The effect of apparent movement on mental rotation

Eleven subjects were timed as they judged whether a small bar perpendicular to one side of a clockhand would point left or right if the hand was pointing upward (i.e., at the "12 o'clock" position). The clockhand was shown in two successive orientations 30 degrees apart, so that it was perceived to jump from one to the other in either a clockwise or a counterclockwise direction. Reaction times were consistent with the interpretation that the subjects "mentally rotated" the clockhand from its perceived orientation back to the upright before making their decisions. The direction of the jump influenced perceived orientation but did not influence either the direction or rate of mental rotation itself.     

Haptic perception of spatial relations

There are some indications that haptic space like visual space is not Euclidean (e.g. Blumenfeld, 1937 Acta Psychologica 2 125-174). In a series of experiments, we investigated the haptic perception of spatial relations in a systematic way. We restricted ourselves to a horizontal plane at waist height. Blindfolded subjects were asked to perform three tasks with their right hand: (i) a reference bar was presented under four different orientations and subjects were asked to rotate a test bar such that it felt to be parallel to the reference bar; (ii) subjects had to rotate two test bars in such a way that they felt collinear; (iii) subjects had to point a test bar in the direction of a marker. Bars and marker could appear at nine different locations. In all experiments large systematic deviations (up to 40 degrees) were made. The deviations strongly correlated with horizontal (right-left) but not with vertical (forward-backward) distance. Subjects showed qualitatively identical trends but the size of the deviations was strongly subject-dependent. In addition, a significant haptic oblique effect was found. These results provide strong evidence that haptic space in non-Euclidean.     

Concurrent validity of tests to measure the coordinated exertion of force by computerized target pursuit

The purpose of this study was to examine concurrent validity of a new test for coordinated exertion of force. Coordinated exertion of force was measured using computerized target pursuit from the following viewpoints: the relations between the new test, a pursuit-rotor test, and a pegboard test. College students (24 men and 24 women) were required to change their grip exertion to match changing demand values (displayed in either a bar chart or a wave form) appearing on the display of a personal computer. The sum of the differences between the demanded values and grip-exertion values for 25 sec. was a parameter to evaluate the new test. The reliabilities of the new test, the pursuit-rotor, and the pegboard test were acceptable (ICC = .70 to .99). Scores on the new test showed low correlations with the pursuit-rotor and the pegboard test. The relation between the two different displays in the new test was significant but low (r = .49, p < .05). It was inferred that the new test measures a somewhat different ability than that measured by the pursuit-rotor and pegboard test and that the abilities tested by the types of displayed demand values are somewhat different.     

The organization of multisegmental pulls made by standing humans: I. Near-maximal pulls

Complex multisegmental movements occur when standing subjects exert forceful, impulse-like pulls on a bimanually held handle. The degrees of freedom of this task were analyzed to provide a principled basis for understanding the act's coordination. Body posture was found to be describable by only two degrees of freedom, expressible as the anterior-posterior and vertical coordinates of the center of mass (CM(AP), CM(V)). Kinetic analysis revealed that the two major contributors to pulling force depended only upon CM(AP) motion and the location of the center of the pressure. Kinematic and kinetic data from six well-practiced subjects pulling near their maxima were used to test the prediction of less intersubject variability in CM(AP) than in CM(V) variation led to different movement patterns among subjects. A dynamic model of CM(AP) motion was developed, and manipulation of its three degrees of freedom yielded CM(AP) trajectories that matched the empirical trajectories. It is suggested that the pull might be controlled with reference to these three parameters.     

Unmasking the standing wave of invisibility: An account in terms of object-mediated representational updating

A central bar presented in counterphase with two flanking bars creates the perception of only two bars, instead of three, flickering (standing wave of invisibility illusion). Current explanations of this illusion highlight the importance of local interactions between the central bar and the flankers as a reason for the invisibility of the central bar. In three experiments, we show that the reduction in visibility of the central bar occurs even when the flankers are spatially separated from the central bar. Thus local mechanisms&#x2014;low-level lateral inhibition or border-ownership competition&#x2014;do not suffice to account for the decreased visibility. Furthermore, the reduced visibility of the central bar is accompanied by the perception of the flankers in apparent motion at all separations. We suggest an account of the standing wave phenomenon in terms of object updating: The representation of the central bar is updated with the representation of the flankers leaving the perception of just the flankers moving across space. The stimuli for the key conditions from this study, in QuickTime format, may be down loaded from http://app.psychonomic-journals.org/content/supplemental.     

