Gardner & Lambert (1959, 1972): Socio-Educational Model
After conducting a study that lasted more than ten years, they concluded that the learner's attitude toward the target language and the culture of the target-language-speaking community play a crucial role in language learning motivation. They introduced the notions of instrumental and integrative motivation.
In the context of language learning, instrumental motivation refers to the learner's desire to learn a language for utilitarian purposes (such as school/university requirement, employment or travel), whereas integrative motivation refers to the desire to learn a language to integrate successfully into the target language community.