1,720,985 research outputs found
Surface organisation influences bistable vision
No full textA priority for the visual system is to construct 3-dimensional surfaces from visual primitives. Information is combined across individual cues to form a robust representation of the external world. Here, it is shown that surface completion relying on multiple visual cues influences relative dominance during binocular rivalry. The shape of a surface determined by 1 nonrivalrous visual cue (disparity, structure-from-motion) alters the dominance patterns of a rivalrous region of the image whose shape is defined by another cue (perspective, texture). The findings indicate that contextual information promotes the perception of the member of the rivalrous pair consistent with a smooth surface representation. The results extend the current description of binocular rivalry as a hierarchical process by implying that cue combination affects image selection during bistable viewing
Motion-aftereffect-induced blindness
No full textMotion-induced blindness (MIB) describes the occasional disappearance of salient visual objects in the presence of moving features (Y. S. Bonneh, A. Cooperman, & D. Sagi, 2001). Here we test whether motion adaptation and the ensuing motion aftereffect (MAE) are sufficient to trigger disappearance of salient targets. In three experiments, observers adapted to either rotating or static stimuli. Immediately afterwards, a static test pattern was presented consisting of a mask with texture elements and three superimposed target dots in a triangular arrangement. Observers reported dot disappearance and reappearance. The results clearly show that illusory motion in a static test pattern, following motion adaptation, promotes the disappearance of target dots. Furthermore, disappearance is modulated by the depth relationship between test pattern and targets, increasing for targets placed stereoscopically behind the test pattern. We conclude that MIB is influenced by perceived relative motion between depth-segregated feature
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Autonomic arousal and attentional orienting to visual threat are predicted by awareness
Full text linkThe rapid detection and evaluation of threat is of fundamental importance for survival. Theories suggest that this evolutionary pressure has driven functional adaptations in a specialized visual pathway that evaluates threat independently of conscious awareness. This is supported by evidence that threat-relevant stimuli rendered invisible by backward masking can induce physiological fear responses and modulate spatial attention. The validity of these findings has since been questioned by research using stringent, objective measures of awareness. Here, we use a modified continuous flash suppression paradigm to ask whether threatening images induce adaptive changes in autonomic arousal, attention, or perception when presented outside of awareness. In trials where stimuli broke suppression to become visible, threatening stimuli induced a significantly larger skin conductance response than nonthreatening stimuli and attracted spatial attention over scrambled images. However, these effects were eliminated in trials where observers were unaware of the stimuli. In addition, concurrent behavioral data provided no evidence that threatening images gained prioritized access to awareness. Taken together, our data suggest that the evaluation and spatial detection of visual threat are predicted by awareness
An Assay to Determine the Level of Glyburide in Human Serum
No full textiv, 23 p.Glyburide Micronase, is an orally active sulfonylurea used in the control of maturity onset diabetes, for which FDA marketing approval is pending. A rapid, specific, and sensitive assay procedure capable of measuring intact glyburide in blood level amounts is desirable. This method would facilitate monitoring clinical blood levels and pharmacological studies. Because of the potency of the drug only a low therapeutic dosage is necessary (2.5-10 mg). The low dosage requires an analytical procedure sensitive to the lower nanogram/ml range. During the S.I.P. quarter, the author worked on such an assay under the direction of W. J. Adams, Ph.D., at The Upjohn Company, Kalamazoo, Michigan. Using a few extractions and high performance liquid chromatographic apparatus, the author could detect a lower limit of 4 ng glyburide/ml serum. This procedure is fairly fast, sensitive, specific and has the potential of clinical applications.Upjohn Company, Kalamazoo, M
Modification of the convexity prior but not the light-from-above prior in visual search with shaded objects
No full textStudies of visual search performance with shaded stimuli, in which the target is rotated by 180º relative to the distracters, typically demonstrate more efficient performance in stimuli with vertical compared to horizontal shading gradients. In addition, performance is usually better for vertically shaded stimuli with top-light (seen as convex) distracters compared to those with bottom-light (seen as concave) distracters. These findings have been cited as evidence for the use of the prior assumptions of overhead lighting and convexity in the interpretation of shaded stimuli and suggest that these priors affect preattentive processing. Here we attempt to modify these priors by providing observers with visual-haptic training in an environment inconsistent with their priors. Observers’ performance was measured in a visual search task and a shape judgement task before and after training. Following training we found a reduced asymmetry between visual search performance with convex and concave distracters, suggesting a modification of the convexity prior. However, although evidence of a change in the light-from-above prior was found in the shape judgement task, no change was found in the visual search task. We conclude that experience can modify the convexity prior at a preattentive stage in processing, however our training did not modify the light-from-above prior that is measured via visual search
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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High-level face adaptation without awareness
No full textWhen a visual stimulus is suppressed from awareness, processing of the suppressed image is necessarily reduced. Although adaptation to simple image properties such as orientation still occurs, adaptation to high-level properties such as face identity is eliminated. Here we show that emotional facial expression continues to be processed even under complete suppression, as indexed by substantial face expression after effects
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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