Children's preference for mixed- versus fixed-ratio schedules of reinforcement: A translational study of risky choice.

Laboratory research has shown that when subjects are given a choice between fixed-ratio and bi-valued mixed-ratio schedules of reinforcement, preference typically emerges for the mixed-ratio schedule even with a larger ratio requirement. The current study sought to replicate and extend these findings to children's math problem completion. Using an ABCBC reversal design, four fourth-grade students were given the choice of completing addition problems reinforced on either a fixed-ratio 5 schedule or one of three mixed-ratio schedules; an equivalent mixed-ratio (1, 9) schedule, a mixed-ratio (1, 11) schedule with a 20% larger ratio requirement, and an equally lean mixed-ratio (5, 7) schedule without the small fixed-ratio 1 component. This was followed by a reversal back to the preceding phase in which preference for the mixed-ratio schedule had been observed, and a final reversal back to the mixed-ratio (5, 7) phase. Findings were consistent with previous research in that all children preferred the mixed-ratio (1, 9) schedule over the equivalent fixed-ratio 5 schedule. Preference persisted for the leaner mixed-ratio (1, 11) schedule for three of the four children. Indifference or preference for the fixed-ratio 5 alternative was observed in phases containing the mixed-ratio (5, 7) schedule. These results extend previous research on risky choice to children's math problem completion and highlight the importance of a small ratio component in the emergence of preference for bi-valued mixed-ratio schedules. Implications of these results for arranging reinforcement to increase children's academic responding are discussed.