ABSTRACT
The present chapter focuses on stimulus processing during selective attention by examining physiological studies of brain activity—mainly studies involving event-related potentials (ERPs), but also important supplementary evidence provided by measurements of the regional cerebral blood flow and of the magnetic fields surrounding the head. On the basis of these physiological studies, sensory processing during selective attention in multichannel stimulus situations can be divided into two categories: (a) task-unrelated, basic, high-speed processing of physical stimulus features per se, which occurs automatically, preconsciously, and in parallel, and is not influenced by selective attention; (b) task-related, selective, sensory processing of physical stimulus features, which is a manifestation of selective attention at the sensory level. This selective sensory processing is conducted by means of a voluntarily maintained neuronal representation of the specific physical features of the stimulus to be attended, called the attentional trace, which acts as a fast, accurate, and efficient mechanism for recognizing these stimuli. The rejected stimuli, however, appear to receive full processing of their physical attributes per se, which can be inferred from the physiological data available. This processing is the task-unrelated, basic, processing described in (a).
