From what I have read, if my memory is correct, the Pleos and Pleo Rb do not and can not distinquish between objects, except the red tracking on leaves. It is the sensors that detect objects, such as a leaf, and when they identifiy it, they will or will not open their mouths. As for walking towards an object, it is only random, Pleos and Pleo Rb will in most instances stop before going off a table top, but it is perception seeing they will fall, not deciding they do not like an object.
It would be nice if they could identify faces, but the closest we have so far with the Pleo RB is voice recognition. Some other member will surely explain it a lot better with the proper lingo than I can. As far as interest, a Hungry Pleo Rb is going to let you know they are hungry, where as a Pleo, like the Ugobe, will open it's mouth randomly and chew it's leaf, your finger or just look like they are grazing like a cow without a object even being there.
RWM