Coffee with co-workers: role of caffeine on evaluations of the self and others in group settings

Abstract

This research explores the effect of consuming a moderate amount of commercially available caffeinated coffee on an individual’s self-evaluated participation in a group activity and subsequent evaluations of the experience. Across two studies, results show that consuming a moderate amount of caffeinated coffee prior to indulging in a group activity enhances an individual’s task-relevant participation in the group activity. In addition, subjective evaluations of the participation of other group members and oneself are also positively influenced. Finally, the positive impact of consuming a moderate amount of caffeinated coffee on the evaluation of participation of other group members and oneself is moderated by a sense of an increased level of alertness.

Keywords

Caffeine group discussion coffee

Introduction

Researchers in various disciplines like psychology, pharmacology and marketing have shown interest in the effects of caffeine on a person’s behavior. Interest in caffeine effects is not surprising because of the general belief that caffeine gives a boost to one’s alertness levels, thus potentially affecting performance on various tasks. Further, coffee consumption has been increasing both in the USA, and in the rest of the world. In a recent report released by the National Coffee Association, 62% of Americans indicated that they have had coffee within the past day, a jump of 5% from 2013 (Brown, 2017).

Previous research on caffeine effects has generally focused on an individual person. That is, researchers have tried to understand how caffeine affects one’s attention to task variables, one’s memory for information and the extent to which information is processed when one is under the influence of caffeine. While the focus on caffeine effects on an individual is appropriate, industry data show that a large amount of coffee is consumed in business meetings with more than one person present at the meeting. In a recent survey by Hilton Worldwide (eHotelier, 2015), nearly 60% of Chinese and British professionals indicated that most successful meetings happen over coffee and tea. They also indicated that coffee and tea are important to a successful meeting.

Reviewing the literature on caffeine effects on the performance of individuals, Faber et al. (2017: p.10) expressed surprise that “no study has been published yet that investigates the influence of caffeine on the group-specific aspects of performance”. Our research addresses this gap in the caffeine effects literature. We examine whether caffeine affects an individual’s extent of participation within a group activity, and the subsequent self-evaluation of their participation and that of the group members. Our results show that a moderate amount of caffeine positively affects participation in a group discussion and subsequent evaluations of oneself and of one’s group members.

Effects of caffeine on individuals

Several studies have shown caffeine increases attention and the distribution of attention over stimuli, suggesting that people focus on their task better when they consume caffeine (Kenemans and Lorist, 1995; Kerr et al., 1991; Ruijter et al., 2000). The increase in attention is generally measured by how alert people are in a given task situation. For example, in one study by Regina et al. (1974) that utilized a simulated driving task, each of 24 study participants drove an automobile simulator for 90 min after ingesting 200 mg of caffeine or a placebo. Assuming caffeine effects to have diminished over the duration of the exercise, and wear-out to have set in due to the driving task, participants were asked to consume a supplemental dose of the same medication taken initially (200 mg of caffeine or placebo) and to drive for another 90 min. The simulator provided a realistic set of stimulus inputs that varied in complexity as is normally found in regular driving, thus providing ample opportunities to measure one’s alertness at various points of driving. Both the initial and the supplemental doses of caffeine significantly enhanced performance beyond that found with placebo on each of four measures of alertness used in the study. Thus, caffeine appears to help individuals focus on important elements of a task.

Caffeine has also been linked with enhanced memory. For example, Ryan et al. (2002) showed caffeine to moderate time-of-day memory effects in older people (i.e., better memory in the early part of the day compared to later in the day). Using older adults (> 65 years) as study participants, the authors found that coffee arrested the decline of memory from morning to evening in older adults. Similar enhanced memory effects were reported by Warburton (1995).