A sideways look at configural encoding: two different effects of face rotation

Inversion has a disproportionate disruptive effect on the recognition of faces. This may be due to the disruption of holistic or configural encoding employed to recognise upright faces. The paradigm developed by Tanaka and Farah (1993 Quarterly Journal of Experimental Psychology, Section A 46 225-246) was used to investigate the effect of 90 degrees (or orthogonal) rotation on configural encoding. Faces learnt in the orthogonal condition were not recognised as well as upright faces, but a whole-face advantage was found in both cases. This whole-face advantage did not occur for inverted faces. It appears that 90 degrees rotation affects recognition but not specifically configural encoding. It is concluded that rotating a face can have at least two different effects on face processing depending on the range of rotation. Implications for the nature of facial dimensions and the expertise account of the inversion effect are considered.     

Visual binding in the standing wave illusion

When two video frames are alternated at the appropriate rate, one with a central bar and the other with two flanking bars, the central bar becomes invisible. Competing explanations for this standing wave illusion are examined, with the results showing an influence of higher level shape representations on lower level edge processes. In Experiment 1, flanking bar duration was found to be more important to masking than central bar duration. Experiment 2 showed strong nonlocal effects in that masking of the central bar depended critically on whether it appeared in the same video frame as other visible bars. Experiments 3 and 4 showed that the contour shared by bars in separate frames was a less important factor than shape and surface similarity. This illusion is therefore an excellent tool for studying recursive interactions between higher level object representations and lower level contour processes.     

Load release balance test under unstable conditions effectively discriminates between physically active and sedentary young adults

This study investigates test-retest reliability and diagnostic accuracy of the load release balance test under four varied conditions. Young, early and late middle-aged physically active and sedentary subjects performed the test over 2 testing sessions spaced 1 week apart while standing on either (1) a stable or (2) an unstable surface with (3) eyes open (EO) and (4) eyes closed (EC), respectively. Results identified that test-retest reliability of parameters of the load release balance test was good to excellent, with high values of ICC (0.78–0.92) and low SEM (7.1%–10.7%). The peak and the time to peak posterior center of pressure (CoP) displacement were significantly lower in physically active as compared to sedentary young adults (21.6% and 21.0%) and early middle-aged adults (22.0% and 20.9%) while standing on a foam surface with EO, and in late middle-aged adults on both unstable (25.6% and 24.5%) and stable support surfaces with EO (20.4% and 20.0%). The area under the ROC curve >0.80 for these variables indicates good discriminatory accuracy. Thus, these variables of the load release balance test measured under unstable conditions have the ability to differentiate between groups of physically active and sedentary adults as early as from 19 years of age.     

How apparent motion affects mental rotation: Push or pull?

Subjects were timed as they judged whether a small bar perpendicular to one side of a clockhand would point left or right if the hand was pointing upward (i.e., at the 12:00 position). The clockhand was shown in two successive orientations 30°apart, so that it was perceived to jump from one to the other, but the bar was included at only one of the two orientations. Analysis of reaction times as a function of angular orientation showed that the subjects “mentally rotated” the clockhand to the upright position before making their decisions. When the bar appeared on the second presentation, the jump had no significant influence on mental rotation but when it appeared on the first presentation, the estimated orientation from which the clockhand was mentally rotated was “dragged” in the direction of the jump.     

The effect of rotation on configural encoding in a face-matching task

Inversion disrupts encoding of faces because of the disruption of configural encoding as evident in the Thatcher illusion (Thompson 1980, Perception 9 483-484). Here we consider the effect of rotation on the loss of configural encoding in a same/different matching paradigm. Participants decided whether two faces were of the same type (both normal or both Thatcherised) or not, at five angles of rotation (0 degrees, 45 degrees , 90 degrees, 135 degrees, 180 degrees). When the faces were both of the same person, the disruption due to rotation for 'same-type' judgments was linear and approximately equal for normal and Thatcherised face pairs. In experiment 2, with different-person face pairs, the effect of rotation was much greater for Thatcherised face pairs than for normal face pairs. These findings are in contrast to those reported by Boutsen and Humphreys (2003, Quarterly Journal of Experimental Psychology A 56 955-975), and reasons for these differences, along with implications, are discussed.     

