The Neural Mechanism Of Confirmation Bias And Matching Bias In Hypothesis Testing

Hypothesis testing (HT) is a high-level cognitive process, which plays an important role in rule discovery, decision making and problem solving. During the Wason’s selection task, only about10%the participants made the correct choice. Many researchers explored the cognitive mechanism underlying this phenomenon, and suggested that people often demonstrated "confirmation bias" and "matching bias" during hypothesis testing. However, the previous studies mainly focused on the behavioral measure of these problems, and few studies explored the neural mechanism of "confirmation bias" and "matching bias". Thus, the present study aimed to investigate neural basis of "’confirmation bias" and "matching bias" in hypothesis testing by using functional magnetic resonance imaging (fMRI).In the Experiment1, we aimed to investigate neural basis of "confirmation bias" in hypothesis testing by using functional magnetic resonance imaging (fMRI). In this study, we used the modified Wason selection task, in which participants were provided with a proposition (hypothesis) and a card, and were asked to evaluate whether the card verified or falsified the given proposition. The behavioral results showed that participants made faster behavioral responses in verification conditions than in falsification condition, and the behavioral response was also faster in forward testing than in backward testing. The fMRI results showed that (1) the comparison of the falsification versus verification revealed the activation in the right middle frontal gyrus, right superior frontal gyrus, right medial frontal gyrus, right cingulated gyrus, left middle frontal gyrus, left inferior frontal gyrus, which might reflect inhibitory control and conflict monitoring;(2) the comparison of the forward testing versus backward testing revealed the activation in medial frontal gyrus and ACC, which reflect forward-thinking tendency and anticipatory bias during the process of the hypothesis evaluation. These finds suggested that ACC and PFC play an important role in modulating confirmation bias.In the Experiment2, we aimed to investigate neural basis of "matching bias" in hypothesis testing by using functional magnetic resonance imaging (fMRI). The task in the Experiment2was similar with that in the Experiment1. We added a negative proposition, and the test card contained both the antecedent and consequent of the proposition. Participants were asked to evaluate whether the test card verified or falsified the given proposition. The behavioral results showed that participants responded more fast and accurate in verification condition and in positive proposition than in falsification condition and in negative proposition condition. Moreover, participants responded faster in matching condition than in non-matching condition. The fMRI results showed that (1) the comparison of the non-matching condition versus matching condition revealed the activation in the bilateral middle frontal gyrus, bilateral inferior frontal gyrus, bilateral inferior parietal gyrus, right medial frontal gyrus, right superior frontal gyrus, bilateral middle temporal gyrus and right superior temporal gyrus;(2) the comparison of the falsification versus verification revealed the activation in the medial frontal gyrus, cingulate cortex, right superior frontal gyrus, right middle frontal gyrus, right inferior frontal gyrus, right middle temporal gyrus, left occipital lobe and left thalamus;(3) the comparison of the negative proposition condition versus positive proposition condition revealed the activation in left middle temporal gyrus, bilateral inferior frontal gyrus, bilateral middle frontal gyrus, right medial frontal gyrus, bilateral occipital lobe. These finds suggested that PFC play an important role in modulating matching bias.Thus, both Experiment1and Experiment2found that the confirmation bias and matching bias in hypothesis testing were both related to the activation of prefrontal cortex and anterior cingulate cortex. These findings reflected that prefrontal cortex and anterior cingulate cortex play an important role in modulating confirmation bias and matching bias, and the activation of prefrontal cortex and anterior cingulate cortex reflected inhibitory control and outcome evaluation in hypothesis testing.