Babies can read body language. They sit and observe people eating their chips, looking at the chips even when they have a mouthful desiring more. They can see other children reaching for chips, fighting over chips, protecting their chips from other people! LOL Plus I guess they can smell them but I think it's more the body language that we exhibit while eating them. If we did the same thing while eating vegies they would be similarly desirous... infact i make more of a fuss (a positive fuss) over a bowl of vegies "mmmm" than I do chips... i often deliberately make a negative remark about chips like "uch, too salty" just to create a bit of balance. My kids love their vegies so it seems to be working.... they also like chips... but don't go crazy over them... they'd prefer a sushi handroll if given the choice.