Cognitive representation of linear motion: Possible direction and gravity effects in judged displacement

The judged vanishing point of a target undergoing apparent motion in a horizontal, vertical, or oblique direction was examined. In Experiment 1, subjects indicated the vanishing point by positioning a crosshair. Judged vanishing point was displaced forward in the direction of motion, with the magnitude of displacement being largest for horizontal motion, intermediate for oblique motion, and smallest for vertical motion. In addition, the magnitude of displacement increased with faster apparent velocities. In Experiment 2, subjects judged whether a stationary probe presented after the moving target vanished was at the same location where the moving target vanished. Probes were located along the axis of motion, and probes located beyond the vanishing point evidenced a higher probability of a same response than did probes behind the vanishing point. In Experiment 3, subjects judged whether a stationary probe presented after the moving target vanished was located on a straight-line extension of the path of motion of the moving target. Probes below the path of motion evidenced a higher probability of a same response than did probes above the path of motion for horizontal and ascending oblique motion; probes above the path of motion evidenced a higher probability for a same response than did probes below the path of motion for descending oblique motion. Overall, the pattern of results suggests that the magnitude of displacement increases as proximity to a horizontal axis increases, and that in some conditions there may be a component analogous to a gravitational influence incorporated into the mental representation.     

Adaptation to vertical displacement of the visual direction

Sixty Ss wore vertically displacing wedge prisms and adapted by looking at their feet for 10 min. Half of them did this while standing and the others in supine position. The latter condition produced adaptation measurable with a visual-motor test and with a test of egocentric localization, but on a purely motoric test no adaptation was apparent. Standing during the adaptation period produced no effect.     

Gaze direction affects visuo-spatial short-term memory

Hemispheric asymmetries were investigated by changing the horizontal position of stimuli that had to be remembered in a visuo-spatial short-term memory task. Observers looked at matrices containing a variable number of filled squares on the left or right side of the screen center. At stimulus offset, participants reproduced the positions of the filled squares in an empty response matrix. Stimulus and response matrices were presented in the same quadrant. We observed that memory performance was better when the matrices were shown on the left side of the screen. We distinguished between recall strategies that relied on visual or non-visual (verbal) cues and found that the effect of gaze position occurred more reliably in participants using visual recall strategies. Overall, the results show that there is a solid enhancement of visuo-spatial short-term memory when observers look to the left. In contrast, vertical position had no influence on performance. We suggest that unilateral gaze to the left activates centers in the right hemisphere contributing to visuo-spatial memory.     

Tilt from ahead-inverted position produces displacement of visual subjective vertical in the opposite direction

Observers who lie supine with their heads inverted report large (up to 60°) tilt of a light line in an otherwise dark room when their heads and/or bodies are tilted. Most observers report that visual subjective vertical is tilted in the direction opposite to the head/body tilt. The results can be interpreted by employing a model developed by Mittelstaedt (1983), which suggests that visual subjective vertical is derived from a gravity vector transduced by vestibular and somesthetic receptors combined with “idiotropic vectors” that represent the orientation of the observer’s own head and body axes.     

Independent coding of target distance and direction in visuo-spatial working memory

The organization of manual reaching movements suggests considerable independence in the initial programming with respect to the direction and the distance of the intended movement. It was hypothesized that short-term memory for a visually-presented location within reaching space, in the absence of other allocentric reference points, might also be represented in a motoric code, showing similar independence in the encoding of direction and distance. This hypothesis was tested in two experiments, using adult human subjects who were required to remember the location of a briefly presented luminous spot. Stimuli were presented in the dark, thus providing purely egocentric spatial information. After the specified delay, subjects were instructed to point to the remembered location. In Exp. 1, temporal decay of location memory was studied, over a range of 4–30 s. The results showed that (a) memory for both the direction and the distance of the visual target location declined over time, at about the same rate for both parameters; however, (b) errors of distance were much greater in the left than in the right hemispace, whereas direction errors showed no such effect; (c) the distance and direction errors were essentially uncorrelated, at all delays. These findings suggest independent representation of these two parameters in working memory. In Exp. 2 the subjects were required to remember the locations of two visual stimuli presented sequentially, one after the other. Only after both stimuli had been presented did the subject receive a signal from the experimenter as to which one was to be pointed to. The results showed that the encoding of a second location selectively interfered with memory for the direction but not for the distance of the to-be-remembered target location. As in Exp. 1, direction and distance errors were again uncorrelated. The results of both experiments indicate that memory for egocentrically-specified visual locations can encode the direction and distance of the target independently. Use of motor-related representation in spatial working memory is thus strongly suggested. The findings are discussed in the context of multiple representations of space in visuo-spatial short-term memory.     

