Second language acquisition

Definition
Second language acquisition refers to the process of language acquisition by a speaker who already has a knowledge of another language. The study of second language acquisition aims to describe and explain that process (cf. Frawley, William J. 2003. International Encylopedia of Linguistics. 2nd edition. Vol. 1. Oxford: Oxford Univ. Press, p. 24).

The contrastive (analysis) hypothesis (CAH)
In the 1950s, the study of second language acquisition (SLA) was largely based on the contrastive hypothesis (or 'contrastive analysis hypothesis', CAH). According to this hypothesis, interference was a main source of errors in the process of second language acquisition. On the basis of a behaviourist view of language acquisition (stimulus-and-response model), the contrastive hypothesis regarded instances of interference between L1 and L2 as a result of (linguistic) habits that were transferred from the mother tongue to the language to be learnt. Accordingly, the contrastive analysis implied that most of the errors made by learners could be predicted by carefully comparing the two languages under comparison (similar language patterns => positive transfer; different language patterns => negative transfer) (Ellis, Rod. 1986. Understanding Second Language Acquisition. 2nd, Improved Edition. Oxford: Oxford Univ. Press, p. 22.) Practitioners of contrastive linguistics at that time mainly aimed at improving foreign language teaching on the basis of a pairwise language comparison.

Creative Construction Hypothesis (CCH)
The CCH emerged in the 1970s. It was based on a critical appraisal of the role of interference in second language acquisition. According to the CCH, the native language of a learner does not have much influence on the acquisition of another language. Moreover, the CCH held that there is not much difference between first and second language acquisition. According to Heidi C. Dulay and Marina K. Burt, both processes are guided by creative construction, i.e. every learner constantly creates hypotheses about the patterns of the language which s/he is learning. These hypotheses are based on input from the target language. A study conducted by Dulay and Burt showed that only three per cent of learner errors could be explained in terms of interference. However, the study itself was discussed controversially after its publication (cf. Ellis, Rod. 1986. Understanding Second Language Acquisition. 2nd, Improved Edition. Oxford: Oxford Univ. Press, p. 29).

Interlanguage Hypothesis (ILH)
The ILH was most notably formulated by Larry Selinker in 1972 and included interference as a possible source of error. It explained that learners access a particular linguistic system when they try to acquire another language. This systematic set of rules is called interlanguage and differs from both the native and the target language. It approximates the target language during the learning process, however. Interlanguage is thus regarded as a dynamic and constantly changing learner language (cf. Ellis, Rod. 1997. The Study of Second Language Acquisition. 5th, improved edition. Oxford: Oxford Univ. Press, pp. 114f., p. 350, p. 416, p. 710).