BEHAVIORAL-RESPONSES OF COMMERCIALLY FARMED LAYING HENS TO HUMANS - EVIDENCE OF STIMULUS-GENERALIZATION

The behavioural responses of birds to experimenters varying in a numbe r of attributes, such as sex, height, clothing and the wearing of spec tacles, were determined in a series of five experiments. A total of 32 0 birds aged between 50 and 57 weeks of age and housed in single-hen c ages at a large commercial farm were used. The hens' responses were ob served in a standardized test in which their position, orientation and posture were recorded when a stationary human stood 60 cm from the fr ont of the cage. The hens' responses to humans were unaffected by vari ations in the majority of human attributes tested, including sex, heig ht and the presence of spectacles. Only one of the eight variables mea sured appeared to be sensitive to the type of clothing; more crouch or escape postures, indicative of greater fear, were seen when the exper imenter wore overalls (to which the birds were less accustomed), rathe r than street clothes. Collectively, the results demonstrate that stim ulus generalization across a wide range of human attributes can occur at commercial farms, or at least those at which the hens have had prev ious experience of a number of humans.