THE EFFECTS OF VERBAL REINFORCEMENT COMBINATIONS ON DISCRIMINATION LEARNING AND DISCRIMINATION SHIFT LEARNING IN NORMAL AND MENTALLY RETARDED CHILDREN

This experiment was designed to examine the effects of verbal reinforcement combinations on discrimination learning and discrimination shift learning in normal and mentally retarded children.The apparatus was the same as in our previous study. We set 9 trials as one block and defined the criterion of learning as the state of all correct responses in a block. After the Ss had reached the criterion in the discrimination learning, in which one of three colors was the correct stimulus, they learned the discrimination shift learning to the criterion, in which another color was the correct stimulus.Besides three combinations of verbal reinforcement, that is, Right-Wrong (RW), Right-Nothing (RN), and Nothing-Wrong (NW), but there were also RNw and NrW that were RN and NW in which S was instructed about meaning of Nothing before the begining of learning.The results as were follows:1. In the discrimination learning, mentally retarded children learned faster under NrW, RW and NW conditions than under RN, RNw. For normal children, there were no differences in the speed of learning among 5 conditions. Under RNw, RN and NW mentally retarded children learned more slowly than normal children, but under NrW and RW they learned as fast as normal children (see Table 3 and Table 4).In the discrimination shift learning there were no differences among 5 conditions and between normal and mentally retarded children (see Table 4).2. In the discrimination learning for mentally retarded children, the mean rate of error responses was smaller under NrW than under NW and RNw, and it was smaller under RW and RN than under RNw. In the discrimination shift learning, it was smaller under NrW than under RNw and RN, and it was smaller under RW than under RN (see Fig. 1, Table 5 and Table 6).In the discrimination learning for normal children, the mean rate of error responses was not significantly different among 5 conditions, but in the discrimination shift learning it was smaller under RW than under any other conditions (see Fig. 1, Table 7 and Table 8).3. In the discrimination learning for mentally retarded children, the rate of error responses decreased largely toward the end of learning (see Fig. 1 and Table 5). For normal children it decreased rather early in the period of learning under NrW, decreased linearly under RW and RNw, but under RN the curve of decreasing was like that of mentally retarded children (see Fig. 1 and Table 7).In the discrimination shift learning it decreased rather early in the period of learning under all conditions for both groups of subjects (see Fig. 1, Table 6 and Table 8).These findings suggest that N is a positive reinforcer at the start of the experiment and its positive reinforcement value is increased under NW, while it is weakened to turn into a negative reinforcer under RN. In other words, the positive reinforcement value of N is stronger than its negative reinforcement value. This is especially true for mentally retarded children.The acquirement of negative reinforcement value of N seems more difficult for mentally retarded children because of their functional rigidity.The instruction as to the positiveness of N under NrW was perhaps easy to accept for both normal and mentally retarded children, but the instruction as to be negativeness of N under RNw might have been difficult for mentally-retarded children because of N's strong possitiveness for them.