A correspondence is suggested between the two different abilities underlying performance on intellectual or learning tasks discussed by Jensen and the two response processes postulated by various mediational models of discrimination learning. To test this, two groups of nursery school children differentiated by the measurable social class of their families were given discrimination training. One half of those in each social class group then experienced an intradimensional shift in discrimination transfer operation, with the remainder experiencing an extradimensional shift. After administration of object discrimination problems to the children, data indicate that some correlate of social class is related to performance in discrimination transfer problems. White upper class nursery school children performed at a level superior to white lower class nursery school children, and the difference occurred in spite of a lack of difference in testable IQ. The deficiency appears to be related to differences in mediational ability and is consistent with Jensen's two-ability model. (LH)