Let us suppose that I assert the proposition ‘This is white’, and my words are taken to refer, not, as they normally would, to some material thing, but to a sense-content. Then what I am saying about this sense-content is that it is an element in the class of sense-contents which constitutes ‘white’ for me; or in other words that it is similar in colour to certain other sense-contents, namely those which I should call, or actually have called, white. And I think I am saying also that it corresponds in some fashion to the sense-contents which go to constitute ‘white’ for other people: so that if I discovered that I had an abnormal colour-sense, I should admit that the sense-content in question was not white. But even if we exclude all reference to other people, it is still possible to think of a situation which would lead me to suppose that my classification of a sense-content was mistaken. I might, for example, have discovered that whenever I sensed a sense-content of a certain quality, I made some distinctive overt bodily movement; and I might on one occasion be presented with a sense-content which I asserted to be of that quality, and then fail to make the bodily reaction which I had come to associate with it.
This is quote from Ayer's "Language, truth and logic", chapter 5.
Can someone give an example of the situation described in the end of the quote, the one about bodily reaction?