When observation of the human face is missing from an individual’s community of reinforcers, the individual will likely not respond to or even observe the presence of another individual, let alone verbal antecedents delivered by another (speaker). A child who lacks conditioned reinforcement for human faces and/or voices does not orient toward others, whether they are speaking or not speaking, and is not likely to respond to greetings or instructions from a speaker. A child at this level of verbal capability will most likely present at a pre-listener level of verbal behavior