Readers’ eye movements are influenced by many cognitive processes such as visual perception, word processing, syntax processing, semantic processing, and pragmatics processing. These cognitive processes are in turn influced by working memory capacity, and also by motivation. This dissertation describe three studies investing how reading ability, working memory and motivation such as self-In the first study, the Support Vector Machines (SVM) was used to analyze eye movements. data from 61 undergraduate students who read a multiple-paragraph, multiple-topic expository text. Forward fixation time, first-pass rereading time, second-pass fixation time, and regression path reading time on different regions of the text were provided as features. The SVM classification algorithm assisted in distinguishing high-literacy-skilled readers from low-literacy-skilled readers with 80.3% accuracy, 84% sensitivity, and 77.8% specificity. Results demonstrate the effectiveness of combining eye tracking and machine learning techniques to detect readers with low literacy skills, and suggest that such approaches can be potentially used in predicting other cognitive abilities.
The second study included two experiments, which investigated how eye movement behavior are mediated by working memory. In Experiment 1, the critical region was two-character word with different frequencies. In Experiment 2, the critical region was a 3-characters overlapping ambiguous string. For this kind of overlapping ambiguous string, the first two characters could constitute a word, and the last two charactes could constitute another word. Readers have to decide whether the middle character belongs to the first word or the last word during reading. Average eye fixation, average saccade length were all influenced by working memory. Fixations were shorter and saccades were longer for readers with a higher working memory capacity than readers with lower working memory capacity. What’s more, in the first experiment, we found that fixation durations were shorter in the high-frequency condition than in the low-frequency, and outgoing saccade length was longer in the high-frequency condition than in the low-frequency condition. Interestingly, this effect only appeared in the people with high working memory capacity, but did not appear for readers with low working memory capacity. In Experiment 2, for the people with high working memory, fixation duration and saccade length all influenced by the semantic information from the region to the right of the critical region. For the readers with low working memory capacity, we failed to find such effect. These results suggest that the effect foveal and parafoveal information influence the eye movement behavior were mediated by working memory. What’s more, our study provides additional evidence that support the processing-based strategy for saccade target selection in Chinese reading.
In the third study, we further showed that readers' eye movements are influenced by a social motivation of self-enhancement. We asked participants to silently read sentences that describe self or others with positive or negative traits while their eyes were monitored. First fixation duration and gaze duration were longer when positive words were used to describe self than to describe others. These results suggested that eye movements can be influenced by the motivation of self-enhancement beyond various stimuli features and cognitive factors. This finding not only deepen the understanding the implication of eye movements but also highlight the potential of eye movements in studying (implicit) social cognition.
Taken together, these three studies showed that reading ability, working memory capacity, and the motivation of self-enhancement all affect eye movements. Therefore, all of these factors have to be taken into account when we understand the mechanism of eye movement control during reading, and all of eye movement models should also be able to explain the findings from these studies.