U-Shaped Course of Development

Michael Long perhaps says it best when speaking of the trajectory of a language learner’s progress: “Progress is not linear; backsliding is common, giving rise to so-called U-shaped behavior observed in first and second language acquisition” (659). U-shaped behavior or a “U-shaped course of development” as Ellis refers to it, describes situations in L2 acquisition when a learner’s proficiency suddenly but temporarily drops off only to return once again to their usual level. The attached graphic is based on a table found in Ellis’s Second Language Acquisition (23).

According to Ellis, “It is clear that this occurs because learners reorganize their existing knowledge to accommodate new knowledge” (23). The reorganization of prior knowledge is often referred to as restructuring (Young 9; Shirai 8). Language instructors whose students regress upon learning about and attempting to practice a new linguistic form should understand that their students are actually advancing, even when, early on, they already seemed to have “acquired” the form (Ellis 23). In second language acquisition and teaching, patience is indeed a virtue.


Ellis, Rod. Second Language Acquisition. Oxford, 1997.

Long, Michael H. “The Least a Second Language Acquisition Theory Needs to Explain.” TESOL Quarterly, vol. 24, no. 4, 1990, pp. 649–666. JSTOR, www.jstor.org/stable/3587113.

Shirai, Yaauhiro. “U-shaped Behavior in L2 Acquisition.” Burmeister, H. y Rounds, LP (eds.) (1990).

Young, Richard. “Discontinuous interlanguage development and its implications for oral proficiency rating scales.” Applied Language Learning 6 (1995): 13-26.