In a recent study, researcher Katarzyna Ożańska-Ponikwia examined why some people report feeling different while others do not. She asked some 100 bilinguals made up of people who had grown up speaking two languages, immigrants who acquired their second language later on in life, as well as students who had stayed in a foreign country for an extended period of time, to give answers to two personality questionnaires and to give scale values to statements such as, "I feel I'm someone else while speaking English", or "Friends say that I'm a different person when I speak English".
More: Change of Language, Change of Personality? Part II | Psychology Today
According to the information in the below quotation, can I say what has been written in the underlined parts are not interchangeable?
When emphasized the exact moment. While suggests a long duration.