I don't believe this was in the original edition, but someone can correct me if I am wrong: he proposed the concept of "signifiers" to fill the definition that

I don't believe this was in the original edition, but someone can correct me if I am wrong: he proposed the concept of "signifiers" to fill the definition that people were increasingly giving to "affordances". A signifier helps to indicate the presence of an affordance that might not be immediately apparent.