Tiber, N., & Kennedy, W. A. (1964). The effects of incentives on the intelligence test performance of different social groups . Journal of Consulting Psychology , 28 (2), 187–187. https://doi.org/10.1037/h0048465

Students were randomly assigned to one of four incentive groups: verbal praise, verbal reproof, candy reward, and control. Incentives were provided at the end of each subtest.

480 second- and third-grade students selected equally from three social groups (middle- and lower-class white and lower-class African-American groups).

The 1960 Stanford-Binet form L-M was used as the dependent variable.

No differences between incentive groups and no significant interaction between type of incentive and social group were identified.