Definitions: what is a dog: we know something akin to a dictionary definition, ex. a dog is (a) a mammal, (b) has four legs, (c) barks, (d) wags its tail, etc. Exemplars prototype theory is not the only way you can think about data. Difficulties with categorizing via resemblance typicality plays a huge role in people"s thinking, these also become privileged. The participants successfully rendered to the task and many responded differently: some thought that 4 was considered to be a more typical even number than. 7432: something peculiar about mathematical concepts so we turn to other examples ex. The complexity of similarity: we cannot bases category membership on resemblance alone (ex. Categorizing heuristics: heuristic: a strategy that is reasonably efficient and works most of the time. Also gives up the guarantee of accuracy in order to gain efficiency: example, birds are creatures that fly, however, a bat ca easily be mistaken as a bird.