Perception of circular heading from optical flow

Observers viewed random-dot optical flow displays that simulated self-motion on a circular path and judged whether they would pass to the right or left of a target at 16 m. Two dots in two frames are theoretically sufficient to specify circular heading if the orientation of the rotation axis is known. Heading accuracies were better than 1.5 degrees with a ground surface, wall surface, and 3D cloud of dots, and were constant over densities down to 2 dots, consistent with the theory. However, there was an inverse relation between the radius of the observer's path and constant heading error, such that at small radii observers reported heading 3 degrees to the outside of the actual path with the ground and to the inside with the wall and cloud. This may be an artifact of a small display screen.     

Perception of voicing and place features in whispered speech: A dichotic choice analysis

To offset shortcomings of existing demonstrations of right-ear superiority in the analysis of formant transitions, an experiment was performed on whispered speech. Two aspects of dichotic listening performance were examined in a single-report paradigm: the right-ear advantage (REA) for the perception of the voicing distinction and the feature sharing advantage (FSA) for both voicing and place features. A significant REA was obtained for the voicing distinction cued by first formant transition in the absence of a switch from aperiodic to periodic excitation. This, plus a greater incidence of voiced responses to right-ear stimuli, suggests that a distinction involving transitions can specifically augment the REA. The data also showed better identification of place and of voicing feature values when the competing dichotic speech stimuli shared these respective features (FSA) than when they did not. This FSA was restricted to the feature shared and hence not an effect of response uncertainty. The implications of these results for models of speech processing are discussed.     

Perception of signals presented in the periphery of the visual field

Two experiments were performed which tested the type of information that can be extracted from the periphery of the visual field, i.e. content information or position information. In both studies two digits were compared, one presented at the left and one at the right of the subject's meridian, seperated by a binocular visual angle, comprising either an eye-field (45°) or a head-field display (100°). In the first experiment the right signal was presented in separate blocks of either degraded or undegraded digits. In the case of undegraded digits, processing efficiency was better in the eye-field than in the head-field. With degraded digits this eye-field advantage was significantly smaller, but did not altogether disappear, suggesting that information about both the content and the position of digits in the periphery is acquired in the eye-field as opposed to the head-field. In the second experiment degraded and undegraded digits occured randomly within the same block of trials. This was done to investigate whether peripheral information is acquired automatically or through controlled processing. The results indicate a small eye-field advantage, about equal for both degraded and undegraded digits. This supports the controlled processing hypothesis, at least with regard to the acquisition of content information from the periphery.     

Psychophysics in the field: Perception and memory for labor pain

Separate groups of women estimated the painfulness of labor contractions either immediately (perceptual judgments) or at time intervals varying from 8 to 48 h after their completion (memorial judgments). The pain judgments of individual uterine contractions were related functionally to the biometrically measured magnitude of these contractions. Perceived and remembered painful sensations were related to referent intensities by power functions governed, as a rule, by exponents greater than unity. Exponents for the memory functions were consistently greater than those for the perceptual functions. Psychophysics done in the field can help decide theoretical issues in addition to providing useful practical information.     

Grey is a place

Reprinted from the Harvard Library Bulletin, Volume X, Number I (Winter 1936) by permission. © 1956 The President and Fellows of Harvard College.     

Multiple points of entry into a circular enclosure prevent place learning despite normal vestibular orientation and cue arrays: evidence for map resetting

This study identified sources of map orientation critical for successful spatial problem solving by rats of a plus maze embedded in water. Disorientation slowed, but it did not prevent acquisition of goal location. Use of a circular enclosure with multiple points of entry prevented reliable goal location. A single entry point enabled the rats to locate a fixed goal. A cue array within the enclosure was ineffective in providing orientation. These data suggest that stable map orientation can be derived from entry location when enclosure geometry is uniformative, but is not readily taken from cue arrays. They further suggest that map orientation is reset when rats enter an enclosure.     

Perception without awareness in a dichoptic viewing situation

One way of investigating perception without awareness is to utilize the phenomenon of binocular rivalry. The dichoptic viewing situation can be so arranged that a stimulus may be above identification level (when presented alone) but masked by contiguous stimulation, i.e. a brighter image to the other eye. This experimental situation was used to replicate an experiment of Smith et al. (1959) which claimed to demonstrate that differences in meaning between words registered below recognition threshold could affect associated conscious thoughts. In the two experiments reported here, a neutral face was paired with affect words presented subliminally and subjects were asked to rate its expression using a forced-choice indicator. Additional controls to those of Smith et al. were used. In Expt. I it was established that words presented outside of awareness had an effect on semantically related judgements, which was at least as great as that with the same words presented supraliminally. In Expt. II this was confirmed and it was found that increasing the similarity of contour between critical and control words of different meaning suggested differences between subliminal and supraliminal sessions. Responses tended to be meaning-related in the former and structure-related in the latter. It was suggested that the experiments have relevance to current theories of selective attention.     

Creating a safe place for growth in supervision

When people are afraid, learning is inhibited. In too many disturbed families, institutional settings, rigid organizations, and some supervision groups, a feeling of emotional safety is missing. The first step in teaching, supervising, or therapy is the necessity to provide a safe environment. The author suggests a model applicable to any supervision group, work group, organization, classroom, or family. A group model, specifically applied to the relationship between family therapy students or interns and supervisors, suggests ways to enhance growth by minimizing fear.     

Towards the Realistic Perception of a Culture

Four objective, measurable criteria are proposed to measure the position of a culture relative to other cultures. The use of such criteria will avoid, in part, distortions of perception. While this is an initial step toward the realistic perception of a culture, it has many limitations that are discussed at the end of the paper.     

An analysis of response,direction, and place learning in an open field and T maze

Rats were trained to locate food in a response, direction, or place problem on an open field located at 2 positions. In Experiment 1, both the response and direction groups solved the problem. The place group failed to solve the task in approximately 300 trials. Experiment 2 demonstrated that rats need distinguishable start points to solve a place problem when neither a response nor a direction solution is available. Findings from Experiment 3 suggest that a combination of path traveled and distinct cues help to differentiate start points. Experiment 4 replicated the findings using a T maze. These results suggest "place" solutions are difficult for rats. The data are discussed with respect to conditional learning and modern spatial mapping theory.     

Perception in chess

This paper develops a technique for isolating and studying the perceptual structures that chess players perceive. Three chess players of varying strength — from master to novice — were confronted with two tasks: (1) A perception task, where the player reproduces a chess position in plain view, and (2) de Groot's (1965) short-term recall task, where the player reproduces a chess position after viewing it for 5 sec. The successive glances at the position in the perceptual task and long pauses in the memory task were used to segment the structures in the reconstruction protocol. The size and nature of these structures were then analyzed as a function of chess skill.     

Perception of visual illusions in a sample of Nigerian children

This study examined the effects of cultural factors on perception of 15 boys and 21 girls in Nigeria. The five geometric illusions of Segall, Campbell, and Herskovitz were shown in booklets. Previously tested Afghan boys gave evidence of greater illusion than the Nigerian children. The findings also supported previous research on perception of illusion.