通常,一天中的时间可以改变内存性能。它对人脸记忆识别性能的影响,这对日常接触新人或证词很重要,尚未调查。重要的是,高水平的应激激素皮质醇会损害记忆识别,特别是情感材料。然而,一些研究还报道了高皮质醇水平可以增强记忆识别能力。由于早上的皮质醇水平通常高于晚上,一天中的时间也可能影响识别性能。在这项为期两天的预注册研究中,51名健康男性在中午左右的第一天编码了男性和女性面孔的图片,这些图片具有不同的情感表情。两天后,在早上(内源性皮质醇水平高和中度增加)或晚上(内源性皮质醇水平低)的两个连续测试时间恢复了面部记忆。此外,评估了不同时间点的警觉性和唾液皮质醇水平.与预期的晚上组相比,早上的皮质醇水平显着升高,而两组的警觉性没有差异。女性刺激的熟悉度等级在参与者在早晨适度增加的内源性皮质醇水平比在晚上较低的内源性皮质醇水平时明显更好。以前也观察到压力与非压力参与者的模式。此外,早晨这段时间的皮质醇水平与面部刺激的回忆呈正相关。因此,识别记忆性能可能取决于一天中的时间以及刺激类型,例如男性和女性面孔的差异。最重要的是,结果表明,在研究一天中的时间对记忆表现的影响时,皮质醇可能是有意义的,值得研究。这项研究提供了两者,对日常接触以及法律相关领域的见解,例如证词。
Time of day can alter memory performance in general. Its influence on memory recognition performance for faces, which is important for daily encounters with new persons or testimonies, has not been investigated yet. Importantly, high levels of the stress hormone cortisol impair memory recognition, in particular for emotional material. However, some studies also reported high cortisol levels to enhance memory recognition. Since cortisol levels in the morning are usually higher than in the evening, time of day might also influence recognition performance. In this pre-registered study with a two-day design, 51 healthy men encoded pictures of male and female faces with distinct emotional expressions on day one around noon. Memory for the faces was retrieved two days later at two consecutive testing times either in the morning (high and moderately increased endogenous cortisol levels) or in the evening (low endogenous cortisol levels). Additionally, alertness as well as salivary cortisol levels at the different timepoints was assessed. Cortisol levels were significantly higher in the morning compared to the evening group as expected, while both groups did not differ in alertness. Familiarity ratings for female stimuli were significantly better when participants were tested during moderately increased endogenous cortisol levels in the morning than during low endogenous cortisol levels in the evening, a pattern which was previously also observed for stressed versus non-stressed participants. In addition, cortisol levels during that time in the morning were positively correlated with the recollection of face stimuli in general. Thus, recognition memory performance may depend on the time of day and as well as on stimulus type, such as the difference of male and female faces. Most importantly, the results suggest that cortisol may be meaningful and worth investigating when studying the effects of time of day on memory performance. This research offers both, insights into daily encounters as well as legally relevant domains as for instance testimonies.