Exploring the impact of stimulus-stimulus and stimulus-response conflicts on computer mouse trajectories: continuous flow of information from stimulus encoding to response preparation to motor action.

In recent years, mouse tracking (designing experiments in which participants provide responses via dynamic computer mouse movements) has enjoyed increasing experience in experimental psychology. Mouse-tracking studies typically involve some form of stimulus-response (S-R) conflict, and S-R effects emerge in movement trajectories (as well as in latencies). By contrast, it is currently unclear how stimulus-stimulus (S-S) compatibility affects movements. Here, we used a spatial arrow task which allowed us to generate S-R and S-S effects within the same experiment. Experiment 1 clarified in a key press experiment that this manipulation generates clear S-S and S-R effects in latencies. More critically, Experiment 2 demonstrated that both types of conflict impact mouse trajectories with incompatibility emerging as increased 'curvature' of responses when compared to congruent responses. We argue that these results are best explained via the assumption of 'continuous flow' of information, from stimulus encoding to response preparation and finally into motor action. By contrast, the S-S effect on trajectories contradicts the notion that processing is 'thresholded' between stimulus encoding and response preparation.