Abstract
In a color-motion pairing task with red dots moving inward alternating with green dots moving outward, red inward is most likely to be reported when red is delayed ∼100 ms relative to the inward motion appearance (Moutoussis & Zeki, 1997). Enns & Oriet (VSS 2004) reported that this perceptual asynchrony could be reversed by instructing participants to attend to color before attending to motion. However, our Experiment 1 found that this variation of instructions and endogenous attention only reduced the asynchrony rather than reversing it. In contrast, Experiment 2 manipulated exogenous attention and found a large effect. In Experiment 1, 7 observers monitored for inward motion and reported the associated color, and 7 monitored for redness and reported the associated motion. For those monitoring for inward motion, the most consistent pairing occurred when red followed the inward motion by ∼134 ms. In the other group, red also had to follow inward motion, by ∼100 ms. A reversal in the asynchrony was not obtained for any observer. In Experiment 2, an exogenous attentional cue (a ring) encircled the stimulus at various delays relative to the motion and color changes. Results indicated that optimal timing of inward and red varied with ring timing. In some observers, the best delay for red relative to inward was driven to zero. In summary, attentional cues modulate and in some cases eliminate the feature asynchrony, arguing against differential latencies.