"James while John had had had had had had had had had had had a better effect on the teacher" is an English sentence used to demonstrate lexical ambiguity and the necessity of punctuation,
which serves as a substitute for the intonation,stress, and pauses found in speech.
In human information processing research, the sentence has been used to show how readers depend on punctuation to give sentences meaning, especially in the context of scanning across lines of text. The sentence is sometimes presented as a puzzle, where the solver must add the punctuation.