2 resultados para visual-spatial attention

em Research Open Access Repository of the University of East London.


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The effects of spatial attention and part-whole configuration on recognition of repeated objects were investigated with behavioral and event-related potential (ERP) measures. Short-term repetition effects were measured for probe objects as a function of whether a preceding prime object was shown as an intact image or coarsely scrambled (split into two halves) and whether or not it had been attended during the prime display. In line with previous behavioral experiments, priming effects were observed from both intact and split primes for attended objects, but only from intact (repeated same-view) objects when they were unattended. These behavioral results were reflected in ERP waveforms at occipital-temporal locations as more negative-going deflections for repeated items in the time window between 220 and 300 ms after probe onset (N250r). Attended intact images showed generally more enhanced repetition effects than split ones. Unattended images showed repetition effects only when presented in an intact configuration, and this finding was limited to the right-hemisphere electrodes. Repetition effects in earlier (before 200 ms) time-windows were limited to attended conditions at occipito-temporal sites (N1), a component linked to the encoding of object structure, while repetition effects at central locations during the same time window (P150) were found only from objects repeated in the same intact configuration—both previously attended and unattended probe objects. The data indicate that view-generalization is mediated by a combination of analytic (part-based) representations and automatic view-dependent representations.

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The degree to which a person relies on visual stimuli for spatial orientation is termed visual dependency (VD). VD is considered a perceptual trait or cognitive style influenced by psychological factors and mediated by central re-weighting of the sensory inputs involved in spatial orientation. VD is often measured using the rod-and-disk test, wherein participants align a central rod to the subjective visual vertical (SVV) in the presence of a background that is either stationary or rotating around the line of sight - dynamic SVV. Although this task has been employed to assess VD in health and vestibular disease, it is unknown what effect torsional nystagmic eye movements may have on individual performance. Using caloric ear irrigation, 3D video-oculography and the rod-and-disk test, we show that caloric torsional nystagmus modulates measures of visual dependency and demonstrate that increases in tilt after irrigation are positively correlated with changes in ocular torsional eye movements. When the direction of the slow phase of the torsional eye movement induced by the caloric is congruent with that induced by the rotating visual stimulus, there is a significant increase in tilt. When these two torsional components are in opposition there is a decrease. These findings show that measures of visual dependence can be influenced by oculomotor responses induced by caloric stimulation. The findings are of significance for clinical studies as they indicate that VD, which often increases in vestibular disorders, is not only modulated by changes in cognitive style but also by eye movements, in particular nystagmus.