Complex sentence: After a few weeks Genie became much more responsive to nonverbal and verbal stimuli, although at first she remained mostly unexpressive and doctors were unsure whether she responded more to verbal or nonverbal stimuli when listening to speech.
Split into simpler sentences: After a few weeks Genie became much more responsive to nonverbal and verbal stimuli, although at first she remained mostly unexpressive. Shortly afterwards she began paying attention to people speaking, but it was unclear whether she responded more to verbal or nonverbal stimuli when listening to speech.