The truth effect is the stable tendency to rate repeated statements as being more truthful than novel statements. Widespread theoretical explanations for this finding are the subjective feeling of familiarity or fluency or the activation of referential networks that increase with repetition and presumably inform truth judgements. Only one alteration in the classic truth effect paradigm has been able to reliably prevent the effect, which is the rating of validity instead of interest (or other shallow processing instructions) at the initial presentation of the statements. In fact, some studies even find a negative effect under these encoding conditions. Two theoretical accounts exist to explain this finding.

Here we tested the first account, that rests on the following assumptions: if people are able to recall their initial statement rating, they will show decision inertia, i.e they will stick to the initial rating. If they fail to recall their rating, but assume that they have encountered the statement before in the experiment, they will discount fluency as the experimental setting induces skepticism. To test these predictions, we experimentally manipulated decision inertia and skepticism to disentangle the different processes. Our results showed a negative main effect of repetition across all experimental conditions. Although decision inertia was generally present, the negative truth effect remained unexplained. In upcoming research, we aim to test the second theoretical approach, claiming that the activation of prior knowledge by the initial truth ratings can account for the elimination or reversal of the truth effect, respectively.