An Introduction to “Mechanisms of Visual Attention: ACognitiveNeuroscience Perspective”

Thereis agrowing consensus thatthecomputationof the“internal visual world” does not occur in a purely automatic and obligatory way. Humans process part of the available visual information with priority dependent either on the current task (intention) or the structure of the stimulation. This assignment of priority in visual processing is usually termed “visual attention”. Most of what we currently know about visual attention is based on behavioural studies in humans. Such experimental paradigms as “spatial pre-cueing” (e.g. Posner & Petersen, 1990), “visual search” (e.g. Wolfe, 1994), “partial report” (e.g. van der Heijden, 1992), “flanker interference” (e.g. Eriksen, 1995) and “negative priming” (e.g. Fox, 1995) have been developed in the tradition of experimental psychology over the last decades. During the past few years, an increasing number of neuropsychological and neuroscience studies on visual attention have extended the database. Neuropsychological experiments with brain-damaged patients and animals have attempted to identify the role of different brain areas for the control of visual processing priority (for overviews, see Driver & Mattingley, 1995; Duncan, Humphreys, Ward, & Shapiro,1997; Humphreys & Bruce, 1989; Posner & Petersen, 1990); the dependent variables in the main have been behavioural measures, such as reaction time and accuracy. In the neurosciences, the effects of visual attention have been measured in modulations of brain activity. At the level of individual neurons, single-unit recordings have revealed firing rate changes of attentional manipulations (for overviews, see Desimone & Duncan, 1995; Duncan et al., 1997). Event-related potentials (ERP) derived from very large populations of neurons have provided insights