Redirected behavior in learning tasks: the commercial laying hen (Gallus gallus domesticus) as model.

Redirected behaviors occur when some course of action is thwarted or inhibited (frustration). They also occur as adjunctive behaviors in operant conditioning tasks, where they might reflect frustration about unrewarded responses. Because frustration is associated with stress, which could interfere with learning and memory, we studied whether the occurrence of redirected behavior is correlated with learning success in a series of visual-cue discrimination tasks. Eleven hens, aged 34 wk, were tested on acquisition, reversal, extinction, and relearning of a simple visual discrimination task. The experimenters randomly assigned red and blue cardboard discs as discriminative stimuli. A correct response was recorded when a hen pecked at the correct disc. The learning criterion was 90% correct responses in 20 trials in 2 consecutive task sessions. The following data were documented: number of pecks needed to achieve the learning criterion, latency in choosing, pecks at the experimenter, and pecks at the surroundings. The behavioral responses were analyzed using linear mixed model ANOVA. Redirected pecking at the surroundings was a significant indicator of learning failure in that the more the hens performed this behavior, the more trials they needed to complete the discrimination tasks (P = 0.012). The number of pecks at the experimenter during the tasks significantly influenced learning success (P = 0.020), with hens directing more pecks at the experimenter during reversal, reaching the learning criterion in fewer trials (P = 0.027). The more the hens pecked at the experimenter during acquisition and extinction, however, the more trials they needed to meet the learning criteria (acquisition: P = 0.048; extinction: P = 0.003). Thus, laying hens are susceptible to the effects of frustration as measured in terms of redirected pecking elicited by operant procedures in visual discrimination tasks. In general, any situation in which a desirable goal is obstructed or an expected reward is omitted may lead to frustration-related activities, such as redirected behavior, which could in turn lead to abnormal behavior and welfare issues for the animals.