began with six practice sentences, one of each type that the subject was to see. On each trial a sentence appeared on the screen; the subject decided whether it was true or false, and pressed one of two keys marker T and F to indicate her/ his decision. The computer measured decision latency with millisecond accu- racy. After the response the word correct or incorrect appeared on the screen for a variable interval of about 2 sec and was then replaced by the next stimulus pair. Subjects were told to respond as accurately as possible without making an error. Trials followed one another without pause. Every 20 trials the subject was given an opportunity to pause and was encouraged to rest. The practice trial following each pause was not included in the data.