Gender differences in spatial perception of body tilt

The tendency for observers to overestimate slant is not simply a visual illusion but can also occur with another sense, such as proprioception, as in the case of overestimation of self-body tilt. In the present study, distortion in the perception of body tilt was examined as a function of gender and multisensory spatial information. We used a full-body-tilt apparatus to test when participants experienced being tilted by 45 degrees, with visual and auditory cues present or absent. Body tilt was overestimated in all conditions, with the largest bias occurring when there were no visual or auditory cues. Both visual and auditory information independently improved performance. We also found a gender difference, with women exhibiting more bias in the absence of auditory information and more improvement when auditory information was added. The findings support the view that perception of body tilt is multisensory and that women more strongly utilize auditory information in such multisensory spatial judgments.     

To pass or not to pass: More a question of body orientation than visual cues

This study investigated the influence of pitch body tilt on judging the possibility of passing under high obstacles in the presence of an illusory horizontal self-motion. Seated subjects tilted at various body orientations were asked to estimate the possibility of passing under a projected bar (i.e., a parking barrier), while imagining a forward whole-body displacement normal to gravity. This task was performed under two visual conditions, providing either no visual surroundings or a translational horizontal optic flow that stopped just before the barrier appeared. The results showed a main overestimation of the possibility of passing under the bar in both cases and most importantly revealed a strong influence of body orientation despite the visual specification of horizontal self-motion by optic flow (i.e., both visual conditions yielded a comparable body tilt effect). Specifically, the subjective passability was proportionally deviated towards the body tilt by 46% of its magnitude when facing a horizontal optic flow and 43% without visual surroundings. This suggests that the egocentric attraction exerted by body tilt when referring the subjective passability to horizontal self-motion still persists even when anchoring horizontally related visual cues are displayed. These findings are discussed in terms of interaction between spatial references. The link between the reliability of available sensory inputs and the weight attributed to each reference is also addressed.     

美感对西方绘画无意识加工的影响

采用连续闪烁抑制范式(Continuous Flash Suppression, CFS), 通过比较不同美感的图片的突破抑制时间,考察了美感对西方绘画无意识加工的影响。实验1使用黑白噪音图片, 通过单因素被试内设计考察了高、中、低三种美感等级的彩色西方绘画的突破抑制时间。结果发现, 美感高和美感中等的西方绘画比美感低的西方绘画能更快突破噪音图片的抑制进入意识。实验2考察在彩色噪音图片的抑制下, 美感是否依然影响彩色西方绘画突破抑制的时间。结果发现, 美感不影响西方绘画突破抑制时间, 且突破抑制时间显著长于实验1。这些结果表明美感对西方绘画无意识加工的影响受到双眼竞争的眼间抑制过程的限制, 只有在黑白噪音图抑制的情况下, 美感会影响西方绘画进入意识的速度。与黑白噪音图片相比, 彩色噪音图片可能对颜色信息的抑制更强, 干扰了美感对西方绘画无意识加工的影响。     

Apparent head position as a basis for a visual aftereffect of prolonged head tilt

A possible explanation of the visual spatial aftereffect following head tilt with eyes closed is that it is an outcome of a proprioceptive aftereffect of head position. If the upright head is apparently tilted then it might be expected that a vertical line in a dark room would also be apparently tilted. This explanation predicts that the direction and magnitude of the visual and proprioceptive aftereffects would correspond. The second of two experiments showed that the trends of the two aftereffects as a function of head tilt angle were different. It was concluded that the visual aftereffect cannot be explained in terms of a proprioceptive aftereffect.     

Perception of self-tilt in a true and illusory vertical plane

A tilted furnished room can induce strong visual reorientation illusions in stationary subjects. Supine subjects may perceive themselves upright when the room is tilted 90 degrees so that the visual polarity axis is kept aligned with the subject. This 'upright illusion' was used to induce roll tilt in a truly horizontal, but perceptually vertical, plane. A semistatic tilt profile was applied, in which the tilt angle gradually changed from 0 degrees to 90 degrees, and vice versa. This method produced larger illusory self-tilt than usually found with static tilt of a visual scene. Ten subjects indicated self-tilt by setting a tactile rod to perceived vertical. Six of them experienced the upright illusion and indicated illusory self-tilt with an average gain of about 0.5. This value is smaller than with true self-tilt (0.8), but comparable to the gain of visually induced self-tilt in erect subjects. Apparently, the contribution of nonvisual cues to gravity was independent of the subject's orientation to gravity itself. It therefore seems that the gain of visually induced self-tilt is smaller because of lacking, rather than conflicting, nonvisual cues. A vector analysis is used to discuss the results in terms of relative sensory weightings.     

