Effects of constraint and validity of sentence contexts on lexical decisions

Recent models of sentence context effects predict that the pattern of facilitation and inhibition of response to sentence completions should be influenced by the experiment-wide contextual “environment.” In the present experiments, this environment was manipulated in several ways, including the degree to which contexts constrained possible completions, the probability of predictable completions’ being presented, and the probability of congruous completions’ being presented. In Experiment 1, decreasing the proportion of congruent test words had no effect on either the facilitation for highly likely words or the inhibition for incongruent words; increasing the proportion of predictable words produced no increase in facilitation for these words, but did increase the inhibition for incongruous words. In Experiment 2, contexts with very high or very low degrees of constraint produced equivalent results when predictability was uniformly low: no facilitation for unlikely but congruent words, and inhibition for incongruent words. In general, the patterns of change in facilitation and inhibition caused by changes in the contextual environment were more consistent with the modified two-process model (Stanovich & West, 1983) than with the verification model (Becker, 1982). But the limited range of influence suggests that, under conditions approximating normal reading, little use is made of such “metacontextual” information.