Abstract
We have shown that the vector inversion process required for antisaccades engenders a mode of control that diminishes online and feedback-based trajectory corrections (Heath et al, 2010, 2011; Weiler et al, 2011). Here we investigated how switching from this mode of control to a stimulus-driven mode of control (e.g., prosaccade) and vice versa influences the extent to which a saccade trajectory is controlled online. Participants completed pro- and antisaccades in a task switching (e.g. pro- followed by antisaccade or vice versa) and task repetition (e.g., pro- or antisaccade repeated) paradigm to a target located 9.5° left or right of a central fixation (i.e., AABB paradigm). Online control was indexed by evaluating the relationship between the spatial location of the eye at decile increments of normalized movement time relative to the eye's final location (i.e., R2 values). As expected, antisaccades demonstrated larger R2 values than their prosaccade counterparts: a result we interpret to reflect a reduced level of online control. In addition, R2 values for prosaccades, but not antisaccades, demonstrated a switch cost; that is, prosaccades completed after a task switch (i.e., following an antisaccade) exhibited reduced online control compared to their task repetition counterparts. As such, we propose that the intentional nature of the antisaccade task engenders a persistent and slow mode of cognitive control that inhibits online oculomotor corrections.
