To Örebro University

The sensibility to deictic gaze declines naturally with age and often results in reduced social perception. Thus, the increasing efforts in developing social robots that assist older adults during daily life tasks need to consider the effects of aging. In this context, as non-verbal cues such as deictic gaze are important in natural communication in human-robot interaction, this paper investigates the performance of older adults, as compared to younger adults, during a controlled, online (visual search) task inspired by daily life activities, while assisted by a social robot. This paper also examines age-related differences in social perception. Our results showed a significant facilitation effect of head movement representing deictic gaze from a Pepper robot on task performance. This facilitation effect was not significantly different between the age groups. However, social perception of the robot was less influenced by its deictic gaze behavior in older adults, as compared to younger adults. This line of research may ultimately help informing the design of adaptive non-verbal cues from social robots for a wide range of end users.

There is an increased interest in using social robots to assist older adults during their daily life activities. As social robots are designed to interact with older users, it becomes relevant to study these interactions under the lens of social cognition. Gaze following, the social ability to infer where other people are looking at, deteriorates with older age. Therefore, the referential gaze from robots might not be an effective social cue to indicate spatial locations to older users. In this study, we explored the performance of older adults, middle-aged adults, and younger controls in a task assisted by the referential gaze of a Pepper robot. We examined age-related differences in task performance, and in self-reported social perception of the robot. Our main findings show that referential gaze from a robot benefited task performance, although the magnitude of this facilitation was lower for older participants. Moreover, perceived anthropomorphism of the robot varied less as a result of its referential gaze in older adults. This research supports that social robots, even if limited in their gazing capabilities, can be effectively perceived as social entities. Additionally, this research suggests that robotic social cues, usually validated with young participants, might be less optimal signs for older adults.

Supplementary Information: The online version contains supplementary material available at 10.1007/s12369-022-00926-6.

Robots can direct human attention using their eyes. However, it remains unclear whether it is the gaze or the low-level motion of the head rotation that drives attention. We isolated these components in a non-predictive gaze cueing task with a robot to explore how limited robotic signals orient attention. In each trial, the head of a NAO robot turned towards the left or right. To isolate the direction of rotation from its gaze, NAO was presented frontally and backward along blocks. Participants responded faster to targets on the gazed-at site, even when the eyes of the robot were not visible and the direction of rotation was opposed to that of the frontal condition. Our results showed that low-level motion did not orient attention, but the gaze direction of the robot did. These findings suggest that the robotic gaze is perceived as a social signal, similar to human gaze.

The ability to follow the gaze of others deteriorates with age. This decline is typically tested with gaze cueing tasks, in which the time it takes to respond to targets on a screen is faster when they are preceded by a facial cue looking in the direction of the target (i.e., gaze cueing effect). It is unclear whether age-related differences in this effect occur with gaze cues other than the eyes, such as head orientation, and how these vary in function of the cue-target timing. Based on the perceived usefulness of social robots to assist older adults, we asked older and young adults to perform a gaze cueing task with the head of a NAO robot as the central cue. Crucially, the head was viewed from the back, and so its eye gaze was conveyed. In a control condition, the head was static and faced away from the participant. The stimulus onset asynchrony (SOA) between cue and target was 340 ms or 1000 ms. Both age groups showed a gaze cueing effect at both SOAs. Older participants showed a reduced facilitation effect (i.e., faster on congruent gazing trials than on neutral trials) at the 340-ms SOA compared to the 1000-ms SOA, and no differences between incongruent trials and neutral trials at the 340-ms SOA. Our results show that a robot with non-visible eyes can elicit gaze cueing effects. Age-related differences in the other effects are discussed regarding differences in processing time.

Mentalizing, where humans infer the mental states of others, facilitates understanding and interaction in social situations. Humans also tend to adopt mentalizing strategies when interacting with robotic agents. There is an ongoing debate about how inferred mental states affect gaze following, a key component of joint attention. Although the gaze from a robot induces gaze following, the impact of mental state attribution on robotic gaze following remains unclear. To address this question, we asked forty-nine young adults to perform a gaze cueing task during which mental state attribution was manipulated as follows. Participants sat facing a robot that turned its head to the screen at its left or right. Their task was to respond to targets that appeared either at the screen the robot gazed at or at the other screen. At the baseline, the robot was positioned so that participants would perceive it as being able to see the screens. We expected faster response times to targets at the screen the robot gazed at than targets at the non-gazed screen (i.e., gaze cueing effect). In the experimental condition, the robot's line of sight was occluded by a physical barrier such that participants would perceive it as unable to see the screens. Our results revealed gaze cueing effects in both conditions although the effect was reduced in the occluded condition compared to the baseline. These results add to the expanding fields of social cognition and human-robot interaction by suggesting that mentalizing has an impact on robotic gaze following.