Zebunke Manuela, Kreiser Maren, Melzer Nina, Langbein Jan, Puppe Birger
Institute of Genetics and Biometry, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany.
Institute of Behavioural Physiology, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany.
Front Psychol. 2018 Nov 6;9:2099. doi: 10.3389/fpsyg.2018.02099. eCollection 2018.
Delay-of-gratification paradigms, such as the famous "Marshmallow Test," are designed to investigate the complex cognitive concepts of self-control and impulse control in humans and animals. Such tests determine whether a subject will demonstrate impulse control by choosing a large, delayed reward over an immediate, but smaller reward. Documented relationships between impulsive behavior and aggression in humans and animals suggest important implications for farm animal husbandry and welfare, especially in terms of inadequate social behavior, tail biting and maternal behavior. In a preliminary study, we investigated whether the extent of impulse control would differ between quantitatively and qualitatively different aspects of reward in pigs. Twenty female piglets were randomly divided into two groups, with 10 piglets each. After a preference test to determine individual reward preference among six different food items, a discrimination test was conducted to train for successful discrimination between different amounts of reward (one piece vs. four pieces) and different qualitative aspects of reward (highly preferred vs. least preferred food item). Then, an increasing delay (2, 4, 8, 16, 24, 32 s) was introduced for the larger/highly preferred reward. Each piglet could choose to get the smaller/least preferred reward immediately or to wait for the larger/highly preferred reward. Piglets showed clear differences in their preference for food items. Moreover, the "quality group" displayed faster learning in the discrimination test (number of sessions until 90% of the animals completed the discrimination test: "quality group"-3 days vs. "quantity group"-5 days) and reached a higher level of impulse control in the delay-of-gratification test compared to the "quantity group" (maximum delay that was mastered: "quality group"-24 s vs. "quantity group"-8 s). These results demonstrate that impulse control is present in piglets but that the opportunity to get a highly preferred reward is more valued than the opportunity to get more of a given reward. This outcome also underlines the crucial role of motivation in cognitive test paradigms. Further investigations will examine whether impulse control is related to traits that are relevant to animal husbandry and welfare.
延迟满足范式，比如著名的“棉花糖测试”，旨在研究人类和动物自我控制与冲动控制的复杂认知概念。此类测试通过让受试者在一个大的、延迟的奖励和一个即时的、但较小的奖励之间做出选择，来确定其是否会表现出冲动控制。在人类和动物中，冲动行为与攻击性之间已被记录的关系对家畜养殖和福利具有重要意义，特别是在社交行为不足、咬尾和母性行为方面。在一项初步研究中，我们调查了猪在奖励的数量和质量不同方面的冲动控制程度是否存在差异。20只雌性仔猪被随机分为两组，每组10只。在进行偏好测试以确定六类不同食物中个体的奖励偏好后，进行辨别测试，训练猪成功区分不同数量的奖励（一块与四块）以及奖励的不同质量方面（最偏好的食物与最不偏好的食物）。然后，对于更大/更偏好的奖励引入逐渐增加的延迟（2、4、8、16、24、32秒）。每只仔猪可以选择立即获得较小/最不偏好的奖励，或者等待更大/更偏好的奖励。仔猪在对食物的偏好上表现出明显差异。此外，“质量组”在辨别测试中学习速度更快（直到90%的动物完成辨别测试所需的测试次数：“质量组”-3天，“数量组”-5天），并且与“数量组”相比，在延迟满足测试中达到了更高水平的冲动控制（掌握的最大延迟：“质量组”-24秒，“数量组”-8秒）。这些结果表明仔猪存在冲动控制，但获得高度偏好奖励的机会比获得更多给定奖励的机会更受重视。这一结果也强调了动机在认知测试范式中的关键作用。进一步的研究将考察冲动控制是否与家畜养殖和福利相关的特征有关。