Adaptation to field displacement during head movement unrelated to the constancy of visual direction

Adaptation to vertical field displacements dependent on head turning about a vertical axis was demonstrated under two conditions, rapid training with 100 head movements and 1-h-long training with continuous head turning. The effect of rapid training was measured with the slant estimation method. Adaptation after the longer training was ascertained by comparing the uncertainty ranges for apparent target immobility before and after the adaptation period. Adaptation to field displacements in directions parallel to the plane of the head rotation obtained under corresponding conditions was also measured and found to be somewhat greater than adaptation to vertical field displacements. The result of work by Wallach and Frey that adaptation to field displacement in the direction with the head rotation is greater than to displacement against it was corroborated. While the previous result had, been obtained with rapid adaptation and with the slant estimation method, we confirmed it with 1-h training and by measuring the uncertainty ranges before and after the adaptation period.     

Segregation of study items in memory determines the magnitude and direction of directed forgetting

When words at study are divided into to‐be‐remembered and to‐be‐forgotten ones, people recall more of the former than of the latter in a surprise memory test for all words. In this study, we also tapped memory for word identity at study (forget or remember) by asking participants to reproduce in memory selected portions of the original words. We found word identity to be parasitic on word reproduction. As a result, there is a noted tendency to recall forget‐words from study as remember‐words in the memory test more than vice versa.     

The effect of height in the picture plane on the forward displacement of ascending and descending targets.

The effect of height in the picture plane on the remembered location of ascending or descending targets was examined. Consistent with previous research, memory was displaced forward in the direction of motion. The magnitude of forward displacement was larger for targets low in the picture plane than for targets high in the picture plane, and this was observed with ascending motion and with descending motion. This pattern is consistent with the hypothesis that memory for the location of ascending or descending targets is biased by the effects of implied gravitational attraction on the velocity of those targets, and some implications of such a bias for issues in mental representation are noted.     

Looking the other way: The role of gaze direction in the cross-race memory effect

One of the most replicable findings reported in the social psychological literature is the cross-race memory effect. We argue this effect derives from higher-order interactions among social cues that determine the perceived relevance of a face to an observer. The current research tested this hypothesis by examining the combined influences of eye gaze direction and race on face memory. The physical subtlety of eye gaze belies its powerful influence on social perception, and in this case helps specify the relevance of same- versus other-race faces. We found that only in faces making direct eye contact—not those displaying averted eye gaze—was the cross-race memory effect evident. Likewise, only in same-race faces did direct relative to averted-gaze enhance face memory. These findings have implications for our general understanding of the combinatorial nature of social perception and help clarify the underlying cause of the cross-race memory effect.     

Body configuration as a predictor of centre of mass displacement in a forward reactive step

