Note that this effect is strong when the coloured patches are the names of the colours, and less when the patches are separate from the names. Since the Stroop effect is strong when the patches are the names, and less when separate, some strategy is relevant to the task. If we attempt the task with different strategies and affect the outcome , then it is not entirely automatic. Often improvement with practice is a matter of finding new ways to accomplish the task. Colour vision is slow and brightness vision is fast.
Sensitivity lessens over time when there are frequent signals, and sensitivity is low anyway.
The Yerkes-Dodson law holds that performance is best at moderate arousal levels. There are curious effects of arousal on attention to brief sounds versus flashes. After arousing mild shocks tones become more detectable than flashes, and peripheral flashes become detectable than foveal flashes. Very useful in lots of areas perceptually and cognitively. Cued signals were detected with a benefit of -30 msec in a Posner experiment with two possible locations for a signal.