Document Detail

Effects of expectation and caffeine on arousal, well-being, and reaction time.
MedLine Citation:
PMID:  17228991     Owner:  NLM     Status:  MEDLINE    
The objective of this study is to determine the impact of expectation associated with placebo and caffeine ingestion. We used a three-armed, randomized, double-blind design. Two three-armed experiments varying instruction (true, false, control) investigated the role of expectations of changes in arousal (blood pressure, heart rate), subjective well-being, and reaction time (RT). In Experiment 1 (N = 45), decaffeinated coffee was administered, and expectations were produced in one group by making them believe they had ingested caffeinated coffee. In Experiment 2 (N = 45), caffeinated orange juice was given in both experimental groups, but only one was informed about the true content. In Experiment 1, a significant effect for subjective alertness was found in the placebo treatment compared to the control group. However, for RT and well-being no significant effects were found. In Experiment 2, no significant expectancy effects were found. Caffeine produced large effects for blood pressure in both treatments compared to the control group, but the effects were larger for the false information group. For subjective well-being (alertness, calmness), considerable but nonsignificant changes were found for correctly informed participants, indicating possible additivity of pharmacologic effect and expectations. The results tentatively indicate that placebo and expectancy effects primarily show through introspection.
Rainer Schneider; Mauritz Grüner; Alexandra Heiland; Martina Keller; Zuzana Kujanová; Martin Peper; Maximilian Riegl; Stefan Schmidt; Petra Volz; Harald Walach
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of behavioral medicine     Volume:  13     ISSN:  1070-5503     ISO Abbreviation:  Int J Behav Med     Publication Date:  2006  
Date Detail:
Created Date:  2007-01-18     Completed Date:  2007-04-03     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9421097     Medline TA:  Int J Behav Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  330-9     Citation Subset:  IM    
Institute for Environmental Medicine and Hospital Epidemiology & European Office of the Samueli Institute, University Hospital, Freiburg, Germany.
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MeSH Terms
Affect / drug effects*
Arousal / drug effects*
Blood Pressure / drug effects
Caffeine / pharmacology*
Double-Blind Method
Heart Rate / drug effects
Middle Aged
Placebo Effect
Reaction Time / drug effects*
Set (Psychology)*
Reg. No./Substance:
0/Coffee; 58-08-2/Caffeine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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