Pigeons' tracking of relevant attributes in categorization learning

Most theories and experimental investigations of discrimination learning and categorization, in both humans and animals, hypothesize that attention must be allocated to the relevant attributes of the training stimuli for learning to occur. Attention has conventionally been inferred after learning has transpired rather than examined while learning is transpiring. We presented pigeons with a visual categorization task in which we monitored their choice accuracy through their responses to different report buttons; critically, we tracked the location of the pigeons' pecks to both the relevant and irrelevant attributes of the training stimuli using touchscreen technology, in order to find out where the birds may have been attending during the course of categorization learning. Pigeons readily mastered the categorization task; most importantly, as training progressed, they increasingly concentrated their pecks on the relevant features of the category exemplars, suggesting that the birds were tracking the relevant information to solve the task. When either new irrelevant features were introduced (Experiment 1) or when new relevant features were introduced and later the discriminative value of these new relevant features was reversed (Experiment 2), pigeons' choice accuracy and peck tracking were strongly affected. These results help elucidate the dynamics and interplay of attention and learning; they also suggest that peck tracking can be a suitable measure of the allocation of attention in pigeons, much as eyetracking is deemed to be a suitable measure of attention in humans.