Advances in speech recognition and voice synthesis software now allow "smart agents" (e.g., voice-controlled devices like Amazon's Alexa and Google Home) to interact naturally with humans. The machines have a skills repertoire with which they can "communicate" and form relationships with consumers – managing aspects of their daily lives and providing advice on various issues including purchases. This dissertation develops three essays that examine the role played by the smart agent's voice (rational vs. emotional) in such relationships. The social cognition and persuasion literature on interpersonal communication serves as a comparison backdrop. In Essay 1, I investigate how identical purchase recommendations delivered in a rational or an emotional voice elicit different consumer responses, when the voice is ascribed to a human versus a smart agent. I argue that consumers distinctively categorize smart agents and humans, which, in turn, leads them to have different expectations when interacting with them. In Essay 2, I focus on how a smart agent's vocal tone (rational vs. emotional) influences consumer compliance with the agent's recommendation as well as the role of trust as a mediator of the underlying process. I find that the level of intimacy in the relationship between the smart agent and the human user moderates whether the voice effect on persuasion operates through trust that is cognitively or affectively rooted. In Essay 3, I examine the proposition that consumers may anthropomorphize a smart agent both mindfully (consciously) and mindlessly (non-consciously), depending on the agent's voice. In addition to using extant measures of the degree to which anthropomorphism is explicit (conscious), I develop an auditory analog of the implicit association test (IAT) that assesses implicit (non-conscious) anthropomorphism. In additional experiments, I further assess the robustness of the auditory IAT test and demonstrated a dissociation between the measures of the explicit and implicit subconstructs of anthropomorphism. Taken together, these essays contribute to our understanding of the factors driving consumer relationships with smart agents in the rapidly evolving IoT world. / Doctor of Philosophy / Advances in artificial intelligence technologies are creating "smart devices," i.e., machines that can "understand" how people talk and respond meaningfully to such communication in their own voices. Thus, familiar voice-controlled devices like Amazon's Alexa and Google Home are now increasingly able to "communicate" and form relationships with consumers – managing aspects of their daily lives and providing advice on various issues including purchases. However, little is known about how a smart agent's vocal tones (rational vs. emotional) may influence how consumers perceive and relate to the smart agent. My primary goal in this research is to contribute to our understanding of the role played by the smart agent's voice (rational vs. emotional) in such relationships. Specifically, in Essay 1, I investigate how identical purchase recommendations delivered in a rational or an emotional voice elicit different consumer responses, when the voice is ascribed to a human versus a smart agent. I argue that consumers perceive smart agents and humans as belonging to distinct categories, which leads them to have different expectations when interacting with them. In Essay 2, I focus on how a smart agent's vocal tone (rational vs. emotional) influences consumer compliance with the agent's recommendation as well as the role of trust as a mediator of the underlying process. The level of intimacy in the relationship between the smart agent and the human user influences whether the voice effect on persuasion is driven by trust that is rooted in cognition (knowledge, competence) or affect (caring, warmth). In Essay 3, I examine whether consumers imbue humanlike qualities (anthropomorphize) a smart agent both mindfully (consciously) and mindlessly (non-consciously) based on the agent's voice. In addition to using available measures of conscious anthropomorphism, I develop an auditory analog of the implicit association test (IAT) to assesses implicit (non-conscious) anthropomorphism. In additional experiments, I assess the robustness of the auditory IAT test and the relationship between measures of mindful and mindless anthropomorphism. Taken together, the research reported in these three essays contributes to our understanding of the factors driving consumer relationships with smart agents in the rapidly evolving IoT (Internet of Things) world.