有一些概念是比較抽象的，例如：「基金經理人」、「斷奶」、「CLIL」等等，在這些概念下的事物，應該存在某些基本特質使它們可以被歸類為同一個概念。既然如此，那關於這些抽象概念中，使事物間彼此有關的特質是什麼？我們對這些事物的知識又是從何而來的？
經驗主義(empiricist)認為，基於我們認為的相似之處(可能是感官上或因為語言經驗)，它會逐漸形成一個抽象的表徵。經由對於環境的特質進行類似統計的分析，我們會形成一些表徵，形狀和顏色都是這麼來的。當我們對於「基金經理人」這個概念的特質更敏感時，我們就會形成這樣的概念。
但是，也有一些人認為「基金經理人」並不是來自於我們的感官；它可能是根植於一些我們本來就有的隱性知識，例如「社會」、「金錢」或「工作」等等。這個叫「理論的理論」(theory theory)。在比較溫和的版本，理論的角色在於引導我們在給定的情境下對於可能有關特質進行選擇，例如適合食物的顏色或著適合手工藝品的形狀。比較強的版本認為理論會產生新的特質(Wisniewski & Medin, 1994) 。最強硬的版本甚至完全拒絕基本的特徵。Murphy and Medin (1985) 給了一個例子，想像在派對上，一個盛裝打扮的人跳到游泳池中，我們會認為這個人「醉了」。「醉了」這個概念並沒有和其它「醉了」有共享的特徵，我們是因為這個人的行為而形成這個概念的。
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