What separates strong and weak ESL readers?

My proposed research sets out to address one very simple, yet equally complex question: What separates strong and weak ESL1 readers? While much of the emphasis and discussion surrounding ESL reading research hitherto appears to have focused primarily on the use of cognitive and metacognitive reading strategies (e.g. Knight et al, 1985; Carrell et al, 1989; Sheorey & Mokhtari, 2001; Fung et al, 2003; Phakiti, 2003; Abbott, 2006), my proposal intends rather to use a combination of eye-tracking technology and introspective research methodologies (e.g. think-aloud and stimulated-recall interviews [Dornyei, 2007:147]), to investigate how stronger and weaker learners of English for Academic Purposes (EAP) process academic texts on a word-by-word basis, as they seek incrementally to construct meaning from the texts they engage with. I have been motivated in this idea by the several years I have spent teaching university foundation-level reading courses in China. Specifically, I have noticed that despite receiving similar instruction in ESL reading strategies (e.g. predicting content, mentally summarizing content, guessing the meaning of unknown vocabulary from context etc.), considerable differences invariably appear in the speed and ease with which strong and weak readers are able to learn to apply these strategies, and more generally to construct meaning from the texts they read.

In an attempt to elucidate how ESL readers process markers of cohesion in academic texts, and the extent to which their success or failure in this endeavor influences their ability to decode those texts, this research aims to explore the following four questions:
I. Is there a difference in the patterns of fixations and saccades in stronger and weaker ESL readers regarding lexical, grammatical and syntactic markers of textual cohesion?
II. To what extent do processing difficulties occur at the site of markers of textual cohesion?
III. To what extent can an intervention program designed to address potentially problematic markers of textual cohesion lead to improved outcomes for ESL readers?
IV. To what extent can eye-tracking technology be used to investigate reading difficulties in ESL students?