Early and late selection in young and old adults: An event-related potential study.

There were no differences in processing found between 24 young (aged 18-24 yrs) and 24 old (aged 65-75 yrs) adults in a combined visual selection and memory search paradigm. Data suggest that old Ss achieved relatively fast reaction times (RTs) in the task at the cost of a high error percentage. These findings, and the morphology of event-related potentials (ERPs), suggest that old Ss performed the task more superficially than did young Ss. In both old and young Ss, high memory load was associated with decreased positivity in the P3 and slow wave ERP components. This finding is interpreted in terms of the concept of search negativity. The finding that N2 amplitude was larger in response to nontarget trials for both attended and unattended inputs is discussed in relation to theories about N2 as an indicator of automatic mismatch detection.