So, take to boxes 3' x 3' x 3' in size. They are physically identical on the outside, but one is rigged with a motion sensitive device so that it will explode if you move near it.
I say they are visually perceived to be the same, but that they afford different things (one affords alight-on-ability; the other does not). So, one does not perceive alight-on-ability. (Cf. TSRM, 1981, p. 261 for the example of alight-on-overability).