Well I was skeptical, wondering if maybe people posted darker / grayer images because of where they live; so seasonal affective depression (SAD) was causing the

Well I was skeptical, wondering if maybe people posted darker / grayer images because of where they live; so seasonal affective depression (SAD) was causing the depression, not that depression was swaying people's filter choices. However this study seems to account for that causation (I only skimmed it quickly): "We also checked metadata to assess whether an Instagram­ provided filter was applied to alter the appearance of a photograph." [...] "A closer look at filter usage in depressed versus healthy participants provided additional texture. Instagram filters were used differently by depressed and healthy individuals. In particular, depressed participants were less likely than healthy participants to use any filters at all. When depressed participants did employ filters, they most disproportionately favored the “Inkwell” filter, which converts color photographs to black­ and­ white images. Conversely, healthy participants most disproportionately favored the Valencia filter, which lightens the tint of photos." > Also, I think detecting depression premtively via social media is a terrifying idea. Yeah, they also called their model "Pre­-diagnosis". :)