“James while John had had had had had had had had had had had a better effect on the teacher”这个英文句子是用来说明用词歧义和标点符号的重要性；标点符号的作用就是代替口语中的语调、重音和停顿。在探讨人类如何处理资讯的研究中，常用这句话来说明读者会借助标点符号来理解句子的意思，尤其在扫读多行文字时更是如此。
故事起自有两个学生，James（詹姆斯）和John（约翰）。他们曾经需要在一个英语考试上描述一个曾经着凉的人。约翰写的句子是“The man had a cold”，这句在文法上不正确；而詹姆斯写的句子在文法上正确：“The man had had a cold”。老师于是注记“由于詹姆斯的答案是正确的，所以它对于老师有一个较好的效果。”
如果加了标点符号，这句句子会比较清楚：
James, while John had had "had", had had "had had"; "had had" had had a better effect on the teacher.
（翻译：詹姆斯在当约翰用“had”时用了“had had”，老师认为“had had”的效果更好。）
如果重排句子，意思会更清楚：
James had had "had had", while John had had "had"; "had had" had had a better effect on the teacher.
（翻译：詹姆斯用了“had had”，而约翰用了“had”，老师认为“had had”的效果更好。）
这句子可以作为一个文法游戏或一条考试题目，考生需要赋予合适的标点符号来明晰句子意思。汉斯·赖申巴赫（Hans Reichenbach）在1947年出版的《符号逻辑要素》一书中用了一个类似的句子（“John where Jack...”），给读者作为练习，以说明语言的不同层次，例如目标语言及元语言，其用意是让读者为句子添加所需的标点符号，使之具有语法意义。
在说明人们如何理解环境中不同信息的意义是，这个句子被用来证明看似随意的决定能极大地改变其意义。类似于句子中标点符号的变化如何使老师时而喜欢詹姆斯的作品，时而喜欢约翰的作品。例子：“James, while John had had "had," had...”与“James, while John had had "had had,"...”。
这句话也是为了显示“had”（完了）的语义模糊性，也是为了说明用字和提字的区别。也有人以它为例，说明语言的复杂性、语言的解释及其对人的认知的影响。
为了让读者清楚地了解句法结构，这个句子至少要求两个短语之间用分号、句号、横线分开。不过，贾斯珀·福尔德的小说《失落的情节之井》还是采用了这一短语的变体，以说明即使是标点良好的写作也可能产生混乱：
""Okay," said the Bellman, whose head was in danger of falling apart like a chocolate orange, "let me get this straight: , unlike , which had had 'had', had had 'had had'. Had 'had had' had TGC’s approval?""
