Abstract
By moving through the environment, an observer generates flow field patterns from which information about the movement's speed and trajectory can be extracted. Onset of peripheral object motion or a change of object motion direction disturbs this observer-generated flow field by producing a relative motion stimulus. Can relative motion in the near and far periphery of the visual field act as a cue to attract visuo-spatial attention? How powerful is such a relative motion cue (RMC) in comparison with conventional cueing with a ring-shaped frame?
At 20, 30, 40, and 60 degrees eccentricity, we tested the performance of 10 subjects in a near-threshold, 4-afc Gabor orientation discrimination task without vs. with a briefly appearing ring-shaped cue attracting attention to the target location. In the second part of the study, the Gabor gratings were embedded in a random-dot flow field, and subjects performed the same task as above after presentation of a RMC (a group of random dots moving in the direction opposite from that of the flow-field) compared to a baseline without the RMC.
Both types of cues induced a significant improvement of discrimination performance at all test locations. The RMC effect was stronger at more eccentric positions while the ring-shaped cue had a more pronounced effect closer to the center. Thus RMC is at least as powerful attracting attention as conventional spatial cueing.
Our data point to the special role of peripheral vision in motion processing. The results have high practical relevance for tasks involving navigation and mobility.
Thanks to Isabel Pallauf for help with data acquisition, Alex Gofen for programming. Supported by grant Str 354/3-1 Deutsche Forschungsgemeinschaft