Operant response in infants as a function of time interval following signal onset

This study investigated the hypothesis that estimates of infant auditory threshold are lowered by extending the duration of individual test trials such that infants have more time to detect and respond to the acoustic signal. Forty 8- and 12-month-old infants were evaluated with an operant procedure to determine response latencies at four near-threshold levels. Resulting data were used to estimate the effect of trial duration on threshold by calculating the response performance that occurred at several intervals following signal onset. Findings indicate that most detection responses occurred in the initial 4 sec of the test trial, and use of an 8-sec trial interval yielded little gain in performance. The data reflect an insignificant shift (< 5.0 dB) in threshold as a function of extended trial intervals.