The EZ Diffusion Model: An overview with derivation, software, and an application to the Same-Different task

Abstract

The diffusion model is useful for analyzing data from decision making experiments as it gives information about a dataset that regular statistical tests cannot, including: the rate of processing, the encoding and motor response times, and decision thresholds. The EZ diffusion model is a restricted version of the diffusion model with some parameter variability set to zero, allowing for quicker analyses. Here we describe the EZ diffusion model-including how it was derived mathematically- the measurement units of the parameters, and how it can be generalized to starting points other than the mid-point. We also show how its parameters can be estimated using computer software (the model is available with many software programs such as R and Excel, to which we add SPSS and a Mathematica code). Finally, an EZ analysis was run on one dataset obtained from a ``Same{''}-{''}Different{''} experiment.