The Neurophysiological Mechanism Of The Premise Diversity Effect During Category-based Induction

Category-based induction is the process that people extend the known knowledge of category to other categories based on category membership.It is the basis of people’s cognitive life.For example,if people know that apples and lemons are rich in vitamins,one can infer that all fruits are rich in vitamins.Premise diversity effect is a basic phenomenon of which drawing stronger and broader inductive inferences from diverse sets of evidence than homogeneous(non-diverse)sets of premises during category-based induction.However,previous studies focused on the exploration of behavioral characteristics,and the cognitive neural mechanism is still unclear.In this study,four experiments(pre-experiment 1 and 1b,experiment 1 and experiment 2)were conducted to explore the cognitive neural mechanism of the premise diversity effect with the help of high temporal resolution ERP and high spatial resolution fMRI.Pre-experiment included two behavioral experiments.Pre-experiment 1 explored the behavioral characteristics of the premise diversity effect.Preliminary experiment 2verifies the validity of the experimental paradigm.In pre-experiment 1,we used a 2(premises type: diverse premises vs non-diverse premises)× 2(conclusion type:near-distance conclusion vs remote-distance conclusion)within-subject study design.Subjects were asked to evaluate the likelihood of the conclusion by using Likert 4 scale(“definitely weak”,“possibly weak”,“possibly strong”,“definitely strong”)according to the premise.The results showed that the diverse premise produced stronger response strength than the non-diverse premise during both near-distance and remote-distance conclusions.Diverse premises conditions produced higher “definitely” response proportions than non-diverse premises conditions during near-distance conclusions,but produced lower “definitely” response proportions than non-diverse premises conditions during remote-distance conclusions.There was no significant difference in reaction time between the diverse and non-diverse premise during both near-distance and remote-distance conclusions.In pre-experiment 2,using the same experimental paradigm and experimental materials as pre-experiment 1,subjects need to ignore the attributes and judge the possibility that the premise category belongs to the conclusion category.The results showed that categorization task had stronger response strength,“definitely” response proportions and shorter reaction time than category-based task.Categorization and category-based induction have different cognitive processing,which verifies that the premise diversity effect shown in pre-experiment 1 is caused by the induction task rather than the categorization task.On the basis of pre-experiment 1,Experiment 1 further explored the cognitive process of premise diversity effect through ERP technology.The results of behavior were consistent with those of pre-experiment 1.ERP results showed that the non-diverse premise produced larger FN400(250-450 ms)and SN amplitudes(450-750 ms)than the diverse premise.This indicates that in inductive reasoning,non-diverse premises have greater processing differences(familiarity)or lower conceptual fluency and require more cognitive effort to integrate information than diverse premises.Based on experiment 1,experiment 2 further explored the fMRI characteristics of premise diversity effect.The behavior results were similar to experiment 1.fMRI results showed that the left dorsolateral prefrontal lobe(left middle frontal gyrus /BA9)was activated more in the non-diverse premise than in the diverse premise.In addition,the left medial temporal gyrus(BA21,39),left paracentral lobule(BA31),and right anterior central gyrus(BA6)were activated more in the non-diverse premise than in the diverse premise.This suggested that non-diverse premises require more cognitive resources for hypothesis generation,more cognitive effort to obtain background knowledge,and more involvement in strategic retrieval of semantic information.In addition,the reasoning process of the premise diversity effect mainly activated the left frontal-temporal system,which also showed the left brain lateralization of the reasoning cognitive process of the premise diversity effect.In conclusion,our results preliminarily revealed the cognitive neural mechanism of the premise diversity effect.The induction force of the non-diverse premise was smaller than that of the diverse premise,and the electrophysiological /ERP features showed greater FN400 and SN amplitudes,while the fMRI features showed greater activation of the left frontal-temporal system,especially the left dorsolateral prefrontal lobe.