Electrophysiological Indicators of Cognitive Function
Robert Chapman
When a person processes information, the cognitive and neural processing depends not just on the physical characteristics of the stimuli, but on the tasks engaging the subject at that time, the allocation of attention, stimulus relevance, memories of related past experiences, expectancies, motivation, etc. Because these processes occur between the stimuli and the behavioral responses, they are difficult to study by behavioral methods alone. However, the electrical activity of the brain can be recorded with good temporal resolution using non-invasive techniques while human subjects are engaged in experimentally controlled information processing. These Event-Related Potentials (ERP) have separable components that are quite sensitive to a wide variety of sensory and cognitive manipulations.
My work explores how human beings process information and use that information to understand and act appropriately. The kinds of information processing I have been studying include initial sensory and perceptual acts, classification, memory, language, and meaning. The experimental methods involve the presentation of stimuli, especially visual and auditory stimuli, while human subjects are performing tasks that systematically manipulate the perceptual or cognitive processes being investigated. I make behavioral measures of the subject's performance, along with electrical measurements of the subject's brain activity. I study ERPs that provide measures of the dynamics of the processes affected by our experimental manipulations. These methods are being used to study simultaneously brain and cognitive functions in human beings.