Streaming x, y Coordinates Imply Continuous Interaction During On-line Syntactic Processing

Although many theories of on-line syntactic processing invoke the parallel activation of multiple syntactic representations, evidence supporting simultaneous activation has been inconclusive. Here, we exploited the continuous and non-ballistic properties of computer mouse movements, identified by recording streaming x, y coordinates, in order to determine the validity of serial versus parallel accounts of sentence processing. Participants heard structurally ambiguous sentences while viewing scenes with properties either supporting or not supporting the difficult relative clause interpretation. The curvatures of the elicited mousemovement trajectories revealed both an effect of visual scene, and competition between the simultaneously active syntactic representations.