Final answer:
Facial expressions are a specific type of non-manual behavior in ASL that convey grammatical elements and differentiate between similar signs. Non-verbal cues such as head nods and head tilts are also used in ASL for agreement and confirmation.
Step-by-step explanation:
A specific type of non-manual behavior that is specific to American Sign Language (ASL) is facial expressions. Facial expressions are an integral part of ASL and convey various grammatical elements, such as tense, intensity, and emotions. For example, raising the eyebrows can indicate a question, while furrowing the brow can express doubt or disbelief.
Facial expressions in ASL can also be used to differentiate between similar signs that have different meanings. For instance, the signs for 'expensive' and 'cheap' are identical in terms of handshape and movement, but the facial expression of raising the eyebrows and widening the eyes is added to convey the opposite meanings.
Additionally, non-manual behaviors like head nods and head tilts are used in ASL to indicate agreement, confirmation, or negation. These non-verbal cues enhance the clarity and meaning of the signed messages in ASL.