Harmonization of the fastest and densest responses embodies the humanlike reaction time of mice

Reaction time (RT) is important in evaluating delayed latency in behavior. Unlike that of humans, the RT of animals, in which the stimulus–response relationship is not one-to-one due to repeated responses per trial, may exhibit two peaks of the fastest and densest responses in a distribution of responses. We determined whether the two peak latencies are aligned for a single RT by controlling stimulus duration. In delay conditioning with mice using sound cues of 10, 5, and 2s, the 2s group exhibited the strongest positive correlations between the two peaks, as well as responses’ number and accuracy rate, suggesting coupling of the fastest and densest responses, and a one-to-one relationship between stimulus and response, respectively. We propose the use of harmonization of the two peaks, elicited by stimuli that induce minimal responses, as a criterion for designing animal experiments to mimic humanlike RT.