Internal and external control: A two-factor model of amplitude change of event-related potentials

Examines the contributions of event-related potential (ERP) measures in mental chronometry research. Amplitude variation in ERP components may provide valuable information regarding the intensity and timing of information processes, and these amplitude changes are related to energetical rather than to computational processes. Amplitude variations of ERP components in visual discrimination and selective attention tasks may be caused by 2 different processing modes, denoted as external and internal control, that are associated with different neural structures. These 2 control systems might converge on thalamic neurons that regulate the sensory input to cortex, and the direction of sustained ERP amplitude changes might reflect the dominant system.