Psychologists have shown that people tend to underestimate how long things will take them, both in their personal and business lives. But most research into ‘the planning fallacy’, as it’s known, has been with individuals. Now psychologists in Canada have shown that when working in a group, we’re even more unrealistically optimistic about how quickly we can get things done.
In two studies, Roger Buehler at Wilfrid Laurier University and his colleagues followed hundreds of business students as they undertook lengthy group projects. They asked the students to estimate individually how long the different project stages would take, and they also asked them to make a group estimate once they had discussed the projects together. Their estimates were compared with how long the work actually took. In a third study, hundreds of participants estimated individually, and in groups, how long a group puzzle task would take them. As a guide, they were even told how long the task had taken other groups. Findings from all three studies pointed to the same conclusion – in groups we become even more unrealistically optimistic about how long things will take us.
Why might this happen? From notes they were asked to make afterwards, it was found that when participants made time estimates in a group, they tended to think more positively, focusing on things like their skill at the task, or the apparent ability of their team-mates. It’s also possible that in groups people might want to be seen to be positive by their team mates, thus encouraging them to make more optimistic estimates.
“These findings may be applicable to many collaborative work ventures” the authors said. “…Forecasters may well be advised to collect and aggregate individual forecasts, instead of engaging in group discussion”.
Buehler, R., Messervey, D. & Griffin, D. (2005). Collaborative planning and prediction: does group discussion affect optimistic biases in time estimation. Organisational Behaviour and Human Decision Processes, 97, 47-63.