A questioning of a few of the assumptions behind these medical terms might be a useful clause next to this definition. Is there even a real pathology of these kinds of mental phenomena? There is a lot more going on in this definition than meets the eye. A supposedly objective piece of "science" has to be seen in social context. The longest I have ever spent in the same room as a psychiatrist is about a quarter of an hour...presumably the person then wrote notes about me showing evidence of various disorders. Their superhuman intellect was able to form a summary picture of my whole mind in this time. Minds are complex things - how well does a lifetime of knowing someone close enable us to understand their mind ? Ok - you will end up with some knowledge of their reactions after years, but 15 minutes ? I have met many "schizophrenics" in my career as a nut, and lack of emotion is not a characteristic that sticks in my mind - although the definition above acknowledges the symptom is not universal, I question that it is to be found among the sample at any higher frequency than any other group - (except perhaps news readers).
No, like with all human individuals, personal uniquenesses mean that such character traits vary very widely. Some people express more, some less. One axis. Some situations entail different spectrums of affect. Another axis. Also of course there are issues of emotional insincerity. Could it be that some of these people, for personal reasons don't wish to use the polite show of emotion that isn't really felt, but merely expressed? Some of the practitioners of this pseudo-science want you to laugh at their creepy jokes and act as if they are really caring towards you for their professional egos. But oh no - doctors are parental, responsible, so you should be respectful... When you won't play along they always get sulky and allege more "symptoms". Disrespect for authority is not an illness, and if you won't accept the assumptions behind being in consultation with a psychiatrist they often note it as evidence of illness. I have seen it many times. Tell them to "fuck off" and you'll likely end up being "restrained" (pinned down or locked in solitary). Free speech counts for absolutely nothing in all the psychiatric wards I have been unlucky enough to visit.
Of course even uttering criticisms of the mental health system like I am doing here will usually be associated with the supposed illness too. It's enough to drive you crazy. Oh yes - that's another thing they won't recognize - IRONY.