Humans’ impressive cognitive abilities — map reading, understanding numerical structure, learning grammar rules — rest on the ability to abstract sameness of relations. How does this ability arise and why do animals not read maps or learn grammars like humans do? Here, I review evidence suggesting that object similarity — perceiving that two events look alike — is crucial for learning to perceive relational similarity. While both humans and nonhuman animals perceive object similarity, species differ in their initial preference for objects relative to relations and in their learning trajectories. Human children spontaneously prefer object over relational similarity and this preference benefits their relational reasoning; animals do not favor object similarity. For animals, relational abstraction is easier when the underlying objects are dissimilar, but in humans this relationship is concave.

人类令人印象深刻的认知能力-阅读地图，理解数字结构，学习语法规则-取决于抽象关系的能力。这种能力如何产生？为什么动物不像人类那样阅读地图或学习语法？在这里，我回顾了一些证据，这些证据表明对象相似性（感知到两个事件看起来相似）对于学习至关重要感知关系的相似性。尽管人类和非人类动物都感觉到物体的相似性，但物种在相对于关系的初始偏好和学习轨迹上却有所不同。人类儿童自发地喜欢对象而不是关系相似性，这种偏好有利于他们的关系推理。动物不喜欢对象相似性。对于动物，当基础对象不同时，关系抽象更容易，但是在人类中，这种关系是凹的。