It appears that caffeine’s effects on various performance variables are mediated by the increased attention or alertness experienced by people. The increased attention typically leads to enhanced performance on a number of tasks, such as problem solving, logical reasoning and mental arithmetic (Van der Stelt, 1999). Echoing the mediating role of attention, Nehlig (2010) concluded that caffeine may not be viewed as a “pure cognitive enhancer” but instead act indirectly through its effects on arousal and alertness in a person. It is worth noting that enhancements in learning or other memory tasks due to caffeine ingestion have not been found uniformly by researchers. Several studies have failed to show effects of caffeine on memory tasks (e.g., Loke, 1988; Mitchell and Redman, 1992; Schmitt et al., 2003; Terry and Phifer, 1986). In her review of the literature on caffeine effects on memory, Nehlig (2010) concluded that caffeine effects vary with the type of task, and are most likely to manifest in tasks that require the use of working memory to a limited extent.

Some researchers have investigated whether caffeine increases one’s likelihood of processing information that they have been exposed to. Such increases in systematic processing should lead to predictable persuasion effects based on prior literature in this area. In fact, caffeine has been shown to increase persuasion compared to a non-caffeine (placebo) condition (Martin et al., 2005; Mintz and Mills, 1971). In the Martin et al. (2005) study, it was found that study participants showed greater attitude change after reading a message on euthanasia having consumed orange juice that was caffeinated before they read the message; further, message-relevant arguments were found to mediate changes in attitude. Thus, caffeine appears to increase one’s processing of relevant information that is presented to them, and if the information is persuasive, it results in greater persuasion.

Caffeine and group decision making

There are several occasions when individuals work as part of groups to achieve intended outcomes. These groups can be work groups at the office, ad hoc groups formed for social activities or other group activities (e.g., students working on group projects at school). In general, research on group performance has identified process gains and losses as the outcomes of group work, compared to individual work (e.g., Ziegler et al., 2000). These gains and losses are expected to arise from three sources: increased or decreased motivation to perform the task when one is part of a group, increased or decreased learning that occurs within a group that will affect an individual’s contribution, and increased or decreased coordination among group members that aids or hinders collective wisdom to affect group outcomes positively.

Faber et al. (2017) propose that caffeine consumption can interact with these group process gains or losses to affect final outcomes of a group task. For example, if an individual is feeling tired and unmotivated, caffeine can increase alertness and enable the individual to participate more actively in group activities. Similarly, because of increased alertness, caffeine may make individuals feed off each other more positively, thus increasing gains from coordination. At least one study (Smith et al., 1992) has shown that caffeine affected how people felt about themselves in a positive way, which may aid one’s participation in group work.

In sum, caffeine has been shown to affect an individual’s alertness, which then leads to better performance on tasks involving reaction time and other such alertness variables. The increased alertness has been shown to enhance memory in certain situations, and increase systematic processing of messages encountered. Caffeine has also been shown to make people feel better. All of these effects lead us to the prediction that caffeine will increase individuals’ participation in a group activity, increase topic-relevant thoughts because of increased focus and lead to a more positive evaluation of the overall group performance. These predictions were tested in two experiments that are described below.

Experiment 1

Experiment 1 was conducted to test our expectation that members of a group that consume caffeine before participating in a group task evaluate themselves and other members of the group more positively compared to those who consume caffeine after the group activity. Therefore, the study was a simple two-cell design with one group consuming coffee before the group discussion and the other consuming coffee after the group discussion.

Method

Participants and design

Seventy-two undergraduate students at a large Midwestern university participated in this study in exchange for extra course credit. For participant recruitment, the study was described as two ostensibly separate studies merged together: one being tasting a new brand of coffee scheduled for launch in the United States and secondly the selection of a new group discussion topic to be added to an existing list of topics for a group discussion competition in graduate school. Participants were recruited on the basis of pre-determined criteria that they: (a) were low to moderate coffee drinkers with maximum consumption of four cups of coffee per day, (b) were not allergic to any form of coffee and (c) were committed to restraining from drinking coffee 5 h prior to the study (participants were informed that a minimum of a 5 h gap was essential to clear the pallet). The recruitment criteria were set up with the objective of recruiting a sample reflective of moderate coffee drinking consumers. A two-cell between-subjects design (caffeinated coffee before vs. after) was employed for the study and participants were randomly assigned to any one condition.

