The tap is the brief discontinuation of contact of the hand at a placement on the face (mouth, chin, throat) when a syllable at that same placement immediately follows. For example, when cueing boo boo, the cuer places handshape 4 at the chin for the first syllable, but must release contact — briefly moving the hand forward in order to contact the chin again for the second syllable. The hand never maintains contact at a placement from one syllable to the next.
The tap is similar to the flick. However, the necessity to tap is based on an immediate reoccurence of a placement and happens regardless of handshape. In other words, when cueing, birdie, the cuer must tap because the mouth placement is used in consecutive syllables. The transition from handshape 4 to handshape 1 occurs after the hand has left the placement and must be complete before it contacts the mouth placement again.
The tap is important for synchronization. The production of manual cues with the correlating information on the mouth must be timed to occur together. The touching of placements on the face provides by kinesthetic feedback to the cuer which can be synchronized with articulation of vowels on the mouth.