Social factors in the facilitation of feeding in chickens: Effects of imitation, arousal, or disinhibition?

Two experiments investigated the generality of socially enhanced consummatory behavior in chickens and the conditions that influence such enhancement. The first experiment placed two consummatory responses (pecking and drinking) in competition. The design of the experiment contrasted three common interpretations of social facilitation of feeding in chickens: (a) the imitation of specific responses of another bird, (b) the arousing effect of another bird that energizes dominant responses (to a greater degree or at the expense of subordinate responses), and (c) the calming effect of another bird that results in the disinhibition of all responses inhibited by fear. The first two interpretations were cast into doubt since (a) social facilitation effects were found regardless of the behavior of the companion, and (b) both dominant and subordinate responses were enhanced in about the same proportion. The third interpretation received some support. Additional evidence for the disinhibition interpretation was found in a second experiment. Animals placed in the test situation alone exhibited significantly more fear (as measured by the distress call) than animals tested in pairs.