Procedure

The study was conducted between 8:00 a.m. and 11:00 a.m. After checking in, participants were randomly assigned to one of two rooms, each with a table and five chairs. For the caffeine-before condition, the first task was a 15 min coffee-tasting task. Participants were administered 12 oz of “Starbucks light roast” coffee (approximately 270 mg of caffeine) in a plain white cup. To make them drink the full 12 oz, they were instructed to focus on and identify any potential difference in taste between the first four sips of coffee from the top and the last four sips from the bottom of the cup. Participants were allowed to add sugar and cream per their preference.

Given reports in the literature about a 30 min ingestion time for caffeine effects to manifest, participants were directed to multiple filler tasks before the critical group discussion task was administered. First, a 5 min filler task of rating the coffee was employed to support the cover story. Then, participants watched two neutral videos featuring future technology along with a filler questionnaire rating the videos. These filler tasks consumed slightly over 30 min, after which the critical task was administered. Participants first read a brief description about the Occupy movement (Appendix). The article contained both the supporting groups’ and critics’ perspectives after the description of the Occupy movement. Participants were instructed to discuss the topic and make a recommendation about its inclusion in the competition; 15 min were allotted for the group discussion and participants conducted the group discussion without any supervision. Finally, participants were shifted to individual desks where the dependent measures (Appendix) evaluating the group members and self were incorporated. For the caffeine-after condition, all the stages were held constant except that the coffee-drinking and rating task was employed at the end of the study.

Results and discussion

Evaluation of the group

The group-evaluation index was calculated (mean of the items in the scale) and subjected to one-way ANOVA (analysis of variance) with the condition (caffeine before vs. after) as the independent variable. The results revealed a main effect of drinking caffeinated coffee before the group discussion. Participants who consumed caffeinated coffee before the group discussion rated their group more positively compared to those who consumed it after (M_{caffeine-before} = 1.3 vs. M_{caffeine-after} = 0.47; F (1, 70) = 13.35, P = 0.00) (Table 1).

Table 1.

Results.

Experiment 1	Dependent measure	Conditions
		Caffeine mean (SD)	No-caffeine mean (SD)
	Group-evaluation index	1.3264 (0.82)	0.4722 (1.33)
	Self-evaluation index	1.9352 (0.798)	1.37 (1.077)
Experiment 2		Caffeine mean (SD)	Decaffeinated mean (SD)
	Group-evaluation index	0.951 (0.99)	0.28 (1.4)
	Self-evaluation index	1.76 (0.93)	0.99 (1.2)
	Attitude toward group members	6.09 (1.00)	5.38 (1.18)
	Willingness to work with the group again	1.81 (1.25)	0.50 (1.65)
	Alertness	36.70 (7.76)	31.63 (9.45)
	Group discussion data	Caffeine mean (SD)	Decaffeinated mean (SD)
	Total number of arguments	46.64 (23.70)	39.12 (19.66)
	Relevant arguments	25.50 (6.92)	16.25 (8.27)
	Irrelevant arguments	21.14 (21.37)	22.87 (21.06)

Evaluation of self

The self-evaluation index was calculated in a similar way and subjected to one-way ANOVA with the condition (caffeine before vs. after) as the independent variable. The results again revealed a main effect of caffeinated coffee. Participants who consumed caffeinated coffee before the group discussion task rated their own performance more positively compared to those who did not consume caffeinated coffee (M_{caffeine before} = 1.93 vs. M_{caffeine after} = 1.37; F (1, 70) = 6.38, P = 0.01).

