Sound enhances visual perception: cross-modal effects of auditory organization on vision

Six experiments demonstrated cross-modal influences from the auditory modality on the visual modality at an early level of perceptual organization. Participants had to detect a visual target in a rapidly changing sequence of visual distractors. A high tone embedded in a sequence of low tones improved detection of a synchronously presented visual target (Experiment 1), but the effect disappeared when the high tone was presented before the target (Experiment 2). Rhythmically based or order-based anticipation was unlikely to account for the effect because the improvement was unaffected by whether there was jitter (Experiment 3) or a random number of distractors between successive targets (Experiment 4). The facilitatory effect was greatly reduced when the tone was less abrupt and part of a melody (Experiments 5 and 6). These results show that perceptual organization in the auditory modality can have an effect on perceptibility in the visual modality.     

A visual display system for reading and visual perception research

The selection of a computer visual display system suitable for word recognition and reading research is described. The software character generation routines permit flexible definition of character sets. The display software permits control of size scaling and point density of characters being displayed as well as control over the temporal microstructure of presenting and refreshing the displayed text.     

The visual perception of velocity

Summary In this section it is concluded that velocity is perceived directly and is dynamically conditioned by the structure and general properties of the visual field in which the movement occurs. The visual perception of velocity follows dynamic laws that are not immediately deducible from the velocity of the stimulus as physically defined. No physiological theory is offered but it is pointed out that the theory of physiological Gestalten is essentially correct in its basic assumptions concerning the perception of movement.The investigation has bearing on the problems of movement thresholds, movement after-images and the perception of time.This paper is abridged from a thesis presented to the faculty of the graduate school of Yale University in partial fulfilment of the requirements for the degree of Doctor of Philosophy. The study was started in the Psychological Institute of the University of Berlin in 1926–1927 and completed at Yale University in 1928–1929. The work at Berlin, which has been already reported [cf. J. F. Brown, Über gesehene Geschwindigkeit. Psychol. Forschg 10, 84–101 (1927)] was largely exploratory in nature; that at Yale was undertaken to fill the gaps in the experimental series and to control more completely the causal factors. For clarity of exposition the previously reported data are included here so far as necessary. The writer is indebted to Professor W. Köhler of the University of Berlin for suggesting the problem, and to Professors R. P. Angier, R. Dodge, and L. T. Spencer of Yale University for many valuable suggestions. He wishes also to express his thanks to the subjects who served in the experiments.     

The limits of visual mass perception

The theory of direct perception suggests that observers can accurately judge the mass of a box picked up by a lifter shown in a point-light display. However, accurate perceptual performance may be limited to specific circumstances. The purpose of the present study was to systematically examine the factors that determine perception of mass, including display type, lifting speed, response type, and lifter's strength. In contrast to previous research, a wider range of viewing manipulations of point-light display conditions was investigated. In Experiment 1, we first created a circumstance where observers could accurately judge lifts of five box masses performed by a lifter of average strength. In Experiments 2–5, we manipulated the spatial and temporal aspects of the lift, the judgement type, and lifter's strength, respectively. Results showed that mass judgement gets worse whenever the context deviates from ideal conditions, such as when only the lifted object was shown, when video play speed was changed, or when lifters of different strength performed the same task. In conclusion, observers' perception of kinetic properties is compromised whenever viewing conditions are not ideal.     

The visual perception of 3D shape

A fundamental problem for the visual perception of 3D shape is that patterns of optical stimulation are inherently ambiguous. Recent mathematical analyses have shown, however, that these ambiguities can be highly constrained, so that many aspects of 3D structure are uniquely specified even though others might be underdetermined. Empirical results with human observers reveal a similar pattern of performance. Judgments about 3D shape are often systematically distorted relative to the actual structure of an observed scene, but these distortions are typically constrained to a limited class of transformations. These findings suggest that the perceptual representation of 3D shape involves a relatively abstract data structure that is based primarily on qualitative properties that can be reliably determined from visual information.     

The visual perception of distance ratios outdoors

We conducted an experiment to evaluate the ability of 32 younger and older adults to visually perceive distances in an outdoor setting. On any given trial, the observers viewed 2 environmental distances and were required to estimate the distance ratio—the length of the (usually) larger distance relative to that of the shorter. The stimulus distance ratios ranged from 1.0 (the stimulus distances were identical) to 8.0 (1 distance interval was 8.0 times longer than the other). The stimulus distances were presented within a 26 m × 60 m portion of a grassy field. The observers were able to reliably estimate the stimulus distance ratios: The overall Pearson r correlation coefficient relating the judged and actual distance ratios was 0.762. Fifty-eight percent of the variance in the observers’ perceived distance ratios could thus be accounted for by variations in the actual stimulus ratios. About half of the observers significantly underestimated the distance ratios, while the judgments of the remainder were essentially accurate. Significant modulatory effects of sex and age occurred, such that the male observers’ judgments were the most precise, while those of the older males were the most accurate.     

