The easiest and strongest way to move our eye around the canvas is by differences/contrasts in value. If we have an extremely middle-value painting with no contrasting value areas, we can move our eye around with color. In this extremely middle-value painting - and if everything was quite desaturated - then two complementary and more highly saturated colors of the same value would definitely draw our eye. But please remember that this is only secondary to value contrasts. For example, if you introduced a desaturated color that was of lighter/ darker value - even though it was a desaturated color - this value contrast will draw our eye before the color variances will.