Performance in continuously available multiple schedules

Three pigeons were given continuous access in their home cages to food reinforcement on two-component multiple variable-interval variable-interval schedules. The reinforcer rates in the two components were varied over seven experimental conditions, and a partial replication over five conditions was arranged one year later. When component reinforcer rates were unequal, ratios of component response rates were more extreme than ratios of obtained component reinforcer rates, a result which in a generalized-matching analysis is termed overmatching. This finding contrasts sharply with results obtained when multiple schedules are arranged in shorter sessions, in which performance is characterized by undermatching when subjects are deprived of food, and by matching, or equality between component response- and reinforcer-rate ratios, when deprivation is minimal. More molecular data obtained in two subsequent conditions suggested that this finding did not reflect local fluctuations or asymmetries in deprivation. Theories of multiple-schedule performance that predict that matching cannot be exceeded are disconfirmed by the present results.