I believe all fish use many different factors to find and catch their prey. Movement, size, smell, sound, color, and any other advantage they can find. If the prey they are feeding on is a certain size, and moves in a specific way, but its color doesn't stand out in any way then the fish would have a difficult time finding and catching the prey by keying in on its color. The opposite would be true if size and movement were varied, with no distinct features to key in on, but all of the prey had a distinct color patch, or certain flash. Then the fish would probably be concentrating on this aspect to find its food. The smaller the prey, the more chance, of the fish keying in on a single trait to find it. It would be much easier to notice large prey regardless of any particular features. Most of the time the best lure will match a combination of features. If there is no particular prey that is abundant at the time, then a lure that is large, with lots of action, flash, and color might be the ticket. If there are lots of one kind of prey that the fish are used to feeding on at that time and place, then match the hatch could be very important. The same applies to a hunter. If a person is hunting for a well camouflaged animal, that tends to move around, then the hunter will be looking for a certain movement to spot the animal. If the animal moves very little, but has a color that doesn't blend in then he will concentrate on looking for that color. Just a theory, may be completely wrong, That is why I'm very good friends with the bait monkey I try everything.