The eye also influences our perception in terms of haptics. At least that's what we found out in one particular case. Same material, same surface coating (soft-touch cellophane, applied after printing), only the printing was different. One variant was printed in black with negative white lettering, the other variant was printed in white with black lettering. And the result: the surface of the fully black printed version feels more velvety. The only explanation - for us - is that the colour and coating convey to the eye that it must be a different material from the white version.