Biomedical subjects

Geoffrey P Bingham

Publications and source records attributed to Geoffrey P Bingham.

7 recordsLinked to original sources

PubMed2005

Human movement coordination implicates relative direction as the information for relative phase.

The current studies explore the informational basis of the coupling in human rhythmic movement coordination tasks. Movement stability in these tasks is an asymmetric U-shaped function of mean relative phase; 0 degrees is maximally stable, 90 degrees is maximally unstable and 180 degrees is intermediate. Bingham (2001, 2004a, 2004b) hypothesized that the information used to perform coordinated rhythmic movement is the relative direction of movement, the resolution of which is determined by relative speed. We used an experimental paradigm that entails using a circular movement to produce a linear motion of a dot on a screen, which must then be coordinated with a linearly moving computer controlled dot. This adds a component to the movement that is orthogonal to the display. Relative direction is not uniquely defined between orthogonal components of motion, but relative speed is; it was therefore predicted that the addition of the component would only introduce a symmetric noise component and not otherwise contribute to the U-shape structure of movement stability. Results for experiment 1 supported the hypothesis; movement that involved the additional component was overall less stable than movement that involved only the parallel component along which relative direction can be defined. Two additional studies ruled out alternative explanations for the pattern of data in experiment 1. Overall, the results strongly implicate relative direction as the information underlying performance in rhythmic movement coordination tasks.

Adult↗

PubMed2005

Perceptual coupling in rhythmic movement coordination: stable perception leads to stable action.

Rhythmic movement coordination exhibits characteristic patterns of stability, specifically that movements at 0 degrees mean relative phase are maximally stable, 180 degrees is stable but less so than 0 degrees, and other coordinations are unstable without training. Recent research has demonstrated a role for perception in creating this pattern; perceptual variability judgments covary with movement variability results. This suggests that the movement results could be due in part to differential perceptual resolution of the target movement coordinations. The current study used a paradigm that enabled simultaneous access to both perception (between-trial) and movement (within-trial) stability measures. A visually specified 0 degrees target mean relative phase enabled participants to produce stable movements when the movements were at a non-0 degrees relationship to the target being tracked. Strong relationships were found between within-trial stability (the traditional movement measure) and between-trial stability (the traditional perceptual judgment measure), suggestive of a role for perception in producing coordination stability phenomena. The stabilization was incomplete, however, indicating that visual perception was not the sole determinant of movement stability. Rhythmic movement coordination is intrinsically a perception/action system.

Adolescent↗

PubMed2004

Distortions of distance and shape are not produced by a single continuous transformation of reach space.

We investigated whether distortions of perceived distance and shape could be captured by a single continuous one-to-one transformation of the underlying space. In Experiment 1, the participants reached to touch points around the perimeter of spherical targets viewed at five different distances, to yield simultaneous measures of perceived distance and shape. Different participants reached while using dynamic monocular, static binocular, or dynamic binocular vision. Thin plate spline (TPS) analysis was applied so as to transform a Cartesian grid in such a way as to carry the original target points to the mean reach locations. In all cases, discontinuities appeared in the transformed grid from folding of the space. In Experiment 2, the participants reached to points that lay at the same locus in reach space, but on different portions of the visible target spheres (e.g., front vs. side). The participants reached to different locations when the points were different with respect to shape (e.g., front vs. side) but reached to the same locations when the points were the same with respect to shape (left vs. right side). TPS analysis revealed discontinuities from holes torn in the underlying space. The results show that perceived distance and perceived shape entail different distortions and cannot be captured by a single continuous transformation of reach space.

Adult↗

PubMed2004

Perspective distortion of trajectory forms and perceptual constancy in visual event identification.

Previous studies have shown that people can use the information in trajectory forms to recognize visual events. A trajectory form is composed of the path of motion and the change in speed along that path. In past studies, however, only sensitivity to trajectory forms viewed from a single perspective was examined. The optical components change when an event is viewed from different perspectives, and the projected form of the trajectory is transformed. Does event recognition exhibit constancy despite these changes? In Experiment 1, participants were familiarized with five different trajectory forms viewed from a single perspective. Then the participants had to identify the same events viewed from different perspectives: from the side, at an angle, and entirely in depth. The participants exhibited perceptual constancy. Experiment 2 revealed, however, that both the change in optical components and the perspective transformations affected recognition.

Feedback↗

PubMed2003

Proprioceptive perception of phase variability.

Previous work has established that judgments of relative phase variability of 2 visually presented oscillators covary with mean relative phase. Ninety degrees is judged to be more variable than 0 degrees or 180 degrees, independently of the actual level of phase variability. Judged levels of variability also increase at 180 degrees. This pattern of judgments matches the pattern of movement coordination results. Here, participants judged the phase variability of their own finger movements, which they generated by actively tracking a manipulandum moving at 0 degrees, 90 degrees, or 180 degrees, and with 1 of 4 levels of Phase Variability. Judgments covaried as an inverted U-shaped function of mean relative phase. With an increase in frequency, 180 degrees was judged more variable whereas 0 degrees was not. Higher frequency also reduced discrimination of the levels of Phase Variability. This matching of the proprioceptive and visual results, and of both to movement results, supports the hypothesized role of online perception in the coupling of limb movements. Differences in the 2 cases are discussed as due primarily to the different sensitivities of the systems to the information.

Adolescent↗

PubMed2002

Trajectory forms as a source of information about events.

The ability to use trajectory forms as visual information about events was tested. A trajectory form is defined as the variation in velocity along a path of motion. In Experiment 1, we tested the ability to detect trajectory form differences between simulations of a freely swinging pendulum and a hand-moved pendulum. The trajectory form of the freely swinging pendulum was symmetric around the mid-point, whereas the hand moved was not. In Experiment 2, we isolated trajectory form information by varying the amplitudes of events while holding their periods constant. Straight path versions of the harmonic events from Experiment 1 were tested. In Experiment 3, we tested sensitivity to symmetrical peakening or flattening of trajectory forms. Participants detected small differences in all three experiments. In Experiment 4, we tested the ability to identify specific events based only on differences in trajectory forms. Participants were able to identify four different events. We investigated properties of trajectory forms that might potentially be detected and used as information, and we found that the curvature yielded good results.

Humans↗

PubMed2002

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.

Discrimination, Psychological↗