Here's an alternate theory that should be controlled for in future studies: Crappy photos are more likely to be grey/less colorful, and the average MTurker like

Here's an alternate theory that should be controlled for in future studies: Crappy photos are more likely to be grey/less colorful, and the average MTurker likely has a less than stellar camera. Thus photos are more depressing because the camera is crappy, not because these people are subconsciously expressing their mental state with IG filters. I'd be much more interested in the results if, say, only photos from an iPhone 5 or 6 were considered.