Cognitive Psychology, 9(2), 129–154.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) and Kinematic Specification of Dynamics (KSD; Runeson & Frykholm, 1983 Runeson, S., & Frykholm, G. (1983). Kinematic specification of dynamics as an informational bias for person-and-action perception: Expectation, gender recognition, and deceptive intent. Journal of Experimental Psychology: General, 112, 585–615.[Crossref], [Web of Science ®] , [Google Scholar]). The 2 theories diverge in attributing perceptual ability to either motor or visual experience, respectively. To test predictions of the CC theory, we performed 3 experiments to manipulate observers' specific motor experience while they judged the targeted location of throwing by watching point-light displays. In Experiment 1, we tested whether the identity of the thrower in the display mattered. In Experiment 2, we tested whether the motor expertise of the observer mattered. In Experiment 3, we tested whether the gender/style of throwing demonstrated by the point-light thrower mattered. The combined results failed to support CC theory, suggesting that motor experience is not required for the perception of action. Because all participants judged the target location of throwing quite well, KSD theory suggests that the kinematic information available in the displays may have enabled the perception. We performed Experiment 4 to analyze the information. We found that the judgment pattern exhibited by the observers in both Experiments 1 and 2 was well predicted by the KSD theory. Thus, we concluded that the perception of biological motion is enabled by visual information and improved by visual experience.     

When kinesthetic information is neglected in learning a Novel bimanual rhythmic coordination

Many studies have shown that rhythmic interlimb coordination involves perception of the coupled limb movements, and different sensory modalities can be used. Using visual displays to inform the coupled bimanual movement, novel bimanual coordination patterns can be learned with practice. A recent study showed that similar learning occurred without vision when a coach provided manual guidance during practice. The information provided via the two different modalities may be same (amodal) or different (modality specific). If it is different, then learning with both is a dual task, and one source of information might be used in preference to the other in performing the task when both are available. In the current study, participants learned a novel 90° bimanual coordination pattern without or with visual information in addition to kinesthesis. In posttest, all participants were tested without and with visual information in addition to kinesthesis. When tested with visual information, all participants exhibited performance that was significantly improved by practice. When tested without visual information, participants who practiced using only kinesthetic information showed improvement, but those who practiced with visual information in addition showed remarkably less improvement. The results indicate that (1) the information is not amodal, (2) use of a single type of information was preferred, and (3) the preferred information was visual. We also hypothesized that older participants might be more likely to acquire dual task performance given their greater experience of the two sensory modes in combination, but results were replicated with both 20- and 50-year-olds.     

Ontological issues in distance perception: cue use under full cue conditions cannot be inferred from use under controlled conditions

Phosphorescent square tiles (arranged to yield a single image size) were viewed in the dark by 56 monocular observers who utilized a chinrest. The targets were placed at one of three horizontal distances and at one of three eye heights, allowing us to study the relative effect of height in the visual field (HVF) and sagittal distance on observers' verbal reports of the horizontal distance at which the object lay (near, middle, or far). In Experiment 1, we found that reports covaried primarily with HVF and, as predicted, they exhibited a weak paradoxical inverse relation with horizontal distance. In a second and third experiment, a visible surface was placed under the targets at the three eye heights in both dark and fully lighted conditions. In this situation, the inverse distance relation disappeared, and HVF no longer influenced the judgments of most observers. The results show that information projected from relevant support surfaces is essential for veridical information about object distance. These results raise fundamental issues for perceptual researchers regarding how to decide when a cue has been properly delineated, given the assumption that the relation between a cue and what it specifies is probabilistic.     

Reaching measures of monocular distance perception: forward versus side-to-side head movements and haptic feedback

We investigated whether forward or side-to-side head movements yielded more accurate and precise monocular egocentric distance information, as shown by performance in a reaching task. Observers wore a head-mounted camera and display to isolate the optic flow generated by their head movements and had to reach to align a stylus directly under a target surface. Performance in the two head movement conditions was also tested with normal monocular vision. We tested performance in the two head movement conditions when the observers were given haptic feedback and compared performance when haptic feedback was removed. Performance was both more accurate and more precise in the forward head movement condition than in the side-to-side head movement condition. Performance in the side-to-side condition also deteriorated more after the removal of haptic feedback than did performance in the forward head movement condition. In the normal monocular condition, performance was comparable for the two head movement conditions. The implications for enucleated patients are discussed.     

Center of mass perception: Perturbation of symmetry

Bingham and Muchisky (1993) found that observers were very accurate in determining the location of the center of mass in planar objects. Systematic errors were affected primarily by object orientation, while random errors varied with the amount of symmetry. Radial and axial reflective symmetry affected errors in different ways. In the current study, we investigated the different effects of axial reflective versus rotational symmetry. All random errors decreased with increasing rotational symmetry. Axial reflective symmetry further reduced errors in the direction perpendicular to the axis. We replicated the effect on systematic error of orientation. However, we also found an effect of the perturbation of symmetry that suggested that observers used an approximation to symmetry. To investigate this possibility, we constructed a series of objects in which axial reflective symmetry was established and then perturbed by varying amounts. We found that systematic errors were structured by the underlying approximate symmetries, and we discuss the problem of quantifying symmetry.     

Causation,causal perception,and conservation laws

We investigated the perception of causation via the ability to detect conservation violations in simple events. We showed that observers were sensitive to energy conservation violations in free-fall events. Furthermore, observers were sensitive to gradually perturbed energy dynamics in such events. However, they were more sensitive to the effect of decreasing gravity than to that of increasing gravity. Displays with decreasing gravity were the only displays in which the energy profile was dominated by (apparent) potential energy, leading to an asymmetric trajectory.