Contextual validity and the effects of low-constraint sentence contexts on lexical decisions

Subjects made lexical decisions after reading either (a) low-constraint sentence contexts that did not predict the identity or meaning of congruous targets (e.g. “Mary went to her room to look at her XXXX”), or (b) control contexts that were randomly ordered lists of words. The crucial variable was the validity of the contextual information. When the sentence contexts were incongrous with the word targets as often as they were congruous (the “less-valid environment”), the congruous contexts had a slight inhibitory effect on decision latency relative to the baseline condition. In contrast, when the contexts were always congruous with the word targets (“valid environment”), they had a large facilitatory effect on decision latency. These results suggest that (a) the effects of congruous contexts can depend on the validity of the contexts across the entire experimental session, and (b) contextual facilitation may be due in part to sentence level processes.