Abstract
Abrams and Christ (2003, Psychological Science, Christ & Abrams, 2008, Journal of Vision) reported that new motion in a scene (motion onset) captures attention in a bottom-up fashion. This is contradictory to findings by von Muhlenen et al. (2005, Psychological Science), who reported no capture for motion onset, unless the onset represents a temporally unique event. Methodological differences between the two studies make a direct comparison difficult. For example, von Muhlenen et al. looked at slope reductions in the search function to measure the effect of attentional capture, whereas Abrams and Christ looked at simple reductions in Reaction Time (RT). The aim of Experiment 1 was to further explore these differences by employing the same method and design used by Abrams and Christ. However, the result of twelve participants show no RT reduction for motion-onset targets in comparison to static targets, which supports von Muhlenen et al. findings. Another difference between the two studies concerns the quality of motion: von Muhlenen et al. used relatively smooth motion (updating the moving stimulus at 60 Hertz), whereas Abrams and Christ used relatively jerky motion (updating the moving stimulus at 15 Hertz). Experiment 2 addressed this difference by systematically varying motion quality across trials from 100, 33, 17, to 8 Hertz. The results show that motion quality plays a crucial role: motion-onset stimuli only capture attention when motion is jerky (8 and 17 Hertz), not when it is smooth (33 and 100 Hertz), thus, replicating the findings of both studies. Finally, Experiment 3 shows that simple flicker without motion (100, 33, 17, or 8 Hertz) has not the same effect on attention. We conclude that it is the motion onset in conjunction with the continuous stream of transient signals produced by jerky motion that captures attention.