The Effect of Patterned Sound Deprivation upon Auditory Discrimination in Albino Rats

Abstract

To test the hypothesis that prior patterned or varied auditory experience was necessary for the development of auditory frequency discrimination and auditory pattern discrimination, groups of sprague-Dawley albino rats were deprived of patterned sound from birth by the novel technique of rearing them in ‘white’ noise. The sound deprived rats learned a frequency discrimination as easily as controls reared in varied sound conditions, but showed inferior performance on an auditory pattern discrimination task. supporting experiments showed that the inferiority of varied sound deprived animals on the pattern discrimination task was not likely to have been due to their emotional state at the time of the testing nor to their inferiority in learning to respond in a discrimination task compared with non-deprived controls. Open-field testing shoved that the sound deprived subjects did not differ from non-deprived controls in ‘emotionality’. The sound deprived rats were not inferior, either, to controls on a complex visual discrimination task. Experiments were also carried out to explore the effect of various durations of patterned sound deprivation and the effect of the deprivation at various times in the life cycle of the rat on auditory pattern discrimination. The results of these experiments favoured an explanation for the effect of varied sound experience which proposed that patterned auditory discrimination development depended, simply, on prior experience with varied sound rather than an explanation which proposed that the effect depended on varied sound experience during a particular sensitive period in the life of the rat. The research involved a total of seven different experiments, the similarities in the findings of which when compared with those of other investigators working in the area of the effects of deprivation of patterned light on visual discriminations were noted. The present experiments support generalizations about the role of prior experience on later behaviour, based largely on experiments in the visual mode, by supplying evidence from another sensory mode.