A pair of studies conducted by scientists from the University of California at Davis and the Ohio State University found that people gave more positive reviews for their group’s performance on a task if they drank caffeinated coffee beforehand; one of the studies also showed that people talked more in a group setting under the influence of caffeinated coffee — but they also were more on-topic than those who drank decaf. The studies are described in a paper published in the Journal of Psychopharmacology.
“Coffee seems to work its magic in teams by making people more alert. We found that increased alertness was what led to the positive results for team performance,” said co-author Amit Singh, a doctoral student at the Ohio State University.
“Not surprisingly, people who drank caffeinated coffee tended to be more alert.”
“While many studies have looked at how caffeine affects individual performance, this is the first to examine the impact it has on teams.”
The first study involved 72 students who said they were coffee drinkers. They were instructed not to drink coffee before the experiment.
Half of them first participated in what they were told was a coffee-tasting task. They were split into groups of five.
After drinking a cup of coffee and rating its flavor, they were given 30 min of filler tasks to give the caffeine a chance to kick in. The other half of the participants did the coffee tasting at the end of the experiment.
Each group then read about and were asked to discuss a controversial topic. After a 15-min discussion, group members evaluated themselves and the other group members.
“The results showed that those who drank the coffee before the discussion rated themselves and their fellow team members more positively than did those who drank coffee after the discussion,” Singh said.
The second study was similar, except that 61 students all drank coffee at the beginning of the study. However, half drank decaf and the others drank caffeinated brew.
Those who drank caffeinated coffee rated themselves and their fellow group members more positively than those who drank decaf. It had to do with alertness.
All participants rated how alert they felt at the end of the study, and those who drank the caffeinated coffee rated themselves as more alert than the others.
A key finding was that people who rated themselves as more alert — whether they drank caffeinated coffee or not — also tended to give higher marks to themselves and their fellow group members.
This suggests that any intervention that increases alertness may also produce similar results.
“We suspect that when people are more alert they see themselves and the other group members contributing more, and that gives them a more positive attitude,” Singh said.
But the caffeine does more than just increase good feelings. Singh and co-authors did an analysis of the group discussion in the second study, rating how much each group member talked and stayed on topic.
The results showed that people tended to talk more after drinking caffeine, but they also tended to stay more on topic.
“They’re talking about more relevant things after drinking caffeinated coffee,” Singh said.
People who drank caffeinated coffee were more likely than those who drank decaf to say they would be willing to work with their group again.
“Even though they are talking more, agreeing and disagreeing, they still want to work with them again. Coffee didn’t seem to make group discussions too uncomfortable and disagreeable,” Singh said.