Visual search asymmetry for viewing direction

In visual search experiments, we examined the existence of a search asymmetry for the direction with which three-dimensional objects are viewed. It was found that an upward-tilted target object among downward-tilted distracting objects was detected faster than when the orientation of target and distractors was reversed. This indicates that the early visual process regards objects tilted downward with respect to the observer as the situation that is more likely to be encountered. That is, the system is set up to expect to see the tops of these objects. We also found a visual field anisotropy, in that the asymmetry was more pronounced in the lower visual field. These findings are consistent with the idea that the tops of objects are usually situated in the lower visual field and less often in the upper field. Examination of the conditions under which the asymmetry and the anisotropy occur demonstrated the importance of the three-dimensional nature of the stimulus objects. Early visual processing thus makes use of heuristics that take into account specific relationships between the relative locations in space of the observer and 3-D objects.     

Behavioral and physiological findings of gender differences in global-local visual processing

Hemispheric asymmetries in global-local visual processing are well-established, as are gender differences in cognition. Although hemispheric asymmetry presumably underlies gender differences in cognition, the literature on gender differences in global-local processing is sparse. We employed event related brain potential (ERP) recordings during performance of a global-local reaction time task to compare hemispheric asymmetries and processing biases in adult men (n=15) and women (n=15). Women responded more quickly to local targets while men did not differentially respond to hierarchical stimuli. ERP data indicated that women had P100 responses that were selectively lateralized to the left hemisphere in response to local targets and N150 responses that were smaller for global targets. They also had P300 responses that were greater following local stimuli. The physiological data demonstrate that male-female performance differences arise from biologically based differences in hemispheric asymmetry. Findings are discussed in the context of existing literature regarding gender differences, hemispheric specialization, and the role of stimulus characteristics.     

Tactile memory in sighted and blind observers: the influence of orientation and rate of presentation

Sighted, early blind, and late blind subjects attempted to identify numerals or number sequences printed on their palms. The numerals were either upright, or inverted, or rotated perpendicular to the arm axis. Stimulus rotation degraded recognition in the early blind subjects, suggesting the influence of experience with visual frames of reference. Slower rates of presentation with upright number sequences improved recall in both sighted and blind observers. An experiment on tactual-visual braille recognition in the sighted observers showed that tilt degraded pattern identification, but visual guidance of the fingertip and ballpoint minimized this loss. A further experiment was performed to distinguish between visual imagery and visual frame of reference explanations of the visual guidance effect on recognition of rotated braille. Subjects explored upright or tilted braille characters while viewing only a light emitting diode on the exploratory fingertip. Sight of scanning movements did not aid pattern recognition with tilt. The results indicate that the benefits of visual guidance on recognition of tilted patterns were probably due to frame of reference information. It is concluded that spatial reference information may aid tactile memory in the sighted and late blind, since the early blind performed at a lower level in the retention task. It is proposed that visual imagery may only explain the superiority of the sighted and late blind when familiar stimuli are studied.     

Sex of child preferences among college students

In both 1985 and 1988, college student preferences for the sex of an only child were examined using social surveys. For both years, it was found that male students strongly prefer a male child, but that female students moderately prefer a female child. Gender of respondent accounted for most of the sex preference difference. The sex role attitude of agreement with having the wife retain her own name was the only other variable significantly related to sex preference. It is argued that differing male-female role expectations for women as wives and mothers partly explained the gender differences in sex preference for a child.     

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.     

Gender differences in distributive justice preferences: The impact of domain

Past research has found that distributive justice preferences vary markedly both as a function of gender of allocator and the domain in which outcomes or rewards are allocated (e.g., relationships vs. work contexts). This study examined the interaction of these two factors in determining distributive justice preferences. Subjects were asked to fill out two scales designed to assess the degree to which their general distributive preferences in work contexts and in relationships were benevolent (prefer inputs to exceed outcomes), equity sensitive (prefer outcome/input ratios to be equal), or entitled (prefer outcomes to exceed inputs). Results revealed that women's preferences were significantly more benevolent (or less entitled) than men's in work domains, but that men's and women's distributive preferences did not differ significantly in relationships. In addition, both sexes indicated significantly more entitled preferences in work domains than in relationships, but the difference between domains was much greater for men than for women. These results suggest that, when considering issues of justice, men make a greater distinction between domains than do women, and that previously observed gender differences in distributive justice preferences may be specific to the work domain.     

