This paper presents a study on private speech in a task conducted by a group of undergraduate physics students and mediated by a virtual Mach-Zehnder interferometer. The aim of this study is to verify the occurrence of private speech among adults and to analyze how this means of mediation is used in a solving-problem situation involving quantum physics concepts. The results of an analysis of discourse based on socio-cultural perspectives showed that private speech came from interaction between students and cultural tools provided by the socio-cultural setting (guide and software). This mean of mediation is used in the ordering of own actions, as well as in the planning of new actions in solving-problems situations.
Private Speech; Science Education; Socio-cultural Perspective