Is an accelerating robot perceived as energetic or as gaining in speed?

Previous studies have found that basic movement characteristics of a robot influence the emotional attributes people perceive independent of the embodiment of the motion (e.g. iCat vs. Roomba). Here, with a very simple LEGO robot, we replicate these associations between levels of acceleration and curvature and the extent to which positive and negative emotions are attributed. Importantly, we also show that these associations might not be valid. Prior to the emotional questionnaires participants were asked neutral questions on what they deemed relevant observations pertaining to the different robot motions. Only 3% of the remarks coincided with the emotional terms found in the questionnaires. HRI researchers interested in what people attribute to robot motion should be mindful of participant heuristics and experimenter biases. We provide some suggestions how to create experiments that are robust against these biases.