The Generation Mechanisms And Neural Bases Of Bidirectional Conflicts

Cognitive control,which is the core component of human advanced cognitive activities,plays an important role in memory,attention,emotion regulation and reasoning and other cognitive functions.The research about cognitive control has experienced four stages of development.The first phase which lasted from the 1960 s to the end of the 1980 s focused on the generation mechanisms of conflicts and the use of cognitive control.With the rise of cognitive neuroscience and its profound influence on psychological research in the late 1980 s and the early 1990 s,the studies of cognitive control moved to the second stage.Since 2005,research into cognitive control has entered the third stage.The researchers mainly investigated the brain network bases of cognitive control from the perspective of large-scale brain networks.And the fourth stage mainly investigates how the control network expresses its function.Ample previous empirical studies investigated cognitive control based on conflict effect,hence,to understand the generation mechanisms of conflicts is the core problem in the field of cognitive control research.The advance of scientific research depends on new research findings,and the theories should be also updated.Recently,some studies reported that bidirectional conflicts are robust and stable in musical Stroop task and Chinese character sizecongruity task.Bidirectional conflicts refer to that in a congruency task,whichever dimension was selected out as target,it would be disturbed by the another dimension(as distractor).Extant theories which developed based on unidirectional conflict could not provide reasonable interpretation for the generation of bidirectional conflicts.Hence,in order to understand conflcits more comprehensively and accurately,a rigorous theory is needed which is applicable for not only bidirectional conflicts but also unidirectional conflict.Chen et al.(2015)proposed that if the two dimensions of a congruency task are automatic,bidirectional conflicts would be elicited.In the present study,the generation of bidirectional conflicts is necessary that the two dimensions of stimulation were automated,and other conditions may be required.Moreover,to better understand the generation of bidirectional conflicts,we used functional magnetic resonance imaging(fMRI)technique to enable us to propose an in-depth explanation for the generation of conflicts.Experiment 1 mainly explored the generation of bidirectional conflicts which was not only necessary for the target and distrator to be automatic,but the target and distrator belonged to the same category or occupy the same domain-specific processing resources.Combined with Simon task,Experiment 1 employed automatic Chinese character stimuli(“?”,“?”,“?”,“?”)which included two tasks(color-words Simon task,locationwords Simon task).Participants completed two tasks successively,and each task required participants to respond to the meaning or location of character.Results indicated that there were no bidirectional conflicts in color-words Simon task,but only produce bidirectional conflicts in location-word Simon task.Experiment 2 adopted automatic numbers and symbol(“2”,“3”,“7”,“8”;“?”,“?”)which included two tasks(number Simon task,arrow Simon task)to verify the results of the Experiment 1.Results also indicated that only arrow Simon task which included spatial information processing existed stable bidirectional conflicts.In Experiment 3,combined with functional magnetic resonance imaging(fMRI),we adopted a Chinese character size-congruity task to investigate the underlying brain mechanisms of bidirectional conflicts.Interestingly,high-conflict from meaning was associated with positive activations in bilateral occipital lobe and left pre-supplementary motor(pre-SMA),while the low-conflict from size led to negative activations in right temporal lobe,bilateral occipital lobe and SMA.Further,PPI analysis revealed that the functional coupling between pre-SMA and right dorsolateral prefrontal cortex was greater in high-conflict than in low-conflict,and the functional coupling between preSMA and primary motor cortex was smaller in high-conflict than in low-conflict.In conclusion,the generation of bidirectional conflict is not only need for the target and distrator to be automatic,but also occupy the same domain-specific processing resources.Additionally,the fMRI results revealed the different generation mechanisms of asymmetric bidirectional conflicts: high-conflict is a kind of interference from prepotent distractor,while low-conflict may be due to the reduced processing resources for target.The present findings provided new insights for understanding bidirectional conflicts,especially for low-conflict,which enable us to completely understand conflict generation.