Lie detection research indicates that perceivers have difficulty interpreting bodily, facial, voice and language content cues indicative of deception. Therefore, what cues do perceivers use to form veracity judgements? Perceivers easily learn to associate perceptual fluency cues (e.g., visibility, colour contrast and pronunciation ease) with truthfulness. However, research is yet to explore how conceptual fluency cues (i.e., statement comprehension) influences the credibility of writers and what they are saying. To test this, I used statements that had been previously manipulated for word brevity. In Studies 1a and 1b, participant ‘judges’ read statements that contained essentially similar content but using either short or long words. The statements containing simpler, shorter words were judged as more credible, and this relation was mediated by comprehension ease (fluency), even after accounting for perceived writer intelligence and positivity.
To expand the simplicity manipulation, in Studies 2 and 3, participant ‘writers’ were instructed to create their own simple or complex statements by altering a variety of complex language features. Once more, language simplicity influenced judges’ perceived credibility of the statements via fluency. Features of complexity that accounted for a reduction in fluent comprehension varied between groups of judges; however, word information accounted for most of the variance in the fluency effect.
I also investigated whether the writers themselves felt and behaved more honestly after using simple language. Finally, I extended the fluency–perceived credibility association to ecologically valid writing contexts, namely, the persuasiveness of film reviews (Study 5) and in writing for different audiences (Study 6). Although perceivers attend to fluency cues to infer credibility, fluency was not an ecologically valid cue to real truth (Study 4) and may account for why people are poor lie detectors.
