Courts and cops rely on Psychological pseudoscience all the time. Treating nonverbal language as if it were a fixed language with one reading looks exactly the same to me. There's a reason you will not find it taught in linguistics departments.

Indeed, but in investigations and undercover work they also tend to go with what works best. Indeed, in undercover work their ability to get the body language right can mean the difference between life and death. No on claiming this is a hard science; it's a form of communication. Dismissing it as pseudoscience is like saying that linguistics is a pseudoscience because words can be ambiguous. Some body language is arbitrary and meaningful only to individuals, some is meaningful only within cultures, and some is universal. A baby crying means the same thing in all cultures: the baby is in distress. Look, I don't care if you believe me or not, but at least educate yourself about it a little more thoroughly than "Well, this guy said this."

I would be interested, though, if there were any studies on the predictive powers of "body language;" particularly in those areas where verbal communication is ambiguous.

I know of this study. And it looks like there are some other studies where I got that from that look to be relevant to your interest.

You might, but I wouldn't. Without explicit assent, I will ask for explicit assent. But hey, that's just me. I'm the guy who was the buzz-kill for an adult lover with a "rape fantasy" until we worked out the safe-words whereby she could say "yes" with her body and be as ambiguous or contradictory as she wanted with her verbal cues.

Okay, back the truck up for a sec. When I said we can assume from an attempt at seduction that she wants to fuck, that doesn't mean I necessarily support jumping right in bed with her without a word spoken. An assumption is an assumption; an action is an action. In most cases I would also be inclined to verify it verbally too. But you did agree with me previously that it would be wrong to assume rape took place just because she didn't verbally verify she wanted to screw. There are times when words are unnecessary.

Its easy enough to declare the body language self-evident after the verbal language ends ambiguity. But if there actually is a fixed language ( rather than a series of "ink-blot-tests" being interpreted to conform to the tester's readings ) then we should be able to predict what was ambiguous in the one language to perhaps overlap with what wasn't ambiguous in another "language."

There are some (imperfect) universals, and you probably take them for granted without even realizing it. I mentioned the baby crying. I recall Lindsay Ashford making the point (when confronted in an interview with the fact that babies could not verbally consent to sex) that babies could experience pleasure. How would one know if babies are experiencing pleasure or not unless there were some general rules of nonverbal communication? I'm not going to argue in favor of sexual stimulation for babies based on body language (or anything else), but the point remains: as a species we developed the ability to communicate nonverbally long before we developed language. It is deeply ingrained in us, instinctive in some cases and semi-instinctive in many others, such as in the use of paralanguage.

I would never assume anything that conformed with what I wanted to hear until I heard it. The Antis already do that to those they wish to disempower, or worse yet, advocate on behalf of.

You do it all the time. You just don't realize you're doing it. What do you think schemas are? They are assumptions based on stereotypes we form from previous experiences.

On an unrelated note, someone pointed out that the pseudomystical "Profiler" beloved of serial-killer Films and TV series has no better a track record than those detectives who make no claim to understand the criminal mind from within. Old fashioned casework and statistics on file produce the same pronouncements without the attempt to use Psychology as a basis for "mind-reading."

Profiling is a different sort of animal altogether, because it's not based on immediate nonverbal cues. Profiling in this sense is used to track a criminal, and I agree that it is largely ineffective because there is no single serial killer profile.