We conducted psychological experiments in which participants were presented with artificial sounds that were intended to convey the attitudes of three different agents: a Mindstorms robot, an AIBO, and a laptop PC. The participants were asked to select the correct attitudes based on the sounds expressed by these three agents. The results showed that the participants had higher interpretation rates when the PC presented the sounds, even though the utilized artificial sounds were the same for all three agents. Keywords Agent appearance, agent attitudes, human-agent interaction ACM Classification Keywords J.4 [Computer Applications]: Social and Behavioral Sciences?Psychology.