Learning set in squirrel monkeys as affected by pretraining with differentially rewarded single objects

The possibility of developing discrimination learning set (LS) by some method other than discrimination training was investigated. In Phase I, 3 groups were given LS pretraining with single objects. Two groups were presented 500 objects, each for 6 trials; one group was rewarded at a 50% random rate, the other at a 100% rate. A third group encountered one object throughout Phase I with all trials rewarded. Their Phase II LS performances were compared with an LS control condition. No pretraining group exhibited LS at the beginning of Phase II. The pretraining group having a 50% random reward rate was significantly suppressed in developing LS. Thus, (a) LS in squirrel monkeys is dependent upon the processes of discrimination learning; (b) the rate at which LS is formed may involve expectancies concerning probable reward rate.