In the previous experiment you assessed the truthfulness of statements. In some cases you had seen the statements earlier and were led to believe they were true, in other cases you had seen the statements earlier and you were led to believe they were false, and in some cases you had not seen the statement before. This experiment tested the extent to which explicit recollection and familiarity each influenced your evaluation of the truthfulness of statements you have seen before. The statements were based on facts that most participants would not be familiar with already. About half the statements in each condition were actually true and half the statements were actually false.

In the present experiment, explicit recollection occurred when you recalled whether a statement had previously been coded as true or false. Explicit recollection likely influenced some of your responses; you likely coded some answers as true because they were presented in blue during learning and some as false because you remembered them being shown in orange during learning. If explicit recollection was the only process to influence your evaluation of the statements, you would rate previous true statements as true most of the time, previous false statements as false most of the time, and would probably guess when responding to new statements. You may make a few mistakes but overall your data would look something like the orange bars in the chart.

The yellow bars represent the typical data from an experiment like the one you just participated in. Note that in this experiment participants were more likely to rate a statement as true if it was previously learned to be FALSE than if it was an unfamiliar statement. Participants typically guess their responses for unfamiliar statements, about half are rated as true and half as false.

Explicit recollection cannot explain this result; if explicit recollection was solely responsible for truth judgements then familiar false statements would not be rated as true more often than unfamiliar statements (they should be rated as true less often). The results from this type of experiment show that familiarity, in addition to explicit recollection, affect truth judgements. Having just seen a statement before, regardless of whether it was framed as true to false, leads people to be more likely to judge the statement as true. This is known as the illusory truth effect and it is a robust finding replicated in dozens of experiments.

The blue, green and orange bars represent the data from the present experiment. Is there evidence for the illusion of truth?

If you are like most people, you were more likely to rate a familiar false statement as true than an unfamiliar statement (the percentage reported as true was greater for the familiar FALSE condition than the new/unfamiliar condition). This finding shows that familiarity plays a role in peoples’ judgement of what is true.