A flanker effect for moving visual stimuli.

Visual motion perception is essential for appropriate behavior in a dynamic visual world. It is influenced by voluntary attention towards or away from moving objects as well as by the capture of automatic attention by salient stimuli. Both kinds of attention play a major role in the Eriksen Flanker Task (EFT),where a central stimulus has to be identified in the presence of flanking distractors. For static visual stimuli incongruent peripheral flankers are known to reduce accuracy rates and prolong reaction times. However,it is not known if a similar flanker effect also affects speeded responses to moving stimuli. We therefore examined whether a flanker effect exists for moving random dot patterns (RDPs) and compared it to the effect elicited by static visual triangles in human subjects. We observed a motion flanker effect,both for response times and accuracy rates. Incongruently moving peripheral flankers caused a slowing of response time and a reduction of accuracy rates compared to congruently moving RDPs. These motion flanker effects were not significantly different from those in the static flanker task. The presence of a motion flanker effect and its similarity to the flanker effect for static stimuli suggests that visual motion engages competitive attention and control mechanisms for perception and decision-making similar to those engaged by non-moving features.