PubMed · 4465922
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J Presland. 1974. Modifying behavior now.. https://pubmed.ncbi.nlm.nih.gov/4465922/
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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.
There is a traditional view of pain as a conscious phenomenon which satisfies the following two principles at least: Pain is essentially a belief- or cognition-independent sensation, given for consciousness in an immediate way, and pain's unitary physical base is responsible for both its phenomenal or felt qualities and its functional, causal features. These are "The Raw Feels Principle" (P) and "The Unity of Pain Principle" (Q). Each is shown to be implausible. Evidence comes from recent pain research in a number of dimensions. A further argument against The Unity of Pain Principle is constructed by analogy with facts about blindsight. The consequences of rejecting P or Q are examined in light of (i) the traditional epistemological role of pain as exemplar of sensations thought to be foundational for knowledge, (ii) the prospects of a modularity theory of the pain system, (iii) recent accounts of pain among contemporary philosophers, (iv) a naturalist and realist conception of pain, and (v) views about the status of Folk Psychology.