Asymmetric listening conditions perturb verbal and nonverbal coordination dynamics during conversation
Human conversation depends on continuous coordination across verbal and nonverbal behaviour. Yet this coordination may become perturbed when one person experiences greater listening difficulty. Previous nonverbal joint action studies show that unequal task demands between partners can lead to complementary leader-follower dynamics, but whether similar patterns emerge during natural conversation remains unclear. We investigated how unequal listening conditions affect verbal and nonverbal coordination in 40 same-gender stranger dyads during three 10-minute face-to-face conversations. Each dyad participated in noise-free and asymmetric noise conditions, with one person exposed to speech-shaped noise at a time. Asymmetric noise reduced conversational flow and enjoyment, and shifted the balance of verbal contributions: noise-exposed participants took longer turns and contributed more speaking time, while their noise-free partners produced more backchannels. Interpersonal head-movement coordination became temporally asymmetric under noise, with movements of the noise-exposed participant more often preceding those of their partner. In contrast, interpersonal hand-movement coordination did not differ between conditions. Within individuals, hand coordination was stronger when participants themselves experienced noise than when their partner experienced noise. These findings demonstrate that perturbing one partner's auditory access affects coordination within and between individuals, revealing how unequal interaction demands produce different coordination patterns across verbal and nonverbal behaviour.