Semantic Processing Differences Between Thematic And Taxonomic Relations

The ability of the human brain to representation the concept and the semantic relation between concepts is crucial to human cognition.In our semantic memory,the knowledge that is stored about the world is huge and complex.On the one hand,human knowledge of the external world characterized by the brain is classified in various forms.On the other hand,knowledge of the connection between different concepts is also acquired in the environment.In a word,there are two different semantic relations between these object concepts.The first one is the similarity relation based on shared features,which is called taxonomic relation.The second one is the proximity relation based on the co-occurrence of events or scenes,which is called thematic relation.Previous studies showed that the thematic relation represented the left temporal and parietal junction area(TPJ).However,the researchers found that bilateral anterior temporal lobe(ATLs)was the semantic representation center of taxonomic relation.In addition,the researchers found that the processing of taxonomic relation needed more cognitive resources;and it was found that the thematic relation was processed in the early stages.So the relation between themes and taxonomic relation representation in different brain regions,Whether or not it is different in the way of semantic processing?Through three experiments,we explore the semantic and cognitive mechanism of thematic and taxonomic relation under different processing modes.Separate narration as follows:In Experiment 1,at the behavioral level,use the priming paradigm,and adopts within-subjects design and text materials.This paper mainly discusses whether there are differences in semantic processing between thematic and taxonomic relation under different processing modes,and provides a solid basis for further research of the following experiments.In the experiment,Priming word were first presented to the subjects,and then the target words with different time intervals(SOA:150ms,700ms)were randomly presented.It is required that the subjects be both quick and accurate to judge whether there is a semantic relation between the priming and the target words.The results showed that:(1)under the condition of automatic processing,the relation between thematic and taxonomic had priming effect;(2)under controlled processing conditions,only thematic relation had priming effect.In different processing methods,the relation between thematic and taxonomic is different in the priming effect.Experiment 2,at the electrophysiological level,by using brain function event-related potential(ERP)technology,we used the same experimental design,experimental material and paradigm as experiment 1.The main purpose of this study is to investigate whether the semantic relation between thematic and taxonomic is different in different processing mode.The results were as follows:(1)under the condition of automatic response and controlled processing,only the thematic relation shows the priming effect.(2)In the ERP results,the unrelation pairs caused a significant N400 under the automatic and controlled processing conditions.In addition,the significant amplitude of the taxonomic relation on P600 was found only under the controlled processing conditions.This shows that the relation between thematic and taxonomic is not only different in the priming effect,but also in the ERP index.Experiment 3 at the level of cerebral blood oxygen,the experimental materials and paradigms were the same as those in Experiment 1.Functional Near-Infrared Spectroscopy(fNIRS)technology was used to collect data of blood oxygen changes in the brain during the experiment.The influence of processing methods on semantic processing of thematic and taxonomic relation under different SOA conditions was explored.The results were as follows:(1)behavioral response time: under the condition of automatic processing,only thematic relations showed priming effect;under control conditions,thematic and taxonomic relations all had priming effects.(2)level of blood oxygen: under the condition of automatic processing,taxonomic relations cause significant changes in channel blood oxygen concentration.Under controlled processing conditions,thematic relations cause significant changes in channel blood oxygen concentration;And the activated channels correspond to different brain regions.From the above experiments,we can draw three conclusions:(1)Under the automatic and controlled processing mode,the relation between the thematic and taxonomic has a stable priming effect.(2)Under the control processing conditions,compared to the thematic relation,the taxonomic relation is also processed in the later period.(3)Under the condition of automatic and controlled processing,the brain regions activated by semantic processing of thematic and taxonomic relation are different.Under the condition of controlled and automatic processing,thematic and taxonomic relation lead to more significant changes in blood oxygen.In a word,thematic and taxonomic relation show semantic processing differences in behavior,ERP and fNIRS.