Newborn response to auditory stimulus discrepancy.

Newborns were assessed for their recovery of head turning toward laterally presented auditory stimuli (titi) that varied from a familiar standard on 1 of 5 levels of fundamental frequency. Following habituation to repeated standard trials, newborns recovered to 14% and 21%, but not to 0%, 7%, or 28% discrepancies, indicating that recovery was a quadratic function of the degree of stimulus-schema discrepancy. Moreover, newborns reliably turned away from the standard stimulus during posthabituation no-change control trials, indicating that the neural network associated with that stimulus was not fatigued. Infants in every condition showed recovery of head turning to a novel posttest stimulus (papa). These data are interpreted with a dual processing model postulated to include both reflexive (context-independent) orientation and stimulus-schema comparison process (context-dependent) orientation.