On homogeneous retinal stimulation and the perception of depth.

A review of recent experiments showing that where the perception of voluminous fog does not occur consistently under conditions attempting homogeneity of visual stimulation, there are sources of inhomogeneity which can produce the impression of a surface. As homogeneity is approached, the volume experience becomes more reliable. A view of this phenomenon, other than Gibson's—which does not deal with it on the grounds of poor reliability—or Koffka's—which attributes it to the fundamental nature of the perceptual system, is presented. It is based on kinesthetic stimulation as a likely source of visual space anisotropy with respect to perceived distance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric asymmetries for global and local visual perception: Effects of stimulus and task factors.

Although neurological and physiological studies indicate a right hemisphere superiority in global processing and a left hemisphere superiority in local processing of Navon-type hierarchical letters (D. Navon, 1977), most investigations of lateralized perception in healthy participants report neither asymmetry. In 6 experiments the authors examined the influence of attentional demands, stimulus properties, and mode of response on perceptual asymmetries for global and local perception. Consistent with their theoretical predictions, asymmetries were more robust on divided- than focused-attention tasks and in response to stimuli in which local and global levels were equally salient compared with those with greater global than local saliency. Contrary to their prediction, perceptual asymmetries were not influenced by the complexity of the motor response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of object onset on the distribution of visual attention.

There now exists considerable evidence to suggest that the appearance of a new object in the visual field captures visual attention. One of the consequences of this attentional capture is that the object initiates a redistribution of attentional resources across visual space. This is classically observed in the precuing paradigm in which the onset of an abrupt cue influences the processing of a subsequently presented target. The present research describes a new phenomenon that occurs as a result of a new object appearing in the visual field. A stimulus presented in a region of space adjacent to a comer of an onsetting object receives an enhancement of processing relative to a stimulus presented adjacent to one of the object's straight edges. With the use of 2 converging methods, evidence is presented that suggests that the effect is a higher order attentional phenomenon whereby greater resources become directed to the comers of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of selective attention in the perception of multiple-element stimulus arrays.

To access the role of attention in visual processing, we have recorded single-unit activity from area V4 of visual cortex in macaque monkeys, and the results of these experiments provide a clear demonstration of the relationship between inter-stimulus competition and attention. Specifically, attended stimuli elicit larger responses than ignored stimuli, and these attention effects are increased when: a) the total number of distracting stimuli is increased; b) both attended and ignored stimuli are located inside the neuron's receptive field; and c) the attended and ignored stimuli are presented simultaneously rather than sequentially. We have also examined the role of inter-stimulus competition in human subjects by recording event-related potentials (ERPs), which are electrophysiological responses that can be recorded noninvasively from the scalp. In these experiments, we have found that the attention-sensitive N2pc wave is present when subjects focus attention onto target stimuli when they are surrounded by competing distractor stimuli, but is absent when the competition is eliminated (e.g. by removing the distractors). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An examination of visual acuity and depth perception as a function of magnification.

The effectiveness of magnification, (comparing binoculars of three powers, 6 X, 7 X, 10 X, with unaided vision) as an aid to ordnance optics was studied under desert conditions. Visual acuity was studied with a modified Landolt ring display, depth perception with method of constant stimuli in which a movable target had to be aligned with a stationary target. Visual acuity at a range of 100 yards was significantly better with binoculars than with the unaided eye, but there was no significant difference among the binoculars. For depth perception, sensitivity was independent of magnification and nearly independent of range. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A reappraisal of the roles of past experience and innate organizing processes in visual perception.

This paper is an attempt to evaluate the controversy existing between those theories which emphasize the role of learning on perception and the theory which emphasizes the role of innate organizing processes on perception. The writers conclude "that various aspects of the phenomenal world and, in particular, the segregation and shape of visual forms are given by innate organizing processes. Percepts may be modified and enriched by experimental factors but the effects of such factors presuppose the prior existence of visual forms." 82 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and perception of visual form from temporal structure.

