Review of Attentional processing: The brain's art of mindfulness.

Abstract

David LaBerge has crafted a book on visual attention that will be accessible and interesting to a broad audience, from students doing their first project in cognitive psychology, to accomplished researchers in the field. The goal of the book is to present a coherent cognitive - neuroscience model of attention - a framework within which one can understand the rich database of findings pertaining to visual attention. In some respects, the book is also an overview and synthesis of LaBerge's own work on spatial attention. The first half of the book covers behavioural investigations; the second half covers cognitive - neuroscience investigations. For scientists studying attention, it has been apparent for some time that distinctions must be made between different varieties of attention if progress is to be made in understanding this psychological phenomenon. In sections of the book which follow the initial overview and historical treatment, LaBerge wrestles with the diversities and similarities among different forms of attention, and arrives at his particular cut, developed formally in the Preparation/Selection model. Preparatory attention is engendered by detailed expectations about a future event. Preparatory attention can be directed to a spatial location (e.g., left of center), to an attribute (e.g., upwards motion) or to an entire object (e.g., a car). For example, the expectation of a visual attribute, such as upwards motion, induces top - down preparatory activity in brain areas that specialize in sensory processing of that attribute. When the particular expected attribute appears in the visual field, preparatory attention facilitates its processing by speeding information flow. Selective attention is engendered by the need to process a portion of a cluttered visual array. The purpose of selective attention is to route desired input for further processing and to attenuate undesired input. Both the degree of clutter and the similarity of the desired input to distracting input play prominent roles in LaBerge's analysis of selective attention. These two varieties of attention, preparatory and selective, differ in terms of their spatial distribution and temporal performance. Preparatory attention is distributed broadly in space and takes appreciable time to accrue and decay. By contrast, selective attention is distributed narrowly and operates nearly instantaneously. The two forms of attention interact, in that preparatory attention modulates the speed at which selective attention can be initiated. Selection will occur faster if the desired input appears near the center of the preparatory gradient than if it appears away from the center. An important assumption of the Preparation/Selection model is that attentional selection need not alter the location of a preparatory attentional gradient. The highlight of the behavioural section of the book is an intriguing experiment that tests this assumption of the model. In the experiment, a preparatory gradient was established at a given location in the visual field, and a triplet (three adjacent letters) was presented on - center or off - center of this gradient. Shortly thereafter, a second triplet was presented. The goal of the subject was to select and identify the central letter of both triplets and to execute a speeded response after the second triplet. In the critical conditions of the experiment, the first triplet was displayed off - center of the preparatory gradient, and the second triplet was presented at a range of positions. The question was whether selection of the central letter of the first triplet would cause the preparatory gradient to move from its initial position to the center of the first triplet. It was found that the preparatory gradient did not move; reaction times were faster when the second triplet was presented at the location of the preparatory gradient than at the location of the first triplet. LaBerge concluded that preparatory and selective attention could operate simultaneously at different spatial locations. …