Mostly while on medication.

I do experience them, however, when I'm in a deep major depressive episode. Level of severity of the episode tends to effect the symptoms in my case.

You can usually tell how I'm feeling by my voice, too. Deeper episodes usually involve slowed speech in my case, slowed response rate, less facial expressions, and a monotonous tone of voice.

This all varies from person to person, though. Depression manifests in so many different ways between people, really.