Optimum take-off angle in the standing long jump

The aim of this study was to identify and explain the optimum projection angle that maximises the distance achieved in a standing long jump. Five physically active males performed maximum-effort jumps over a wide range of take-off angles, and the jumps were recorded and analysed using a 2-D video analysis procedure. The total jump distance achieved was considered as the sum of three component distances (take-off, flight, and landing), and the dependence of each component distance on the take-off angle was systematically investigated. The flight distance was strongly affected by a decrease in the jumper's take-off speed with increasing take-off angle, and the take-off distance and landing distance steadily decreased with increasing take-off angle due to changes in the jumper's body configuration. The optimum take-off angle for the jumper was the angle at which the three component distances combined to produce the greatest jump distance. Although the calculated optimum take-off angles (19-27 degrees) were lower than the jumpers' preferred take-off angles (31-39 degrees), the loss in jump distance through using a sub-optimum take-off angle was relatively small.     

Visual evoked potential augmenting/reducing slopes in cats—2. Correlations with behavior

Relationships were studied in cats between the augmenting/reducing slopes of visual evoked potentials (VEP) and three types of behavioral responses: learning and performance measures in (1) fixed interval (FI), and (2) differential reinforcement of low rate of response (DRL) bar pressing tasks for food reward, and (3) the effect of noise stress or increasing task difficulty on performance of an FI, DRL or 2 bar discrimination task. The most reliable slope measure (N1 at a medium intensity range) was found to correlate most highly with inhibitory behaviors such that reducers were most successful in controlling bar pressing behavior during an inhibitory DRL task or when stress was introduced. At a higher range of flash intensity slopes tended to be more negative, and the P1 - N1 slopes although more variable correlated most consistently with general temperament. Augmenters at a high intensity range were more active and explaratory, and learmed to bar press more quickly and efficiently.     

Applications of mental rotation figures of the Shepard and Metzler type and description of a mental rotation stimulus library

The 3D cube figures used by Shepard and Metzler [Shepard, R. N., & Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171, 701-703] have been applied in a broad range of studies on mental rotation. This note provides a brief background on these figures, their general use in cognitive psychology and their role in studying spatial behavior. In particular, it is pointed out that large sex differences with the 3D mental rotation figures tend to be observed only in particular tasks, such as the Vandenberg and Kuse test [Vandenberg, S. G., & Kuse, A. R. (1978). Mental rotations, a group test of three-dimensional spatial visualization. Perceptual and Motor Skills, 47, 599-604] that involve multiple figures within a single problem. In contrast, pairwise presentation of the same 3D figures yields either small or no significant sex differences. In the context of the very broad range of ongoing research done with 3D figures, and the desirability of uniformity in the stimulus material used, we introduce a library of 16 cube mental rotation figures, each presented in orientations ranging from 0 to 360 degr in 5 degr steps, and with its mirror image, for a total of 2336 figures. This library, freely available to researchers, will help in the creation of mental rotation tasks both for presentation on the computer screen and for pencil and paper applications.     

Influence of body roll on visually induced sensations of self-tilt and rotation

Illusory self-tilt and illusory self-motion (vection) produced by rotation of a 360 degrees visual scene about the subject's roll axis was measured as a function of the presence or absence of actual rotation of the subject during acceleration of the visual scene. Rotation of the subject to a tilt of 15 degrees was at two levels of acceleration (onset) and with or without a delay between initial rotation and subsequent return (washout) to the vertical position. In one set of conditions, visual motion and subject motion were in opposite directions (concordant) and in another set they were in the same direction (discordant). In two control conditions, the subject was rotated while the visual scene remained stationary. For concordant motion the main effect of body rotation was to reduce the time taken by the subject to indicate self-tilt as compared with the response time to visual motion alone. The magnitude of estimated self-tilt was increased by actual body tilt as could be expected from addition of the perceived actual body tilt and the illusory body tilt induced by visual rotation. This effect of augmented body tilt did not persist after the body was returned to the vertical. The magnitude of vection was not markedly influenced by body rotation and washout. For discordant motion of body and the visual scene, subjects were confused and their responses were very variable, suggesting a nonlinear visual--vestibular interaction.     

