It is possible to consider attention as the modulating dimension of consciousness. Understood in this sense, attention can be a privileged theme for relating the first person point of view (conceived as a psycho-phenomenology inspired by the work of Husserl) to the experimental sciences (e.g. psychology, neuropsychology, etc.), which have done a great deal of work on attention. This article will take up in succession some different points of view regarding the status of attention and its structure (e.g. static aspects). (...) It will also consider the dynamic of attention from a micro-genetic point of view as well as a functional point of view. The final section will seek to show not only the unique and original contributions of each perspective, but also each perspective''s limitations and biases. (shrink)

The general problem of visual search can be shown to be computationally intractable in a formal, complexity-theoretic sense, yet visual search is extensively involved in everyday perception, and biological systems manage to perform it remarkably well. Complexity level analysis may resolve this contradiction. Visual search can be reshaped into tractability through approximations and by optimizing the resources devoted to visual processing. Architectural constraints can be derived using the minimum cost principle to rule out a large class of potential solutions. The (...) evidence speaks strongly against bottom-up approaches to vision. In particular, the constraints suggest an attentional mechanism that exploits knowledge of the specific problem being solved. This analysis of visual search performance in terms of attentional influences on visual information processing and complexity satisfaction allows a large body of neurophysiological and psychological evidence to be tied together. (shrink)

Purely parallel neural networks can model object recognition in brief displays – the same conditions under which illusory conjunctions have been demonstrated empirically. Correcting errors of illusory conjunction is the “tag-assignment” problem for a purely parallel processor: the problem of assigning a spatial tag to nonspatial features, feature combinations, and objects. This problem must be solved to model human object recognition over a longer time scale. Our model simulates both the parallel processes that may underlie illusory conjunctions and the serial (...) processes that may solve the tag-assignment problem in normal perception. One component of the model extracts pooled features and another provides attentional tags that correct illusory conjunctions. Our approach addresses two questions: How can objects be identified from simultaneously attended features in a parallel, distributed representation? How can the spatial selectional requirements of such an attentional process be met by a separation of pathways for spatial and nonspatial processing? Our analysis of these questions yields a neurally plausible simulation of tag assignment based on synchronizing feature processing activity in a spatial focus of attention. (shrink)

A prominent but poorly understood domain of human agency is mental action, i.e., thecapacity for reaching specific desirable mental statesthrough an appropriate monitoring of one's own mentalprocesses. The present paper aims to define mentalacts, and to defend their explanatory role againsttwo objections. One is Gilbert Ryle's contention thatpostulating mental acts leads to an infinite regress.The other is a different although related difficulty,here called the access puzzle: How can the mindalready know how to act in order to reach somepredefined result? A (...) crucial element in the solutionof these puzzles consists in making explicit thecontingency between mental acts and mentaloperations, parallel to the contingency betweenphysical acts and bodily movements. The paper finallydiscusses the kind of reflexivity at stake in mentalacts; it is shown that the capacity to refer tooneself is not a necessary condition of the successfulexecution of mental acts. (shrink)

The effect of attention on perceived brightness and contrast was investigated in eight experiments. Attention was manipulated by engaging observers in an attention-demanding concurrent task or by directing attention to a location with a peripheral cue. In all of the dual-task manipulations, attention reduced the variability of responses. However, attention did not affect the brightness of stimuli, nor did it affect the amount of simultaneous brightness contrast. Results with peripheral location cues were similar; however, the effect of attention in these (...) experiments could be attributed to nonperceptual factors. The metaphorical “spotlight” of attention reduces observers' uncertainty about the brightness of a stimulus, but it does not “illuminate” in terms of brightness or contrast. (shrink)