Devriese S, Winters W, Stegen K, Van Diest I, Veulemans H, Nemery B, Eelen P, Van de Woestijne K, Van den Bergh O
Department of Psychology, University of Leuven, Belgium.
Psychosom Med. 2000 Nov-Dec;62(6):751-9. doi: 10.1097/00006842-200011000-00003.
Somatic symptoms that occur in response to odors can be acquired in a pavlovian conditioning paradigm. The present study investigated 1) whether learned symptoms can generalize to new odors, 2) whether the generalization gradient is linked to the affective or irritant quality of the new odors, and 3) whether the delay between acquisition and testing modulates generalization.
Conditional odor stimuli (CS) were (diluted) ammonia and niaouli. One odor was mixed with 7.4% CO2-enriched air (unconditional stimulus) during 2-minute breathing trials (CS+ trial), and the other odor was presented with air (CS- trial). Three CS+ and three CS- trials were conducted in a semirandomized order (acquisition phase). The test phase involved one CS+-only (CS+ without CO2) and one CS- test trial, followed by three trials using new odors (butyric acid, acetic acid, and citric aroma). Half of the subjects (N = 28) were tested immediately, and the other half were tested after 1 week. Ventilatory responses were measured during and somatic symptoms were measured after each trial.
Participants had more symptoms in response to CS+-only exposures, but only when ammonia was used as the CS+. Also, generalization occurred: More symptoms were reported in response to butyric and acetic acid than to citric aroma and only in participants who had been conditioned. Both the selective conditioning and the generalization effect were mediated by negative affectivity of the participants. The delay between the acquisition and test phases had no effect.
Symptoms that occur in response to odorous substances can be learned and generalize to new substances, especially in persons with high negative affectivity. The findings further support the plausibility of a pavlovian perspective of multiple chemical sensitivity.
在巴甫洛夫条件反射范式中可习得因气味引发的躯体症状。本研究调查了：1）习得的症状是否能泛化到新气味；2）泛化梯度是否与新气味的情感或刺激性质相关；3）习得与测试之间的延迟是否会调节泛化。
条件性气味刺激（CS）为（稀释后的）氨水和芳樟醇。在2分钟的呼吸试验（CS+试验）中，一种气味与富含7.4%二氧化碳的空气（无条件刺激）混合，另一种气味与空气一起呈现（CS-试验）。三个CS+试验和三个CS-试验以半随机顺序进行（习得阶段）。测试阶段包括一次仅CS+（无二氧化碳的CS+）试验和一次CS-试验，随后是使用新气味（丁酸、乙酸和柠檬酸香精）的三次试验。一半受试者（N = 28）立即接受测试，另一半在1周后接受测试。在每次试验期间测量通气反应，并在试验后测量躯体症状。
参与者对仅CS+暴露有更多症状，但仅当使用氨水作为CS+时。此外，发生了泛化：与柠檬酸香精相比，对丁酸和乙酸报告的症状更多，且仅在接受过条件反射的参与者中。选择性条件反射和泛化效应均由参与者的负性情感介导。习得阶段和测试阶段之间的延迟没有影响。
对有气味物质产生的症状可以习得并泛化到新物质，尤其是在负性情感高的人群中。这些发现进一步支持了巴甫洛夫多重化学敏感性观点的合理性。
