TY - JOUR
T1 - Pre-existent expectancy effects in the relationship between caffeine and performance
AU - Elliman, Nicola A.
AU - Ash, Jennifer
AU - Green, Michael W.
PY - 2010/10
Y1 - 2010/10
N2 - The present study investigated the impact of pre-existent expectancy regarding the effects of the caffeine load of a drink and the perception of the caffeine content on subjective mood and vigilance performance. Caffeine deprived participants (N=25) were tested in four conditions (within subjects design), using a 2 × 2 design, with caffeine load and information regarding the caffeine content of the drink. In two sessions, they were given caffeinated coffee and in two were given decaffeinated coffee. Within these two conditions, on one occasion they were given accurate information about the drink and on the other they were given inaccurate information about the drink. Mood and vigilance performance were assessed post ingestion. Caffeine was found to enhance performance, but only when participants were accurately told they were receiving it. When decaffeinated coffee was given, performance was poorer, irrespective of expectancy. However, when caffeine was given, but participants were told it was decaffeinated coffee, performance was as poor as when no caffeine had been administered. There were no easily interpretable effects on mood. The pharmacological effects of caffeine appear to act synergistically with expectancy.
AB - The present study investigated the impact of pre-existent expectancy regarding the effects of the caffeine load of a drink and the perception of the caffeine content on subjective mood and vigilance performance. Caffeine deprived participants (N=25) were tested in four conditions (within subjects design), using a 2 × 2 design, with caffeine load and information regarding the caffeine content of the drink. In two sessions, they were given caffeinated coffee and in two were given decaffeinated coffee. Within these two conditions, on one occasion they were given accurate information about the drink and on the other they were given inaccurate information about the drink. Mood and vigilance performance were assessed post ingestion. Caffeine was found to enhance performance, but only when participants were accurately told they were receiving it. When decaffeinated coffee was given, performance was poorer, irrespective of expectancy. However, when caffeine was given, but participants were told it was decaffeinated coffee, performance was as poor as when no caffeine had been administered. There were no easily interpretable effects on mood. The pharmacological effects of caffeine appear to act synergistically with expectancy.
KW - caffeine
KW - placebo expectancy
KW - vigilance performance
UR - http://www.scopus.com/inward/record.url?scp=77956402362&partnerID=8YFLogxK
U2 - 10.1016/j.appet.2010.03.016
DO - 10.1016/j.appet.2010.03.016
M3 - Article
C2 - 20382192
AN - SCOPUS:77956402362
SN - 0195-6663
VL - 55
SP - 355
EP - 358
JO - Appetite
JF - Appetite
IS - 2
ER -