The Effects Of Top-down And Salience Processing On Category Attentional Selection

Category-based attentional selection(CAS)refers to the process that a stimulu matches the target-defined category can be superiorly selected by attention system.The role of CAS can help people select and process the category stimuli efficiently.Previous studies have focused on the integration of top-down processing and salience on the attentional selection.However,most of them investigated the effects of two processing at feature level.In the complex real scenes,as a collection of features,category can further help us to understand the higher-level information.In terms of composition,category can be defined by two types: semantic-based category and prototype-based category.Exploring how top-down processing and salience processing affect the different types of CAS can provide more evidence for the mechanism of categorical processing and attentional selection.To investigate the effects of top-down processing and salience on different types of CAS,four behavioral experiments and one functional magnetic resonance imaging(f MRI)experiment were used,employed by combining with the majority function task(MFT)and oddball paradigm.The possible category of target were defined as the semantic-based numbers or letters(Study 1)or the prototype-based "O" or "X" shapes(Study 2).In the search array,the effects of top-down processing was reflected by the cognitive load,in addition,the effects of salience was divided into task irrelevant effects(Study 1)and task relevant effects(Study 2).The f MRI experiment comprehensively investigated the neural mechanism of top-down and salience processes on CAS(Study 3).Four important results were found.First,a main effect of cognitive load showed that the performance of low load was better than that of high load,suggesting the effects of top-down processing on CAS,which activated the left central posterior gyrus.In addition,the significant main effect of salience showed that the performance of the standard stimulus was better than the oddball stimulus.However,the main effect of salience was only found in the task-relevant situations,and the effect of salience processing on CAS activated the medial and paracingulate gyrus.Importantly,there was an interaction between top-down and salience processing on CAS was found,which was mirrored by the neural response of middle occipital gyrus.Interestingly,a main effects of category type was found,showing that the performance for the prototype-based category was better than semantic-based category.And further interaction of category type indicated that the prototype-based CAS may involve more salience processing.The present study confirmed the integrated processing of top-down and salience processing on different types of CAS and provided further evidence for the mechanisms of category formation and category selection.