Reinforcing properties of access to litter in hens
Operant conditioning techniques were used to investigate whether access to litter can act as a positive reinforcer for hens. Access to litter did not appear to be reinforcing for hens when the operant response required of them was to peck a key (Experiments 1 and 2). When allowed access to litter, their preference for it was, however, very pronounced (Experiment 3). When the operant response was changed from key-pecking to breaking a photobeam, the hens did show that they found litter reinforcing, although only after a large number of trials (Experiment 4).
Dawkins, M.S. and Beardsley, T., 1986. Reinforcing properties of access to litter in hens. Appl. Anita. Behav. Sci., 15: 351-364. DOI: https://doi.org/10.1016/0168-1591(86)90127-9