Biomedical subjects

G P Bingham

Publications and source records attributed to G P Bingham.

At least 19 recordsLinked to original sources

PubMed2001

The effect of frequency on the visual perception of relative phase and phase variability of two oscillating objects.

Relative phase has been studied extensively as a measure of interlimb coordination. Only two relative phases, namely 0 degrees and 180 degrees, are stably produced at the preferred frequency (approximately 1 Hz). When frequency is increased, movement at 180 degrees becomes unstable and relative phase typically switches to 0 degrees, which remains stable at higher frequencies. The current study was designed to investigate the perception of relative phase and of phase variability. Observers viewed two circles moving rhythmically in a computer display. Mean phases varied from 0 degrees to 180 degrees in 30 degrees steps. Phase variability at each mean phase varied from 0 degrees to 5 degrees, 10 degrees, and 15 degrees phase standard deviation (SD). Frequency of oscillation was either 0.75 Hz or 1.25 Hz. One group of ten observers judged mean relative phase. Another group judged phase variability. As predicted, increase in frequency yielded an increase in perceived phase variability at 180 degrees mean phase and other mean phases, but not at 0 degrees mean phase. In contrast, increase in actual phase variability affected judgments of 0 degrees mean phase most strongly. A second control experiment showed that the frequency effects were not produced by changes in display durations or frames per cycle of oscillation. The results are consistent with those in studies of interlimb coordination and indicate that understanding of interlimb coordination requires further investigation of phase perception.

Adolescent↗

PubMed2001

Accommodation, occlusion, and disparity matching are used to guide reaching: a comparison of actual versus virtual environments.

The authors used a virtual environment to investigate visual control of reaching and monocular and binocular perception of egocentric distance, size, and shape. With binocular vision, the results suggested use of disparity matching. This was tested and confirmed in the virtual environment by eliminating other information about contact of hand and target. Elimination of occlusion of hand by target destabilized monocular but not binocular performance. Because the virtual environment entails accommodation of an image beyond reach, the authors predicted overestimation of egocentric distances in the virtual relative to actual environment. This was confirmed. The authors used -2 diopter glasses to reduce the focal distance in the virtual environment. Overestimates were reduced by half. The authors conclude that calibration of perception is required for accurate feedforward reaching and that disparity matching is optimal visual information for calibration.

Accommodation, Ocular↗

PubMed2001

Commentary on Jacobs and Michaels (2001): calibration and perceptual learning in event perception.

Jacobs and Michaels (2001) have argued that increased precision in judgments of the viewing distance to a perceived event should be attributed in part to perceptual learning. They found that observers used feedback to attune to the appropriate information variables gradually. McConnell, Muchisky, and Bingham (1998) had found that observers used feedback to calibrate event-specific scaling coefficients, that the calibration of one type of event generalized to other types, and that calibration occurred suddenly. We argue that Jacobs and Michaels must be partially correct and that, in our experiments, both calibration and perceptual attunement were required for accurate and precise judgments.

Discrimination Learning↗

PubMed2001

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.

Child Development↗

PubMed2000

Visual perception of mean relative phase and phase variability.

Perception of relative phase and phase variability may play a fundamental role in interlimb coordination. This study was designed to investigate the perception of relative phase and of phase variability and the stability of perception in each case. Observers judged the relative phasing of two circles rhythmically moving on a computer display. The circles moved from side to side, simulating movement in the frontoparallel plane, or increased and decreased in size, simulating movement in depth. Under each viewing condition, participants observed the same displays but were to judge either mean relative phase or phase variability. Phase variability interfered with the mean-relative-phase judgments, in particular when the mean relative phase was 0 degrees. Judgments of phase variability varied as a function of mean relative phase. Furthermore, the stability of the judgments followed an asymmetric inverted U-shaped relation with mean relative phase, as predicted by the Haken-Kelso-Bunz model.

Adolescent↗

PubMed2000

Distortions in definite distance and shape perception as measured by reaching without and with haptic feedback.

