Attention, according to William James, is "the taking possession by the mind, in clear and vivid form, of one out of what may seem several simultaneously possible objects or trains of thought." Any model of attention must account for its selectivity, for the fact that, after an animal learns a skill, it becomes automatic (or unconscious), for the ability to interrupt automatic acts by attention to novelty, and for the ability to direct attention specifically by conscious means. (Edelman) 

Attention is generally thought of as occurring at a bottleneck. The basic idea is that early processing is largely parallel. Then there appear to be one or two more stages where there is a bottleneck in information processing. Only one (or a few) "objects" can be dealt with at a time. This is done by temporarily filtering out the information coming from the unattended objects. The attentional system moves fairly rapidly to the next object, so that attention is largely serial. In everyday experience, the passage between views --attention deflection -- works so smoothly that we do not notice the discontinuities or jumps.

In Techniques of the Observor and Suspensions of Perception, Jonathan Crary focussed on the interrelations between the development of modern subjective aesthetics and the disciplines of the modern subject. For Crary, 19th century quantitative psychological research and the aesthetics of Schopenhauer are constituted by the same discourse of the subject, in which the physiological is fully immanent to the subjective. "It is knowledge that simultaneously provided technniques for the external control and domination of the human subject and was the emancipating ground for notions of subjective vision within modernist art theory and experimentation." (Techniques of the Observor, p. 85)