The development of separability in visual perception

Under conditions that do not allow focused attention, reports of illusory conjunctions (i.e. errors that wrongly recombine the features of different objects) constitute evidence of the separate registering of features at an early processing level. The occurrence of illusory conjunctions was used to determine whether there is preattentive analysis of component dimensions (colour and form) and of parts of shapes (triangles and arrows) in young children aged 5 to 8 years. Evidence of preattentive analysis was found, even for the youngest children, for colour and form but not for parts of shapes. Although developmental effects hardly reached significance, inspection of abilities assumed to affect the illusory conjunctions phenomenon suggests that at the preattentive stage children can integrate spatially separate segments but lack the capacity to fully analyse connected segments.     

The dynamic-stimulus advantage of visual symmetry perception

It has been speculated that visual symmetry perception from dynamic stimuli involves mechanisms different from those for static stimuli. However, previous studies found no evidence that dynamic stimuli lead to active temporal processing and improve symmetry detection. In this study, four psychophysical experiments investigated temporal processing in symmetry perception using both dynamic and static stimulus presentations of dot patterns. In Experiment 1, rapid successive presentations of symmetric patterns (e.g., 16 patterns per 853 ms) produced more accurate discrimination of orientations of symmetry axes than static stimuli (single pattern presented through 853 ms). In Experiments 2-4, we confirmed that the dynamic-stimulus advantage depended upon presentation of a large number of unique patterns within a brief period (853 ms) in the dynamic conditions. Evidently, human vision takes advantage of temporal processing for symmetry perception from dynamic stimuli.     

Visual memory and visual perception: when memory improves visual search

This study examined the relationship between memory and perception in order to identify the influence of a memory dimension in perceptual processing. Our aim was to determine whether the variation of typical size between items (i.e., the size in real life) affects visual search. In two experiments, the congruency between typical size difference and perceptual size difference was manipulated in a visual search task. We observed that congruency between the typical and perceptual size differences decreased reaction times in the visual search (Exp. 1), and noncongruency between these two differences increased reaction times in the visual search (Exp. 2). We argue that these results highlight that memory and perception share some resources and reveal the intervention of typical size difference on the computation of the perceptual size difference.     

The size illusion: visual and kinaesthetic information in size perception

Earlier studies have shown the size of kinaesthetically presented two-dimensional movement patterns to be significantly overestimated. Whether this size overestimation is characteristic of the kinaesthetic system alone has not been established. Two experiments are reported which were designed to investigate size judgment made after kinaesthetic and visual pattern presentation and the effect of environmental cues on the perception of movement patterns. In experiment 1 patterns were presented kinaesthetically (experimenter guided hand movements around the outline of the pattern) or in combination with visual information given by a moving light (pinpoint light attached to the stylus which was moved around the pattern); visual and kinaesthetic cues were either congruent or conflicting with each other; and environmental cues were either present or absent. In experiment 2 static visual display was compared with visually traced pattern presentation, again with or without environmental cues. Overall the results showed that, regardless of experimental manipulation, in all cases where the information was given over time the subject perceived the pattern larger than reality. After static visual display, overestimation of size did not occur.     

Hazard perception performance and visual scanning behaviours: The effect of sleepiness

Driver sleepiness accounts for a substantial proportion of crashes in Australia and Worldwide. Young adults are overrepresented in sleep-related crashes and are more susceptible to sleepiness, resulting in impaired attention and driving performance. Visual scanning behaviour can affect the role between attention and information acquisition from the driver's environment. Thus, if attention is impaired, visual scanning behaviours are likely to show decrements as well. Overall, 32 young adults aged between 20 and 25 years completed a 60-minute hazard perception task to examine the effect of sleepiness and time-on-task on hazard perception performance, visual scanning behaviours, subjective sleepiness scores, and psychomotor vigilance test performance. The main outcomes include decrements in hazard perception performance and a restriction in horizontal and vertical eye scanning ranges across the 60-minute session, but with a more pronounced effect when sleep-restricted. These outcomes were consistent with increases in subjective sleepiness and behavioural metrics of sleepiness assessed via the PVT. Reductions in scanning range could limit opportunities to attend to hazards and other critical safety events. The current study outcomes provide an important contribution regarding the risks associated with sleepy driving performance.     

The visual and haptic perception of natural object shape

In this study, we evaluated observers' ability to compare naturally shaped three-dimensional (3-D) objects, using their senses of vision and touch. In one experiment, the observers haptically manipulated 1 object and then indicated which of 12 visible objects possessed the same shape. In the second experiment, pairs of objects were presented, and the observers indicated whether their 3-D shape was the same or different. The 2 objects were presented either unimodally (vision-vision or haptic-haptic) or cross-modally (vision-haptic or haptic-vision). In both experiments, the observers were able to compare 3-D shape across modalities with reasonably high levels of accuracy. In Experiment 1, for example, the observers' matching performance rose to 72% correct (chance performance was 8.3%) after five experimental sessions. In Experiment 2, small (but significant) differences in performance were obtained between the unimodal vision-vision condition and the two cross-modal conditions. Taken together, the results suggest that vision and touch have functionally overlapping, but not necessarily equivalent, representations of 3-D shape.