Comparison of Background Stimulation and Handling as Forms of Infantile Stimulation

Abstract

Between birth and weaning rats ( N = 92) were housed in the laboratory maternity room or in a separate quiet room; half were handled, the other half not disturbed; after weaning half were reared in the laboratory colony room while half were put into the quiet room. Weaning weight was significantly reduced by handling and by being reared in the quiet room; adult weight was an interactive function of handling and the preweaning environment. Handled Ss and those reared in the quiet room postweaning were significantly more active in the open field. Open-field defecation was significantly reduced if S spent at least some time in a quiet environment. The data refute the hypothesis that stimulus input from the surrounding environment during infancy has the same functional effects as does handling. However, the ambient environment does play a dynamic role in the shaping of future biological and behavioral processes.