Pre-attention Processing Mechanism Of Sensation Seeking

Sensation seeking is a personality trait to describe and evaluate personal differences on sensation need.The adolescents with high sensation seeking trait are prone to have problem behavior,so it is much valuable to study the physiological foundation of sensation seeking trait in explaining the mechanism of adolescent's problems.Zuckerman defined Sensation seeking as a need to seek novel,changing and complex stimulus and experiences,accompanied by a willingness to take personal and social risks for the sake of such experiences.Zuckerman thought sensation seeking is a trait determined by biological factors.In order to increase the brain arousal level,high sensation seekers have a strong need on outside stimulation.It is supported by the research on brainstem evoked potential.A lot of researchers found the result that the amplitude of the potential evoked by the same auditory stimulation is higher on high sensation seekers than low sensation seeking ones'.They thought this phenomenon is the biological proof of high sensation seekers inclining to seeking strong stimulus.When they measured the brainstem evoked potential secondly,the researchers found the amplitude of the potential is much lower than initial measurement in higher sensation seekers,but the decreasing of the amplitude in low sensation seekers is insignificant.Zucherman called it as sensation adaptation.However,there are some shortcomings in their studies on the biological mechanism of sensation seeking.The first is,all the experiments are undergone at the subjects' awareness,so the results can easily be confused with subjects' subjective factors.The second is,they didn't study the relationship on the changing stimulus and the need of complex stimulus of sensation seekers.The third is,their studies just paid attention on cognitive processing stage of attention,they ignored pre-attention processing stage.In fact,it is often processed under subconscious state when a person choice his attention to outside stimulus.Before he choice his meaningful attentive target,a person should discriminate among different objectives at his brain cortex.The mental procedure of determining what is valuable to be noticed is called pre-attention.Pre-attention is the preparing stage of vuluntary attention or selective attention,it reflects the early processing of brain cortex.Studies on pre-attentive processing of sensation seeking trait is much important for probing the bio-psychological mechanism of the early stage of cognitive processing.Pre-attention is prior to invuluntary attention and out of a person's awareness,So it is difficult to study deeply on this stage with traditional behavioral method.Event-related Potential(ERP)has an unique advantage on probing pre-attentive processing mechanism for its superior temporal resolution.The researches indicated that mismatch negativity(MMN)is the main biological index of pre attentive processing.MMN is a negative component of ERP to an odd stimulus and is free from the effects of the subjects' subjective factors.MMN reflects the pre-attentive power of the brain cortex to deviant stimulus,so it can be used to probe the biological mechanism of high sensation seekers pursuing stimulus change.By analyzing the MMN elicited by sensation seeking relative sounds,we can disclose the sensitivity differences of pre-attentive stage of sensation seeking trait to complex information and highlight the biological mechanism of high sensation seekers inclining to pursue specific and complex stimulus.This study use ERP technique,combing with classical Oddball and newly developed Control MMN experimental paradigm to compare the pre-attention processing characteristic of high sensation seeking participants with low sensation seekers.There are two kinds of stimulating material employed in the study.The first one is tone.Using changes in sound intensity as deviant stimulation to evoke MMN,we compared and analyzed the high-and low-sensation seekers' pre-attention automatic processing in the face of sound intensity changes.While sound intensity of standard stimulation is70 dB,sound intensity of deviant stimulation divides into two directions,the small ones being called small-oriented deviant and the major ones big-oriented deviant.Each direction has three deviant stimulations,the deviant rate being 7dB,10% of the standard stimulation.Total probability of deviant stimulation is about 25%.In accordance with the deviation intensity sequence from low to high,the three deviant stimulations of small-oriented deviant are 63 dB,56 dB,49 dB,and the ones of big-oriented deviant are 77 dB,84 dB,91 dB.The second kind of stimulating material is complex sound.Standard stimulation being animals' voice,deviant stimulation is violence sound or strange ones,which are called the sensation seeking relative sounds with a total deviant probability of 13%.Looking into MMN induced by sensation seeking relative sounds,we compared and analyzed the high-and low-sensation seekers' pre-attention automatic processing on the specific sound of social significance.The present study also discussed the physiological mechanism of some adolescent behavior.Main experimental results and conclusions:Con.1: The amplitude of MMN generated by small-oriented deviant stimulation of high sensation seeking participants is significantly larger than low sensation seeking ones'.Besides,as the deviant stimulation changes,the amplitude of high sensation seekers' MMN enhanced showing a significant deviation intensity effect,while low-sensation seekers have no such effects.This suggests that high sensation seekers have better pre-attentive automatic detection ability to small-oriented stimulation compared with low sensation seekers.It exposed from pre-attention perspective the physiological mechanism of high sensation seekers pursuing ever-changing behaviors.Con.2: As for the MMN amplitude elicited by big directional deviant stimulation,there are no obvious differences between high sensation seeking participants with low sensation seeking ones'.By comparing the two experiments result and analyzing the behavioral experimental result,we think the result of big-oriented deviant experiment was probably affected by floor effect.Therefore,it should be verified in further research to identify whether the high-and low-sensation seekers are different on pre-attention automatic processing to big-oriented deviant.For example,we can reduce the deviant stimulation intensity of big-oriented deviant to eliminate the floor effect.Con.3: Being elicited by sensation seeking relative sound as deviant stimulation,the MMN amplitude of high sensation seeking participants is significantly higher than low sensation seeking ones'.This result implicates the pre-attentive detection power of high sensation seekers is significantly stronger than the low sensation seekers.It highlighted the physiological mechanism of some specific behavior(eg.Violence,weird behavior)of high sensation seeking people.Con.4: The adaptation phenomenon of the later phase of MMN generated by small directional deviant stimulation of high sensation seeking participants indicates the pre-attentive automatic detection power of high sensation seekers is adaptive.It can explain the physiological mechanism of high sensation seekers that have inclination for pursuing odd behavior.High sensation seekers did not show the expected adaption to MMN induced by sensation seeking relative sounds.One possible reason may be that sensation seeking relative sounds are too attractive to high sensation seekers to manifest adoptive feelings in a shorter period of ERP experiment.This may be examined through the duplicate experimental design paradigm.