Many studies suggest that the motivation - as well as the other constitutive factors of language acquisition and teaching - can be interpreted within the epistemological framework of complexity theory (TC) (Hiver and Papi 2019; Dörnyei et all.2015; Ortega and Han 2017; Larsen-Freeman 1997, 2006; Martari 2021). In the first part of this paper, we describe the motivation in second language acquisition as a dynamic model. Secondly, we briefly observe some key elements of CT in relation to applied linguistics and educational linguistics. In the third part, we analyze a case study evaluating the learning experience of Italian as a second language described by seven adult learners during structured interviews. Unlike other research on this topic, the aim of this study is to reflect on the complex dimension of motivational processes in relation to the following elements of CT: a) the ecosystemic and dynamic vision of motivation to learn; b) the complex relation of self-similarity and the feedback loops; c) the emergence of the motivation to learn from the interaction between different levels of linguistic and social perception of self. Through the analysis of the interviews we observe how language learning is constantly set in an ecological framework in which learning and acquisition are in relation with the communicative (cultural, social and affective) ecosystem of the human subject
