title: Reinforcement learning accounts for moody conditional cooperation behavior: experimental results.
abstract: In social dilemma games, human participants often show conditional cooperation (CC) behavior or its variant called moody conditional cooperation (MCC), with which they basically tend to cooperate when many other peers have previously cooperated. Recent computational studies showed that CC and MCC behavioral patterns could be explained by reinforcement learning. In the present study, we use a repeated multiplayer prisoner's dilemma game and the repeated public goods game played by human participants to examine whether MCC is observed across different types of game and the possibility that reinforcement learning explains observed behavior. We observed MCC behavior in both games, but the MCC that we observed was different from that observed in the past experiments. In the present study, whether or not a focal participant cooperated previously affected the overall level of cooperation, instead of changing the tendency of cooperation in response to cooperation of other participants in the previous time step. We found that, across different conditions, reinforcement learning models were approximately as accurate as a MCC model in describing the experimental results. Consistent with the previous computational studies, the present results suggest that reinforcement learning may be a major proximate mechanism governing MCC behavior.
authors.affiliation: National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.|JST, ERATO, Kawarabayashi large graph project, c/o Global Research Center for Big Data Mathematics, NII, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Horita
authors.affiliation: Department of Behavioral Science, Hokkaido University, N10W7, Kita-ku, Sapporo, 060-0810, Japan.|Center for Experimental Research in Social Sciences, Hokkaido University, N10W7, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Takezawa
authors.affiliation: Institute of Social and Economic Research, Osaka University, 6-1, Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Inukai
authors.affiliation: Department of Behavioral Science, Hokkaido University, N10W7, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Kita
authors.affiliation: Department of Engineering Mathematics, University of Bristol, Merchant Venturers Building, Woodland Road, Clifton, Bristol BS8 1UB, United Kingdom.
authors.forename: Naoki
authors.initials: N
authors.lastname: Masuda
mesh_terms: D000293:Adolescent; D000328:Adult; D003299:Cooperative Behavior; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D012054:Reinforcement, Psychology; D055815:Young Adult