Experimental group (combined social-appetitive and social-only subgroups). (a) Percentage of time spent in food cup for discrimination learning between aCS+ and aCS- over days. (b) Percentage of time spent in food cup for the compounds BR (aCS+, pCS+), OR (aCS+, pCS-), and NR (aCS-, pCS-) over days. Control group 1 (combined inserted wall and no partner present subgroups). (c) Percentage of time spent in food cup for discrimination learning between aCS+ and aCS- over days. (d) Percentage of time spent in food cup for the compounds BR (aCS+, pCS+), OR (aCS+, pCS-), and NR (aCS-, pCS-) over days. Control group 2 (unequal outcomes). (e) Percentage of time spent in food cup for discrimination learning between aCS+ and aCS- over days. (f) Percentage of time spent in food cup for the compounds PR (aCS-, pCS+), OR (aCS+, pCS-), and NR (aCS-, pCS-) over days. Error bars indicate SEM.