title: Theory meets pigeons: the influence of reward-magnitude on discrimination-learning.
abstract: Modern theoretical accounts on reward-based learning are commonly based on reinforcement learning algorithms. Most noted in this context is the temporal-difference (TD) algorithm in which the difference between predicted and obtained reward, the prediction-error, serves as a learning signal. Consequently, larger rewards cause bigger prediction-errors and lead to faster learning than smaller rewards. Therefore, if animals employ a neural implementation of TD learning, reward-magnitude should affect learning in animals accordingly. Here we test this prediction by training pigeons on a simple color-discrimination task with two pairs of colors. In each pair, correct discrimination is rewarded; in pair one with a large-reward, in pair two with a small-reward. Pigeons acquired the 'large-reward' discrimination faster than the 'small-reward' discrimination. Animal behavior and an implementation of the TD-algorithm yielded comparable results with respect to the difference between learning curves in the large-reward and in the small-reward conditions. We conclude that the influence of reward-magnitude on the acquisition of a simple discrimination paradigm is accurately reflected by a TD implementation of reinforcement learning.
authors.affiliation: Institute of Cognitive Neuroscience, Biopsychology, Department of Psychology, Ruhr-University of Bochum, 44780 Bochum, Germany. jonas.rose@rub.de
authors.forename: Jonas
authors.initials: J
authors.lastname: Rose
authors.forename: Robert
authors.initials: R
authors.lastname: Schmidt
authors.forename: Marco
authors.initials: M
authors.lastname: Grabemann
authors.forename: Onur
authors.initials: O
authors.lastname: Güntürkün
mesh_terms: D000465:Algorithms; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003118:Color Perception / Q000502:physiology; D010856:Columbidae; D003214:Conditioning, Classical / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology*; D009042:Motivation; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012201:Reward