In this study, the authors examined age-related changes in participants' ability to perceive global spatial structure defined by temporal fine structure among elements undergoing rapid, irregular change. Participants were also tested on a task involving form recognition from luminance contrast and on a task dependent on perception of 3-dimensional shape from motion. Compared with young adults, older individuals were less sensitive to spatial form defined by temporal structure. In contrast, older observers performed as well as young adults on the other two tasks that were not dependent on temporal sensitivity, ruling out nonsensory factors as the cause of the deficits on the temporal structure task. This selective deficit may reveal reduced sensitivity within the temporal impulse response of the aging visual system, a deficit that could be related to reduced effectiveness of neural inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychosexual conflicts and defenses in visual perception.

Tachistoscopically presented stimulus material (Blacky pictures) is used to study perceptual defense and vigilance in persons with different psychosexual conflict dimensions and ego-defense preferences. It is hypothesized that when stimulus material is presented below the threshold of conscious recognition, perceptually vigilant behavior will be evoked under conditions where ego-defense mechanisms are not likely to operate, and perceptually defensive behavior will be evoked where ego-defense mechanisms are likely to operate. The vigilance and defense hypotheses are confirmed by the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemiface contributions to hemispheric dominance in visual speech perception.

Lateralized displays are used widely to investigate hemispheric asymmetry in language perception. However, few studies have used lateralized displays to investigate hemispheric asymmetry in visual speech perception, and those that have yielded mixed results. This issue was investigated in the current study by presenting visual speech to either the left hemisphere (LH) or the right hemisphere (RH) using the face as recorded (normal), a mirror image of the normal face (reversed), and chimeric displays constructed by duplicating and reversing just one hemiface (left or right) to form symmetrical images (left-duplicated, right-duplicated). The projection of displays to each hemisphere was controlled precisely by an automated eye-tracking technique. Visual speech perception showed the same, clear LH advantage for normal and reversed displays, a greater LH advantage for right-duplicated displays, and no hemispheric difference for left-duplicated displays. Of particular note is that perception of LH displays was affected greatly by the presence of right-hemiface information, whereas perception of RH displays was unaffected by changes in hemiface content. Thus, when investigated under precise viewing conditions, the indications are not only that the dominant processes of visual speech perception are located in the LH but that these processes are uniquely sensitive to right-hemiface information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation between location and shape in visual space.

There are often large perceptual distortions of shapes lying on the ground plane, even in well-lit environments. These distortions occur under conditions for which the perception of location is accurate. Four hypotheses are considered for reconciling these seemingly paradoxical results, after which 2 experiments are reported that lend further support to 1 of them-that perception of shape and perception of location are sometimes dissociable. The 2 experiments show that whereas perception of location does not depend on whether viewing is monocular or binocular (when other distance cues are abundant), perception of shape becomes more veridical when viewing is binocular. This means that perception of shape is not fully constrained by the perceived locations of the vertices that define the shape. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory enhances visual perception: Evidence from signal detection analysis.

We show that perceptual sensitivity to visual stimuli can be modulated by matches between the contents of working memory (WM) and stimuli in the visual field. Observers were presented with an object cue (to hold in WM or to merely attend) and subsequently had to identify a brief target presented within a colored shape. The cue could be re-presented in the display, where it surrounded either the target (on valid trials) or a distractor (on invalid trials). Perceptual identification of the target, as indexed by A′, was enhanced on valid relative to invalid trials but only when the cue was kept in WM. There was minimal effect of the cue when it was merely attended and not kept in WM. Verbal cues were as effective as visual cues at modulating perceptual identification, and the effects were independent of the effects of target saliency. Matches to the contents of WM influenced perceptual sensitivity even under conditions that minimized competition for selecting the target. WM cues were also effective when targets were less likely to fall in a repeated WM stimulus than in other stimuli in the search display. There were no effects of WM on decisional criteria, in contrast to sensitivity. The findings suggest that reentrant feedback from WM can affect early stages of perceptual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in reaction to meprobamate: A study in visual perception.

An investigation of the effect of meprobamate upon reactions to Necker Cube, Retinal Rivalry, Archimedes Spiral, and Peripheral Span on 68 college-age males, divided equally between drug and placebo conditions by the doubleblind method. No significant relationship appeared between the Maudsley Personality Inventory Extraversion scale and the test scores, nor between the tests themselves, with exception of cube and rivalry (r = + .35, p     

Stimulus pooling and social perception.

