A dynamic adjustment model of saccade lengths in reading for word-spaced orthographies: evidence from simulations and invisible boundary experiments

Jarkko Hautala,Stefan Hawelka,Otto Loberg,Paavo H.T Leppänen

doi:10.1080/20445911.2021.2011895

Abstract

ABSTRACT Contemporary models of eye movement control in reading assume a discrete target word selection process preceding saccade length computation, while the selection itself is assumed to be driven by word identification processes. However, a potentially more parsimonious, dynamic adjustment view allows both next word length and its content (e.g. orthographic) to modulate saccade length in a continuous manner. Based on a recently proposed center-based saccade length account a new regression model of forward saccade length is introduced and validated in a simulation study. Further, additional simulations and gaze-contingent invisible boundary experiments were used to study the cognitive mechanisms underlying skipping. Overall, the results support the plausibility of dynamic adjustment of saccade length in word-spaced orthographies. In the future, the present regression formula-based computational model will allow a straightforward implementation of influences of current and next word content (visual, orthographic, or contextual) on saccade length computation.

Highlights

Research on eye movements during reading has provided a wealth of knowledge about the interplay among visual perception, cognition, and motor control, leading to highly complex and accurate computational models (Engbert et al, 2005; Reichle et al, 1999; Reichle & Sheridan, 2015; Reilly & Radach, 2006; Risse et al, 2014; Snell et al, 2018)
The prevalent models further assume that intended word skipping occurs when a word is parafoveally recognized to a sufficient degree, in which case saccade is targeted to a subsequent word
We investigated whether a novel computational model of the center-based saccade length (CBSL) could produce the benchmark word length effects of a shift of landing position toward the word beginning, increase refixation probability, and decrease skipping probability

Summary

Introduction

Research on eye movements during reading has provided a wealth of knowledge about the interplay among visual perception, cognition, and motor control, leading to highly complex and accurate computational models (Engbert et al, 2005; Reichle et al, 1999; Reichle & Sheridan, 2015; Reilly & Radach, 2006; Risse et al, 2014; Snell et al, 2018). As soon as the foveal word has been recognized, attention shifts to the parafoveal word starting the first stage of lexical processing, the “familiarity check”, which consists of orthographic processing leading to activation of a word form Skipping occurs if this “familiarity check” is completed early enough to cancel the default saccade to the word—no full recognition of the word is required. Reanalyzing McConkie et al.’s (1988) data, Reilly and O’Regan (1998) found a best fit for a model in which the eyes were targeted to the longest word in a 20letter perceptual window Such a mechanism is not psychologically plausible, as it would suggest that readers stereotypically skip even words of moderate length if the words are followed by longer words. The conclusion drawn from these studies is that readers tend to proceed with much more uniform saccade lengths than would be expected on the basis of interword saccades only

Methods

Results

Conclusion