A framework for evaluating multimodal integration by humans and a role for embodied conversational agents

One of the implicit assumptions of multi-modal interfaces is that human-computer interaction is significantly facilitated by providing multiple input and output modalities. Surprisingly, however, there is very little theoretical and empirical research testing this assumption in terms of the presentation of multimodal displays to the user. The goal of this paper is provide both a theoretical and empirical framework for addressing this important issue. Two contrasting models of human information processing are formulated and contrasted in experimental tests. According to integration models, multiple sensory influences are continuously combined during categorization, leading to perceptual experience and action. The Fuzzy Logical Model of Perception (FLMP) assumes that processing occurs in three successive but overlapping stages: evaluation, integration, and decision (Massaro, 1998). According to nonintegration models, any perceptual experience and action results from only a single sensory influence. These models are tested in expanded factorial designs in which two input modalities are varied independently of one another in a factorial design and each modality is also presented alone. Results from a variety of experiments on speech, emotion, and gesture support the predictions of the FLMP. Baldi, an embodied conversational agent, is described and implications for applications of multimodal interfaces are discussed.