Upper-middle and low socio-economic level (SEL) subjects were compared on a discrimination learning task and on personality measures of locus of control of reinforcement and need for approval (Napp). Upper-middle SEL subjects were found to be faster discrimination learners than low SEL subjects only when the relevant stimulus cue was on a highly attended stimulus dimension. No SEL differences occurred when training was on a cue of a low attention level dimension. As predicted, internal subjects learned the discrimination task faster than external subjects, but this relationship held only for the upper-middle SEL subjects and only after the correlation was corrected for the attentuating effects of the low reliability on the IE scale. No relationship between Napp and the learning task was found for either SEL. Low SEL girls were found to be more external and higher in Napp than low SEL boys and upper-middle SEL girls and boys. Results suggest that the attention level of the relevant dimension is a major variable in discrimination learning. Further investigation of the personality correlates of discrimination learning is also suggested. (Author)