Dunn Jonathon, Andrews Clare, Nettle Daniel, Bateson Melissa
Centre for Behaviour and Evolution and Institute of Neuroscience, Newcastle University, Newcastle, UK.
Anim Cogn. 2019 May;22(3):413-421. doi: 10.1007/s10071-019-01254-5. Epub 2019 Mar 6.
Impulsivity-the extent to which a reward is devalued by the amount of time until it is realized-can be affected by an individual's current energetic state and long-term developmental history. In European starlings (Sturnus vulgaris), a previous study found that birds that were lighter for their skeletal size, and birds that had undergone greater shortening of erythrocyte telomeres over the course of development, were more impulsive as adults. Here, we studied the impulsivity of a separate cohort of 29 starlings hand-reared under different combinations of food amount and begging effort. The task involved repeated choice between a key yielding one pellet after 3 s and another key yielding two pellets after 8 s. Impulsivity was operationalised as the proportion of choices for the short-delay option. We found striking variation in impulsivity. We did not replicate the results of the previous study concerning developmental telomere attrition, though combining all the evidence to date in a meta-analysis did support that robustness of that association. We also found that early-life conditions and mass for skeletal size interacted in predicting impulsivity. Specifically, birds that had experienced the combination of high begging effort and low food amount were less impulsive than other groups, and the usual negative relationship between impulsivity and body mass was abolished in birds that had experienced high begging effort. We discuss methodological differences between our study and studies that measure impulsivity using an adjusting-delay procedure.
冲动性——奖励因距离实现的时间长短而贬值的程度——可能会受到个体当前的精力状态和长期发育史的影响。在欧洲椋鸟（家八哥）中，先前的一项研究发现，骨骼大小较轻的鸟类，以及在发育过程中红细胞端粒缩短程度更大的鸟类，成年后更冲动。在此，我们研究了另一组29只在不同食物量和乞食努力组合下人工饲养的椋鸟的冲动性。该任务包括在一个3秒后产生一粒食丸的按键和另一个8秒后产生两粒食丸的按键之间进行重复选择。冲动性被定义为选择短延迟选项的比例。我们发现冲动性存在显著差异。我们没有重复先前关于发育端粒损耗的研究结果，不过将迄今为止所有证据进行荟萃分析确实支持了该关联的稳健性。我们还发现，早期生活条件和相对于骨骼大小的体重在预测冲动性方面存在相互作用。具体而言，经历过高乞食努力和低食物量组合的鸟类比其他组更不冲动，并且在经历过高乞食努力的鸟类中，冲动性与体重之间通常的负相关关系消失了。我们讨论了我们的研究与使用调整延迟程序测量冲动性的研究之间的方法差异。
