Explaining individual differences in fixation durations during scene viewing

Active vision is a process that involves moving one's gaze to gather detailed visual information for various tasks. Most of the visual information which is processed is extracted from relatively stable periods of the eyes termed fixations. Individuals vary in their fixation durations, however, the factors that contribute to this variability are not fully understood. This study examines two factors that are intrinsic to all instances of fixations – foveal processing time (examined by speed of processing task) and preparation of the next saccade (examined by pro-saccade latency), and their relation to fixation durations that were decomposed using an ex-Gaussian mixture model. Individuals with shorter pro-saccade latencies exhibited shorter (reflected by the μ parameter) and less variable fixations (reflected by the σ parameter) during scene viewing. Individuals with better speed of processing exhibited less variable fixations. The study sheds light on the cognitive factors related to individual differences in eye movements during scene viewing and highlights the importance of considering the observer characteristics in computational models of eye movement.