Return-sweep saccades during reading in adults and children.
Parker AJ., Slattery TJ., Kirkby JA.
During reading, eye movement patterns differ between children and adults. Children make more fixations that are longer in duration and make shorter saccades. Return-sweeps are saccadic eye movements that move a reader's fixation to a new line of text. Return-sweeps move fixation further than intra-line saccades and often undershoot their target. This necessitates a corrective saccade to bring fixation closer to the start of the line. There have been few empirical investigations of return-sweep saccades in adults, and even fewer in children. In the present study, we examined return-sweeps of 47 adults and 48 children who read identical multiline texts. We found that children launch their return-sweeps closer to the end of the line and target a position closer to the left margin. Therefore, children fixate more extreme positions on the screen when reading for comprehension. Furthermore, children required a corrective saccade following a return-sweep more often than adults. Analysis of the duration of the fixation preceding the corrective saccade indicated that children are as efficient as adults at responding to retinal feedback following a saccade. Rather than consider differences in adult's and children's return-sweep behaviour an artefact of oculomotor control, we believe that these differences represent adult's ability to utilise parafoveal processing to encode text at extreme positions.