Psychophysical studies reveal distortions in perception of distance and shape. Are reaches calibrated to eliminate distortions? Participants reached to the front, side, or back of a target sphere. In Experiment 1, feedforward reaches yielded distortion and outward drift. In Experiment 2, haptic feedback corrected distortions and instability. In Experiment 3, feedforward reaches with only haptic experience of targets replicated the shape distortions but drifted inward. This showed that outward drift in Experiment 1 was visually driven. In Experiment 4, visually guided reaches were accurate when participants used binocular vision but when they used monocular vision, reaches were distorted. Haptic feedback corrected inaccuracy and instability of distance but did not correct monocular shape distortions. Dynamic binocular vision is representative and accurate and merits further study.

Adult↗

PubMed2000

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.

Distance Perception↗

PubMed1999

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.

Adolescent↗

PubMed1998

The necessity of a perception-action approach to definite distance perception: monocular distance perception to guide reaching.

In this investigation of monocular perception of egocentric distance, the authors advocate the necessity of a perception-action approach because calibration is intrinsic to definite distance perception. A helmet-mounted camera and display were used to isolate optic flow generated by participants' head movements toward a target, and participants' reaches to place a stylus either in a target hole (Experiments 1, 2, and 4) or aligned under a target surface (Experiment 3) were analyzed. Conclusions are that binocular distance perception is accurate, monocular distance perception yields compression that is not eliminated by feedback, but feedback is used to eliminate underestimation generated by restriction of the size of the visual field.

Adult↗

PubMed1998

Comparing measures of monocular distance perception: verbal and reaching errors are not correlated.

Monocular perception of egocentric distance via optic flow generated by head movement toward a target was investigated with a helmet-mounted video camera and display. Ability to perceive target distance was assessed with 2 response measures: verbal reports and reaches. Systematic and random errors differed as a function of the response measure. Verbal estimates of targets within and beyond reach were obtained before and after the performance of reaches to targets within reach. Systematic errors of verbal estimates changed but did not decrease overall. Random error decreased. Verbal estimates and reaches were performed concurrently to targets within reach. Verbal and reaching errors were uncorrelated. Verbal judgments appear to have been anchored using the range of distances experienced while reaching rather than being calibrated to the perceptual information itself. Discussion focuses on the advantages of action response measures.

Adult↗

PubMed1998

The use of time and trajectory forms as visual information about spatial scale in events.

Spatial metrics are lost but temporal metrics are preserved in the mapping from events to optic flow. In inanimate events governed by gravity, temporal scale is linked to spatial scale in ways specific to particular events. We tested whether time can be used as information about spatial scale in visually recognizable events. On average, observers were able to judge object size in event displays that eliminated information other than time and trajectory forms. However, judgment variability was substantial. After feedback on one event, observers judging distance performed better and generalized training to other events. Observers are sensitive to the general form of the scaling relation, but they require feedback to attune event-specific constants.

Adult↗

PubMed1995

Dynamics and the orientation of kinematic forms in visual event recognition.

The authors investigated event dynamics as a determinant of the perceptual significance of forms of motion. Patch-light displays were recorded for 9 simple events selected to represent rigid-body dynamics, biodynamics, hydrodynamics, and aerodynamics. Observers described events in a free-response task or by circling properties on a list. Cluster analyses performed on descriptor frequencies reflected the dynamics. Observers discriminated hydro- versus aerodynamic events and animate versus inanimate events. The latter result was confirmed by using a forced-choice task. Dynamical models of the events led us to consider energy flows as a determinant of kinematic properties that allowed animacy to be distinguished. Orientation was manipulated in 3 viewing conditions. Descriptions varied with absolute display orientation rather than the relative orientation of display and observer.

Adult↗

PubMed1993

Perceiving the size of trees: biological form and the horizon ratio.

