Take, for instance, the concept of derived stimulus relations. In the 1990s, these were the Great New Discovery that behavior analysts were researching. What are they? Well... my book's explanation involves the following:
... subjects in the Steele and Hayes (1991) experiment learned that A1 was the opposite of B3 and C3 and the same as B1 and C1. Testing showed that the subjects then derived that B3 and C3 were the same, and that each of these were the opposite of B1 and C1. When they later learned that the arbitrary stimulus D1 was opposite to C3 during a test phase, they then treated D1 as the opposite and not the same as B3. (p. 234)
Yes, really. That's a direct quote. Grad school textbooks tend to overcomplicate things.
Now... this research does have its applications. For instance, this work let them make the following observation:
A derived stimulus relation based view of language suggests that the event and the description of the event interact bidirectionally with one another. If so, verbal self-awareness will be painful when what is known is painful. For example, a trauma survivor may avoid thinking and talking about the trauma, because the very process of contacting it verbally will bring some of the stimulus functions of the original experience to bear in the description (Hayes & Gifford, 1997). (p. 235)
In other words, people tend to avoid doing things that are painful and talking about painful events in your past is painful because thinking about them is painful.
Note the date on that citation, too. The book's citing a 1997 paper.
Skinner published The Behavior of Organisms in 1938. Behavior analytic research has been going on ever since... and its history goes back even further.
In other words, it took behavior analysts nearly sixty years to figure that out.
By contrast, Anna Freud published Ego and Mechanisms of Defense in 1936.
Similarly, the "Great New Thing" in the 1980s was what's called "functional analysis". It boils down to an acknowledgement that people do things for a reason, and that knowing the reason why someone does something is helpful in getting them to do something else instead.
I have my issues with functional analysis methodology, but it was a great leap forward. It's hardly enough, but it's a great improvement and a step in the right direction.
Ethically speaking, we need to take into account things which current behavior analytic theory doesn't even acknowledge as existing. Far too many practitioners of the techniques that ABA has developed tend to forget that.
Hayes, S. & Bissett, R. (2000). Behavioral psychotherapy and the rise of clinical behavior analysis. In Ausin, J. & Carr, J. (Eds.), Handbook of applied behavior analysis (pp. 231-245). Reno, NV: Context Press.