Final answer:
A vertical arrow from the speaker's operant chain to that of the listener's indicates that the speaker's behavior causes stimulation and/or reinforcement for the listener's behavior.
Step-by-step explanation:
In terms of interlocking contingencies, a vertical arrow (downward) from the speaker's operant chain to that of the listener's indicates that the speaker's behavior causes stimulation and/or reinforcement for the listener's behavior.
For example, if a teacher asks a student to raise their hand and the student complies, the teacher's behavior of requesting the student to raise their hand serves as a cue for the student's behavior of raising their hand.
This vertical arrow signifies that the speaker's behavior influences the listener's behavior through environmental consequences.