[8][9][10] The degree of perceptual asynchrony can be considerably reduced by manipulating the stimuli in a variety of ways,[11][12][13] which complicates its attribution to a simple difference in processing times for color and motion.
[14] The theory that the phenomenon is caused by difference in color and motion processing time has been challenged by multiple lines of evidence.
For example, the evidence for an asynchrony is much smaller or absent when people are asked to judge the relative timing of color and motion changes rather than their pairing.
[15] Nishida & Johnston created displays in which the color onset also was not signalled by a unique feature and found that greatly reduced the asynchrony.
Changing the duration of the color, but not of the motion, shifted the timing required to maximize the consistency of pairing judgments.