It is widely acknowledged that the accommodation-vergence-conflict contributes a lot to strain and stress happening in stereoscopic vision. Astonishingly little is known, however, regarding the cognitive consequences. A set-up is developed and introduced which enables the quantification of recognition performance for objects which are viewed out of focus. Experiment 1 showed that in stereoscopic environments, recognition performance for objects behind fixation was in mean twice as good as in real environments. In real environments, recognition of objects presented behind fixation was even worse than in the upper visual field (Exp. 2). Although retinal disparity seems to contribute to this low recognition performance, Experiment 3 showed that in real environments, even without disparate images, processing of objects in depth is rather limited. The data provide a first estimate on how much defocus blur affects cognitive processing in real environments and hence, how much cognitive effort is required in stereoscopic scenes to enable comparable information processing in virtual and in real surrounds.

Virtual reality (VR) enables users to experience informal learning activities, such as visiting museum exhibitions or attending tours independent of their physical locations. Consequently, VR offers compelling use cases by making informal learning and education accessible to a broader audience and simultaneously reducing the carbon footprint. For many learning activities, the presence of a human guide is essential for participants' experience. The effect of the presence of a guide and its appearance in VR is, however, unclear. In this paper, we compare a real-world guide with a realistic, an abstract, and an audio-only representation of a virtual guide. Participants followed four multimodal presentations while we investigated the effect on comprehension, presence, co-presence and the perception of the guide. Our results show that even a realistic presentation of a guide results in significantly lower co-presence, humanness, and attractiveness compared to a human guide. Qualitative results and participants' feedback indicate that having no visual representation of the guide helps to focus on the content but can reduce the connection with the guide.

Avatars are our digital embodied alter egos. Virtual embodiment by avatars allows social interaction with others using the full spectrum of verbal and non-verbal behaviour. Still, one's avatar appearances is elective. Hence, avatars make it possible for users to discuss and exchange sensible or even problematic personal topics potentially hiding their real identity and hence preserving anonymity and privacy. While previous works identified similarities how participants perceive avatars compared to human stimuli, there is a question as to whether avatar-mediated self-disclosure is authentic and results in similar social responses. In the present study, we created a comparable stimulus set to investigate this issue and conducted an online study (N=172) for comparison. Our results indicate that avatars can be perceived as authentic and that empathy is attributed in similar level than to a human stimulus. In an exploratory model, we found that for in the overall results, authenticity fostered emotional empathy which in turn fostered pro-social intentions. We argue that avatars may serve as a valuable supporting medium for HCI applications related to mental well-being, self-disclosure, and support.

Computer agents are increasingly endowed with anthropomorphic characteristics and autonomous behavior to improve their capabilities for problem-solving and make interactions with humans more natural. This poses new challenges for human users who need to make trust-based decisions in dynamic and complex environments. It remains unclear if people trust agents like other humans and thus apply the same social rules to human-computer interaction (HCI), or rather, if interactions with computers are characterized by idiosyncratic attributions and responses. To this ongoing and crucial debate we contribute an experiment on the impact of anthropomorphic cues on trust and trust-related attributions in a cooperative human-agent setting, permitting the investigation of interdependent, continued, and coordinated decision-making toward a joint goal. Our results reveal an incongruence between self-reported and behavioral trust measures. First, the varying degree of agent anthropomorphism (computer vs. virtual vs. human agent) did not affect people's decision to behaviorally trust the agent by adopting task-specific advice. Behavioral trust was affected by advice quality only. Second, subjective ratings indicate that anthropomorphism did increase self-reported trust.

In this paper we report results from a web- and video-based study on the perception of a request for help from a robot head. Colored lights, eye-expressions and politeness of speech were varied. We measured effects on expression identification, hedonic user experience, perceived politeness, and help intention. Additionally, sociodemographic data, a 'face blindness' questionnaire, and negative attitudes towards robots were collected to control for possible influences on the dependent variables. A total of n=139 participants were included in the analysis. Significant differences were found for the identification performance for our intended eye-expressions, for perceived politeness, help intentions and hedonic user experience. Especially for the negative attitudes towards robots, we found significant relationships with perceived politeness and help intentions.