Using machine learning techniques, Robotics Institute researchers Alexei Efros and Martial Hebert, along with graduate student Derek Hoiem, have taught computers how to spot the visual cues that differentiate between vertical surfaces and horizontal surfaces in photographs of outdoor scenes. They've even developed a program that allows the computer to automatically generate 3-D reconstructions of scenes based on a single image.

There's also an article in NYer this week by neurologist Oliver Sacks about stereoscopy that deals with the divide between various forms of depth- and contextual-cueing and true depth perception.