[Jimbee (OP)]

On the sci-fi series Star Trek: the Next Generation (1987-94), Lieutenant Commander Data had a unique problem. He couldn't use contractions when he spoke. That is actually one of the ways Commander Riker was able to tell he was really in a computer simulation in the 1990 episode Future Imperfect. I know that the Star Trek series often are often closer to actual fact than other series in the science fiction genre. At least I think they are. But of course not always. In the 1994 episode Genesis the crew de-evolves into primitive forms of life, like spiders, amphibians and cave men. I don't think that could really happen that way. The crew was all fully grown. Maybe if they were still in the uterus or even young children.

So is there a problem like that? Where a person is unable to use contractions when they speak? Maybe a form of brain damage? Or in his case it was because he hadn't grown yet into a full human. Which could have either meant mentally or emotionally.

[Eternal Student]

Hi.

   Data did act out some Shakespearian plays in the holodeck.   Shakespeare is famous for having used quite a lot of contractions in his work.    Changing any of the original lines would be a serious corruption of these works.  So, the viewer is really left to make their own rules and assumptions about when Data can and cannot use contractions.

     Finally, no, I'm not aware of any medical condition where the only thing about your speech that would be affected is that you can't use contractions.

Best Wishes.

[Bored chemist]

Being unable to use contractions would require that you could always recognise them and, if that was always clear, people would not make nearly as many mistakes with apostrophes.
You have to teach kids that the word "can't" is a contraction of "can not" when you teach them to spell.

[alancalverd]

I did have a client who would not use contractions, and had a few other behavioral oddities, but I'm pretty sure her speech idiosyncrasy was a voluntary affectation and not pathological.

We acquire our native language by copying the demotic, so our primary spoken communication necessarily involves contractions and dialect, unlike languages we learn formally from textbooks or other written material - you won't find many apostrophes in a scientific journal or a legal argument.  The writers of Star Trek were pretty clever to use this as a character definition.