Abstract
Previous research has revealed that the presentation of non-target information in an alternate modality from the target can influence performance on perceptual localization tasks. This influence is enhanced as the potential for information gain from the second stimulus increases. If this enhanced influence can also be observed in goal-directed aiming movements, the influence of a visual distractor on an auditory target should be greater than vice versa because a visual stimulus provides more accurate spatial information than an auditory stimulus. The present study tested this prediction by examining the kinematics of aiming movements towards visual or auditory targets with or without a distracting stimulus in the other modality. When present, the distracting stimulus was delivered simultaneous to the target modality at: a spatially coincident location, to the left, or to the right of the target. The results revealed that movement trajectories and endpoints were biased towards the distracting stimulus only when aiming to auditory target locations (the distractor was visual). No biases were observed when the targets were visual (the distractor was auditory). Thus, the distractor influenced participants' movements only when the secondary modality provided more accurate spatial information than the target modality. The unidirectional nature of this effect supports the notion that the influence of a secondary stimulus depends on the potential for information transmission.
