On the Evidence of Generalized Learning in the Single-Case Literature

Single-case research methods have long been used to develop and refine interventions and practices for individuals with developmental disabilities. To ensure that such practices lead to meaningful outcomes, improvements in learner behavior must generalize to real-world scenarios. In recent years, arguments have been put forth about the capacity of single-case methods to rigorously evaluate generalized learning, with some critics going as far as to question the utility of single-case methods for developing and informing educational and behavioral interventions. By leveraging data from a prior systematic review examining 40 years of single-case research, we sought to provide empirical data to this conversation by examining the extent to which experimental single-case studies have demonstrated rigorous evidence of stimulus and response generalization. Our results indicate that 32 of the 59 designs in our sample demonstrate rigorous evidence of generalized behavior change. This finding suggests that theoretical arguments about single-case methodology being ill-equipped to answer questions about the generality of outcomes are misplaced. To support future single-case researchers in designing studies to rigorously understand the generality of their investigated interventions and outcomes, we perceive that new professional development and researcher training resources will be needed.