Effects of tilted orientations and face-like configurations on visual search asymmetry in macaques

Visual search asymmetry has been used as an important tool for exploring cognitive mechanisms in humans. Here, we examined visual search asymmetry in two macaques toward two types of stimulus: the orientation of line stimuli and face-like stimuli. In the experiment, the monkeys were required to detect an odd target among numerous uniform distracters. The monkeys detected a tilted-lines target among horizontal- or vertical-lined distracters significantly faster than a horizontal- or vertical-lined target among tilted-lined distracters, regardless of the display size. However, unlike the situation in which inverted-face stimuli were introduced as distracters, this effect was diminished if upright-face stimuli were used as distracters. Additionally, monkeys detected an upright-face target among inverted-face distracters significantly faster than an inverted-face target among upright-face distracters, regardless of the display size. These results demonstrate that macaques can search a target efficiently to detect both tilted lines among non-tilted lines and upright faces among inverted faces. This clarifies that there are several types of visual search asymmetry in macaques.     

The role of gravitational cues in the judgment of visual orientation

It is argued that, contrary to the views of some theorists, the role of gravitational cues is essentially one of maintaining orientation constancy. In support of this claim, it is shown that the loss of relevant gravitational information when the body is supine results in a significant increase in the disorienting effects of both a tilted visual frame and tilt of the head relative to the trunk.     

The role of frame size on vertical and horizontal observers in the rod-and-frame illusion.

The rod-and-frame illusion was used to examine a proposed distinction between the mechanism responsible for frame effects on rod-adjustment errors with large displays and the mechanism responsible for errors with small displays. It was suggested that visual-vestibular mechanisms are involved only when the rod is surrounded by a large tilted frame. Errors in the perceived vertical with small frame would instead be due to purely visual mechanisms. To examine this dual process model, we compared errors at small and large frame when the body was vertical or horizontal. There is evidence to suggest that tilting the body affects visual-vestibular interactions, but there is no reason to expect that body tilt would affect intravisual interactions. Hence, we hypothesized that body tilt would increase errors for large frame, but not for small frame. Eight subjects were tested in four different conditions, corresponding to the combination of two body orientations (vertical versus horizontal) and two frame sizes (47.5 versus 10.5 deg of visual angle). Fourier analysis of data was performed. Repeated measures ANOVA tested the hypothesis about frame size and body orientation. The hypothesis was not confirmed. More specifically, we found that tilting the body increased errors for the small frame as well as for the large frame. The interaction between frame size and body orientation was not significant. Results are discussed in relation to the proposed dual-process model.     

The role of cognitive factors in the rod-and-frame effect

We compared the contribution and the effectiveness of modulating the orientation perception of two types of visual information: the visual frame and the visual polarity of objects. In experiment 1, we examined the effect of a square frame, a mouse, an elephant, and a map of France on the apparent vertical. In the upright position, despite the presence of tilted individual component features, the visual objects had no illusory visual tilt effects. When tilted, these objects had a substantial effect on the direction that appeared to be vertical. However, rod-setting errors were smaller in the inducing objects than when observed with the frame display. In the second experiment, the results of experiment 1 were replicated with a meaningful circular contour--a porthole and a clock. The presence of the external circular contour did not abolish the illusion on the apparent vertical. Moreover, in experiment 3, a clock whose numbers were displaced and not tilted--to avoid the possible tilt influence of visual cues--was also able to deflect the subjective visual vertical. This finding suggests that through top-down processing shapes can act as a framework which serves as a reference influencing the perceived orientation of the inner objects.     

Assessment of the relationship of cerebral hemisphere arousal asymmetry to perceptual asymmetry.

This study examined the hypothesis that characteristic individual differences in cerebral hemisphere arousal asymmetry are related to individual differences in perceptual asymmetry observed in verbally based visual half-field tasks. The study used electrophysiological measures of arousal asymmetry rather than behaviorally derived measures (Levy, Heller, Banich, & Burton, 1983). Measures of alpha asymmetry were obtained from 20 right-handed males during a baseline relaxation condition and during a visual half-field version of the lexical decision task. Reaction time measures of perceptual asymmetry were obtained during this task. The results indicated that a basal arousal asymmetry measured at the temporal recording location during the baseline condition was significantly related to individual perceptual asymmetry during the subsequent lexical decision task. This basal arousal asymmetry was relatively stable across different task conditions. A task-related arousal asymmetry measured at the parietal location during the lexical decision task also made a significant contribution in predicting individual perceptual asymmetry. These two measures of individual arousal asymmetry were able to predict 50% of the variance in perceptual asymmetry. The implications of the results for explaining more wide-ranging individual differences in behavioral style and personality are discussed.     

