Some effects of early social stimulation on the emotional reactivity of ducklings

Abstract

Newly hatched Khaki Campbell ducklings were housed with a con specific for 24 h beginning at either 1 or 5 days of age. A third group of ducklings received no social stimulation. When tested on Day 7, ducklings afforded early social stimulation exhibited less distress calling and crouching in a novel open field than ducklings exposed to late or no social stimulation. A second experiment asked whether the above result was due to early social stimulation per se or to the separation which occurred at its termination. Newly hatched ducklings were housed with a conspecific beginning on Day 1. One-half of the birds were separated from their companions on Day 2; the rest were separated on Day 6. On Day 7, the ducklings that were separated early exhibited less crouching and distress calling in a novel open field than the birds that were separated late. This finding implies that the withdrawal of social stimulation, rather than social stimulation per se, was responsible for the reduced emotional behavior observed in Experiment I. It is concluded that early withdrawal of social stimulation generated a strong aversive reaction and that it was the strength and timing of this reaction that mediated the emotionality moderating effects found here. Under these circumstances, the primary function of early social stimulation was to establish a condition whereby the aversive reaction generated by separation would occur early.A number of studies have revealed that animals stimulated by stressful electrical shock in infancy exhibit reduced emotional behavior when they are tested at a later age in an open field or other fearprovoking situation (Denenberg, Carlson, & Stephen, 1962;Lindholm, 1962). In these studies, the subjects were rats or mice, but similar early stimulation effects have recently been obtained in ducklings (Ratner, in press). Ratner found that when ducklings were shocked soon after hatching they showed less distress calling and crouching in a subsequent openfield test than ducklings that were either shocked at a later age or were never shocked.The research reported here was designed to elaborate on Ratner's work by asking whether the emotionality moderating effects of early stimulation in ducklings were limited to forms of stimulation that, like electrical shock, are clearly aversive. In particular, the work asked whether or not the social stimulation provided by early exposure to a conspecific might not also engender reduced emotional behavior when subjects were subsequently tested in an open field. That the stimulation provided by a conspecific is not aversive to the very young duckling seems clear from the finding that they immediately approach and stay near a conspecific when first

Using the life course health development model to address pediatric mental health disparities

“…Life events and experiences, interacting with genetically inherited traits, also have profound effects on mental health trajectories including the occurrence of depression (Brody et al, 2016). For decades, researchers have documented temporal relationships between exposures and physiological and mental attributes (Guiton, 1966; Klein et al, 1976). However, much remains unknown about how critical developmental periods (i.e., “sensitive periods”) are influenced by particular social or biological factors.…”