Pam Peter Ruijten

I didn't know that virtual agent was angry at me: investigating effects of gaze direction on emotion recognition and evaluation

Previous research has shown a link between gazing behavior and type of emotion felt. It appears that approach-oriented emotions are better perceived in combination with a direct gaze, whereas avoidance-oriented emotions are better perceived in combination with an averted gaze. In this study, we investigate whether this effect can be applied to persuasive social agents. We hypothesized that an approach-oriented emotion is more credible when combined with a direct gaze, whereas an avoidance-oriented emotion is more credible when combined with an averted gaze. This was tested with both an implicit categorization task and an explicit evaluation. The hypothesis was supported for angry expressions, but not for sad ones. Implications for further research and the design of effective persuasive agents are discussed.

Unconscious persuasion needs goal-striving: the effect of goal activation on the persuasive power of subliminal feedback

A fundamental characteristic of ambient persuasive technology is the ability to persuade users outside of conscious attention. One method of influencing people outside of their conscious awareness is subliminal priming: Presenting a stimulus for less than 50 milliseconds so people can not consciously perceive it but they are able to process the information unconsciously. Earlier research has shown that subliminal feedback on energy consumption leads to more optimal choices in an energy-related choice task compared with no feedback. Would subliminal feedback always be effective in influencing peoples choices, or do people need to be motivated to reach a specific goal for it to work? In the current research, we investigate if persuasion by subliminal feedback comprises a goal-striving related process in which people strive for a goal and use the subliminal information to reach that goal. In an experimental study, half of the participants were primed with the goal to perform well, and the other half was not primed with this goal. Next, half of the participants received subliminal feedback in a learning task, whereas the other half received no feedback. Results indicated that participants primed with a performance goal made more correct choices in the task when given the subliminal feedback compared with given no feedback. Participants who were not primed with a goal were not influenced by this feedback. This finding indicates the need for a behavior-relevant goal to make subliminal information effective, which in turn has important implications for research and design of ambient persuasive technology.

Lonely and Susceptible: The Influence of Social Exclusion and Gender on Persuasion by an Artificial Agent

Earlier research showed that artificial social agents can influence human behavior. This article argues that, especially under certain circumstances, people are sensitive to persuasion by (artificial) social agents. For example, when people feel socially excluded, they are motivated to increase their social connections with others. It was hypothesized that socially excluded people would attribute more human-likeness and be persuaded more by an artificial agent than socially included people. These hypotheses were investigated in two studies in which participants were either socially included or excluded, after which they performed an energy-saving task while receiving social feedback from an artificial agent. Results did not support the expectation that socially excluded people ascribe more human-likeness to an artificial agent, but they did show the expected effects on behavior change, indicating the importance of including a person’s psychological state in the design of human–agent interactions. Also, in line with earlier findings, female participants were more susceptible to the agent’s feedback than male participants, indicating that a user’s gender may also determine the effectiveness of persuasive technology.

Bridging the gap between the home and the lab: a qualitative study of acceptance of an avatar feedback system

The current study provides a first step in the design and development of a persuasive agent in the natural context of the household. We developed two persuasive probe studies: one paper-based probe and one email-based probe on the use, experience, and effectiveness of persuasive agents. Participants had used these prototypes for a week, after which their experiences were explored in depth interviews and a focus group. Results indicated that a persuasive agent in the household is experienced as fairly pleasant, but important issues need to be solved before it can effectively influence behavior.

Stopping distance for a robot approaching two conversating persons

In recent years, much attention has been given to developing robots with various social skills. An important social skill is navigation in the presence of people. Earlier research has indicated preferred approach angles and stopping distances for a robot when approaching people who are interacting with each other. However, an experimental validation of user experiences with such a robot is largely missing. The current study investigates the shape and size of a shared interaction space and evaluations of a robot approaching from various angles. Results show an expected pattern of stopping distances, but only when a robot approaches the middle point between two persons. Additionally, more positive evaluations were found when a robot approached on the side of the participant compared to other participants side. These findings highlight the importance of using a smart path planning method for robots when joining an interaction between users.

Dynamic Perceptions of Human-Likeness While Interacting With a Social Robot

In human-robot interaction research, much attention is given to the development of socially assistive robots that can have natural interactions with their users. One crucial aspect of such natural interactions is that the robot is perceived as human-like. Much research already exists that investigated perceptions of the human-likeness of social robots, but the duration of the interaction is often overlooked. In an experiment we show that peoples human-like perceptions of social robots change substantially over time. With this we show the importance of taking multiple measurements of perceived human-likeness.

Ambiguous Agents: The Influence of Consistency of an Artificial Agent’s Social Cues on Emotion Recognition, Recall, and Persuasiveness

ABSTRACT This article explores the relation between consistency of social cues and persuasion by an artificial agent. Including (minimal) social cues in Persuasive Technology (PT) increases the probability that people attribute human-like characteristics to that technology, which in turn can make that technology more persuasive (see, e.g., Nass, Steuer, Tauber, & Reeder, 1993). PT in the social actor role can be equipped with a variety of social cues to create opportunities for applying social influence strategies (for an overview, see Fogg, 2003). However, multiple social cues may not always be perceived as being consistent, which could decrease their perceived human-likeness and their persuasiveness. In the current article, we investigate the relation between consistency of social cues and persuasion by an artificial agent. Findings of two studies show that consistency of social cues increases people’s recognition and recall of artificial agents’ emotional expressions, and make those agents more persuasive. These findings show the importance of the combined meaning of social cues in the design of persuasive artificial agents.