Reinforcers may increase operant responding via a response-strengthening mechanism whereby the probability of the preceding response increases, or via some discriminative process whereby the response more likely to provide subsequent reinforcement becomes, itself, more likely. We tested these two accounts. Six pigeons responded for food…

In baseball, it is believed that "hitting is contagious," that is, probability of success increases if the previous few batters get a hit. Could this effect be partially explained by action induction--that is, the tendency to perform an action related to one that has just been observed? A simulation was used to investigate the effect of inducing…

In recent years, single-case designs have increasingly been used to establish an empirical basis for evidence-based interventions and techniques in a variety of disciplines, including psychology and education. Although traditional single-case designs have typically not met the criteria for a randomized controlled trial relative to conventional…

While Spearman's rho and Kendall's tau are equally powerful rank-order correlation coefficients under conditions of normality, they have different metrics. Applied to the same data, tau is smaller in absolute value, often no more than two-thirds of the size of rho. This difference in correlational metric appears to need emphasis. (Author/CM)

Problems with experimental research on mental retardation include: (1) difficulties with defining mental retardation; (2) neglect in demonstrating causal relationships; and (3) reliance on methodology not necessarily appropriate for defining the criteria of retardation. The author advocates abandoning definitions based on intelligence tests and…