Information retrieval plays an important role in high level cognitive activities such as learning,problem solving.It is commonly held that objects are first identified at the basic level.However,there are researches suggest that basic level advantage do not necessarily take place.It will switch to subordinate level or superordinate level.A possible explanation for different level precedence may relate to external differences in the processing demands of task used in the experiment.The functional magnetic resonance imaging(Fmri),with the high spatial resolution,can probes the brain activies.It is revealed that some regions are task-specific.Therefore,the present study will take effort to reveal the neural mechanism underlying different cognitive tasks.Two tasks are designed to measure information retrieval performance,word-picture matching task and picture-word matching task respectively.They are exactly the same excepting the reverse order of the word and picture stimuli.Behavioural results have shown that superordinate concepts were performed most quickly and differentiated from intermediate and subordinate concepts in word-picture matching task,however,in word-picture matching task,intermediate concepts took shortest to perform,Fmri results are consistent with previous studies in areas involved with memory retrieval and semantic processing,some areas are commonly actived in both tasks,mainly including inferior frontal gyus,anterior cingulated gyus,inferior parietal lobe,fusiform and occipital lobe.Contrast analysis show that areas of inferior parietal lobe(BA40)and fusiform gyri(BA37)were activated more strongly in word-picture matching task compared with picture-word matching task.This may reflect much visual requirements in this task.In picture-word matching task,however,activations in IFG(BA45A7)may relate to semantic process.Besides,between-level differences in each task suggeste that inferior parietal lobe(BA40)are mainly activated at the precedence level.Further functional connectivity analysis demonstrates that connections between regions are simplest at the superordinate level in word-picture matching task while at mediate level in picture-word matching task.On the contrary,More cognitive resources are needed when participants identify items at subordinate level.It is also found that regions connect closely with inferior parietal lobe and fusiform gyri in word-picture matching task while in picture-word matching task they are highly correlated with inferior frontal gyus.All of these results strengthen the hypothesis that Word-picture matching task may load up more visual-based processes since comparison between mental imagery and visual stimuli.Howerver,in the case of picture-word matching task,semantic memory retrieval is much involved.In conclusion,our research provides evidence for the viewpoint that external environment such as the processing demands of tasks has its effect over information retrieval strategy.