[paulrpotts]

In case you don't know, this all started with ELIZA, so:

https://en.wikipedia.org/wiki/ELIZA

You might follow that into background of other "chatterbots" - https://en.wikipedia.org/wiki/Outline_of_natural_language_pr...

These would traditionally be in some variant of Lisp, for its metaprogramming capabilities. But see also: https://en.wikipedia.org/wiki/AIML

User interface? Well, see Alexa, Siri, etc.

[willmhorne]

Ah, yes. Thank you. As for interface, I had the sense it would be non-verbal (i.e., textual) so that the "patient" would have so subvocalize the responses. But I will consider audio like Alexa et al.