Effects of early and delayed visual experience on intersensory functioning in bobwhite quail chicks
The issue of the relative importance of early vs. delayed experience to behavioral development has proven to be a difficult one to address empirically. I focused on this issue by manipulating the timing of the onset of visual experience of avian embryos and hatchlings. Normally reared bobwhite quail chicks are known to require only maternal auditory cues to direct their social preferences in the first days following hatching. However, by 3 days following hatching quail chicks require both auditory and visual cues to direct their social preferences. In contrast, birds which have received unusually early visual experience as embryos require both auditory and visual cues on the day following hatching, indicating an accelerated pattern of the emergence of this type of early intersensory functioning.
Hatchlings reared under conditions of delayed visual experience (deprivation) continue to rely on maternal auditory cues alone up to 4 days following hatching, and do not demonstrate a preference for combined audio-visual cues, indicating a decelerated pattern of the emergence of this type of early intersensory functioning. Here I report that quail chicks that received both early visual experience as embryos and delayed visual experience as hatchlings exhibit a pattern of intersensory functioning similar to that seen in normally reared chicks. That is, they do not require combined auditory and visual cues to direct their social preferences until 3 days following hatching. These results indicate that, at least under the present experimental conditions, the influence of early and delayed visual experience on the development of intersensory functioning is essentially equivalent. These findings are discussed in terms of the role of timing of sensory experience in early perceptual organization.