PubMed · 4089082
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A R Gellatly. 1985. Hemisphere specific effects in reasoning performance.. https://doi.org/10.1007/bf00309449
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Although attention plays a significant role in vision, its spatial deployment and spread in the third dimension is not well understood. In visual search experiments we show that we cannot easily focus attention across isodepth loci unless they are part of a well-formed surface with locally coplanar elements. Yet we can easily spread our attention selectively across well-formed surfaces that span an extreme range of stereoscopic depths. In cueing experiments, we show that this spread of attention is, in part, obligatory. Attentional selectivity is reduced when targets and distractors are coplanar with or rest on a common receding stereoscopic plane. We conclude that attention cannot be efficiently allocated to arbitrary depths and extents in space but is linked to and spreads automatically across perceived surfaces.
Positron emission tomography was used to measure changes in the regional cerebral blood flow of normal people while they searched visual displays for targets defined by color, by motion, or by a conjunction of color and motion. A region in the superior parietal cortex was activated only during the conjunction task, at a location that had previously been shown to be engaged by successive shifts of spatial attention. Correspondingly, the time needed to detect a conjunction target increased with the number of items in the display, which is consistent with the use of a mechanism that successively analyzes each item in the visual field.
In this paper we review the assessment and measurement of normal unwanted intrusive thoughts, images, and impulses that are considered the basis of clinical obsessions. After highlighting some difficulties with how the definition of cognitive intrusion has been applied to the development of assessment measures, we evaluate the construct validity of a number of retrospective self-report instruments such as the Intrusive Thoughts Questionnaire, Cognitive Intrusions Questionnaire, and Obsessional Intrusions Inventory, as well as interview and diary procedures. Measures of personal responsibility and meta-cognitive beliefs, which are still in the developmental phase, are also discussed. We conclude with a number of recommendations and areas of further research which would strengthen the construct validity of measures of intrusive thoughts and related constructs.