Stronger and faster pupillary light reflexes in infants at risk for autism. (A) Relative pupil constriction, (A0
2 − Am2)/A0
2, was calculated for individual trials. Latency was determined from the minima of the second derivative of the pupil-size time series (maximum constriction acceleration). Traces show actual data from one trial from one infant. (B) Scatterplot showing individual data for both measures. (C, D) Groups differed in both latency and constriction amplitude. *P < .05, ***P < .005; error bars show standard error of the mean.