Postural coordination patterns as a function of dynamics of the support surface

The present study investigated the compensatory postural coordination patterns that emerge in the face of dynamic changes in the surface of support. Adult subjects stood on a moving platform that was sinusoidally translated in the anterior-posterior direction. The frequency and amplitude of the support surface translation were manipulated over a wide range of parameter values. The results revealed that as the frequency of platform motion increased, the postural system systematically exploited the available joint-space degrees of freedom and generated four distinct postural coordination modes (a rigid mode --> ankle mode --> ankle-hip mode --> ankle-hip-knee mode). It appears that upright standing posture has a small set of coordination patterns that are particular to the dynamics of the surface of support.     

Keeping balance during head-free smooth pursuit: The role of aging

Standing balance is often more unstable when visually pursuing a moving target than when fixating on a stationary one. These effects are common in both young and older adults when the head is restrained during visual task performance. The present study focused on the role of head motion on standing balance during smooth pursuit as a function of age. Three predictions were tested: a) standing balance is compromised to a greater extent in older than young adults by gaze target pursuit compared to fixation, b) older adults pursue a moving target with greater and more variable head rotation than young adults, and c) greater and more variable head rotation during the smooth pursuit task is associated with greater Center of Pressure (CoP) sway. Twenty-two (22) older (age: 71.7 ± 8.1, 12 M / 10 F) and twenty-three (23) young adults (age: 23.6 ± 2.5, 12 M / 11 F) stood on a force plate while either fixating a stationary or smoothly pursuing a horizontally moving target (31.9° peak-to-peak visual angle). CoP (Bertec Balance Plate), head kinematics (Vicon Motion Analysis) and head-unconstrained gaze (Pupil Labs Invisible) were synchronously recorded. The root means square (RMS) of CoP velocity increased during smooth pursuit compared to fixation regardless of age (p < .05), while the interquartile CoP range increased only in older and not in young participants (p < .05). We also calculated the head rotation range (peak to peak cycle amplitude) of motion and variability (SD of range of motion) across the cycles of the smooth pursuit task. Older adults pursued the moving target employing more variable (p = .022) head yaw rotation than young participants although the mean range of head rotation was similar between groups (p =. 077). The amplitude and variability of head yaw rotation did not correlate with CoP sway measures. Results suggest that head-free pursuing of a moving target decreased balance to a greater extent in old than young individuals when compared to fixation. Nevertheless, postural sway during head-free smooth pursuit was not associated with the extent or variability of head rotation.     

Starting position of movement and perception of angle of trunk flexion while standing with eyes closed.

The present study attempted to investigate the effect of position on the perception of angle of trunk flexion while standing. For this purpose, the range effect was factored out by setting the constant target angle at 10 degrees, with varied starting positions of trunk flexion. We found that subjects underestimated angle of trunk flexion when the starting position was close to a quiet standing posture, overestimated when close to maximum trunk flexion, and correctly perceived it when at the middle position. Less perceptual distortion was observed at the positions close to maximum trunk flexion in the present study than in our previous one, in which various target angles of trunk flexion were reproduced from a quiet standing posture. The reduced distortion in the present study was believed to have resulted from factoring out the range effect. The flexion angle of the hip joint changed in tandem with that of the trunk, while very little movement was observed in the ankle, knee, and neck joints. Judging from the changing pattern of hip-joint angle, the muscle activity of the erector spinae and biceps femoris increased gradually to 90 degrees trunk flexion. In contrast, the actual increment of muscle activity reached zero or a minimum value at the middle angles as the angle of trunk flexion increased. It was assumed that the abrupt change in kinesthetic information associated with muscle activity exerted a great influence on the perception of trunk flexion.