Abstract: The pure presence of others describes an experimental manipulation variable that someone sit behind another one seeing without doing anything. Clinically, social anxiety disorder (SAD) patients are sensitive to the presence of others. In this study, we examined whether the presence of others show maladaptive fear learning and stronger fear generalization than alone. The answers to such questions could provide a new perspective on the pathogenesis of social anxiety disorder patients. Eighty-four college students participated in this study. Three participants were excluded form analysis due to unsuccessful physiological recording. Eight other participants who could not learn the rules of shock and thus were also excluded. We also excluded eight participants for their preference degree of familiar others reach below 2 points, and six participants for their preference degree of strange others reach over 0 point. Finally, we analyzed 72 participants’ (Female:47, Male: 25) behavioral and physiological data. The experiment has been conducted in two stages: acquisition and generalization. Ten growing rings served as conditioned stimuli (CS) and generalized stimuli (GS). The smallest and the largest rings were set as the conditioned threat stimuli (CS+) and conditioned safety stimuli (CS-), separately. The eight midsized rings were used as for classes of generalization stimuli (i.e., Class1, Class2, Class3, Class4), with Class1 being the most similar to CS+ in perception. The unconditioned stimulus (US) was a 500ms electric shock, which was set at a level that was “uncomfortable yet not painful”. CS+ was probably paired with the US (reinforcement rate: 66.67%), whereas CS- was never paired with US. During the experiment, the online shock expectancy ratings of US and skin conductance responses were recorded. The results showed that there is no difference between the groups in the fear acquisition phase. CS+ has always resulted in higher shock expectancy and SCR than CS-. However, in the generalization test, there was a tendency in the presence of others group with higher shock expectancy, but it is insignificant. In the index of SCR, the main effect of stimulus type depicted a downward gradient. The configuration of these downward gradients differed across groups, as evidenced by a significant stimulus type-by-group interaction. With respect to Class1, the presence of others group displayed a greater SCR than group alone. In the group alone, Class1 induced a greater SCR than Class3 and Class 4, and Class 2 induced greater SCR than Class4, indexed by a steeper gradient than the presence of others group. These results indicated that the presence of others group had a broader generalization than the group alone. According to the theory of negativity bias, threat stimuli would attract more attention resource, leading to a steady attentional bias. During the fear acquisition phase, participants’ attention resources were more easily captured by novel fear stimuli and thus ignored the existence of others present. While in the subsequent generalization test, subjects have learned the rules of CS-US contingencies and therefor the variable of presence of others distracted the subjects’ attention in turn. This is consistent with previous research that individuals tend to allocate resources to the stimulus with higher threat value and inhibit the processing of other elements to better focus on the current target. Our results suggest that the presence of other enhanced fear generalization at the physiological level, rather than at the subjective level. Our findings may have potential value for etiology and treatment of social anxiety disorders in clinical.

Key words: conditioned fear generalization, the pure presence of others, skin conductance response

摘要： 社会影响理论指出，他人在场会分散个体注意力，影响个体表现。本研究采用知觉辨别恐惧条件反射范式，将主观电击预期和皮肤电反应作为主要指标，考察他人在场对恐惧联结过程和恐惧泛化程度的影响。结果发现，在恐惧习得过程，未出现显著的习得组间差异。在恐惧泛化上，表现为他人在场增强了恐惧泛化水平，泛化梯度更广。研究结果表明，他人在场作为潜在的威胁因素可能会使个体的恐惧泛化水平更广，这或许可以推断，社交焦虑群体在他人在场情况下会扩大他们的恐惧泛化水平。

关键词: 条件性恐惧泛化, 纯粹他人在场, 皮肤电