Visual cues that are effective for contextual saccade adaptation

The accuracy of saccades, as maintained by saccade adaptation, has been shown to be context-dependent: able to have different amplitude movements to the same retinal displacement dependent on motor contexts such as orbital starting location. There is conflicting evidence as to whether purely visual cues also effect contextual saccade adaptation, and if so what function this might serve. We tested what visual cues might evoke contextual adaptation. Over 5 experiments, 78 naive subjects made saccades to circularly moving targets, which stepped outward or inward during the saccade depending on target movement direction, speed, or color and shape. To test if the movement or context post-saccade were critical, we stopped the post-saccade target motion (Exp. 4), or neutralized the contexts by equating post-saccade target speed to an intermediate value (Exp. 5). We found contextual adaptation in all conditions except those defined by color and shape. We conclude that some, but not all, visual cues before the saccade are sufficient for contextual adaptation. We conjecture that this visual contextuality functions to allow for different motor states for different co-ordinated movement patterns, such as co-ordinated saccade and pursuit motor planning.