An ERP Study Of Attention Bias In Obsessive-compulsive Tendency Individuals With Contamination Fear

Obsessive-Compulsive Disorder(OCD) is an common mental disease, which characterized by persistent and unwanted obsessions mostly accompanied with ritualistic compulsions.The onset of OCD is teenage or youth. There is no difference distribution on sex among adult, however, boys are more vulnerable to OCD than girls among children. According to WHO (World Health Organization), OCD is the top ten disease which can cause people disability, causing 2.5% people lose their life. The individuals with OCD is harder at marriage, being employed and easier at social or professional dysfunction, comparing with other mental disorders.However, the cause of OCD is not consistent, plenty researchers thought that attention bias to OCD related threats is the cause and maintenance to OCD. There are numbers of studies about the attention bias of OCD, but the conclusions were controversial. On one hand, Some researchers found that the OCD manifested attention bias. For instance, Rao, Arasappa. Reddy, Venkatasubramanian, & Reddy (2010) found that OCD group showed Stroop interference only on OCD related negative words, while its stimuli type containing OCD related positive words. This results evidenced that attention bias existed only to OCD relevance negative words instead of positive ones among OCD patients. On the other hand, others cannot find the attention bias within OCD group. For instance, Harkness, Harris, Jones, & Vaccaro (2009) found that the OCD checkers did not allocated inequable attention resource on OCD-related stimuli.There is three reasons accounting for this controversial findings. First, the heterogeneous of OCD symptoms may be the cause of this uncongruent conclusions. In order to expel this influence, we use only OCD washers as the subjects. Second, the attenuation of attention bias scores is another reason. For instance, Amir, Najmi, & Morrison (2009) found that HOC not LOC showed attenuation of attention bias scores across experiment. So, we used the dot probe paradigm, which can measure the attention bias scores and the component of attention bias to test this hypothesis.The third and the most important reason why they did not find out the phenomenon is it can occur independently of behavioral interference. Former studies detected attention bias through measuring behavior response times, which is easy to understand and perform. However, those behavioral studies provide little information about the relative involvement of sensory versus cognitive processes in biases. Therefore, we use ERP (Event Related Potentials), which can exquisite temporal resolution and sensitivity to emotional processing(Hajcak, MacNamara, & Olvet,2010), to explore the time course of attention bias in OCD. Therefore, we use ERP to help us to detect the time course of attention bias.The study aims at exploring the neural time course of attention bias among Obsessive-Compulsive tendency individuals, including two concrete experiments.In experiment Ⅰ, we used emotional facial expressions as stimuli with the same procedure. Behavior response time cannot tell us whether HOC show attention bias to different facial expressions or not. On the contrary, the ERP results provided evidence that HOC manifest attention bias to emotional facial expression.In experiment Ⅱ, we manipulated different emotional pictures with dot probe paradigm. According to the behavior results, we can not find evidence to prove HOC manifested attention bias to contamination threat pictures. In contrast, ERP results showed that HOC manifested higher LPP to contamination threat pictures, which proved that HOC showed sustained attention to contamination threat pictures.