Raw Data from Individual ant workers show self-control

Often, the first option is not the best. Self-control can allow humans and animals to improve resource intake under such conditions. Self-control in animals is often investigated using intertemporal choice tasks—choosing a smaller reward immediately or a larger reward after a delay. However, intertemporal choice tasks may underestimate self-control, as test subjects may not fully understand the task. Vertebrates show much greater apparent self-control in more natural foraging contexts and spatial discounting tasks than in intertemporal choice tasks. However, little is still known about self-control in invertebrates. Here, we investigate self-control in the black garden ant Lasius niger. We confront individual workers with a spatial discounting task, offering a high-quality reward far from the nest and a poor-quality reward closer to the nest. Most ants (69%) successfully ignored the closer, poorer reward in favour of the further, better one. However, when both the far and the close rewards were of the same quality, most ants (83%) chose the closer feeder, indicating that the ants were indeed exercising self-control, as opposed to a fixation on an already known food source.

通常，首选项并非最优选择。在这类情境下，自控能力可帮助人类与动物提升资源获取量。动物的自控能力通常通过跨期选择任务（intertemporal choice tasks）进行研究：即受试者需在即时获取小额奖励与延迟获取大额奖励之间做出抉择。然而，跨期选择任务可能会低估受试对象的自控能力，因为受试个体可能无法完全理解任务规则。相较于跨期选择任务，脊椎动物在更贴近自然的觅食情境与空间折扣任务（spatial discounting tasks）中表现出更强的显性自控能力。但目前学界对无脊椎动物的自控能力仍知之甚少。本研究以黑花园蚁（Lasius niger）为对象，探究其自控能力。我们为单个工蚁设置了一项空间折扣任务：为其提供远离蚁巢的高品质奖励，以及靠近蚁巢的低品质奖励。大多数蚂蚁（69%）成功避开了更近的低品质奖励，转而选择更远的高品质奖励。但当远近两处奖励的品质相同时，大多数蚂蚁（83%）选择了更近的喂食器，这表明蚂蚁确实是在运用自控能力，而非仅仅依赖对已知食物源的固有偏好。