Document Type


Publication Date



Background—Older adults’ peak performance on memory and cognitive inhibition tasks tends to be in the morning while younger adults’ peak performance tends to be in the afternoon. Although these tasks require efficient attentional processes for optimal performance, previous research examining age differences in the effects of time of day has not measured the distinct aspects of attention quantified by the attentional network test (ANT; Fan, McCandliss, Sommer, & Posner, 2002).

Methods—We examined the relationship between time of testing and the efficiency of alerting, orienting and executive attention networks by randomly assigning younger (18–28 years; N = 27, M = 21.37 years, SD = 2.39) and older adults (65–85 years; N = 32, M = 73.34 years, SD = 5.18) to AM or PM testing of alerting, orienting and executive attention. Mean reaction times for each network was analyzed with a univariate ANOVA with age (younger, older) and time of day (AM, PM) as between-subjects factors.

Results—Consistent with our hypotheses, while time of day had little effect on orienting or executive attention, it affected alerting in opposite ways for younger and older adults, with alerting cues benefitting performance most at participants’ off-peak times of day. A larger benefit from alerting cues was observed when participants’ were tested at their off-peak (M = 30.11 ± 15.66) relative to their peak time (M = 2.18 ± 15.97).

Conclusion—Our findings show that age-related circadian patterns influence the alerting component of attention, with both age groups showing the largest benefit from alerting cues when testing occurs at non-optimal times of day. Overall, our findings underscore the importance of controlling for time of day in investigations of attention and add to our understanding of how age differences in circadian patterns impact attention.


This is an Accepted Manuscript of an article published by Taylor & Francis in Experimental Aging Research: An International Journal Devoted to the Scientific Study of the Aging Process on 22 Apr 2013, available online:

Article also available at



Included in

Psychology Commons