Finke Johannes B, Schippers Anna M, Klucken Tim
Department of Psychology, Clinical Psychology and Psychotherapy, University of Siegen, Siegen, Germany.
Sci Rep. 2025 Jun 20;15(1):20156. doi: 10.1038/s41598-025-05350-0.
Temporal contiguity between conditioned (CS) and unconditioned stimuli (US) is a crucial factor in Pavlovian learning, yet little is known about its role in appetitive conditioning and extinction. In a within-subject design, 60 participants underwent both a delay (DC) and trace conditioning (TC) session with partial reinforcement (75%) by monetary rewards (US) and varying interval between CS offset and US onset (DC: 0s; TC: 4s). In addition to self-report indices (reward expectancy, arousal, valence), psychophysiological markers (pupil dilation, heart-period and startle reflex modulation) were recorded during acquisition and extinction training. For most measures, significant differential conditioned responses emerged, irrespective of temporal contiguity, with no major differences observed between TC and DC during acquisition (except for potentially diminished startle attenuation in TC). Despite overall similar patterns in conditioned responding (with small to moderate effects on physiological measures), there was no intraindividual concordance between sessions, yet evidence for differential TC effects on extinction learning. Specifically, smaller reductions in differential reward expectancy, heart-period deceleration and startle modulation after extinction in TC suggested relatively diminished extinction learning. Conditioned pupil dilation (0-2 s after CS onset) remained comparatively stable. Taken together, our findings extend evidence of differences in underlying learning mechanisms between TC and DC to the context of reward learning.
条件刺激(CS)与非条件刺激(US)之间的时间连续性是经典条件反射学习中的一个关键因素,但对于其在食欲性条件反射和消退中的作用却知之甚少。在一项被试内设计中,60名参与者接受了延迟条件反射(DC)和痕迹条件反射(TC)实验,均采用货币奖励(US)进行部分强化(75%),且CS偏移与US开始之间的间隔不同(DC:0秒;TC:4秒)。除了自我报告指标(奖励预期、唤醒、效价)外,在习得和消退训练期间还记录了心理生理指标(瞳孔扩张、心动周期和惊吓反射调节)。对于大多数指标,无论时间连续性如何,均出现了显著的差异条件反应,在习得过程中TC和DC之间未观察到主要差异(除了TC中惊吓衰减可能减弱)。尽管条件反应的总体模式相似(对生理指标有小到中等程度的影响),但各实验之间不存在个体内一致性,但有证据表明TC对消退学习有不同影响。具体而言,TC消退后差异奖励预期、心动周期减速和惊吓调节的减小幅度较小,表明消退学习相对减弱。条件性瞳孔扩张(CS开始后0 - 2秒)保持相对稳定。综上所述,我们的研究结果将TC和DC之间潜在学习机制差异的证据扩展到了奖励学习的背景下。
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