| Suicide is a leading cause of death worldwide and is among the most perplexing ofall human behaviors. According to the World Health Organization (2012), almost onemillion people die by suicide every year. Suicide accounts for more than all deaths frommurder. In the past45years, suicide rates have increased by60%worldwide. Manyresearchers consider that suicidal thought is the primary antecedent of suicidal behaviors.Many researchers thus believe that by understanding the origin of suicidal thought, we canbetter understand, predict, and treat suicidal behavior. However, suicide is difficult topredict and prevent because people who consider killing themselves often are unwilling orunable to report their intentions. Advances in the measurement of implicit cognition mayprovide a behavioral marker for suicide risk.There are more than20measurement procedures in the measurement of implicit cognition. Among these, the Implicit Association Test (IAT) provides the bulk ofaccumulated research evidence. Furthermore, IAT has been adapted to measure a widevariety of mental contents including stereotypes, attitudes, self-esteem, and self-concepts,across a wide variety of topics such as mental health, consumer decision making, andpolitical behavior. We tested whether individuals who have made a decision to killthemselves would reveal stronger implicit cognition associating self with death andwhether the strength of such an association would predict suicide attempts beyond thatachieved with suicidal thoughts from self-report. And study of the cognitive processesinvolved in the IAT is necessary to establish the validity of this measure and to suggestfurther refinements to its use and interpretation. The current study used ERPs to studycognitive processes associated with the IAT.Escape theory is an integrative framework proposing a causal chain that leads tosuicide. In this framework, suicide involves an orderly progression through six distinctstages. The initial step is a major failure or disappointment that is due to events fallingseverely short of standards or expectations. This may occur because events are verynegative, because standards are too high, or both. It is the discrepancy between the realityand standard that is crucial. The second stage involves self-blame: Responsibility forfailure is attributed to the self. The following steps successively involve highself-awareness, negative affect and feelings, a state of cognitive deconstruction, andfinally several consequences of cognitive deconstruction that may increase the appeal ofsuicide. The other purpose of the present study was to assess the effectiveness of theEscape Theory of Suicide in accounting for the development of implicit cognitionassociating self with death.Through the above study, the mainly results were found as following:(1) Nonsuicidal individuals show a negative association between death and oneself(M=-0.34, SE=0.07); suicide ideators show a small negative association between deathand oneself (M=-0.06, SE=0.06); and suicide attempters show a large positiveassociation between s death and oneself (M=0.34, SE=0.1). A one-way ANOVArevealed a significant group effect, F (2,69)=17.89, p <0.01. These results support the validity of implicit association test as a measure of suicide thoughts.(2) The final model from the Escape Theory of Suicide fit our data very well. Thechi-square for this model was17.54, df=14, p=0.23, RMSEA=0.04, and GFI=0.98.Our findings confirm the predictive validity of the Escape Theory of Suicide.(3) Results revealed significant differences between groups (failure-related priminggroup, success-related priming group, and control group) in accessibility to implicitsuicidal mind, F (2,135)=13.42, p <.001, η2=.17. Furthermore, priming manipulationinteracted with individual differences in locus of control (LOC), F (2,132)=13.38,p <.001, η2=.16. Significant differences in accessibility to implicit suicidal mind wereobserved in individuals with internal LOC, F (2,67)=15.46, p <.001, η2=.32, whileeffects of priming manipulation were eliminated in individuals with external LOC, F (2,65)=1.57, p=.22. The results of our experiment were in line with our predictions thatfailure increases implicit suicidal mind and success decreases implicit suicidal mind. Thisstudy supports our hypothesis that the impact of failure or success priming on associationsbetween self and death is more pronounced among individuals with internal LOC, andabsent among individuals with external LOC.(4) The fourth study found response time was significantly longer in the incongruentcondition (M=621.90ms, SD=64ms) than in the congruent condition (M=566.38ms，SD=60ms), t(20)=3.31, p <0.01. A two-way interaction between condition and task setswitching was found for response time, F (1,20)=4.43, p <0.05. Task switching had noeffect in the congruent condition. Task switching did however significantly prolongresponse time in the Incongruent condition (for task switch: M=654.93ms, SD=71.61ms; for no task switch: M=575.21ms, SD=79.53ms). And the study also foundsignificant differences in P300amplitude in the congruent (M=4.86μV, SD=1.84μV)and incongruent conditions (M=3.51μV, SD=1.55μV), t (20)=4.44, p <0.01. Therewere differences in P300amplitude between trials of the incongruent condition thatrequired (M=3.96μV, SD=1.55μV) or did not require a task switch (M=3.17μV, SD=1.75μV), t (20)=2.58, p <0.05. The less demanding nature of the congruent conditionmay have resulted in greater resources being available to process the stimuli, resulting in less uncertainty about the correct response to the stimulus. In the incongruent condition,there is greater perceived local probability on no switch trials compared to switch trials. |
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