Speed-accuracy trade-offs and individually consistent decision making by individuals and dyads of zebrafish in a colour discrimination task

Speed-accuracy trade-offs are well studied in human decision making, but we are only beginning to understand how such trade-offs affect other animals. Similarly, it is poorly understood how consistent individual differences in decision making are influenced by their social context. Here we investigated whether zebrafish, Danio rerio, show individual consistency ('personality') in speed-accuracy trade-offs based on a colour discrimination task, and how pairs of fish with distinct personalities make consensus choices. The results showed that zebrafish exhibit between-individual speed-accuracy trade-offs: some fish made 'careful', slow but accurate decisions, while others made swift but less accurate choices. We also found that these decision-making strategies were constant over time: fish retained the same strategy for 3 days. When testing pairs of careful and fast-and-inaccurate individuals, the combined choice strategy was intermediate in speed, but statistically indistinguishable from the careful individual, whereas accuracy of the dyad decision was moderately higher than that of each individual when tested singly, although this was again not significantly different from the more careful individual. For the first time, our study thus demonstrates that two individuals influence one another's speed-accuracy trade-off in decision making.