内隐/外显不同水平攻击者的注意偏向:行为和ERP证据

Attentional Bias in Individuals with Different Level of Implicit /Explicit Aggression: Behavioral and ERP Evidence

通过行为实验(点探测)和ERP实验(情绪Stroop)两个实验任务,考察了内隐/外显不同水平攻击者的注意偏向及其脑机制。结果表明:高外显攻击者对愤怒面孔存在注意偏向;高外显攻击者在愤怒面孔上的N100波幅显著低于中性面孔,表明其注意分配和调节能力较弱;高外显攻击者较之低外显攻击者的P300波幅更小表明其存在注意等方面的认知加工缺陷,N400波幅更小表明其对愤怒面孔进行语义编码时加工更为流畅;外显攻击组与内隐攻击组在FCz和Cz电极点上不同。这为内隐/外显攻击二者有着独立结构提供了行为与认知神经科学的证据。

Aggression is a relatively common phenomenon in the general population and usually accompanied with abnormity of cogni tion and the brain. The present study explored the influence factors and mechanisms of different levels of aggression in order to advance our understanding of the mechanisms underlying aggressive behavior. 80 participants were split up into two groups as explicit aggression group and implicit aggression group equally, the Buss Perry Aggression Questionnaire （BPAQ） and the Implicit Associate Test （IAT） were used to differentiate the participants＇explicit and implicit aggression level, and the behavior performance in dot probe task and emotional Stroop task were compared between high and low aggression level participants. The in dot probe task, angry and neutral words/faces are simultaneously presented at different spatial locations on the screen, followed by a mask pair. After the omission of this mask pair, a dot probe appears at the location of one of the stimuli immediately. The participant is required to respond to the location of the probe as fast as possible. Responding on trials where a probe follows at the same location as an emotional face （valid trial） is compared with that where a probe is presented at the opposite location of an emotional face （invalid trial）. The results revealed that high explicit aggression individuals showed significantly longer response latencies than low ex plicit aggression individuals. There is no difference among high implicit aggression individuals and low implicit aggression individuals. It confirmed that high explicit aggression individuals have attentional bias. In the emotional Stroop task, participants have to name the color of the pictures of angry and neutral facial expressions as quickly as possible and EEG was also recorded synchronously. The results indicated that high explicit aggression individuals showed significantly longer response latencies than low explicit aggression individuals on angry facial expression, validating that individuals with high explicit aggression display an attentional bias toward aggressive stimuli. A three way repeated measures Analysis of Variance （ANOVA） on the average latency and amplitude of emotional Stroop task in implicit/explicit aggression group was conducted, with aggression level （ high, low） as a between subjects factor, and emotion facial type （ angry, neutral） and eletrodes （ Fz, FCz, Cz, CPz, Pz） as within subjects factors. The result of the experiment illustrated that compared to neutral facial expression, high explicit aggression individu als showed a smaller N100 amplitude on angry facial expression, indicating that their ability to allocate and regulate attention was weak. The analysis of the P300 components showed that the amplitude was smaller among high explicit aggression individuals than low explicit aggression individuals, indicating that aggressive person had cognitive deficits, especially attention deficits. The single ERP study also found that members who were high in explicit aggression displayed smaller N400 amplitude than low explicit aggression individuals, in dicating more resources may be needed for high explicit aggression individuals to suppress outward angry responses. Compared to low ex plicit aggression members, high explicit aggression members showed lower amplitude on Cz position of N100 and FCz position of N400. However, the result of implicit aggression was contrary to explicit aggression. The results of the present study suggested that N100, P300 and N400 could be used referentially as an objective index for identifying aggressive individuals, and the difference between ex plicit and implicit aggression on EEG provided cognitive neuroscientific evidence for the dual aggression model.