The use of on-line definitions in the facilitation of comprehension of expository text presented by the computer

A 2X2 between subjects design was employed to test the relative effectiveness of two types of definitions in influencing utilization of definitions and enhancing comprehension of text. It was hypothesized that novice readers would look up more definitions, that experts would read faster and have higher levels of comprehension, that both groups would prefer context- sensitive definitions, and that subjects given context- sensitive definitions would have higher levels of comprehension. Text and definitions were presented as described by Lachman (1985, 1986). Comprehension was measured by five recall and recognition measures. Verbal skill was assessed with the WAIS-R vocabulary subtest and employed as a covariate. Analysis of covariance failed to identify the expected differences on three of four process and four of five outcome measures. There were significant interactions between level of domain expertise and type of definition on subjects' rate of reading definitions (F=8.272, p=0.009) and the completion test (F=8.53, p=008).