Judith Dirk

Sleep and affect in older adults: using multilevel modeling to examine daily associations

The main objective of the present study was to examine daily associations (intraindividual variability or IIV) between sleep and affect in older adults. Greater understanding of these associations is important, because both sleep and affect represent modifiable behaviors that can have a major influence on older adults’ health and well‐being. We collected sleep diaries, actigraphy, and affect data concurrently for 14 days in 103 community‐dwelling older adults. Multilevel modeling was used to assess the sleep–affect relationship at both the group (between‐persons) and individual (within‐person or IIV) levels. We hypothesized that nights characterized by better sleep would be associated with days characterized by higher positive affect and lower negative affect, and that the inverse would be true for poor sleep. Daily associations were found between affect and subjective sleep, only and were in the hypothesized direction. Specifically, nights with greater reported awake time or lower sleep quality ratings were associated with days characterized by less positive affect and more negative affect. Gender was not a significant main effect in the present study, despite previous research suggesting gender differences in the sleep–affect relationship. The fact that self‐ratings of sleep emerged as the best predictors of affect may suggest that perceived sleep is a particularly important predictor. Finally, our results suggest exploration of affect as a potential intervention target in late‐life insomnia is warranted.

Life Experience with Death: Relation to Death Attitudes and to the Use of Death-Related Memories

The study examines the relation of death experience to death attitudes and to autobiographical memory use. Participants (N = 52) completed standard death attitude measures and wrote narratives about a death-related autobiographical memory and (for comparison) a memory of a low point. Self-ratings of the memory narratives were used to assess their functional use. Results show that higher levels of experience with death were related to lower levels of death anxiety and avoidance. Participants with higher levels of death experience also more frequently used their death-related memories to serve adaptive functions.

The Influence of Time of Testing on Interference, Working Memory, Processing Speed, and Vocabulary: Age Differences in Adulthood

This research examines the effect of time of testing on adult age differences in resistance to interference, working memory, processing speed, and vocabulary. Results show that time of testing modulates age-related differences only in the ability to resist automatic and prepotent responses. Older adults tested in the afternoon were more susceptible to interference than young adults tested at the same time of the day, and than their peers tested in the morning. In contrast, age-related differences in working memory, processing speed, and vocabulary were not modulated by time of the day. Our findings suggest that age-related modulation of performance as a function of the time of the day is specific to resistance to interference.

Adults’ Versus Children’s Performance on the Stroop Task: Insights From Ex-Gaussian Analysis

In the Geneva Variability Study, the Stroop task was administered to children and young adults. Interference and facilitation effects were investigated by comparing mean reaction times (RTs) and applying ex-Gaussian distribution analysis. Our analyses were motivated by three goals: First, we aimed to replicate the results obtained with young adults by Spieler, Balota, and Faust (2000); second, we applied this method to childrens data; third, the question of age-related differences in these inhibitory processes was investigated with the ex-Gaussian approach. In young adults, findings pertaining to the interference effect reported by Spieler et al. (2000) were replicated; in children, the interference effect was only manifested in the estimated Gaussian parameters (Mean RT, μ, σ); facilitation effects were only observed in children. The substantive meaning of the results and the advantages of ex-Gaussian analyses for describing RT distributions are discussed.