Abstract: The neural mechanism of human inductive reasoning is still unclear. Compared with the sentential, numerical task, the figural inductive reasoning task has its advantage. Therefore, a figural inductive reasoning task was designed in an fMRI experiment to examine the neural substrates of human inductive reasoning. The present study is exploratory one and we have no prior hypothesis.
The figural inductive reasoning task used was composed of simple geometric figures described by shape and stripe orientation, and was homogeneous to the sentential inductive reasoning tasks used in the previous studies. Two experimental tasks were designed according to the magnitude of shared attributes: sharing two common attributes (2T) and sharing one common attribute (1T), and rest acted as the control task. Fourteen college students participated in this study.
The fMRI results showed: 1) Inductive reasoning as contrast to baseline activated a large number of brain regions including the prefrontal cortex (BA 6, 9, 11, 46, 47), caudate, putamen, and thalamus, which might reflect the important role of the fronto-striato-thalamus loop in human figural inductive reasoning. 2) Perceptual information integration in figural inductive reasoning was related to the right inferior frontal gyrus (BA 47), the bilateral head of caudate, putamen.
This study explored the neural substrates of human inductive reasoning by using a figural task, which would be helpful to in-depth understand the information-processing mechanism of human inductive reasoning.

Key words: inductive reasoning, functional magnetic resonance imaging (fMRI), perceptual information integration