I think the effects of cognitive load on code readability can be demonstrated with variable and function names:

  phi
  s
  ses
  session
  cursor_session
  database_session
  dbs
  db.session

Really short variable names reduce the cognitive burden for users that understand that "phi" means "database session", but frustrate users who aren't contextually familiar.

Really long variable names make it too difficult to verbalize and thus comprehend code.

Is 7±2 a practical limit to working memory for seasoned coders, though?