Individual differences in diurnal rhythms and multiple activation states: A reply to M. W. Eysenck and Folkard

Michael S. Humphreys*, William Revelle, Lisa Simon, Kirby Gilliand

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations


Discusses 3 issues raised by M. W. Eysenck and S. Folkard (see record 1981-07363-001) in their discussion of findings by the present authors (see record 1981-07372-001). The issues include (a) the individual difference variable mediating the time of day and caffeine effects; (b) the difference between the diurnal rhythms of low and high impulsives; and (c) the necessity of postulating multiple activation states. (26 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).

Original languageEnglish (US)
Pages (from-to)42-48
Number of pages7
JournalJournal of Experimental Psychology: General
Issue number1
Publication statusPublished - Mar 1 1980



  • S. Folkard
  • caffeine effects, reply to criticism by M. W. Eysenck &
  • individual differences, diurnal rhythms &
  • multiple activation states &

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Psychology(all)
  • Developmental Neuroscience

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