The Role Of Visual-Spatial And Verbal Working Memory In SNARC Effect

To study people's cognition process of numbers,researchers have developed several classic paradigms,such as magnitude comparison and parity judgment.Through the tasks,researchers found that subjects always respond faster to smaller numbers with their left hands,as well as larger numbers with their right hands than the opposite.This systematic association between number magnitude and spatial orientation is called SNARC effect,which means the Spatial Numerical Association of Response Codes effect.SNARC effect is often unaffected by experimental tasks and thought to be generated spontaneous,automatically.The earliest explanation for the mechanism of SNARC effects is the“mental number line”,the theory that people will place the numbers in their psychological space from left to right in ascending order as a simulated line,and when a number is processed,its corresponding position is automatically activated,thus facilitating or interfering with the response in the corresponding position.However,when subjects were asked to memorize a series of numbers while performing the task of magnitude comparison,it was found that the SNARC effect was replaced by the ordinal position effect.Therefore,some people proposed the working memory account of digital-space representation,Considered as the order of the sequences stored in working memory,rather than the number itself determines the relationship between numbers and space.So what is the SNARC effect and the order position effect come from the common working memory basis,or are both based on the inherent response to long-term memory and the temporal order in working memory respectively?This article examines the digital task under working memory load.In Experiment 1,a dual-task paradigm was adopted to allow subjects to judge the size or parity of the memorized numbers(task judgments)after memorizing the order of 3,5 or 7 digits(working memory task).The experiment was designed as a four-factor mixed design,in which working memory load level(3 vs.5 vs.7),spatial orientation of the reaction(left vs.right)and number size(greater than 5 vs.less than 5)The task(size comparison vs.parity)is the group variable.The results show that in the size judgment task,the order position effect and the SNARC effect interact with the increase of working memory load.When the number of memory is 7,the sequence position effect disappears,indicating that the two effects Produced by some similar mechanism,that is,the involvement of working memory is required,which refutes the idea that the SNARC effect in the dual process theory is entirely derived from long-term memory.However,the two effects co-exist in the task of parity determination.We think this is because although both effects require the support of working memory,the SNARC effect needs to mobilize the voice working memory in the task of parity determination while the sequential position effect takes up of the visual-spatial working memory,the two are relatively independent,thus do not interrupted each other.In the second experiment,to further verify the above assumptions,we changed the digital sequential memory of working memory tasks from visual presentation to auditory presentation,that is,from visual working memory task to verbal working memory task.The results show that,in contrast to experiment 1,SNARC effect and sequential position effect coexist in the task of size comparison,but both are affected by the increase of working memory load in the task of parity determination.This result proves that SNARC effect is indeed produced in working memory but takes up different components in different situations:SNARC effect is dominated by the visual-spatial component of working memory when compared in size and therefore only affected by the first visual space in experiment Working memory load,and SNARC effect is formed by verbal working memory processing when performing parity judgement task.Therefore,SNARC effect is affected only by working memory load in experiment two.We made two conclusions:(I)SNARC effect does not only originate from the intrinsic mode of long-term memory as the two-process theory suggests,but has a common production mechanism with the ordinal positional effect.They both require the participation of working memory resources,supporting the working memory account.(2)SNARC effect is dominated by the visual-spatial components of working memory when comparing number magnitude.It is therefore only affected by the visual-spatial working memory tasks.SNARC effect is processed through the verbal working memory when performing parity judgment,and therefore only affected by the verbal working memory tasks.