Green Luke J S, Luck Camilla C, Lipp Ottmar V
School of Psychology, Curtin University, Perth, WA, Australia.
Psychophysiology. 2020 Aug;57(8):e13563. doi: 10.1111/psyp.13563. Epub 2020 Mar 13.
Past research on backward conditioning in evaluative and fear conditioning yielded inconsistent results in that self-report measures suggest that the conditional stimulus (CS) acquired the valence of the unconditional stimulus (US) in fear conditioning (assimilation effects), but the opposite valence in evaluative conditioning (contrast effects). Conversely, implicit measures of CS valence suggest assimilation effects in evaluative backward conditioning, whereas startle modulation indicates contrast effects in backward fear conditioning. The current study investigated whether US intensity could account for the dissociation on implicit measures between fear and evaluative conditioning. Self-report measures of evaluative learning indicated assimilation effects for forward conditioning, whereas backward contrast effects were observed with intense USs only. Blink startle modulation indicated assimilation effects in forward conditioning and contrast effects in backward conditioning, regardless of US intensity. Experiment 2 included a neutral US in order to assess whether the offset of the positive US elicits an opponent emotional response that mirrors relief (disappointment), which is thought to mediate the reduction in startle seen during backward CSs in fear conditioning. This opponent emotional response was evident as startle magnitude during backward CSs increased linearly with increasing US pleasantness. Omission of the forward CSs led to an assimilation effect in self-report measures. The current results extend our understanding of emotional learning to stimuli encountered after salient emotional events. Startle reflects the emotion prevailing after US offset, relief or disappointment, whereas self-report measures seem more attuned to factors such as US predictability and intensity.
过去关于评价性条件作用和恐惧性条件作用中逆向条件作用的研究结果并不一致，即自我报告测量表明，在恐惧性条件作用中条件刺激（CS）获得了无条件刺激（US）的效价（同化效应），但在评价性条件作用中则获得了相反的效价（对比效应）。相反，CS效价的内隐测量表明评价性逆向条件作用中存在同化效应，而惊吓调节则表明逆向恐惧性条件作用中存在对比效应。本研究调查了US强度是否可以解释恐惧性条件作用和评价性条件作用在内隐测量上的分离。评价性学习的自我报告测量表明，正向条件作用存在同化效应，而只有在高强度US时才观察到逆向对比效应。眨眼惊吓调节表明，无论US强度如何，正向条件作用中存在同化效应，逆向条件作用中存在对比效应。实验2纳入了一个中性US，以评估正向US的消失是否会引发一种与解脱（失望）相对应的对立情绪反应，这种反应被认为介导了恐惧性条件作用中逆向CS期间惊吓的减少。这种对立情绪反应很明显，因为逆向CS期间的惊吓幅度随着US愉悦度的增加而线性增加。省略正向CS会导致自我报告测量中出现同化效应。当前结果将我们对情绪学习的理解扩展到了显著情绪事件之后遇到的刺激。惊吓反映了US消失后占主导的情绪，解脱或失望，而自我报告测量似乎更能适应US可预测性和强度等因素。
