To test what information about upcoming words readers
can access and use while reading, researchers use the
gaze-contingent boundary paradigm (Rayner, 1975). In this
paradigm, a preview word is changed to a target word during
the saccade to it (see Experiment 1 Method; Fig. 1).
Reading time measures on the target are compared between
various related preview conditions and an unrelated
control condition. Faster processing in a related condition
compared to the unrelated condition suggests preview benefit—
that information was obtained from the preview word
parafoveally and used to facilitate processing of the target.