Physical constraints produce variations in the shapes of biological objects that correspond to their sizes. Bingham (in press-b) showed that two properties of tree form could be used to evaluate the height of trees. Observers judged simulated tree silhouettes of constant image size appearing on a ground texture gradient with a horizon. According to the horizon ratio hypothesis, the horizon can be used to judge object size because it intersects the image of an object at eye height. The present study was an investigation of whether the locus of the horizon might account for Bingham's previous results. Tree images were projected to a simulated eye height that was twice that used previously. Judgments were not halved, as predicted by the horizon ratio hypothesis. Next, the original results were replicated in viewing conditions that encouraged the use of the horizon ratio by including correct eye height, gaze level, and visual angles. The heights of cylinders were inaccurately judged when they appeared with horizon but without trees. Judgments were much more accurate when the cylinders also appeared in the context of trees.

Adult↗

PubMed1993

Center of mass perception and inertial frames of reference.

Center of mass perception was investigated by varying the shape, size, and orientation of planar objects. Shape was manipulated to investigate symmetries as information. The number of reflective symmetry axes, the amount of rotational symmetry, and the presence of radial symmetry were varied. Orientation affected systematic errors. Judgments tended to undershoot the center of mass. Random errors increased with size and decreased with symmetry. Size had no effect on random errors for maximally symmetric objects, although orientation did. The spatial distributions of judgments were elliptical. Distribution axes were found to align with the principle moments of inertia. Major axes tended to align with gravity in maximally symmetric objects. A functional and physical account was given in terms of the repercussions of error. Overall, judgments were very accurate.

Adolescent↗

PubMed1993

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.

Adolescent↗

PubMed1991

Task dynamics and resource dynamics in the assembly of a coordinated rhythmic activity.

Task dynamics corresponding to rhythmic movements emerge from interactions among dynamical resources composed of the musculature, the link segments, and the nervous and circulatory systems. This article investigated whether perturbations of interlimb coordination might be effect over circulatory and nervous elements. Stiffness of wrist-pendulums oscillated at a common tempo and at 180 degrees relative phase was perturbed through the use of tonic activity about an ankle. Left and right stiffnesses, the common period, and the phase relation all changed. Stiffnesses increased with ankle torque in proportion to the wrist's inertial load. Despite different changes in stiffness at the two wrists, isochrony was preserved. The stability was shown to be consistent with the proportionality of changes in stiffness to the inertial loads. The phase departed from antiphase in proportion to the asymmetry of inertial loads. The size of departures decreased with increasing ankle torque. An account was developed in terms of muscular, circulatory, and nervous functions.

Adult↗

PubMed1989

Hefting for a maximum distance throw: a smart perceptual mechanism.

Objects for throwing to a maximum distance were selected by hefting objects varying in size and weight. Preferred weights increased with size reproducing size-weight illusion scaling between weight and volume. In maximum distance throws, preferred objects were thrown the farthest. Throwing was related to hefting as a smart perceptual mechanism. Two strategies for conveying high kinetic energy to projectiles were investigated by studying the kinematics of hefting light, preferred, and heavy objects. Changes in tendon lengths occurring when objects of varying size were grasped corresponded to changes in stiffness at the wrist. Hefting with preferred objects produced an invariant phase between the wrist and elbow. This result corresponded to an optimal relation at peak kinetic energy for the hefting. A paradigm for the study of perceptual properties was compared to size-weight illusion methodology.

Adult↗

PubMed1987

Kinematic form and scaling: further investigations on the visual perception of lifted weight.

Observers are able to judge accurately the weight lifted by another person when only the motions of reflective patches attached to the lifter's major limb joints and head can be seen (Runeson & Frykholm, 1981). What properties of these complex kinematic patterns allow judgments of weight to be made? The pattern of variation in velocity of the lifted object over position is explored as a source of information for weight: It is found to provide limited information. How are variations in kinematic patterns scaled to allow judgments of weight, a kinetic quantity? The possibility of a source of information for scaling in the kinematics is investigated. Judgments based only on patch-light displays are accurate to a degree that is improved by an extrinsic scaling basis. Finally, the sensitivity to scaling of alternative metrics used in judging is explored. Intrinsic metrics are discovered to be less sensitive to the absence of an extrinsic basis for scaling.

Concept Formation↗