Those are examples of thought disorders. Loose associations are series of ideas that are introduced together but do not have a logical connection. Neologisms are newly created words, which are frequently spoken by children, but that when used by adults may indicate a mental disorder, since they do not make sense. Perseveration can also indicate a mental disorder or brain damage, since the person keeps saying the same word or making the same gesture even though the stimulus (a question asked by an interlocutor, for instance) to do so has ended. Finally, clanging, or clang associations, is a manner of talking in which a series of words are chosen by the speaker not to form a logical meaning, but because of the sound they make when put together.
