A dynamical model of saccade generation in reading based on spatially distributed lexical processing.

The understanding of the control of eye movements has greatly benefited from the analysis of mathematical models. Currently most comprehensive models include sequential shifts of visual attention. Here we propose an alternative model of eye movement control, which includes three new principles: spatially distributed lexical processing, a separation of saccade timing from saccade target selection, and autonomous (random) generation of saccades with foveal inhibition. These three features provide a common control mechanism for fixations, refixations, and regressions. Consequently, the model is called SWIFT (Saccade-generation with inhibition by foveal targets). Results from numerical simulations are in good agreement with effects of word frequency on single-fixation, first-fixation, and gaze durations as well as fixation and word skipping probabilities in first-pass analysis. The model inherently produces complex eye movement patterns including refixations and regressions due to its underlying dynamical principles.