Discussion

Experiment 1 demonstrated that people who consumed caffeinated coffee before a group task evaluated the group’s performance more positively than those who consumed coffee after the group task. Further, they evaluated their own performance more positively compared to the self-evaluations of those who consumed coffee after the group task. Thus, consumption of caffeine during a group task appears to elevate one’s evaluations of themselves and other group members.

Even though the objective of experiment 1 was only to establish the presence of a caffeine effect in a group task, there are several potential criticisms of the methodology that we adopted in the study. First, in the caffeine-before condition, participants were served coffee at the beginning of the session, which could have led to increased familiarity and camaraderie among them as they consumed the coffee. It is possible that this familiarity or the comfort of knowing each other led to greater discussion rather than the ingestion of caffeine. Second, in the caffeine-after condition, coffee consumption occurred after incorporating all the tasks and the dependent measures, leading to an asymmetric study design. That is, the group discussion occurred earlier for the caffeine-before participants than for the caffeine-after participants. One may argue that the participants in the caffeine-after condition were not sufficiently warmed up to participate in the group task. Third, while the effect of caffeine on one’s alertness was argued to be the source of increased participation in the group task, no process measures were included in the study so we do not know what mediated the effects of caffeine on group evaluations. Finally, our measures were self-evaluations and evaluations of other group members rather than the amount of participation in the task itself. Measures showing increased group activity would be more indicative of the effect of caffeine on performance rather than self-reported evaluations. Experiment 2 was designed to overcome the procedural limitations of experiment 1.

Experiment 2

Method

Participants and design

Sixty-one undergraduate students at a large Midwestern university participated in this study in exchange for extra course credit. Recruitment criteria were identical to those of experiment 1. A two-cell (coffee: caffeinated vs. decaffeinated) between-subjects design was employed for this study and participants were randomly assigned to one of the conditions. The decaffeinated coffee condition helped to alleviate concerns with our prior study that students in the coffee condition had more time to get to know each other as they consumed coffee. Thus, every participant consumed coffee with other participants in the group, with the difference being whether they were dosed with caffeine or not, the independent variable in this study. All participants within a group consumed the same type of coffee, either caffeinated or decaffeinated. Due to randomization, participants were not aware of the type of coffee that they were drinking (regular vs. decaffeinated), thus eliminating the potential for demand effects.

Procedure

The procedure employed for this study was similar to that of experiment 1. Each participant was administered 12 oz of either “Starbucks light roast” (approximately 270 mg of caffeine) or “Starbucks decaf” (approximately 3–5 mg of caffeine) with similar instructions as in experiment 1. The filler tasks and group discussion task were identical to those in experiment 1. After participants completed the filler tasks to give time for the caffeine to be ingested, they were moved to breakout rooms for the main task (group discussion) where they were presented with the same task as in experiment 1. Upon completion of the group discussion task, participants came back to their original desks where the other dependent measures were employed. The dependent measures incorporated in the study were evaluation of the group and self-evaluation, level of alertness, attitudes towards the group and willingness to work again with the group. In addition, an audio of the group discussion was collected that was coded and analyzed (Appendix).

Results

Self-reports

The group evaluation (Cronbach’s alpha = 0.758) and self-evaluation scores (Cronbach’s alpha = 0.874) were subjected to one-way ANOVA with the condition (coffee: caffeinated vs. decaffeinated) as the independent factor. The analysis revealed a main effect of caffeine. Participants who consumed caffeinated coffee rated their group more positively (M_Caffeine = 0.95) compared to those who consumed decaffeinated coffee (M_Decaf = 0.28; F (1, 59) = 4.53, P = 0.03). A similar pattern was observed for self-evaluation. That is, participants who consumed coffee with a higher caffeine content rated their own participation in the discussion more positively (M_Caffeine = 1.76) compared to those who consumed decaffeinated coffee (M_Decaf = 0.99; F (1, 59) = 7.66; P = 0.008). These results replicated those found in experiment 1 (Table 1).

