We've currently got the human-factors tag which has been used with varying degrees of appropriety. I do think Human Factors and or Ergonomics are on topic here, but due to the scope I'm not sure "Human Factors" makes much sense as a tag.
Some suggested alternates were usability, ergonomics (technically ergonomics can cover cognitive issues as well) and user-experience. While the tag would effectively be most helpful for us over at the User Experience site, I feel UX is a bit too broad and would be out of place as a tag here. But if we pick another tag it could be aliased into the master tag for easier searching.
I'd also personally consider these distinct from Human Computer Interaction, though very related and occasionally overlapping, Human Factors isn't necessarily computer interaction.