Gardner, Lalonde, & Moorcroft (1987) investigated the nature of L2-French skills attriting by L1-English grade 12 students during the summer vacation, and the role played by attitudes and motivation in promoting language achievement and language maintenance. Students who finished the L2 class highly proficient are more likely to retain what they knew. Yet, interestingly, high achievers in the classroom situation are no more likely to make efforts to use the L2 outside the classroom unless they have positive attitudes and high levels of motivation. The authors write: "an underlying determinant of both acquisition and use is motivation”(p. 44). 

In fact, the nature of language acquisition is still so complex and so much is still unknown, not all students will have the same experiences during the incubation period. It is possible that some students will appear to attrite in some areas and others will appear to attrite in other areas. Some students will appear to maintain the level that they had previously achieved. And still, other students will appear to improve.

Murtagh (2003) investigated retention and attrition of L2-Irish in Ireland with second level school students . At Time 1, she found that most participants were motivated instrumentally, yet the immersion students were most likely to be motivated integratively and they had the most positive attitudes towards learning Irish. Immersion school students were also more likely to have opportunities to use Irish outside the classroom/school environment. Self-reports correlated with ability. She concludes that the educational setting (immersion schools, for example) and the use of the language outside the classroom were the best predictors for L2-Irish acquisition. Eighteen months later, Murtagh finds that the majority of groups 1 and 2 believe their Irish ability has attrited, the immersion group less so. The results from the tests, however, do not show any overall attrition . "'Time' as a factor did not exert any overall significant change on the sample's proficiency in Irish" (Murtagh, p. 159).

Fujita (2002), in a study evaluating attrition among bilingual Japanese children, says that a number of factors are seen as necessary to maintain the two languages in the returnee child. Those factors include: age on arrival in the L2 environment, length of residence in the L2 environment, and proficiency levels of the L1. Furthermore, she found that L2 attrition was closely related to another factor: age of the child on returning to the L1 environment. Children returning around or before 9 were more likely to attrite than those returning later.
Upon returning from overseas, pressure from society, their family, their peers and themselves force returnee children to switch channels back to the L1 and they quickly make effort to attain the level of native-like L1 proficiency of their peers. At the same time, lack of L2 support in the schools in particular and in society in general results in an overall L2 loss .

प्रतिगमन गृहीत-कल्पना The regression hypothesis (last thing learned, first thing lost)
व्याकरणिय L1 झीज
L2 attrition
Other studies on bilingualism and attrition