To have an experience is not necessarily to know that one is having it. Situations such as suddenly realizing that one has not been listening to one's spouse (despite nodding attentively) or catching oneself shouting, “I'm not angry,” illustrate that people sometimes fail to notice what is going on in their own heads. The intuition that there is a difference between having an experience and recognizing it permeates everyday language, as illustrated by the popular expression “getting in touch with your feelings” and the famous lyrical refrain “if you're happy and you know it, clap your hands.” A variety of psychological terms have been used to characterize how people vary in their awareness of their thoughts and feelings, including metacognitive awareness, private self-awareness, reflective awareness, ...