When humans see a face, we apparently focus on the eyes and the lips. Once, for a summer job, I worked with our school photographer retouching the scanned images of the incoming freshman class. For efficiency, we just blurred the images to obliterate any scanning errors, and then restored and hand-retouched only the eyes and lips. Subjectively, the difference between blurred and blurred-with-original-eyes-and-lips was astonishing, while the difference between original and BWOEAL was comparatively rather small. I would assume that human expression and human vision evolved in parallel, in a complimentary fashion.

This also explains why humans so easily find faces in inanimate objects, or in three-character sequences like :-) and ^_^. We're just highly tuned to recognize and parse very particular physical features.

Really? I didn't feel that at all, although I did get an above-average score in the end. I felt I could name an emotion with most images, but I found it hard to select an appropriate match from the choices given and was often not satisfied with my answer. Some images I could not read at all.

Indeed. I only got a 31, but with the exception of one set of eyes that I completely misread each one I got wrong I was waffling between two answers and the one I didn't pick was the actual correct answer.