Low vision rehabilitation is rapidly growing as a specialty practice for occupational therapists. This growth requires practical, evidence-based information on the evaluation and treatment of the ...effects of low vision on occupational performance. Responding to this need, Low Vision Rehabilitation: A Practical Guide for Occupational Therapists blends standards of practice that have been developed over 50 years by low vision therapists and optometrists, with the latest scientific research and the unique perspective of occupational therapists. Low Vision Rehabilitation presents an emerging model in which occupational therapists practice as part of a team of vision rehabilitation professionals serving adults with low vision. Occupational therapists offer a unique contribution to the vision rehabilitation team, with a focus on meaningful occupational goals, the incorporation of occupation into therapy, and the orchestration of environmental, social, and non-visual personal factors into a treatment plan. Mitchell Scheiman, Maxine Scheiman, and Stephen Whittaker have developed a practical and straightforward text outlining an evaluation approach to interventions that focus on recovering occupational performance in adults. Special featuresIncorporates concepts from the AOTA Occupational Therapy Practice Framework: Domain and ProcessProvides most of the core knowledge required for the ACVREP low vision certification examination and AOTA specialty certification in low visionIncludes an occupational therapy vision rehabilitation evaluation consisting of four components: occupational profile/case history, evaluation of visual factors, environmental evaluation, evaluation of occupational performanceEmphasizes intervention and low vision rehabilitation treatment including modification of the environment, use of non-optical assistive devices, use of optical devices, and use of computer technologyProvides valuable information on how to start an independent practice in low vision rehabilitationIncludes chapters on diabetic management and electronic assistive technologyIncludes access to a companion website with printable forms and additional resources with text purchaseWritten by authors who are optometrists, occupational therapists, researchers, and certified low vision therapists (CLVT), Low Vision Rehabilitation employs an interdisciplinary perspective that is unique, practical, and credible. A Doody's Core Title Selection!
The sudden onset of a cue triggers visual attention, which then enhances visual processing in the zone near the cue. This enhancement causes a motion illusion in subsequent stimuli presented near the ...cue. At greater separations from the cue, the illusory motion reverses direction, indicating prolonged processing speed. Measurements of the strength and direction of illusory motion at increasing separations from the cue reveal an attentional ‘perceptive field’ with an excitatory center at the locus cued and an inhibitory surround subtending the remaining visual field. These findings help explain the traditional attentional ‘benefits’ and ‘costs’ of attention.
Visual attention has been defined by different researchers and clinicians in a variety of ways that are sometimes conflicting or confusing. This paper will provide a unified definition of visual ...attention, as well as a putative neurophysiological mechanism that is consistent with this unified definition. In addition, recent data on the mechanisms of visual attention will be presented, including its spatial organization and temporal dependencies, as well as the role of parallel visual pathways in its activation.
Robust visual attentional responses are produced by the sudden onset of a visual cue, but the properties of cues that best elicit an attentional response are not fully known. We used the line-motion ...illusion (Hikosaka et al., 1991) to investigate the optimal cue properties that evoke visual attention. We found that visual attention is driven primarily by the luminance contrast of the cue. Furthermore, by manipulating the spatial, chromatic, and contrast properties of cues, we found that magnocellular (M) stream biased cues always override the response to parvocellular (P) stream biased cues, even when the P stream biased cues are presented first. Our data suggest that cues that preferentially excite the M pathway predominantly capture visual attention.
Este trabajo analiza el desarrollo que Platón hace en el Político del proceso cognitivo necesario para arribar a la definición correcta de un objeto. Tomando como punto de partida los problemas sobre ...la búsqueda de la definición abiertos en el Menón, el análisis muestra que, en el marco de su filosofía tardía, Platón reformuló el proceso que conduce a responder adecuadamente"qué es x". En el Político, "definir" se convierte en un proceso complejo que incluye un acercamiento negativo al objeto. "Decir lo que el objeto no es" constituye uno de los momentos necesarios para arribar a una definición verdadera. Esta perspectiva implica el abandono definitivo de la ignorancia como punto de partida de toda investigación representada, usualmente, en los diálogos platónicos por la intransigencia socrática.This essay analyzes the necessary knowledge process to reach a correct definition of an object, developed by Plato in the Statesman. Starting with the problems found in the search of a definition in the Meno, the paper shows that, in his late philosophy, Plato reshaped the characteristics of the search that leads to answer properly "what is x". In the Statesman, the act of definition becomes a complex process that includes a negative approach to the object. "To say what the object is not" constitutes one of the necessary moments to reach a real definition. This view also implies to move away from the ignorance as a starting point of all kinds of search usually represented in the dialogues by the socratic intransigence.
Recent research in reading disability has discovered that at least some reading-disabled subjects have deficits in their magnocellular (M) visual pathways. However, the mechanism by which M pathway ...deficits affect reading has not been addressed. Abnormal attention has long been known to be associated with reading-disabled individuals, and new research in visual attention has determined that transient visual attention is dominated by M-stream inputs. The purpose of this study was to determine whether visual attention might be the mechanism through which a faulty M pathway could produce visual deficits in reading-disabled subjects. Spatiotemporal attentional response functions were measured using the Line Motion Illusion and compared in normal and disabled readers. Specific abnormalities in the visual attention mechanisms of disabled readers were found which might suggest mechanisms by which reading could be affected by a deficient M stream.
Motion perception was tested by requiring adult subjects to view gratings that remained stationary but reversed in contrast several times per second. Subjects viewed monocularly and judged whether ...the gratings were stationary, or moving in one direction, in successive 3s trials. Subjects who had early-onset strabismus most frequently perceived vertically oriented gratings to be moving nasalward, and horizontally oriented gratings to be moving up or down. Normal subjects and subjects who had late-onset strabismus most frequently perceived the gratings to be stationary. The asymmetries of motion perception in early-onset strabismus imply that the visual motion neurons of cerebral cortex develop properly only if they receive normal binocular input during infancy.
Recent research has shown that visual attention has a center-surround nature. The sudden onset of a stimulus (cue) initiates a visual attention response in which neural processing of subsequent ...visual stimuli is accelerated and enhanced at the cued locus, and simultaneously inhibited, for stimuli falling outside the cued zone. This study further examined the center-surround nature of visual attention by measuring interactions between cues that trigger attention. Attentional cues were displayed on a computer monitor, followed by probe lines. Subjects' percepts of the direction of attentionally-induced illusions of motion within the probe lines were used as a measure of visual attention. Subjective responses were converted into attention index scores. Stimuli studied included (1) two cues displayed at the same locus, but at different times; (2) two similar cues displayed at the same time but at different locations; (3) two similar cues displayed at different times and locations; (4) the shape of the attentional focus. When a second cue is displayed at the same locus, both the excitatory center and inhibitory surround responses are weakened, causing additional attentional responses at the same location to be suppressed, while stimuli at new locations are favored. Two cues displayed on the same side of the probe line at the same time had the same effect as a single cue. Two attentional cues displayed on opposite sides of the probe line produced a varied response, depending on the inter-cue interval. At brief inter-cue intervals (transient, or stimulus-induced) attention tended to favor the stronger of the cues. However, if the interval between cues in longer than 100-150 ms; the second cue presented was favored. The shape and size of the attentional focus varied between subjects, but tended to be centered upwards relative to the cued position. This study provides strong support for the center-surround model of visual attention by confirming the center-surround configuration in all meridians and provides insight into how attention behaves in the presence of multiple stimuli.
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