Sentence:  The <WSD>authors</WSD> set about answering this fundamental question through a detailed investigation of the patient 's ability , tactually , ( 1 ) to perceive figure and ( 2 ) to locate objects in space , with his eyes closed ( or turned away from the object concerned ) . 
Meaning of the word marked with <WSD> tags:  writes (books or stories or articles or the like) professionally (for pay)