| For human,brain is the center for information processing.To save the cognitive resources,some of brain high-order functions are responsible for selecting the task-relevant information processing and suppressing task-irrelevant information processing.These type of modulations are collectively known as cognitive control.However,the mechanism of cognitive control is far from clear now.In conflict tasks,the task-relevant information might congruent or incongruent to the task-irrelevant information;participants respond to a congruent trial(e.g.,read a word ?BLUE‘ in blue)typically with shorter reaction time or lower error rate than to an incongruent trial(e.g.,read a word ?BLUE‘ in red).The performance difference between the two types of trials is called congruency effect(CE).The amplitude of CE reflects the level of cognitive control on the competition of task-relevant with –irrelevant information.The CE is smaller in the trials following an incongruent trial than following a congruent trial,referred as congruency sequence effect(CSE).The CSE has been reported in most conflict tasks.The cognitive control was supposed to accounts for the CSE.But,some of studies argued that the CSE is exclusively resulted from the repetition priming(i.e.,the performance of trials will be improved if it completely repeated previous one)because the CSE disappeared in the analyses removed these repetition priming trials.The judgment of allocentric position was reported to be influenced by egocentric representation,i.e.,a type of congruency effect.And,the CE of the spatial conflict task was reported to be larger at left than at right visual hemifield,indicating the cognitive control on the spatial perception might be asymmetric between two cerebral hemispheres.If the location of target information is cued before it onset,the deployment of cognitive resources will be modified,i.e.,visual spatial attention.In addition,task difficulty or perceptual load is another possible factor that influences cognitive control.Here,our question is that: would visual spatial attention and task difficulty influence several properties of cognitive control in a conflict task(including CE,CE asymmetry and CSE)? Moreover,to address the argument about the account of the CSE,we analyzed the data in the trials with and without repetition priming separately.We employed a task involving conflict between egocentric and allocentric spatial representations,in which we manipulated visual spatial attention and task difficulty by a visual cue and target discriminability respectively.Current study analyzed the fluctuations of CEs(difference between congruent and incongruent trials in reaction time or error rate)under influences of several factors,including visual spatial attention,task difficulty,visual hemifields(i.e.,CE asymmetry),and previous trial type(i.e.,CSE).The main findings and innovations of current study are summarized as the following:1)Visual spatial attention significantly affected the CE,indicating visual spatial attention and the CE might share some relative mechanisms in the spatial conflict task.The CE asymmetry was eliminated by visual spatial attention,indicating a dynamic modulation on an asymmetric function between cerebral hemispheres.2)Our study first time reported the CSE in a task involving conflict between egocentric and allocentric spatial representations.This would promote explorations on mechanisms underlying CSE and the two spatial representations.3)The CSE was influenced by visual spatial attention and task difficulty in some conditions.This provides a new evidence for the cognitive account of CSE.4)Since Mayr et al.first queried the cognitive account of CSE with a repetition priming account in 2003,the question was addressed intensively but without a consensus.The key problem is why some studies found significant CSE in repetition change trials but others not.Here,our results suggest that different level of visual attention and perceptual load might be responsible for those different results. |
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