Neural Mechanism Of Hypothesis Evaluation And Generation In Hypothesis Testing

Hypothesis testing (HT) plays an important role in high-level cognitive processes, such as concept formation, decision making and problem solving, during which people generate and select new rules or apply previously tested ones. Recently, research has focused on elucidating the cognitive and neural underlying of hypothesis testing.In experiment 1, a modified Wason’s selection task was used to explore brain correlates of hypothesis evaluation, a core process of hypothesis testing. Twenty-two undergraduate participants (11 males,11 females) were provided with a proposition (hypothesis) and a card. They were asked to evaluate whether the card verified or falsified the given proposition while event related potentials (ERP) were measured. Behavioral results showed that participants required less time to make correct responses in verification conditions than in falsification conditions. The ERPs time-locked to the second side of each card showed that (1) smaller amplitudes of P2 were elicited in backward falsification than in backward verification, which reflected a lower intensity of perception; (2) a profound negative deflection was found in falsification conditions compared to verification conditions during the N2 time window, which implied the processing of conflicting information; (3) in comparison to verification conditions, falsification conditions evoked a decreased P3 component, which was linked to the process of hypothesis evaluation; and (4) a late positive component (400-600 ms) was only triggered in the forward falsification condition, reflecting the manipulation of cognitive context.In experiment2, to examine the dynamic course of hypothesis generation in brain activation that occurred when a person received three letter biscuits sequentially, participants were provided with three letter biscuits sequentially and were then asked to judge what feature of letter biscuits was edible according to the hypothesis had been formed in their mind. Within each trial, the first three letter biscuits were sequentially displayed, and when the second and the third biscuits presented respectively, participants should excluded a hypothesis, and maintain the rests. The fMRI results revealed that(1)When comparing the activations elicited by hypothesis generation and baseline task, there was no additional activity measured between HGphasel(the first phase of hypothesis generation) and BTphasel(the first phase of baseline task). Four regions showed higher activation during HGphase2 than during BTphase2:the PFC (left/right:middle/inferior/superior/medial frontal cortex, and precentral gyrus, BA6,9,10,46) and parietal cortex (inferior parietal lobule and postcentral gyrus. BA 3,7.40), the cerebellum (culmen, declive) and the bilateral temporal lobe (fusiform gyrus, BA 37). Compared with the BTphase3, the HGphase3 activated the right PPC (inferior parietal lobule, postcentral gyrus, BA 3,40), the cingulated gyrus (BA 24), the left culmen, and the right insula (BA 13). (2) In the process of hypothesis generation, compared with the phasel, the phase2 activated the bilateral prefrontal cortex, including the middle and superior lateral prefrontal cortex (BA 6,10), as well as bilateral inferior parietal lobule (BA 40) and the left cerebellum. (3) In comparison with the phase2, the phase3 activated the right medial frontal cortex (BA9), the right parietal cortex, bilateral cingulate cortex (BA 24,32), left cerebellum, and insula. The DLPFC, parietal cortex and the cerebellum may reflect mainly integration of information and working memory operation. In addition, activity within ACC was related to inhibition control. These findings further suggest that DLPC and related other cortex such as parietal, the cerebellum and ACC played an important role in the process of concept formation.