Tactile interaction plays an essential role in human-to-human interaction. People gain comfort and support from tactile interactions with others and touch is an important predictor for trust. While touch has been explored as a communicative modality in HCI and HRI, we here report on two studies in which touching a social robot is used to regulate people's stress levels and consequently their actions. In the first study, we look at whether different intensities of tactile interaction result in a physiological response related to stress, and whether the interaction impacts risk-taking behaviour and trust. We let 38 participants complete a Balloon Analogue Risk Task (BART), a computer-based game that serves as a proxy for risk-taking behaviour. In our study, participants are supported by a robot during the BART task. The robot builds trust and encourages participants to take more risk. The results show that affective tactile interaction with the robot increases participants' risk-taking behaviour, but gentle affective tactile interaction increases comfort and lowers stress whereas high-intensity touch does not. We also find that male participants exhibit more risk-taking behaviour than females while being less stressed. Based on this experiment, a second study is used to ascertain whether these effects are caused by the social nature of tactile interaction or by the physical interaction alone. For this, instead of a social robot, participants now have a tactile interaction with a non-social device. The non-social interaction does not result in any effect, leading us to conclude that tactile interaction with humanoid robots is a social phenomenon rather than a mere physical phenomenon.

翻译：触觉交互在人际互动中发挥着至关重要的作用。人们通过与他人的触觉交互获得安慰与支持，且触摸是预测信任度的重要指标。尽管触摸作为人机交互（HCI）与人机交互（HRI）中的一种交流模态已被广泛探索，本文报告了两项研究，其中通过触摸社交机器人来调节人们的压力水平，进而影响其行为。在第一项研究中，我们探究不同强度的触觉交互是否会引起与压力相关的生理反应，以及该交互是否影响风险承担行为与信任度。我们让38名参与者完成气球模拟风险任务（BART）——一种作为风险承担行为代理的计算机游戏。在本研究中，参与者在执行BART任务期间得到机器人的支持。该机器人能够建立信任并鼓励参与者承担更高风险。结果表明，与机器人的情感性触觉交互会增加参与者的风险承担行为，但轻柔的情感性触觉交互会提升舒适感并降低压力，而高强度触摸则无此效果。我们还发现，男性参与者比女性表现出更多的风险承担行为，同时压力水平更低。基于此实验，第二项研究旨在确认这些效应是由触觉交互的社会性本质引起，还是仅由物理交互本身导致。为此，参与者改为与非社交设备进行触觉交互，而非社交机器人。非社交交互未产生任何效应，由此我们得出结论：与人形机器人的触觉交互是一种社会现象，而非单纯的物理现象。