Person-directed pointing gestures and inter-personal relationship: Expression of politeness to friendliness by android robots

Pointing at a person is usually deemed to be impolite. However, several different forms of person-directed pointing gestures commonly appear in casual dialogue interactions. In this study, we first analyzed pointing gestures in human-human dialogue interactions and observed different trends in the use of gesture types, based on the inter-personal relationships between dialogue partners. Then we conducted multiple subjective experiments by systematically creating behaviors in an android robot to investigate the effects of different types of pointing gestures on the impressions of its behaviors. Several factors were included: pointing gesture motion types (hand shapes, such as an open palm or an extended index finger, hand orientation, and motion direction), language types (formal or colloquial), gesture speeds, and gesture hold duration. Our evaluation results indicated that impressions of polite or casual are affected by the analyzed factors, and a behavior's appropriateness depends on the inter-personal relationship with the dialogue partner.