Autonomic responsivity during recognition memory processing in three age groups

Thirty male volunteers in the age groups of young (18-34 years), middle-aged (35-54 years), and old (55-72 years) performed a recurrent recognition task of eight emotional and eight neutral words embedded in balanced 50-word lists while their electrodermal (EDR), heart rate (HR), and recognition responses were recorded. During testing, two hours and again one week following presentation of the 16 words, no marked differences among age groups were observed in EDR, but HR responses were lower in the old than in the young group. The old adopted high signal detection decision criteria for emotional words, which accounted for their lower recognition of emotional words in one measure. The old were as proficient as the young in recognition of neutral words. More emotional words were correctly recognized when a person's responsivity in HR and EDR was high, but this correlation was dissociated in the old. Heart rate changes but not EDR reflected a reduced responsivity in the old. The results place in question the use of peripheral autonomic measures as an index to memory processing.