Glucose drinks and self-control (Stroop) (#120)

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APA Style

Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data). Glucose drinks and self-control (Stroop). (2012, March 12). Retrieved 22:15, November 17, 2017 from http://www.PsychFileDrawer.org/replication.php?attempt=MTIw

MLA Style

"Glucose drinks and self-control (Stroop)" Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data). 12 Mar 2012 13:43 17 Nov 2017, 22:15 <http://www.PsychFileDrawer.org/replication.php?attempt=MTIw>

MHRA Style

'Glucose drinks and self-control (Stroop)', Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data), , 12 March 2012 13:43 <http://www.PsychFileDrawer.org/replication.php?attempt=MTIw> [accessed 17 November 2017]

Chicago Style

"Glucose drinks and self-control (Stroop)", Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data), , http://www.PsychFileDrawer.org/replication.php?attempt=MTIw (accessed November 17, 2017)

CBE/CSE Style

Glucose drinks and self-control (Stroop) [Internet]. Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data); 2012 Mar 12, 13:43 [cited 2017 Nov 17]. Available from: http://www.PsychFileDrawer.org/replication.php?attempt=MTIw

Reference to Original Report of Finding Gailliot, M. T., Baumeister, R. F., DeWall, C. N., et al. (2007). Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor. Journal of Personality and Social Psychology, 92, 325-336.
Title Glucose drinks and self-control (Stroop)
If the original article contained multiple experiments, which one did you attempt to replicate? e.g., you might respond 'Study 1' or 'Experiment 4'. Study 7
Link to PDF of Original Report
Brief Statement of Original Result Glucose drink (Kool-Aid w/sugar) prevented "ego-depletion" on Stroop task following an initial self-control task. When participants drank glucose drink (compared to Kool-Aid w/Splenda) following self-control, Stroop performance improved.
Type of Replication Attempted Highly Exact Replication
Result Type Failure to Replicate
Difference? No
Number of Subjects 120
Number of Subjects in Original Study 61
Year in which Replication Attempt was Made 2010
Name of Investigators (Real Names Required) Joseph Cesario (design of studies, direction of undergraduate research assistants who collected data); Katherine Corker (direction of undergraduate research assistants who collected data)
Detailed Description of Method/Results Materials from the original study were graciously provided by M. T. Gailliot, so all materials and methods, including the experimenter scripts, were exact copies of the original. This included the unusual methodology of having the experimenter manually time Ps' Stroop task performance, rather than using a computerized reaction time assessment; this is potentially problematic due to experimenter demand effects. We chose to keep this aspect of the design to provide a more precise replication attempt. We also ensured the experimenter would be blind to drink condition by having a single research assistant mix the two types of drinks at the start of each day and label them "A" and "B." The meanings of these were kept entirely secret from the experimenters carrying out the data collection. (We also instructed our experimenters NOT to taste any of the lemonade.)

METHOD:
1. Ps complete one column (20 trials) of Stroop, to be used as Baseline measure of Stroop performance
2. Attention control manipulation: Ps watch a movie: a) having been instructed to not look at words flashed on the screen, or b) with no attention instruction
3. Drink manipulation: Ps drink: a) lemonade sweetened with sugar or b) lemonade sweetened with Splenda
4. Participants complete filler questionnaires (MediaLab) for 12 minutes
5. Participants complete key dependent measure of 4 columns (80 trials) of Stroop task, with performance recorded manually by (blind) experimenter.

RESULTS:

Following the analysis by Gailliot et al., a 2 (self-control condition: low, high) x 2 (glucose condition: sugar, Splenda) ANCOVA (controlling for baseline errors) was conducted. The key predicted interaction was not significant in our data, F(1, 115) = 0.122, p = .73, indicating that any effects of the self-control manipulation on stroop performance did not differ by glucose condition.

In the original Gailliot et al., participants in the sugar condition did not differ in Stroop performance following high vs. low self-control (F = 1.12, ns) but participants in the Splenda condition performed worse following high vs. low self control (d = 0.73; no means are presented). This serves as the basis for the claim that a glucose drink, but not a placebic Spenda drink, eliminated the depletion effect observed on Stroop task performance. There was no evidence for this difference in our data. The opposite pattern was instead observed, with participants in the Splenda condition performing worse when in the low depletion condition (M = 1.23, SE = .206, 95% CI = 0.83, 1.64) relative to the high depletion condition (M = .74, SE = .201, 95%CI = 0.35, 1.14), d = 0.33. The same pattern was observed for participants in the glucose drink condition, with worse performance following low (M = 1.26, SE = .213, 95% CI = 0.84, 1.68) relative to high (M = 0.92, SE = .210, 95% CI = 0.50, 1.33) depletion, d = .11. Indeed, the only significant effect was a main effect of depletion, F = 4.00, p = .048.

It is also worth noting the relationship between the covariate and the dependent measure (i.e., between baseline error rates and post-manipulation error rates). The correlation in the original Gailliot et al. manuscript is not reported, but in our data this effect was F = 18.24, p < .001. This was a stronger effect than the reported interaction, meaning that for the purposes of understanding self-control, whatever effect a glucose drink may have is likely to be dwarfed by stable individual differences in self-control, at least as measured by Stroop performance.

Data, codebook, and experimenter script are available from cesario@msu.edu
Any Known Methodological Differences
(between original and present study)?
The only methodological difference was that we did not include the manipulation check in which participants report looking at the words less often when instructed to do so.
Email of Investigator
Name of individuals who
actually carried out the project
Location of ProjectMichigan State University, East Lansing, MI, USA
Characteristics of Subjects
(subject pool, paid, etc.)
University students from subject pool
Where did these subjects reside?Unspecified
Was this a Class Project?No
Further Details of Results as pdf
Additional Comments
Email of Original Investigator
Quantitive Information
I have complied with ethical standards for experimentation on human beings and, if necessary, have obtained appropriate permission from an Institutional Review Board or other oversight group.
TAG: Attention TAG: JDM TAG: Language TAG: Learning TAG: Memory TAG: Perception TAG: Performance TAG: Problem Solving TAG: Social Cognition TAG: Social Psychology TAG: Thinking

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