Contrastive Analysis (CA) is an approach to the study of SLA which involves predicting and explaining learner problems based on a comparison of L1 and L2 to determine similarities and differences. It was heavily influenced by theories which were dominant in linguistics and psychology within the USA through the 1940s and 1950s, Structuralism and Behaviorism. The goal of CA (as that of still earlier theories of L2 learning) was primarily pedagogical in nature: to increase efficiency in L2 teaching and testing. Robert Lado states this clearly in his introduction to Linguistics Across Cultures (1957), a book which became a classic guide to this approach:
The plan of the book rests on the assumption that we can predict and describe the patterns that will cause difficulty in learning, and those that will not cause difficulty, by comparing systematically the language and culture to be learned with the native language and culture of the student. In our view, the preparation of up-to-date pedagogical and experimental materials must be based on this kind of comparison. (vii)
Following notions in structuralist linguistics, the focus of CA is on the surface forms of both L1 and L2 systems, and on describing and comparing the languages one level at a time – generally contrasting the phonology ofL1 and L2 first, then morphology, then syntax, with the lexicon receiving relatively little attention, and discourse still less. A “bottom-up” priority for analysis (generally from smaller to larger units) is also expressed as a priority for language learning, of structures before meaning. Charles Fries, who was a leading figure in applying structural linguistics to L2 teaching, makes this priority very clear: “In learning a new language, . . . the chief problem is not at first that of learning vocabulary items. It is, first, the mastery of the sound system. . . . It is, second, the mastery of the features of arrangement that constitute the structure of the language” (Fries 1945:3).
Following notions in behaviorist psychology, early proponents of CA assumed that language acquisition essentially involves habit formation in a process of Stimulus – Response – Reinforcement (S-R-R). Learners respond to the stimulus (linguistic input), and reinforcement strengthens (i.e. habituates) the response; they imitate and repeat the language that they hear, and when they are reinforced for that response, learning occurs. The implication is that “practice makes perfect.” Another assumption of this theory is that there will be transfer in learning: in the case of SLA, this means the transfer of elements acquired (or habituated) in L1 to the target L2. The transfer is called positive (or facilitating) when the same structure is appropriate in both languages, as in the transfer of a Spanish plural morpheme -s on nouns to English (e.g. lenguajes to languages). The transfer is called negative (or interference) when the L1 structure is used inappropriately in the L2, as in the additional transfer of Spanish plural -s to a modifier in number agreement with the noun: e.g. lenguajes modernas to Moderns Languages (a translation which was printed at the top of a letter that I received from South America), or greens beans (for ‘green beans,’ which I saw posted as a vegetable option in a US cafeteria near the Mexican border).
The process of CA involves describing L1 and L2 at each level, analyzing roughly comparable segments of the languages for elements which are likely to cause problems for learners. This information provides a rationale for constructing language lessons that focus on structures which are predicted to most need attention and practice, and for sequencing the L2 structures in order of difficulty.
To summarize Lado’s (1957) position: the easiest L2 structures (and presumably first acquired) are those which exist in L1 with the same form, meaning, and distribution and are thus available for positive transfer; any...