Fig. 2.

Results of Experiment 1 (synchronous coordination). a Reaction times were less variable in the joint condition than in the individual condition. Error bars display within-subject confidence intervals (Loftus and Masson 1994). b Reaction times were faster in the joint compared with the individual condition. c Zero-order correlations showed that response asynchronies were positively correlated with standard deviation and mean reaction times. Moreover, partial correlations (in brackets) suggest that variability had a direct influence on asynchrony (thick black arrow), whereas speeding supported coordination only indirectly (significance levels: *P < .05; **P < .001)