Situated multimodal systems that instruct humans need to handle user uncertainties, as expressed in behaviour, and plan their actions accordingly. Speakers’ decision to reformulate or repair previous utterances depends greatly on the listeners’ signals of uncertainty. In this paper, we estimate uncertainty in a situated guided task, as leveraged in non-verbal cues expressed by the listener, and predict that the speaker will reformulate their utterance. We use a corpus where people instruct how to assemble furniture, and extract their multimodal features. While uncertainty is in cases ver- bally expressed, most instances are expressed non-verbally, which indicates the importance of multimodal approaches. In this work, we present a model for uncertainty estimation. Our findings indicate that uncertainty estimation from non- verbal cues works well, and can exceed human annotator performance when verbal features cannot be perceived.

In face-to-face interaction, speakers establish common ground incrementally, the mutual belief of understanding. Instead of constructing "one-shot" complete utterances, speakers tend to package pieces of information in smaller fragments (what Clark calls "installments"). The aim of this paper was to investigate how speakers' fragmented construction of utterances affect the cognitive load of the conversational partners during utterance production and comprehension. In a collaborative furniture assembly, participants instructed each other how to build an IKEA stool. Pupil diameter was measured as an outcome of effort and cognitive processing in the collaborative task. Pupillometry data and eye-gaze behaviour indicated that more cognitive resources were required by speakers to construct fragmented rather than non-fragmented utterances. Such construction of utterances by audience design was associated with higher cognitive load for speakers. We also found that listeners' cognitive resources were decreased in each new speaker utterance, suggesting that speakers' efforts in the fragmented construction of utterances were successful to resolve ambiguities. The results indicated that speaking in fragments is beneficial for minimising collaboration load, however, adapting to listeners is a demanding task. We discuss implications for future empirical research on the design of task-oriented human-robot interactions, and how assistive social robots may benefit from the production of fragmented instructions.

The adoption of virtual assistants is growing at a rapid pace. However, these assistants are not optimised to simulate key social aspects of human conversational environments. Humans are intellectually biased toward social activity when facing anthropomorphic agents or when presented with subtle social cues. In this paper, we test whether humans respond the same way to assistants in guided tasks, when in different forms of embodiment and social behaviour. In a within-subject study (N=30), we asked subjects to engage in dialogue with a smart speaker and a social robot.We observed shifting of interactive behaviour, as shown in behavioural and subjective measures. Our findings indicate that it is not always favourable for agents to be anthropomorphised or to communicate with nonverbal cues. We found a trade-off between task performance and perceived sociability when controlling for anthropomorphism and social behaviour.

The increasing use of robots in real-world applications will inevitably cause users to encounter more failures in interactions. While there is a longstanding effort in bringing human-likeness to robots, how robot embodiment affects users’ perception of failures remains largely unexplored. In this paper, we extend prior work on robot failures by assessing the impact that embodiment and failure severity have on people’s behaviours and their perception of robots. Our findings show that when using a smart-speaker embodiment, failures negatively affect users’ intention to frequently interact with the device, however not when using a human-like robot embodiment. Additionally, users significantly rate the human-like robot higher in terms of perceived intelligence and social presence. Our results further suggest that in higher severity situations, human-likeness is distracting and detrimental to the interaction. Drawing on quantitative findings, we discuss benefits and drawbacks of embodiment in robot failures that occur in guided tasks.

Conversational interfaces that interact with humans need to continuously establish, maintain and repair common ground in task-oriented dialogues. Uncertainty, repairs and acknowledgements are expressed in user behaviour in the continuous efforts of the conversational partners to maintain mutual understanding. Users change their behaviour when interacting with systems in different forms of embodiment, which affects the abilities of these interfaces to observe users’ recurrent social signals. Additionally, humans are intellectually biased towards social activity when facing anthropomorphic agents or when presented with subtle social cues. Two studies are presented in this paper examining how humans interact in a referential communication task with wizarded interfaces in different forms of embodiment. In study 1 (N = 30), we test whether humans respond the same way to agents, in different forms of embodiment and social behaviour. In study 2 (N = 44), we replicate the same task and agents but introduce conversational failures disrupting the process of grounding. Findings indicate that it is not always favourable for agents to be anthropomorphised or to communicate with non-verbal cues, as human grounding behaviours change when embodiment and failures are manipulated.

Humans and robots will increasingly collaborate in domestic environments which will cause users to encounter more failures in interactions. Robots should be able to infer conversational failures by detecting human users’ behavioural and social signals. In this paper, we study and analyse these behavioural cues in response to robot conversational failures. Using a guided task corpus, where robot embodiment and time pressure are manipulated, we ask human annotators to estimate whether user affective states differ during various types of robot failures. We also train a random forest classifier to detect whether a robot failure has occurred and compare results to human annotator benchmarks. Our findings show that human-like robots augment users’ reactions to failures, as shown in users’ visual attention, in comparison to non-humanlike smart-speaker embodiments. The results further suggest that speech behaviours are utilised more in responses to failures when non-human-like designs are present. This is particularly important to robot failure detection mechanisms that may need to consider the robot’s physical design in its failure detection model.

In this paper, we analyze multimodal behavioral responses to robot failures across different tasks. Two multimodal datasets are examined in which humans interact with guided-task robots in task-oriented dialogues. In both datasets, the robots simulated failures of conversational breakdown and miscommunication typically observed in human-robot interactions. We closely examine human reactions to these failures looking at facial and acoustic features. Our analyses identify the significant behavioral features for automatic detection of such failures in interaction. We also examine human responses to different types of robot failures and if failures occurred early or late in the interaction cause variation in the responses. Our findings indicate that several nonverbal behaviors are consistently present in responses to robots' failures, e.g., gaze and speech prosody, whereas, linguistic features appear to be task-dependent. We discuss how these findings may generalize to other tasks, and how autonomous robots may identify opportunities to detect and recover from failures in interactions with humans.