RESUMEN
The present experiment examined the effect of distraction on reading ability and comprehension in healthy aging and early stage dementia of the Alzheimer type (DAT). A modified version of the reading task used by Connelly, Hasher, and Zacks (1991, Experiment 2) was employed. Healthy young, healthy old (60-79 years, and 80 years and over), very mild DAT, and mild DAT participants read passages aloud and then answered comprehension questions. There were four experimental conditions in which distracting information was embedded in the text: (control), orthographic (xxxxx), lexical (unrelated), and semantic (related). The results indicated that there was greater susceptibility to increasing levels of distraction with age and increasing dementia severity. Moreover, there was a substantial slowdown in reading time in mild DAT when text was used as distracting information, especially conceptually related text. Furthermore, mild DAT participants were more likely to make false alarms in comprehension performance (i.e., choose as an answer the incorrect response which contained the related distracting information). Thus, in early stage DAT, there appears to be increased difficulty inhibiting partially activated information, especially when it is related to the relevant information being processed.
RESUMEN
The effect of two durations of bright light upon sleepiness and performance during typical night shift hours was assessed. Thirty normal, healthy young adults participated in a 2-night protocol. On the 1st night subjects were exposed to bright or dim light beginning at 2400 hours, under one of the following three conditions: bright light for 4 hours, dim light for 2 hours followed by bright light for 2 hours or dim light for 4 hours. Following light exposure, subjects remained awake until 0800 hours in a dimly lit room and slept in the laboratory between 0800 and 1600 hours, during which time sleep was estimated with actigraphy. Throughout the 2nd night, the multiple sleep latency test (MSLT), simulated assembly line task (SALT) performance, and subjective sleepiness were recorded. The single, 4-hour exposure to bright light was found to significantly increase MSLT scores and improve SALT performance during the early morning hours on the night following bright-light exposure. No significant effects were noted with a 2-hour exposure. The most likely explanation for these findings is a phase delay in the circadian rhythm of sleepiness-alertness.