In balance perturbations that elicit backwards reactive steps, body configuration at stepping contact is related to likelihood of balance recovery. However, less is known about the relationship between body configuration (at stepping contact) and underlying centre of mass (COM) dynamics during dynamic perturbations requiring a forward reactive step. Accordingly, the primary objective of this study was to characterize the potential relationships between body configuration and COM displacement during simulated trips. Towards determining the robustness of these relationships, trips were simulated in both baseline and increased passive joint stiffness conditions. Sixteen healthy adults participated in this study. Trips were simulated using a tether release paradigm where participants were suddenly released, necessitating a forward step (onto a force plate) to recover their balance. Trials were performed in a baseline unconstrained condition, and in a ‘corset’ condition to increase passive stiffness of the trunk and hips. In all trials, whole body kinematics and kinetics were collected. Multiple linear regression models were run to assess the relationship of body angles to COM displacement in both the anteroposterior (AP) and mediolateral (ML) planes. Regression models showed a significant association of sagittal plane body configuration to both COM displacement at stepping contact and maximum COM displacement in the AP plane. Across models, the strongest predictor was the trail leg angle. Associations were stronger in the increased passive stiffness condition (average R² = 0.366) compared to the baseline condition (average R² = 0.266). Poor association of body configuration to COM displacement was found in the ML plane. The significant associations observed between body configuration and COM dynamics in simulated trips supports the potential downstream application of these models in identifying individuals with impaired balance control and increased fall risk.     

Spatial memory averaging, the landmark attraction effect, and representational gravity

The effect of a large stationary landmark on memory for the location of a stationary target was examined. Memory for a stationary target was displaced toward the landmark, and targets that were larger, further from, or above the landmark exhibited greater magnitudes of displacement. Displacement was generally larger when the landmark vanished prior to judgment than when the landmark was visible during judgment. Memory for stationary targets offset from the major vertical or horizontal cardinal axis of the landmark was also displaced toward that cardinal axis. The data support the hypotheses that spatial memory averaging of the locations of a target and landmark occurs, and that this averaging may be combined with representational gravity in determining the remembered position of a stationary target. Received: 17 May 1999 / Accepted: 8 February 2000     

On the relation of adaptation to field displacement during head movements to the constancy of visual direction

When the normal constancy process on which the apparent immobility of the visualfield during head movements is based was strengthened by the same method that produces adaptation to abnormal conditions in the constancy of visual direction, and when this training of the normal constancy process immediately preceded experimental adaptation, the effectiveness of the latter was diminished. This result applied not only to adaptation to horizontal field displacement and to vertical field displacement during turning of the head, but also to vertical field displacement during nodding of the head, a condition to which adaptation was here demonstrated for the first time.     

Look into my eyes: gaze direction and person memory

The current research considered the effects of gaze direction on a fundamental aspect of social cogition: person memory. It was anticipated that a person's direction of gaze (i.e., direct or averted) would impact his or her subsequent memorability, such that recognition would be enhanced for targets previously displaying direct gaze. In Experiment 1, participants were presented with faces displaying either direct or averted gaze in a person-classification (i.e., conceptual) task. Then, in a surprise memory test, they were required to report whether a presented face had been seen before. As expected, a recognition advantage was observed for targets displaying direct gaze during the initial classification task. This finding was replicated and extended in a second experiment in which participants initially reported the spatial location (i.e., perceptual task) of each face. We consider the implications of these findings for basic aspects of social-cognitive functioning and person perception.     

Look into my eyes: Gaze direction and person memory

The current research considered the effects of gaze direction on a fundamental aspect of social cogition: person memory. It was anticipated that a person's direction of gaze (i.e., direct or averted) would impact his or her subsequent memorability, such that recognition would be enhanced for targets previously displaying direct gaze. In Experiment 1, participants were presented with faces displaying either direct or averted gaze in a person‐classification (i.e., conceptual) task. Then, in a surprise memory test, they were required to report whether a presented face had been seen before. As expected, a recognition advantage was observed for targets displaying direct gaze during the initial classification task. This finding was replicated and extended in a second experiment in which participants initially reported the spatial location (i.e., perceptual task) of each face. We consider the implications of these findings for basic aspects of social‐cognitive functioning and person perception.     

