Sentence:  Some of the earliest recordings , made in the 1940 's , demonstrated that psychiatrists reacted immediately to anger and anxiety in the sound track , whereas written records of the same interview offered far fewer cues to therapy which - if they were at all discernible in print - were <WSD>picked</WSD> up only by the most skilled and sensitive experts . 
Meaning of the word marked with <WSD> tags:  get to know or become aware of, usually accidentally