Can I believe my voice? Self-similarity and the illusory truth effect

Repeated exposure to information increases the likelihood that people will judge it as accurate. This phenomenon - known as the illusory truth effect - is robust and widely replicated, and particularly relevant in an age of unfiltered information dissemination. In four experiments, we test whether perceptual fluency is necessary for the effect to occur, whether auditory stimuli generated by text-to-speech (TTS) systems can elicit the effect, and whether voice similarity between speaker and recipient increases the perceived truth of statements. The results of our first three experiments indicate that perceptual fluency is likely the primary driver of the effect, and that repeated exposure to TTS-generated auditory stimuli enhances credibility, albeit to a lesser extent than written statements. Building on this, our fourth experiment shows that - although voice similarity only marginally amplifies the illusory truth effect - the credibility of a statement increases when presented in a voice similar to the listener's, even without repetition.