Effect of Normal Aging on Emotional Processing and Impact of Emotion on Memory: Psychophysiological and Cognitive Findings

Abstract: It has long been thought that aging is accompanied by an emotional flattening. Although a different view has started to emerge recently, studies investigating psychophysiological responses in reaction to affective stimuli so far have reported an age-related reduction of the affective response. One of the main goals of this thesis was to revisit this issue by examining subjective reports, phasic heart rate, skin conductance (SCR) and facial electromyography (EMG) in response to a set of neutral and emotional pictures in a group of middle-aged participants (40-55 yrs), as compared with a group of older participants (56-78 yrs). A second main goal was to examine the effect of emotion on memory recollection and familiarity, using a Process Dissociation Procedure (PDP; Jacoby, 1991). In paper I, heart rate changes and reports of emotional experiences when viewing pictures were analysed in middle-aged and older participants. Consistent with previous findings, the results showed a clear differentiation of the heart rate changes as a function of time and picture type. Specifically, aversive pictures gave rise to the steepest initial heart rate deceleration and positive pictures elicited the greatest mid-interval acceleration, the latter being observed only in older participants. Parallel to this finding, older persons rated the positive pictures as being more pleasant than the younger did. The results were in agreement with other recent findings showing that older adults, preferentially pay attention to, and better retrieve positive information as compared with younger. Paper II reported the effects of age and gender on subjective reports, SCR and facial EMG. The effect of gender on subjective reports and psychophysiological measures was consistent with previous studies. No effect of age was found; the response magnitude for affective pictures was of similar size as that of younger adults. However, the gender differences on SCR and facial corrugator electromyography were absent in the group of older persons. The general conclusion that emerged from these two studies is that aging is not associated with a general decline of the emotional response. Nevertheless, the present results indicate that gender-related differences are attenuated in older individuals. Paper III examined the effects of emotion on recollection and familiarity, using a PDP implemented by a list discrimination task. The results revealed a detrimental effect of emotion on recollection process but not on familiarity. The finding was interpreted in the light of the trade-off hypothesis, predicting a memory enhancement of emotion for central information and a compromised effect for irrelevant or background details.