Consistency of handedness, regardless of direction, predicts baseline memory accuracy and potential for memory enhancement

Research has shown that consistently right-handed individuals have poorer memory than do inconsistently right- or left-handed individuals under baseline conditions but more reliably exhibit enhanced memory retrieval after making a series of saccadic eye movements. From this it could be that consistent versus inconsistent handedness, regardless of left/right direction, is an important individual difference factor in memory. Or, more specifically, it could be the presence or absence of consistent right-handedness that matters for memory. To resolve this ambiguity, we compared consistent and inconsistent left- and right-handers on associative recognition tests taken after saccades or a no-saccades control activity. Consistent-handers exhibited poorer memory than did inconsistent-handers following the control activity, and saccades enhanced retrieval for consistent-handers only. Saccades impaired retrieval for inconsistent-handers. None of these effects depended on left/right direction. Hence, this study establishes handedness consistency, regardless of direction, as an important individual difference factor in memory.     

Effect of direction of sequential presentation and redundancy on short-term recognition memory

Short-term recognition memory was tested by presenting six letters, one after the other, followed by a target letter and having S indicate whether or not the target matched one of the six letters. Recognition memory for a letter was better when it was embedded in a six-letter word, rather than a nonword, and when it was included in a sequence presented left-to-right, rather than right-to-left (Experiment 1). Reducing the presentation rate from 4/sec to 2.5/sec largely eliminated the left-to-right effect (Experiment 2). The effect of direction of presentation was greater for redundant (Experiment 1) than for nonredundant sequences (Experiment 3) and was greater for Ss who more frequently formed a word out of the sequence (Experiments 1 and 2), but was no greater for words than nonwords (Experiments 1 and 2) and no greater for letter than for line-figure sequences (Experiment 3). These findings suggest that the left-to-right effect depends as much, or more, on “peripheral” processes (e.g., eye movements) as on “central” processes (e.g., reading).     

Working memory in spatial knowledge acquisition: Differences in encoding processes and sense of direction

This study examined how different components of working memory are involved in spatial knowledge acquisition for good and poor sense‐of‐direction (SOD) people. We employed a dual‐task method, and asked participants to learn routes from videos with verbal, visual and spatial interference tasks and without any interference. Results showed that participants with a good SOD encoded landmarks and routes verbally and spatially, and integrated knowledge about them into survey knowledge with the support of all three components of working memory. In contrast, participants with a poor SOD encoded landmarks only verbally, and tended to rely on the visual component of working memory in the processing of route knowledge. Based on the results, a possible model for explaining the differences in spatial knowledge acquisition and SOD was proposed. Copyright © 2010 John Wiley & Sons, Ltd.     

Reproducibility of distance and direction errors associated with forward, backward, and sideway walking in the context of blind navigation

The ability to navigate without vision towards a previously seen target has been extensively studied, but its reliability over time has yet to be established. Our aims were to determine distance and direction errors made during blind navigation across four different directions involving three different gait patterns (stepping forward, stepping sideway, and stepping backward), and to establish the test-retest reproducibility of these errors. Twenty young healthy adults participated in two testing sessions separated by 7 days. They were shown targets located, respectively, 8 m ahead, 8 m behind, and 8 m to their right and left. With vision occluded by opaque goggles, they walked forward (target ahead), backward (target behind), and sideway (right and left targets) until they perceived to be on the target. Subjects were not provided with feedback about their performance. Walked distance, angular deviation, and body rotation were measured. The mean estimated distance error was similar across the four walking directions and ranged from 16 to 80 cm with respect to the 8 m target. In contrast, direction errors were significantly larger during sideway navigation (walking in the frontal plane: leftward, 10 degrees +/- 15 degrees deviation; rightward, 18 degrees +/- 13 degrees) than during forward and backward navigation (walking in the sagittal plane). In general, distance and direction errors were only moderately reproducible between the two sessions [intraclass correlation coefficients (ICCs) ranging from 0.682 to 0.705]. Among the four directions, rightward navigation showed the best reproducibility with ICCs ranging from 0.607 to 0.726, and backward navigation had the worst reliability with ICCs ranging from 0.094 to 0.554. These findings indicate that errors associated with blind navigation across different walking directions and involving different gait patterns are only moderately to poorly reproducible on repeated testing, especially for walking backward. The biomechanical constraints and increased cognitive loading imposed by changing the walking pattern to backward stepping may underlie the poor performance in this direction.