Functional And Dysfunctional Impulsivity Have Selective Effect On Response Inhibition Under High And Low Pressure

Impulsivity is a multidimensional personality traits,at present,there is no a unified definition on impulsivity.However,there are universal characteristics of impulsivity: rapidly,unplanned,act recklessly.In clinic,high impulsivity is a significant symptom of a variety of mental illness.In normal person,studies also tend to focus on the negative impact of impulsivity in life,such as economic difficulties caused by impulsive consumption,aggressive behavior to others or self,etc.Response inhibition is an important element of the executive function,which have important influence on making decision,adapting to the changing environment.Response inhibition plays an important role in human cognitive and behavior control,it is commonly believed that the typical symptoms of deficient in response inhibition is the improvement of impulsivity,high impulsivity individual has poor inhibition ability.However,Dickman found that the impulsivity also bring positive influence on cognitive reaction.According to a serious experiment,he found that high impulsivity have better performance in cognitive and behavior control.Therefore,he propose that impulsivity should be divided into two constructs: functional impulsivity and dysfunctional impulsivity.Functional impulsivity is related to the tendency to take quick decisions when doing so is beneficial.In contrast,dysfunctional impulsivity is related to the tendency towards speedy and non-reflective decision-making despite the negative consequences of such actions.Studies found that high functional impulsivity can be more flexible and adjust their cognitive and behavior as the task environment changing,while dysfunctional impulsivity significantly associated with the damage of inhibition and mental illness.However,there has no study explored the effect on response inhibition from both the functional and dysfunctional impulsivity,it is still unknown if functional impulsivity modulate the response inhibition or not.In this study,we will explore the effect of functional and dysfunctional impulsivity on response inhibition through the different environmental pressure.An effective task to assess abrupt forms of response inhibition is the stop-signal task in which a choice reaction task(the primary-task)is combined with the presentation of a stop signal.In the Stop-signal task,subjects perform a primaryvisual binary-choice RT task and on a portion of trials are instructed to inhibit that response upon the presentation of a Stop-signal(an auditory or visual stimulus),which can occur at any time at or after the onset of the primary task stimulus.By varying the interval between the onset of the primary task stimulus and the Stop-signal(i.e.the Stop-signal delay),the outcome of inhibition can be biased.The Stop-signal task,which is based on a mathematical(“horse-race”)model,also derives an estimate of the latency of the inhibition process,known as Stop-signal Reaction Time(SSRT).Stop-signal Reaction Time is an important indicator of inhibition ability.Our pressure environment Settings are mainly based on the effective reaction time to go stimulus in primary-task,in general studies,participants need to react to go stimulus in 1000 ms,it is easy to have correct response.So this is low pressure environment.In contrast,the effective reaction time to go stimulus is 500 ms,participants have little time to wait the stop-signal and they must make response to go stimulus correctly and quickly,this is a high pressure environment.In research one,we translate the Dickman impulsivity scale to Chinese version,and test the reliability and validity of the Chinese version in the college students’ group.We selected 500 college students to measure the validity of the translated scale,and selected the aggressive scale to measure the external validity.After four weeks,draw two classes to remeasure the impulsivity scale.In research two,we explored the effect of functional and dysfunctional impulsivity on response inhibition in low time pressure environment.We choose 30 college students to complete the Dickman impulsivity scale and when they started to do the SST task,gathering the EEG data.In research three,we explored the effect of functional and dysfunctional impulsivity on response inhibition in high time pressure environment.We choose 56 college students to complete the Dickman impulsivity scale and when they started to do the SST task,gathering the EEG data.This research results is as follows:(1)The Chinese version Dickman impulsiveness scale has good reliability and validity in college students groups,is a qualified measuring tool.(2)In low time pressure environment,the dysfunctional impulsivity play a regulatory role on response inhibition,which significantly positive correlated with SSRT,negative correlated with probability of successful inhibition,and has a positive correlation with the P3 peak.(3)In high time pressure environment,the functional impulsivity has a negative correlation with the mean reaction time to go stimulus,a positive correlation with the accuracy in primary task.Moreover,the functional impulsivity play a regulatory role on inhibition task,which negatively correlated with the response inhibition ERP component P3 latency.