A Systematic Comparison of Affective Robot Expression Modalities

This paper provides a survey of the different means of expression employed by robots conveying affective states to human recipients. The paper introduces a model of affective expression modalities (MOAM) that describes and compares the emphasis on specific means of expression and applies it to the surveyed robots. Using the model entails viewing the effect of applied expression modalities in light of how well the robot responds to external stimuli and with attention to how aligned the robot's means of affective expressions are with the intended working scenario. The model-based survey shows that a majority (85%) of the surveyed robots contain a category with room for additional affective means of expression, and a quarter (25.6%) of the robots use a single or two affective expression modalities to convey affective states. The result of the survey indicates there is an under-researched opportunity in exploring synergies between the different expression modalities to amplify the overall affective impact of a robot.