In Act 1 of The Miracle Worker, Helen is playing paperdolls with Martha and Percy. As the other two childen speak to each other, Helen thrusts her hands at their faces in turn, "feeling baffledly at the movements of their lips". She goes so far as to actually poke her fingers inside Percy's mouth, to feel his tongue, at which point he bites at her hand with annoyance. Helen then "fingers her own lips, moving them in imitation, but soundlessly". Percy observes that Helen is "tryin' talk", and it appears that he is indeed correct in his assessment. Helen's lips move under her fingertips "in ghostly silence, growing more and more frantic, until in a bizarre rage she bites at her own fingers". It is clear that Helen is aware that the children are communicating through words which come from their mouths, and she is completely frustrated that she cannot do as they do.
A little later, Aunt Ev gives Helen a towel doll, which Helen begins to explore with her fingers. She is obviously troubled when she passes her hand over the doll's face and finds no features there. She goes from person to person, tapping more and more vigorously for eyes, but no one understands. Helen then goes to Mr. Keller's desk and begins groping among the things there on top. Not finding what she wants, she returns to Aunt Ev, fingering her dress, and yanks two buttons from it. Helen pushes the buttons into the doll's face, at which point Kate kneels next to her and lifts Helen's hand to her own eyes in question. Helen "nods energetically", and Kate takes supplies from her sewing basket and attaches the buttons to the doll as eyes. Helen, holding the doll, now "cannot contain herself for joy; she rocks the doll, pats it vigorously, kisses it". Helen is aware that eyes are an important and necessary part of human anatomy. Whether or not she knows that eyes are for seeing might be debated, but at the very least, she is aware that a person is somehow incomplete without eyes.