Perceptual learning during filial imprinting: Evidence from transfer of training studies

Chicks were first imprinted by exposing them to a moving training stimulus, B or C, that was projected onto a screen at one end of an experimental cabinet. Subsequently, subjects selectively approached the stimulus to which they had been exposed. On the following day, the chicks were placed into a chilled experimental cabinet (15°C) and received trials on which two stimuli (A and B) were projected onto screens located at opposite ends of the cabinet. If the subject approached Stimulus A, a stream of warm air was delivered; if it approached B, the trial terminated, and no heat was presented. For subjects that had been imprinted with Stimulus B, those in Group B, Stimulus A was novel, and Stimulus B was familiar. For chicks that had been imprinted with Stimulus C, Group C, both A and B were novel. In two experiments, Group B acquired the discrimination more rapidly than did Group C. This observation, made using a novel training procedure, was taken to support the suggestion that imprinting results in a form of perceptual learning in which the familiar imprinting object has become more discriminable from other novel objects.     

Just War Moralities

This essay discusses four recent books on the Western, and one book on the classical Chinese, traditions of just war. It concentrates on the jus ad bellum moral criteria (legitimate authority, just cause, and right intention), giving attention to the centrality of the state in just war morality, to some challenges in reconceptualizing the jus ad bellum in the context of non‐state agents, and to controversies over a “presumption against war.”