We administered measures of fluid and crystallized intelligence to Morning- and Evening-type adolescents who were tested either during a morning session or an afternoon session, at times chosen to reflect the limits of the average school day schedule. For the fluid intelligence measures, there was a synchrony effect, with better performance at times that matched individuals' preferences. A composite measure of the subtests used (block design, digit span, and vocabulary) computed to a 6 point difference in IQ estimates. We also assessed the behavioral adjustment of these participants and found heightened levels of maladaptive behavior for Evening-type adolescents. Adolescents tested at their nonoptimal times of day and adolescents who are Evening-types appear to be at risk for poor academic performance and Evening-types appear to be at risk for behavioral adjustment problems.
Bibliographical noteFunding Information:
This research was supported by National Institute of Aging Grant NIA R37 AGO 4306 awarded to Lynn Hasher and by grants from the Natural Sciences and Engineering Research Council (NSERC) and the Canada Research Chairs Program to Phil Zelazo. For assistance with data collection we thank Silvia Celucci, Sarah Douglas, Anoop Ganda, Nicole Recel, and David Vitale. The authors also thank Sunghan Kim and Martin Ralph for helpful suggestions in the design of the study.
- Intellectual performance
- Synchrony effect
- Time of day