I had an interesting conversation with my wife while on a walk this evening.

Rachel was asking me if I had seen some pictures online of a friend of our’s new baby and in my answer, I was struck by the semantic difference between to see and to look.

1. I saw the pictures, but I didn’t look at them.
2. *I looked at the pictures, but I didn’t see them.

In the context of the question asked, #2 is ungrammatical. That’s because to look seems to semantically require intention.

We could describe the difference in terms of asymmetrical markedness, where to see is unmarked for intention, while to look is marked for intention. Thus, we can use to see with reference to intentionally looking at something, but it isn’t necessarily required in the word itself. But for to look, it is.

Now, I said that #2 is ungrammatical in that particular context, but it is possible to use in normal speech. The situation would be one where I was telling someone that I had been looking at a picture, but at the time, I completely missed the point of what I was looking at.

1. I looked at the pictures, but I didn’t see them (implied: I didn’t recognize the significance or value of them or something to that effect).