Manipulating Stress and Cognitive Load in Conversational Interactions with a Multimodal System for Crisis Management Support

The quality assessment of multimodal conversational interfaces is influenced by many factors. Stress and cognitive load are two of most important. In the literature, these two factors are considered as being related and accordingly summarized under the single concept of ‘cognitive demand’. However, our assumption is that even if they are related, these two factors can still occur independently. Therefore, it is essential to control their levels during the interaction in order to determine the impact that each factor has on the perceived conversational quality. In this paper we present preliminary experiments in which we tried to achieve a factor separation by inducing alternating low/high levels of both stress and cognitive load. The stress/cognitive load levels were manipulated by varying task difficulty, information presentation and time pressure. Physiological measurements, performance metrics, as well as subjective reports were deployed to validate the induced stress and cognitive load levels. Results showed that our manipulations were successful for the cognitive load and partly for the stress. The levels of both factors were better indicated by subjective reports and performance metrics than by physiological measurements.

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