The averaged evoked potential in the study of infant auditory discrimination

This study was conducted to determine whether an averaged evoked potential technique using a random-versus-repetitive presentation mode, could be used to study auditory discrimination in infants. We were interested in which stimulus mode, random-novel or repetitive, would result in greater responsiveness in terms of central nervous system evoked potential latencies and amplitudes. Recordings were made of 20 normal full-term infants between 14 and 18 weeks of age. Two different stimuli were used to create the random and repetitive modes: a burst of 125-Hz square waves (a buzz) and a burst of white noise. Two interstimulus intervals were also used, fast (1,000 msec) and slow (1,700 msec), to determine which rate is most effective. Ten of the infants were tested at the slow rate and 10 at the fast rate. Results for the N2 component of the averaged evoked potential (AEP) showed a main effect of presentation mode with a shorter latency for random versus repetitive. The shortest onset latency was for the random stimulus at the fast rate. The mean amplitude of N2 for all repetitive presentations at the slow rate was significantly larger.