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Caffeine Withdrawal in Relation to Mood and Performance
by: Jennifer Ivas



coffee

Welcome

Thank you for visiting my site. This study is a caffeine withdrawal study.   A little background on caffeine:

Caffeine Increases

energy, work, confidence, friendliness, alertness

Caffeine Decreases

Fatigue, boredom, Drowsiness

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Introduction

Previous studies

Schuh and Griffiths (1997)

Caffeine withdrawal study

Used POMS

Concluded that when withdrawing from caffeine there were increased feelings of being worn out, peeved, grouchy, fatigued and exhausted.

Caffeine withdrawal is negative & unpleasant

Kenemans, Wieleman, Zeegers, Verbaten (1999)

Caffeine and Cognitive performance

Hypothesized caffeine would increase speed and rate of detection

Used Stroop test

Results found caffeine decreased reaction time

Therefore withdrawal will increase reaction time

Mitchell and Redman (1992)

Caffeine and Academic performance

Measured short-term memory, mental arithmetic, reading comprehension, serial search, and verbal reasoning

Results show caffeine improved performance on all mental speed related tasks

 

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Methods

Participants

1st Sample

38 participants

0-200 ml of caffeine

average intake = 58 ml

2nd Sample

14 participants

0-430 ml of caffeine

average intake = 131 ml


Material

POMS (Profile of Mood States Questionnaire)

Stroop

Tapping

CPT

Diet Diary

Craving Questionnaire

 

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Procedure

1st sample                                   

Instructions                                                    

Consent                                                          

Food diary                                                        

POMS                                                                

Return 48 hours later

POMS

Craving Questionnaire

Debriefing

2nd Sample

Instructions

Consent

Food diary

POMS

Stroop

Tapping 

CPT

Return in 48 hours

POMS

Stroop

Tapping

CPT

Craving Questionnaire

Debriefing

 

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Results

The profile of mood states questionnaire was used to assess self-reported mood in the first sample, which was comprised of the general psychology population.  Paired samples t-tests (p=.05) were used to analyze all measures of self-reported mood. The tests found mood states of depression, anger, friendliness, and fatigue to be significant. There was no significant change for vigor.

In the second sample, which comprised mostly of self-reported high caffeine users, mood and psychomotor performance was examined.  In this sample, the same mood questionnaire was given and results were significant for vigor and friendliness (P<.05).  There was no significant change in depression, anger, and fatigue.  The psychomotor performance task results are also measured.  The first test examined is the Stroop test.  A paired samples T-test was conducted and there was significance for time (P<.05), but not for the number correct.  There was a significant decrease in tapping from baseline to withdrawal.  The continuous performance task showed significance in the errors of omission and time.  There was no significance for the errors of commission or number correct. 

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Discussion

1st Sample

Withdrawal significantly increased Depression, Anger, Fatigue

Withdrawal significantly decreased Friendliness

This supports previous evidence

 

2nd Sample

Only significant decreases in vigor and friendliness

Reasons

Sample size

Midterm week

Stroop

Time was significantly slower at withdrawal

Supports research that caffeine withdrawal increases reaction time

Tapping

Decreased from baseline to withdrawal

CPT

Time significantly changed

Errors of omission changed (not pressing 6,4 when they did appear)

Academic Concentration

Did not change significantly

Should have tested at baseline and withdrawal

 

 

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