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Peripheral Vision (peripheral + vision)
Selected AbstractsBook Reviews: Peripheral Visions: Publics, Power, and Performance in Yemen by Lisa WedeenAMERICAN ANTHROPOLOGIST, Issue 3 2010Steven Caton No abstract is available for this article. [source] Multiple sensitive periods in human visual development: Evidence from visually deprived childrenDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2005Terri L. Lewis Abstract Psychophysical studies of children deprived of early visual experience by dense cataracts indicate that there are multiple sensitive periods during which experience can influence visual development. We note three sensitive periods within acuity, each with different developmental time courses: the period of visually-driven normal development, the sensitive period for damage, and the sensitive period for recovery. Moreover, there are different sensitive periods for different aspects of vision. Relative to the period of visually driven normal development, the sensitive period for damage is surprisingly long for acuity, peripheral vision, and asymmetry of optokinetic nystagmus, but surprisingly short for global motion. A comparison of results from unilaterally versus bilaterally deprived children provides insights into the complex nature of interactions between the eyes during normal visual development. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 163,183, 2005. [source] Detection of animals in natural images using far peripheral visionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2001Simon J. Thorpe Abstract It is generally believed that the acuity of the peripheral visual field is too poor to allow accurate object recognition and, that to be identified, most objects need to be brought into foveal vision by using saccadic eye movements. However, most measures of form vision in the periphery have been done at eccentricities below 10° and have used relatively artificial stimuli such as letters, digits and compound Gabor patterns. Little is known about how such data would apply in the case of more naturalistic stimuli. Here humans were required to categorize briefly flashed (28 ms) unmasked photographs of natural scenes (39° high, and 26° across) on the basis of whether or not they contained an animal. The photographs appeared randomly in nine locations across virtually the entire extent of the horizontal visual field. Accuracy was 93.3% for central vision and decreased almost linearly with increasing eccentricity (89.8% at 13°, 76.1% at 44.5° and 71.2% at 57.5°). Even at the most extreme eccentricity, where the images were centred at 70.5°, subjects scored 60.5% correct. No evidence was found for hemispheric specialization. This level of performance was achieved despite the fact that the position of the image was unpredictable, ruling out the use of precued attention to target locations. The results demonstrate that even high-level visual tasks involving object vision can be performed using the relatively coarse information provided by the peripheral retina. [source] Just how useless is an amblyopic eye?OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2008Eve Panesar Purpose:, The extent to which individuals with amblyopia are visually disadvantaged has generated renewed research interest. Investigation of the contribution of the amblyopic eye to visual performance under habitual conditions is a key component of this issue. This study aims to evaluate the contribution of each eye to a simple light detection task when both eyes are open and in their habitual motor position. Methods:, A custom program on the Humphrey Field Analyzer (Carl Zeiss Meditec Inc., Dublin, CA, USA) was used to measure detection thresholds for a blue light on a yellow background along the horizontal meridian at two degree intervals to an eccentricity of 25 degrees either side of fixation. Three viewing conditions were used: (1) both eyes open, (2) a yellow filter in front of the amblyopic eye and (3) a yellow filter in front of the fellow eye. The purpose of the yellow filter was to produce minimal dissociation as it only prevented the eye behind the filter from seeing the blue stimulus; the fixation mark and the background remained visible to both eyes. Participants included 10 visual normals and 16 volunteers with amblyopia. Results:, Within the sample of amblyopes there were three basic patterns of results, and each applied to around one third of the group: (1) habitual sensitivity governed by the sensitivity of the fellow eye at each stimulus location, (2) habitual sensitivity exceeding the sensitivities of either eye at each stimulus location and (3) a pattern of contribution that varied across the range of eccentricities. Surprisingly, in one amblyope the habitual sensitivity appeared to be governed by the sensitivity of the amblyopic eye. The pattern of contribution of each eye to the habitual sensitivity did not vary in a manner that was predictable by the visual acuity deficit or the presumed aetiology of the amblyopia. The control sample showed either pattern 2 (70%) or pattern 3 (30%). Conclusions:, The amblyopic eye did not contribute to the habitual performance in approximately one-third of cases in this simple detection task. Thus, in many cases the amblyopic eye may be a useful contributor to visual performance in the binocular field. This challenges the traditional view that an amblyopic eye is useful only for peripheral vision. [source] The contrast sensitivity function for detection and resolution of blue-on-yellow gratings in foveal and peripheral visionOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2002R. S. Anderson Abstract Previous studies using polychromatic gratings have shown that the peripheral grating contrast sensitivity function is significantly different when the task is resolution rather than detection. Specifically, in the middle frequency range, while resolution acuity drops suddenly to zero, detection performance continues up to much higher frequencies, accompanied by observations of aliasing. We wanted to determine if the same holds true for blue-cone isolating gratings in either foveal or peripheral vision. Contrast sensitivity function (CSFs) were measured at the fovea and 20 degrees eccentricity in the temporal retina under conditions of short-wavelength-sensitive (SWS)-cone pathway isolation using a two-alternative forced choice paradigm. The detection and resolution CSF were identical at the low frequency end but at higher frequencies resolution sensitivity falls abruptly while contrast detection remained possible till higher frequencies [cut-off frequencies: fovea detection 6.0 cycles (degree),1, resolution 4.6 cycles (degree),1; periphery detection 1.6 cycles (degree),1, resolution 1.05 cycles (degree),1]. Aliasing was observable when spatial frequency exceeded the resolution limit. Medium/high contrast blue-cone-mediated resolution acuity is sampling limited in both the fovea and periphery. Previous studies of blue-cone contrast sensitivity which employed a detection task do not reflect the true resolution limit. [source] Temporal detection in human vision: dependence on eccentricityOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2002R. F. Hess Studies of human perception of time-varying luminance often aim to estimate either temporal impulse response shapes or temporal modulation transfer functions (MTFs) of putative temporal processing mechanisms. Previously, temporal masking data have been used to estimate the properties and numbers of these temporal mechanisms in central vision for 1 cycle per degree (cpd) targets [Fredericksen and Hess (1998)]. The same methods have been used to explore how these properties change with stimulus energy [Fredericksen and Hess (1997)] and spatial frequency [Fredericksen and Hess (1999)]. We present here analyses of the properties of temporal mechanisms that detect temporal variations of luminance in peripheral vision. The results indicate that a two-filter model provides the best model for our masking data, but that no multiple filter model provides an acceptable fit across the range of parameters varied in this study. Single-filter modelling shows differences between processing mechanisms at 1 cpd in central vision and those that operate eccentrically. We find evidence that this change is because of differences in relative sensitivities of the mechanisms, and to differences in fundamental mechanism impulse responses. [source] Globalization and the cultivation of peripheral visionANTHROPOLOGY TODAY, Issue 4 2001June Nash First page of article [source] | ||||||||||