Attitude toward group members

The mean attitude (Cronbach alpha = .809) toward the group members was calculated and subjected to one-way ANOVA with the condition (coffee: caffeinated vs. decaffeinated) as the independent factor. In line with our expectation, the analysis showed a main effect of caffeine. That is, participants who consumed coffee with a higher caffeine content reported more positive attitudes (M_Caffeine = 6.09) towards the group compared to those who consumed decaffeinated coffee (M_Decaf = 5.38; F (1, 58) = 6.29, P = 0.01).

Willingness to work with the group again

The scores of one’s willingness to work with the group again were subjected to one-way ANOVA with the condition (coffee: caffeinated vs. decaffeinated) as an independent measure. The analysis revealed a main effect of caffeine. In line with attitude data, participants who consumed coffee with a higher amount of caffeine expressed an increased willingness to work with the group again (M_Caffeine = 1.81) compared to those who consumed decaffeinated coffee (M_Decaf = 0.50; F (1, 59) = 12.15, P = 0.001 ).

Alertness

The alertness index was calculated, with higher scores indicating higher levels of alertness, and subjected to one-way ANOVA with the condition (coffee: caffeinated vs. decaffeinated) as an independent measure. The analysis revealed a main effect of caffeine. Participants who consumed coffee with a higher caffeine content indicated higher levels of alertness (M_Caffeine = 36.70) compared to those who consumed decaffeinated coffee (M_Decaf = 31.63; F (1, 59) = 5.26, P = 0.02).

Mediation analysis

To further explore the process underlying the effects of caffeine on self-evaluation and group evaluation, three separate mediation analyses were conducted with self-evaluation, evaluation of group members and attitude towards the group as dependent measures using the Hayes method (Preacher and Hayes, 2016). The type of coffee consumed (coffee: caffeinated vs. decaffeinated) was the independent measure. The mediation analysis was conducted using conceptual model 4 of the Hayes process with alertness as the mediating variable using 10,000 bootstrap samples. The analysis revealed a significant indirect effect for the path: type of coffee → alertness → evaluation of the group (β = 0.0897, SEM = 0.014, lower level confidence interval (LLCI) = 0.034 and upper level confidence interval (ULCI) = 0.4942). Similarly, for self-evaluation as THE dependent measure, mediation analysis conducted using alertness level as a mediator revealed a significant indirect effect for the path: Type of coffee → Alertness → self-evaluation (β = 0.086, SEM = 0.0121, LLCI = 0.0331 and ULCI = 0.4776). In addition, for attitudes towards the group as the dependent measure, mediation analysis with alertness level as a mediator revealed a significant indirect effect for the path: type of coffee → alertness → attitude (β = 0.0433, SEM = 0.0157, LLCI = 0.0072 and ULCI = 0.3109).

Group discussion audio data

The group discussion data was coded by two independent coders based on the coding framework (Appendix A) for the total number of arguments generated in the group discussion (correlation among coders = 0.893), the number of arguments that were relevant to the topic (correlation among the coders = 0.887) and the number of arguments that were irrelevant to the topic (correlation among the coders = 0.749). Since the data were collected for each group separately, the coding was done at the group level. The correlation between the two coders was positive and high, so a composite of the ratings was calculated and used for analysis. For one group, there was inconsistency in the direction of the coding and hence a third coder was brought in to code the data. The third coder’s data was closer to second coder’s data and hence they were used for calculating the composite score for this group discussion. A total of 13 (n = 13) groups were coded for this analysis.

