Historically, psychologists have looked at introversion as the absence of extroversion. They measure extroversion, and if you are low in it, then you are considered an introvert. This perpetuates the perception of introversion as negative space, and introverted activities as not really doing anything. We need to train ourselves, and others, out of this idea. We need to start seeing doing nothing (or reading, or working alone on projects, or whatever it is we do to recharge) as activities that are as valid as any social event.