Abstract
A body of research suggests that attention along the depth-axis is concentrated along the line of sight up to the point of fixation and decreases rapidly beyond. However, most previous work used binocular disparity to simulate targets at distances within a few metres of the observer in peri-personal space, and therefore, little is known about how attention is allocated to targets located at far distances. Driving is a particularly interesting context in which to examine attention along the depth-axis. First, objects commonly encountered while driving often are quite far from the driver. Second, attending to different distances is ecologically advantageous because events nearer to the driver have more immediate behavioural consequences. In the current study, we examined whether the distribution of attention along the depth-axis depends on the distance to the plane of fixation in a simulated driving context. In a virtual 3D environment where distance is simulated by pictorial cues and optical flow, participants followed a lead car. To manipulate fixation distance, participants maintained a constant following distance of either 9.25, 18.5, or 37 m. Attention along the depth-axis was assessed with a detection task where targets matched in retinal size could appear at one of three distances (9.25, 18.5, 37 m) and two eccentricities (12, and 24 degrees). Preliminary results indicate that detection was slower for far targets (37 m) compared to the other two distances, and detection was slower and less accurate for targets at an eccentricity of 24 deg compared to 12 deg at all target distances. Finally, car-following distance did not modulate the effects of target distance and eccentricity, although there were fewer misses and faster reaction times in the intermediate car-following distance condition. These results suggest that the effect of distance in far space may be different from that in peri-personal space.