Could you give the details about the research? Where was it published? If you give a link, it would be awesome.

As to looking in the mirror at yourself, it all depends on your mood. If your mood is euthymic (normal), you will appreciate yourself in normal light, focusing equally on your good, bad and ugly points, without being much moved emotionally by it. On the other hand, if you are in a euphoric mood (elated or high), you will only see the good points. In fact, sometimes you would see strengths or allures in yourself, which do not exist in reality. This would only make you more happy. If you are depressed, you would only focus on the negatives sometimes even exaggerating them out of proportion. And this would, I need hardly say, lead to further depression.