Saccade Trajectories Reveal Dynamic Interactions of Semantic and Spatial Information During the Processing of Implicitly Spatial Words

摘要

Implicit up/down words, such as bird and foot, systematically influence performance on visual tasks involving immediately following targets in compatible versus incompatible locations. Recent studies have observed that the semantic relation between prime words and target pictures can strongly influence the size and even the direction of the effect: Semantically related targets are processed faster in congruent versus incongruent locations (location-specific priming), whereas unrelated targets are processed slower in congruent locations. Here, we used eye-tracking to investigate the moment-to-moment processes underlying this pattern. Our reaction time (RD results for related targets replicated the location-specific priming effect and showed a trend toward interference for unrelated targets. We then used growth curve analysis to test how up/down words and their match versus mismatch with immediately following targets in terms of semantics and vertical location influence concurrent saccadic eye movements. There was a strong main effect of spatial association on linear growth, with up words biasing changes in y-coordinates over time upward relative to down words (and vice versa). Similar to the case with the RT data, this effect was strongest for semantically related targets and reversed for unrelated targets. It is intriguing that all conditions showed a bias in the congruent direction in the initial stage of the saccade. Then, at around halfway into the saccade the effect kept increasing in the semantically related condition and reversed in the unrelated condition. These results suggest that online processing of up/down words triggers direction-specific oculomotor processes that are dynamically modulated by the semantic relation between prime words and targets.