Cognitive psychologists believe that our language construction is a result of a two-step word retrieval process. The first step is the search for a word’s meaning, and the second step is the search for the actual sound of a word. Different speech errors occur when you get stuck at different stages of this two-step retrieval process. When you incorrectly substitute one word for another, calling a cat a “dog” for instance, your brain has erred in the first step by choosing an incorrect word for the concept of “small domesticated furry pet.” When you have a word or a name on the tip of your tongue, you’ve gotten stuck in the middle of the retrieval process. You’ve correctly retrieved the meaning of the word, but have been unable to retrieve the sound of the word. Because you’ve successfully completed one of these two steps, you can probably give the word’s definition, but can’t actually say the word.