The total number of statements generated, number of topic-relevant statements and number of topic-irrelevant statements generated in the group discussion were independently subjected to one-way ANOVA with condition (coffee: caffeinated or decaffeinated) as the independent measure. No significant difference was found for the total number of generated statements between the groups (M_Caffeinated = 46.64 vs. M_Decaf = 39.12 F (1, 11) = 0.362, P = 0.56). However, the groups that consumed caffeinated coffee generated more topic-relevant statements (M_Caffeinated = 25.50) compared to those who consumed decaffeinated coffee (M_Decaf = 16.25; F (1, 11) = 4.824, P = 0.050). Interestingly, no significant difference was found in the number of topic-irrelevant statements generated by the two groups (M_Caffeinated = 21.14 vs. M_Decaf = 22.87 F (1, 11) = 0.021, P = 0.886). Thus, caffeine appears to increase topic-relevant statements significantly, but not topic-irrelevant statements. The difference in the number of topic-relevant statements generated, while statistically significant between the two groups, was not sufficient to make the difference in total generated statements significantly different, presumably due to high variance in the number of topic-irrelevant statements.

Discussion

Prior research on caffeine effects on individual task performance has focused on how caffeine affects one’s attention to a task, memory for information, and the type of processing of information. In general, caffeine appears to increase one’s alertness, increase systematic processing and make one feel more sociable. Surprisingly, with much coffee consumption occurring in group settings where significant decision making takes place, there has been no research on coffee and its effects on one’s performance in group tasks. Our study fills this gap in the literature.

Three findings from our research need to be highlighted. First, caffeine enhanced individuals’ evaluations of their own participation in the group work and of the group as a whole. People who ingested coffee felt better about themselves and their group members. Second, caffeine increased topic-relevant discussion, not just overall discussion. It appears that people are able to focus more on the topic after ingesting coffee, a finding that is consistent with prior findings on caffeine sustaining attention to a task. Finally, it is not caffeine that affects group task performance, it is the increased alertness which led to our findings, which is again consistent with prior research on caffeine.

It is not clear how alertness affects group member evaluation. It is possible that people enjoy their own proclivity to participate in the discussion and experience a feeling of increased self-worth. Further, since the interaction is more topic-specific and leads to a closure, people may experience greater satisfaction with the group. An examination of the verbal protocols showed general agreement between members of the group when they ceased their discussion. We do not know whether such positive evaluation of the group would have emerged if the topic was more controversial and the group could not reach a consensus. This issue should be examined in future research because it separates cognitive basis of the evaluation from an affective basis.

Our research consciously avoided getting into the pharmacological effects of caffeine on the central nervous system of individuals. How self-perceptions of increased alertness relate to changes in the brain is an issue that needs further research. Another issue that is not clear is whether it is a real increase in alertness that contributed to increased performance or whether it is relief from withdrawal experienced by subjects who had not consumed coffee before they arrived at the experiment location (e.g., Rogers et al., 2013). We thank one reviewer for pointing this out and consider it an interesting topic for study in the future. Similarly, it would be interesting to know if people feel more relaxed in the presence of others after consuming coffee (cf. Nehlig 2010).

The group task used in our research was fairly simple and did not require much creativity or intellectual resources for its completion. In group tasks involving significant creative thought and collaboration, the role of caffeine is not clear. For example, what would have happened if the task required out-of-the-box thinking? Further, it has been found that increased caffeine consumption (i.e., more than four cups a day) might actually make a person jittery and inattentive. We did not study the potential negative effects of high doses of caffeine.

Yet, we believe that we have an interesting set of findings with respect to how a group performs in a task that requires the exchange of ideas between people when the participants have caffeine in their system vs. not. Caffeine seems to focus their discussion on the topic, make people participate more than they would without caffeine, and leave them feeling better about their own participation and others’ participation.

Supplemental Material

JOP760665_Appendix – Supplemental material for Coffee with co-workers: role of caffeine on evaluations of the self and others in group settings

Supplemental material, JOP760665_Appendix for Coffee with co-workers: role of caffeine on evaluations of the self and others in group settings by Vasu Unnava, Amit Surendra Singh and H. Rao Unnava in Journal of Psychopharmacology

Footnotes

Acknowledgements

We would like to thank King Chan for his assistance in collecting data for the first study reported in this paper

Declaration of Conflicting Interest

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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