Department of Behavioural and Cognitive Biology, University of Vienna, 1090Vienna, Austria.
Animal Comparative Economics Laboratory, Department of Zoology and Evolutionary Biology, University of Regensburg, 93053 Regensburg, Germany.
J Exp Biol. 2021 Jun 1;224(11). doi: 10.1242/jeb.242454. Epub 2021 Jun 4.
Learning allows animals to respond to changes in their environment within their lifespan. However, many responses to the environment are innate, and need not be learned. Depending on the level of cognitive flexibility an animal shows, such responses can either be modified by learning or not. Many ants deposit pheromone trails to resources, and innately follow such trails. Here, we investigated cognitive flexibility in the ant Lasius niger by asking whether ants can overcome their innate tendency and learn to avoid conspecific pheromone trails when these predict a negative stimulus. Ants were allowed to repeatedly visit a Y-maze, one arm of which was marked with a strong but realistic pheromone trail and led to a punishment (electric shock and/or quinine solution), and the other arm of which was unmarked and led to a 1 mol l-1 sucrose reward. After ca. 10 trials, ants stopped relying on the pheromone trail, but even after 25 exposures they failed to improve beyond chance levels. However, the ants did not choose randomly: rather, most ants began to favour just one side of the Y-maze, a strategy which resulted in more efficient food retrieval over time, when compared with the first visits. Even when trained in a go/no-go paradigm which precludes side bias development, ants failed to learn to avoid a pheromone trail. These results show rapid learning flexibility towards an innate social signal, but also demonstrate a rarely seen hard limit to this flexibility.
学习使动物能够在其生命周期内对环境变化做出反应。然而，许多对环境的反应是天生的，不需要学习。根据动物表现出的认知灵活性水平，这种反应可以通过学习来改变，也可以不改变。许多蚂蚁会在资源上留下信息素痕迹，并本能地跟随这些痕迹。在这里，我们通过询问蚂蚁是否能够克服其先天倾向并学会避免同种信息素痕迹，从而研究了黑蚁 Lasius niger 的认知灵活性，当这些信息素痕迹预测到负面刺激时。蚂蚁被允许反复访问一个 Y 形迷宫，其中一条臂用强烈但逼真的信息素痕迹标记，并通向惩罚（电击和/或奎宁溶液），另一条臂未标记，并通向 1 mol l-1 蔗糖奖励。在大约 10 次试验后，蚂蚁停止依赖信息素痕迹，但即使在 25 次暴露后，它们也未能超过随机水平。然而，蚂蚁并没有随机选择：相反，大多数蚂蚁开始偏爱 Y 形迷宫的一侧，与第一次访问相比，这种策略随着时间的推移导致更有效地取回食物。即使在排除侧偏发展的 Go/No-Go 范式中进行训练，蚂蚁也未能学会避免信息素痕迹。这些结果表明，蚂蚁对天生的社会信号具有快速的学习灵活性，但也表明这种灵活性存在着罕见的硬性限制。
