title: Water consumption, not expectancies about water consumption, affects cognitive performance in adults.
abstract: Research has shown that water supplementation positively affects cognitive performance in children and adults. The present study considered whether this could be a result of expectancies that individuals have about the effects of water on cognition. Forty-seven participants were recruited and told the study was examining the effects of repeated testing on cognitive performance. They were assigned either to a condition in which positive expectancies about the effects of drinking water were induced, or a control condition in which no expectancies were induced. Within these groups, approximately half were given a drink of water, while the remainder were not. Performance on a thirst scale, letter cancellation, digit span forwards and backwards and a simple reaction time task was assessed at baseline (before the drink) and 20 min and 40 min after water consumption. Effects of water, but not expectancy, were found on subjective thirst ratings and letter cancellation task performance, but not on digit span or reaction time. This suggests that water consumption effects on letter cancellation are due to the physiological effects of water, rather than expectancies about the effects of drinking water.
authors.affiliation: School of Psychology, University of East London, Stratford Campus, Water Lane, London E15 4LZ, UK. Electronic address: c.edmonds@uel.ac.uk.
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Edmonds
authors.affiliation: School of Psychology, University of East London, Stratford Campus, Water Lane, London E15 4LZ, UK.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Crombie
authors.affiliation: School of Psychology, University of East London, Stratford Campus, Water Lane, London E15 4LZ, UK.
authors.forename: Haiko
authors.initials: H
authors.lastname: Ballieux
authors.affiliation: Department of Psychology, University of Westminster, 309 Regent Street, London W1B 2UW, UK.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Gardner
authors.affiliation: School of Psychology, University of East London, Stratford Campus, Water Lane, London E15 4LZ, UK.
authors.forename: Lynne
authors.initials: L
authors.lastname: Dawkins
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000502:physiology; D001288:Attention / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D003681:Dehydration; D004326:Drinking / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011930:Reaction Time; D013647:Task Performance and Analysis; D013894:Thirst / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology; D055815:Young Adult