"outward behavior" is correct and usable in written English.
It is a phrase used to refer to the behavior or actions that are visible to other people. For example, "Many people concentrate solely on outward behavior, rather than considering someone's inner character."
Stiffness, on the other hand, is an accident of outward behavior.
One person's experiences hanging out with Americans or Indians, in addition to being anecdotal, only tell you about their outward behavior.
The joke lampoons behaviorists' claim that inner experiences — emotions, thoughts, memories, plans, images — are somehow less real than outward behavior, and hence as unscientific as ghosts and fairies.
Again, because you know, imagine if they're not burnt out at all, they're just kind of an introverted, not very expressive person, and you're completely interpreting their outward behavior with no idea about what's going on internally.
And also as a metaphoric presence to talk about what your neighbors might really be like in their hearts– not in their outward behavior, but in their hearts, they might be just like buzzards.
(After all, we can't see "into" another person's subjective awareness anymore than SimSensei can; all we can do is interpret their outward behavior). SimSensei, like any anthropomimetic technology, may be just as useful as a "user interface" for understanding our own wetware as it is for outsourcing it.
Aquinas acknowledges that a range of outward behaviors are associated with religio vows, tithes, offerings, and so on but he regards these as secondary.
The Jesus of the gospels said that we will know the measure of people by their fruits: the outward behaviors and attitudes that spring from their inner selves.
From the systematic analysis of outward motile behavior we can infer the inner workings of neural algorithms.
After 28 days of supplementation, toxicity of the selenazolidines was not evident, as measured by outward appearance and behavior, body and organ weight changes, and histological evaluation of liver and lung tissue.
The idea that all living things are separate, stable, and unchanging [and its corollary that a species' outward appearance and behavior are determined by a hidden causal power or "essence" (Shtulman 2006)] appears to have deep psychological sources in humans (Samarapungavan and Wiers 1997; Evans 2000a; Poling and Evans 2004; Shtulman 2006, 2011; Shtulman and Schulz 2008).
