Methodological and empirical developments for the Ratcliff diffusion model of response times and accuracy

The Ratcliff diffusion model for simple two-choice decisions (e.g., Ratcliff, 1978 Ratcliff, R. 1978. A theory of memory retrieval. Psychological Review, 85: 59–108. Crossref, Web of Science ® , Google Scholar; Ratcliff & McKoon, 2008 Ratcliff, R. and McKoon, G. 2008. The diffusion decision model: Theory and data for two-choice decision tasks. Neural Computation, 20: 873–922. Crossref, PubMed, Web of Science ® , Google Scholar) has two outstanding advantages. First, the model generally provides an excellent fit to the observed data (i.e., response accuracy and the shape of RT distributions, both for correct and error responses). Second, the parameters of the model can be mapped on to latent psychological processes such as the speed of information accumulation, response caution, and a priori bias. In recent years, the advantages of the Ratcliff diffusion model have become increasingly clear. Current advances in methodology allow all researchers to fit the diffusion model to data easily. Recent applications to ageing, lexical decision, IQ, practice, the implicit association test, and the accessory stimulus effect serve to highlight the added value of a diffusion model perspective on simple decision making.