Early-warning signs of depression can be detected in Instagram posts, before a clinical diagnosis is made, according to research.
Researchers at Harvard and Vermont universities asked people to share their Instagram histories, along with details about their mental health history.
Using findings from clinical psychology research, they identified visual and behavioral markers associated with depression.
Sufferers exhibit different preferences for colour, shading, and brightness in imagery, compared with healthy people.
'Darker and greyer'
Pixel analysis of photographs in their 43,950-strong dataset revealed that depressed people tended to post pictures that were, on average, bluer, darker, and greyer.
Using a face detection algorithm, they also found that sufferers posted significantly fewer faces per photograph; signalling an avoidance of social contact.
"Even the way depressed and healthy people chose to present their photos on Instagram was different," said the researchers.
Instagram offers a series of ready-made filters that adjust a photo’s appearance. Among healthy users, the most popular filter was Valencia, which gives photos a warmer, brighter feel.
Among depressed users, however, the most popular filter was Inkwell, turning pictures black-and-white.
"In other words, people suffering from depression were more likely to favour a filter that literally drained all the colour out of the images they wanted to share."
The researchers added: "We do feel strongly that there’s an important ethical discussion that must occur in step with these technological developments, regarding data privacy and the implications of applying sophisticated analytical tools in an online medium which doesn’t forget.
"Even so, the possibility that social media analytics may offer a means of getting help faster to people in need is important, and should be explored further."