INTERNATIONAL JOURNAL OF SPEECH TECHNOLOGY 4, 145-153, 2001 © 2001 Kluwer Academic Publishers. Manufactured in The Netherlands.

Factors that Influence the Perception of Feedback Delivered
by a Pedagogical Agent

KRISTEN E. LINK, ROGER J. KREUZ, ARTHUR C. GRAESSER
AND THE TUTORING RESEARCH GROUP
Department of Psychology, The University of Memphis, Memphis, TN 38152-6400
klink@memphis.edu

Received July 10, 2000; Revised March 13, 2001

Abstract. Three experiments were conducted to assess the relative importance of speech parameters and facial expressions in the delivery of feedback by a pedagogical agent. In Experiment 1, we manipulated linguistic form (i.e., positive, negative, or neutral terms), rate, pitch, pause, and emphasis. In Experiment 2, we manipulated eye size, mouth curve, brow height, and brow curve. In a third study, both speech parameters and facial expressions were manipulated. In all three experiments, the participants were asked to indicate how positive or negative the agent's feedback seemed to be. Across the studies, the variables collectively accounted for a significant amount of the variance. More specifically, the linguistic expressions and mouth curve emerged as significant predictors of the participants' ratings. This suggests that these two features should be implemented by developers wishing to provide appropriate feedback in their pedagogical agents.

Keywords: pedagogical agents, feedback, facial expressions, intonation

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