In your Google+ Notifications (that's the little bell in the upper right), just click on the card that tells you "Eric +1'd your photo" and it will pop up your photo post.
If you want more information on who +1'd/shared/etc., click "View post" at the bottom.
Then, when you have the full view of the post, open the menu (looks like a wide "V") and click "View post activity". There you'll see all the people who +1'd and/or shared the post. Click on Eric's name to see his profile.
It would probably be nice if you could click the link for the person's profile in the first step, but since G+ consolidates notifications, that would be problematic for posts with a lot of activity on them, so I'm sure it's a conscious design decision. (And even Facebook requires some extra clicks if more than a couple people have "Liked" a post of yours.)