“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.
The example refers to two students, James and John, who are required by an English test to describe a man who, in the past, had suffered from a cold. John writes “The man had a cold” which the teacher marks as being incorrect, while James writes the correct “The man had had a cold.” Since James’ answer was right, it had had a better effect on the teacher.
The sentence can be understood more clearly by adding punctuation and emphasis:
James, while John had had “had“, had had “had had”; “had had” had had a better effect on the teacher.
In each of the five “had had” word pairs in the above sentence, the first of the pair is in the past perfect form. The italicized instances denote emphasis of intonation, focusing on the differences in the students’ answers, then finally identifying the correct one.