The size and direction of saccadic curvatures during reading.
Eye movements during the reading of multi-line pages of texts were analyzed to determine the trajectory of reading saccades. The results of two experiments showed that the trajectory of the majority of forward-directed saccades was negatively biased, i.e., the trajectory fell below the start and end location of the saccadic movement. This is attributed to a global top-to-bottom orienting of attention. The curvature size and the proportion of negative trajectories were diminished when linguistic processing demands were high and when the beginning lines of a page were read. Longer pre-saccadic fixations also yielded smaller saccadic curvatures, and they resulted in fewer negatively curved forward-directed saccades in Experiment 1 although not in Experiment 2. These findings indicate that the top-to-bottom pull of saccadic trajectories is modulated by processing demands and processing opportunities. The results are in general agreement with a time-locked attraction-inhibition hypothesis, according to which the horizontal movement component of a saccade is initially subject to an automatic top-to-bottom orienting of attention that is subsequently inhibited.
Inhoff
Albrecht W
AW
Binghamton University, SUNY, NY 13902, USA. inhoff@binghamton.edu
Seymour
Bradley A
BA
Schad
Daniel
D
Greenberg
Seth
S
D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D011932:Reading; D012438:Saccades