Event-related potentials and eyeblink responses in automatic and controlled processing: effects of age.

Seventeen young (mean age = 20.2 years old) and 16 elderly (mean age = 72.6 years old) women were tested with event-related potential (ERP) paradigms designed to elicit responses in reaction time tasks and to a startling noise burst. EEG was analyzed from 17 standard 10-20 electrode sites. Reaction time and performance data suggested that the elderly did not perform worse than the young. Nevertheless, the physiological responses of the elderly differed significantly from those of the young. While the task-dependent P3s at Pz were smaller in the elderly than in the young, the automatic P3 was smaller yet. The distribution of both types of P3 across the scalp was more uniform in the elderly than in the young. Single-trial analyses revealed that the P3 amplitude differences at Pz were not due to latency dispersal of single trials. Single-trial startle eye blink responses to intense noise bursts during the automatic paradigm were considerably less frequent in the elderly, although their individual startle blinks were actually larger. The data demonstrate that the electrophysiological responses of the elderly are different from the young both in tasks eliciting automatic responses and in tasks requiring controlled processing.