Raby C R, Alexis D M, Dickinson A, Clayton N S
Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, UK.
Nature. 2007 Feb 22;445(7130):919-21. doi: 10.1038/nature05575.
Knowledge of and planning for the future is a complex skill that is considered by many to be uniquely human. We are not born with it; children develop a sense of the future at around the age of two and some planning ability by only the age of four to five. According to the Bischof-Köhler hypothesis, only humans can dissociate themselves from their current motivation and take action for future needs: other animals are incapable of anticipating future needs, and any future-oriented behaviours they exhibit are either fixed action patterns or cued by their current motivational state. The experiments described here test whether a member of the corvid family, the western scrub-jay (Aphelocoma californica), plans for the future. We show that the jays make provision for a future need, both by preferentially caching food in a place in which they have learned that they will be hungry the following morning and by differentially storing a particular food in a place in which that type of food will not be available the next morning. Previous studies have shown that, in accord with the Bischof-Köhler hypothesis, rats and pigeons may solve tasks by encoding the future but only over very short time scales. Although some primates and corvids take actions now that are based on their future consequences, these have not been shown to be selected with reference to future motivational states, or without extensive reinforcement of the anticipatory act. The results described here suggest that the jays can spontaneously plan for tomorrow without reference to their current motivational state, thereby challenging the idea that this is a uniquely human ability.
对未来的认知和规划是一项复杂的技能，许多人认为这是人类独有的。我们并非与生俱来就具备这种能力；儿童大约在两岁时开始形成对未来的认知，到四五岁时才具备一定的规划能力。根据比肖夫 - 克勒假说，只有人类能够将自己与当前的动机分离开来，并为未来的需求采取行动：其他动物无法预见未来的需求，它们表现出的任何面向未来的行为要么是固定动作模式，要么是由当前的动机状态所引发。这里所描述的实验测试了鸦科家族的成员——西部灌丛鸦（Aphelocoma californica）是否会为未来做规划。我们发现，灌丛鸦会为未来的需求做准备，它们既会优先将食物藏在一个它们知道第二天早上会饥饿的地方，也会有区别地将特定食物储存在第二天早上该类食物无法获取的地方。先前的研究表明，与比肖夫 - 克勒假说一致，大鼠和鸽子可能通过对未来进行编码来解决任务，但时间跨度非常短。尽管一些灵长类动物和鸦科动物现在会基于未来的后果采取行动，但这些行动尚未被证明是参照未来的动机状态进行选择的，或者是在没有对预期行为进行大量强化的情况下进行的。这里所描述的结果表明，灌丛鸦能够在不参照当前动机状态的情况下自发地为明天做规划，从而挑战了这是人类独有的能力这一观点。
