Bobwhite quail embryos were exposed to 5 or 10 min/hr of either bobwhite chick contentment calls or bobwhite chick distress calls. Results revealed that embryos exposed to 5 or 10 min/hr of distress calls continued to respond to maternal auditory cues into later stages of postnatal development in comparison to controls (Experiments 1A & 2A) and failed to demonstrate species-typical responsiveness to maternal visual cues (Experiments 1B & 2B). In contrast, embryos exposed to 5 min/hr of contentment calls continued to respond to maternal auditory cues into later stages of development (Experiment 2A) and exhibited species-typical patterns of visual responsiveness (Experiment 2B). Embryos exposed to 10 min/hr of contentment calls responded to maternal auditory cues into later stages of postnatal development (Experiment 1A), but showed an accelerated responsiveness to maternal visual cues (Experiment 1B). Behavioral activity measures revealed that augmented auditory stimulation (whether contentment or distress vocalizations) appeared to foster an increase in physical responsiveness when compared to controls (Experiment 3). Taken together, these results suggest that the type and amount of sensory stimulation interact during the prenatal period to influence the course of perceptual development. / Ph. D.