Carolin Straßmann

Robots or Agents – Neither Helps You More or Less During Second Language Acquisition

When designing an artificial tutor, the question arises: should we opt for a virtual or a physical embodied conversational agent? With this work we contribute to the ongoing debate of whether, when and how virtual agents or robots provide more benefits to the user and conducted an experimental study on linguistic alignment processes in HCI in the context of second language acquisition. In our study (n = 130 non-native speakers) we explored the influence of design characteristics and investigated the influence of embodiment (virtual agent vs. robot vs. speech based interaction) and system voice (text-to-speech vs. pre-recorded speech) on participants’ perception of the system, their motivation, their lexical and syntactical alignment during interaction and their learning effect after the interaction. The variation of system characteristics had no influence on the evaluation of the system or participants’ alignment behavior.

The Effect of an Intelligent Virtual Agent’s Nonverbal Behavior with Regard to Dominance and Cooperativity

In order to design a successful human-agent-interaction, knowledge about the effects of a virtual agent’s behavior is important. Therefore, the presented study aims to investigate the effect of different nonverbal behavior on the agent’s person perception with a focus on dominance and cooperativity. An online study with 190 participants was conducted to evaluate the effect of different nonverbal behaviors. 23 nonverbal behaviors of four different experimental conditions (dominant, submissive, cooperative and non-cooperative behavior) were compared. Results emphasize that, indeed, nonverbal behavior is powerful to affect users’ person perception. Data analyses reveal symbolic gestures such as crossing the arms, stemming the hands on the hip or touching one’s neck to most effectively influence dominance perception. Regarding perceived cooperativity expressivity has the most pronounced effect.

Do a robot’s social skills and its objection discourage interactants from switching the robot off?

Building on the notion that people respond to media as if they were real, switching off a robot which exhibits lifelike behavior implies an interesting situation. In an experimental lab study with a 2x2 between-subjects-design (N = 85), people were given the choice to switch off a robot with which they had just interacted. The style of the interaction was either social (mimicking human behavior) or functional (displaying machinelike behavior). Additionally, the robot either voiced an objection against being switched off or it remained silent. Results show that participants rather let the robot stay switched on when the robot objected. After the functional interaction, people evaluated the robot as less likeable, which in turn led to a reduced stress experience after the switching off situation. Furthermore, individuals hesitated longest when they had experienced a functional interaction in combination with an objecting robot. This unexpected result might be due to the fact that the impression people had formed based on the task-focused behavior of the robot conflicted with the emotional nature of the objection.

Interpretation of (In-)Congruent Nonverbal Behavior and Non-Linguistic Utterances

We present an experimental online study examining how participants (N=343) interpret affectively congruent and incongruent body movements/gestures and non-linguistic utterances (NLUs).

With or against Each Other? The Influence of a Virtual Agent’s (Non)cooperative Behavior on User’s Cooperation Behavior in the Prisoners’ Dilemma

Most applications for virtual agents require the user to cooperate. Thus, it is helpful to investigate different strategies for virtual agents to evoke the user’s cooperation. In the present work (N = 80), we experimentally tested the influence of an agent’s (non)cooperative nonverbal behavior and actual decision-making behavior on user’s cooperation in the Prisoners’ Dilemma considering different age groups (students and seniors). Therefore, we used a 2 (nonverbal behavior) x 2 (age group) between-subjects design in Wizard-of-Oz study. Results show age differences with seniors cooperating more often than students do. The nonverbal behavior had no effect on the users’ willingness to cooperate nor on the evaluation of the agent’s cooperativeness. However, the agent’s decision-making behavior in the game influenced the users’ willingness to cooperate. In summary, the nonverbal behavior seemed to be too subtle, while the actions of the agent were important in terms of cooperation.

A Categorization of Virtual Agent Appearances and a Qualitative Study on Age-Related User Preferences.

Various variables influence the perception of appearance, which are difficult to examine holistically in a quantitative approach. To give a holistic overview of appearance variables, a systematic categorization of different dimensions was developed. This is also of special importance with a view to the application field of companions for seniors whose preferences regarding appearance are under-researched. Therefore, based on the categorization, 11 interviews with two different target groups (six students, five elderly) were conducted. Results indicate that seniors tend to prefer a realistic humanoid agent, while students mostly rejected this appearance and instead favored zoomorphic or machinelike agents in comic stylization. In sum, the current research gives a first hint that there are age-related differences with regard to appearance.