setting display format of booleans in psql

Is there a way to set the display format of boolean values in psql just
as one can set the display of nulls using \pset null <some string>? I
find presentation of true as 't' and false as 'f' rather poor since 't'
and 'f' do not look very different from each other. I'd like to instead
get 'TRUE' or 'FALSE'.

Nothing in the manual page for psql seems helpful.