Perceptual differentiation of sequential visual patterns

The aftereffects of viewing diagonal lines for 50, 500, and 1,000 msec were measured by the speed and accuracy of identification of a variably tilted test grating. Significant RT and tilt aftereffects were found as functions of the duration of orientation-specific adaptation and the angle of separation between inspection and test lines. The results throw light on anchoring effects of the main visual coordinates and support a structural interpretation of orientational selectivity in human vision.     

Exposure-time and spatial-frequency effects in the tilt illusion

The exposure durations of a vertical test line and a tilted inducing grating were varied and the tilt illusion thus generated was found to change as a function of this variation. Significant direct effects (acute-angle expansion) and indirect effects (acute-angle contraction) were found to occur at times consistent with Andrew's estimate of the time course of inhibition in the visual system when the inducing grating had a spatial frequency of 10 cycles deg-1. However, a 2.71 cycles deg-1 grating gave significant effects at exposure durations of 10 as well as 1000 ms, while in a further experiment a 10.91 cycles deg-1 grating gave significant effects at 1000 ms only. These results seem to suggest that orientation interactions thought to be due to inhibition (direct effect) and disinhibition (indirect effect) may occur within both sustained and transient channels with concomitant differences in time constants.     

Additivity in adaptation to optical tilt

Tests of proprioceptive adaptation (head-hand), visual adaptation (eye-head), and both components (eye-hand) were made during 15-min exposure to 20 degrees tilt in two experiments. In both experiments, subjects alternated exposures in which they explored hallways (hall) or viewed their active hand (hand), but in Experiment 2 subjects received two exposures to each condition, while in Experiment 1 only one exposure was given. Hall exposure produced greater visual change, and hand exposure produced greater proprioceptive change; but in both conditions, when order of conditions was controlled, the sum of performance on visual and proprioceptive tests was not statistically different from performance on the common test. In Experiment 2, adaptive components appeared to be inversely related, both within and between exposure conditions, thus providing some evidence of a reciprocal relationship, but a reliable negative correlation between components was not found. Finally, adaptation increased over alternation-repetition of exposure tasks in the second experiment, even though adaptation appeared limited within any given exposure. Results are interpreted in terms of the linear model, and the possible role of attentional factors in processing sensory inconsistencies is discussed.     

Testing the tilt-constancy theory of visual illusions

Prinzmetal and Beck (2001) Journal of Experimental Psychology: Human Perception and Performance 27 206 - 217) argued that a subset of visual illusions is caused by the same mechanisms that are responsible for the perception of vertical and horizontal a theory they referred to as the tilt-constancy theory of visual illusions. They argued that these illusions should increase if the observer's head or head and body are tilted because extra reliance would then be placed on the illusion-inducing local visual context. Exactly that result had previously been reported in the case of the tilted-room and the rod-and-frame illusions. Prinzmetal and Beck reported similar increases in the tilt illusion (TI), as well as the Z?llner, Poggendorff, and Ponzo illusions. In two experiments, we re-examined the effect of head tilt on the TI. In experiment 1, we used more conventional TI stimuli, more standard experimental methods, and a more complete experimental design than Prinzmetal and Beck, and additionally extended the investigation to attraction as well as repulsion effects. Experiment 2 more closely replicated the Prinzmetal and Beck stimuli. Although we found that head tilt did increase TIs in both experiments, the increases were of the order of 1 degrees -2 degrees, more modest than the 7 degrees reported by Prinzmetal and Beck. Significantly, the TI increase was larger when inducing tilts and head tilts were in the same direction than when they were in opposite directions, suggesting that the tilt-constancy theory may be oversimplified. In addition, because previous evidence renders unlikely the claim that the Poggendorff illusion can be explained simply in terms of misperceived orientation of the transversals, the question arises whether there might be some other explanation for the increase in the Z?llner, Poggendorff, and Ponzo illusions with body tilt that Prinzmetal and Beck reported.