Bayesian parameter estimation for the SWIFT model of eye-movement control during reading

Process-oriented theories of cognition must be evaluated against time-ordered observations. Here we present a representative example for data assimilation of the SWIFT model, a dynamical model of the control of spatial fixation position and fixation duration during reading. First, we develop and test an approximate likelihood function of the model, which is a combination of a pseudo-marginal spatial likelihood and an approximate temporal likelihood function. Second, we use a Bayesian approach to parameter inference using an adapative Markov chain Monte Carlo procedure. Our results indicate that model parameters can be estimated reliably for individual subjects. We conclude that approximative Bayesian inference represents a considerable step forward for the area of eye-movement modeling, where modelling of individual data on the basis of process-based dynamic models has not been possible before.