Even though depressed people are more likely to struggle socially, they've been found to be more perceptive to the feelings of others. There is a difference between clinical and mild depression, though.
Queen's University researchers found that clinically depressed people are worse at "mental state decoding" - which is identifying other people's emotions from social cues. Eye expressions, posture, tone of voice, etc. are social cues that tip us off to how others are feeling.
Mildly depressed people are better at mental state decoding because they have more concern for their surroundings. They want to stop feeling helpless; they want to gain control of their surroundings again. They may be motivated to look for cues to how others are thinking and feeling as part of the path towards reconnecting with their social world.
The bigger picture is mild versus clinical depression - which can be a controversial issue! Are there significant differences between the two? Often, depression is viewed as a continuum without major "thresholds" or markers like mental state decoding.
Signs of depression range from eating less to sighing more; causes of depression vary from genetics to traumatic events in life. Finding a therapist you connect with is one of the best things you can do to help yourself or a family member with depression. Don't dismiss alternative approaches to combating depression, such as yoga!