Auditory spatial responses of young guinea pigs (Cavia porcellus) during and after ear blocking.

Newborn guinea pigs were tested to determine their ability to approach an auditory stimulus early in development. Observations of the behavior of 1-4-day-old animals in a circular eight-choice maze revealed a pronounced tendency to orient toward and approach a tape-recorded signal of guinea pig vocalizations. The occurrence of approach responses was reduced to chance in animals tested with one ear occluded by wax ear plugs which attenuated but did not totally eliminate sound. The effect of monaural ear blocks was more severe than binaural blocks, which reflects the importance of binaural cues in the maintenance of approach responses to sound. In a second study, the ability of older animals, 11-31 days of age, was examined. Directional approach responses to sound were also evident at this age, and ear plugs disrupted performance only under monaural conditions. Furthermore, in animals raised from birth with monaural ear blocks but tested without ear plugs, there was a subsequent disruption of performance for at least 21 days. These results indicate the importance of binaural cues in the development of early auditory spatial responses and suggest the need for appropriate binaural experience for subsequent localization of sounds.