
Student or Learner
"He turned his interest / interests to literature."
Should the singular or plural form be used?
Welcome to Using English.
That doesn't sound very natural.
He turned his attention to (something)
His interests turned to literature.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.