  Tactile interaction plays a crucial role in interactions between people.
Touch can, for example, help people calm down and lower physiological stress
responses. Consequently, it is believed that tactile and haptic interaction
matter also in human-robot interaction. We study if the intensity of the
tactile interaction has an impact on people, and do so by studying whether
different intensities of tactile interaction modulate physiological measures
and task performance. We use a paradigm in which a small humanoid robot is used
to encourage risk-taking behaviour, relying on peer encouragement to take more
risks which might lead to a higher pay-off, but potentially also to higher
losses. For this, the Balloon Analogue Risk Task (BART) is used as a proxy for
the propensity to take risks. We study four conditions, one control condition
in which the task is completed without a robot, and three experimental
conditions in which a robot is present that encourages risk-taking behaviour
with different degrees of tactile interaction. The results show that both
low-intensity and high-intensity tactile interaction increase people's
risk-taking behaviour. However, low-intensity tactile interaction increases
comfort and lowers stress, whereas high-intensity touch does not.