"The effects of stimulus pooling on judgments of personal attractiveness were investigated in an orthogonal factorial design, using as stimulus components identification type photographs which had been previously scaled on attractiveness… . The implications of the findings for (a) social perception… and (b) group judgment were considered." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directly perceiving Gibson: A further reply to Gyr.

In his 1972 critique of direct theories of perception, J. W. Gyr argued from the view that Gibson believes (a) that stimulus structure can determine perception and (b) that perceiving as a consequence of voluntary activity is virtually the same as perception that is not a consequence of voluntary activity. Since neither of these assumptions is found in Gibson's approach, Gyr's criticisms do not seem to apply. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction to the special issue on object perception and scene analysis.

Work in psychophysics, neuroscience, and visual perception has led to significant recent advances in our understanding of the human visual system. The articles in this special issue represent diverse approaches to the study of visual perception and highlight some of these recent advances, as applied to issues involved in understanding object perception and scene analysis. The special issue grew out of a workshop on object and scene perception held in September 1990 at the University of Leuven. The intent of the original workshop and of the collection of articles in this issue is to bring together the work of researchers using widely differing techniques and theoretical frameworks, and to apply recent results to the issues surrounding object and scene perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

See what you want to see: Motivational influences on visual perception.

People's motivational states--their wishes and preferences--influence their processing of visual stimuli. In 5 studies, participants shown an ambiguous figure (e.g., one that could be seen either as the letter B or the number 13) tended to report seeing the interpretation that assigned them to outcomes they favored. This finding was affirmed by unobtrusive and implicit measures of perception (e.g., eye tracking, lexical decision tasks) and by experimental procedures demonstrating that participants were aware only of the single (usually favored) interpretation they saw at the time they viewed the stimulus. These studies suggest that the impact of motivation on information processing extends down into preconscious processing of stimuli in the visual environment and thus guides what the visual system presents to conscious awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental investigation of subliminal perception.

Does subliminal perception really work? 2 groups of Ss enrolled in a sales and advertising class at Purdue University were used as a control group and an experimental group. A film and a questionnaire were used. The chi square technique was used in comparing the experimental and control group data. "If subliminal perception occurred, it did not affect questionnaire responses… . The burden of proof is placed on those who insist that subliminal perception is capable of influencing behavior." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation effects in visual object perception: Recent results that will make your mind spin!

The time needed to identify objects from two-dimensional depictions can be affected sharply by the orientation of the depicted object. Although it is suspected that the magnitude of orientation effects on identification from drawings ought to depend on various characteristics of the objects and of the depictions, almost nothing is known about these relationships. Work in progress in my laboratory is designed to discover which characteristics of objects and depictions lead to large or small effects of orientation and which lead to peaked functions versus dipped functions. The results are summarized in this article. Overall, the results suggest that orientation effects take place at a perceptual stage of processing that is distinct from subsequent stages involved in retrieving a name and producing a response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An analysis of cues to auditory depth perception in free space.

Physical acoustics reveals a number of stimulus correlates of sound source distance. Quantitative estimates of these stimulus correlates are compared with appropriate psychophysical thesholds. Such comparisons show that most of these stimulus correlates can, with various restrictions, provide distance information detectable by the ear(s). The stimulus correlates dealt with at greatest length are: intensity, frequency spectrum at near and far distances, binaural intensity ratio, and interaural phase (or time) differences. Problems relating to the use of some of these stimulus correlates as cues are discussed. Other possible distance cues are briefly mentioned. The possible use of much of the available physical information in making distance judgments has not yet been adequately evaluated in psychophysical studies. (48 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subliminal perception: Some negative findings.

"Sixty female undergraduates served as Ss in a study designed to investigate subliminal perception. Speed of stimulus presentation and knowledge of results were varied in a three by two factorial design. No evidence of subliminal perception was obtained. Implications of these findings were discussed." (PsycINFO Database Record (c) 2010 APA, all rights reserved)