This paper discusses some possibilities and limitations of laboratory research methods fortesting theories of second language acquisition. The paper includes a review of 20 experimentallab studies. The review focuses on the motivation for conducting lab studies, the use of artificialor semiartificial language structures, and various design features (including pre- and posttesting,number of subjects, random subject assignment, between- and within-subjects comparisons,treatment materials and procedures). The paper calls for lab studies addressing issues central toSLA theory (“learning” vs. “acquisition”) and ends with somemethodological recommendations, concerning the length of experimental treatments, the use ofgrammaticality judgment tasks, the measurement of reaction times, and the use of retrospectiveinterviews.

This paper illustrates the advantages of laboratory research into SLA by describing twostudies of acquisition of second language syntax. The first addresses the question of whetherhuman morphological abilities can be understood in terms of associative processes or whether itis necessary to postulate rule-based symbol processing systems underlying these skills. Wedemonstrate that acquisition of L2 morphology shows frequency effects for both regular andirregular forms and that the acquisition course of learners' accuracy and reaction time canbe accurately simulated by connectionist systems. The second concerns a bootstrapping accountof SLA whereby processes of chunking in phonological memory underpin the acquisition oflong-term memory for utterances and abstractions of grammatical regularities. It shows thatphonological short-term memory is particularly important in the acquisition of long-distancedependencies. In both cases, it is argued that these aspects of SLA reflect associative learningprocesses. When SLA research is properly focused on acquisition, laboratory research allowsinvestigation of the learners' exposure to evidence, their processes of perception andlearning, and their resultant language representations.

A consistent finding in second language acquisition research has been that in the early stagesof acquisition learners often receive simplified input. This finding has led researchers to questionwhether or not simplified input has a facilitative effect on the acquisition process. This studyexamines the effects of simplified input in early L2 acquisition by experimentally manipulatinglanguage input to two groups of learners and then assessing their acquisition longitudinallywithin a controlled laboratory setting. The impetus for the study described here wasGivón's (1990) competition hypothesis that posits that, in early L2 acquisition,vocabulary and grammar compete for memory, attention, and processing capacity. Because onecan communicate with vocabulary in absence of grammar but not vice versa, it was proposed thatlearners receiving pidgin input would acquire vocabulary more efficiently than learnerschallenged with the dual task of acquiring vocabulary and grammar simultaneously. Furthermore,it was hypothesized that once vocabulary processing skills were automated, learners wouldacquire grammar more rapidly. Results of a variety of measures reveal that the dual task ofacquiring vocabulary and grammar does not hinder either and that the longer the exposure togrammatical input the greater the advantage in real-time grammar processing abilities.Converging evidence from all measures of language learning provides strong support for theusefulness and viability of laboratory study of SLA.

This study is a fine-grained analysis of extensive empirical data on the automatization ofexplicitly learned rules of morphosyntax in a second language. Sixty-one subjects were taughtfour morphosyntactic rules and 32 vocabulary items in an artificial language. After they hadreached criterion on a set of metalinguistic tests of grammar and vocabulary, they engaged insystematic, computer-controlled comprehension and production practice for 8 weeks.Comprehension practice consisted of choosing between pictures displayed on the computerscreen to match a sentence; production practice consisted of typing the correct sentencecorresponding to a picture. All subjects were taught the same rules and then practiced them, andall subjects had the same amount of comprehension and production practice, but which ruleswere practiced in comprehension and which in production varied between groups. Results showthat the learning of morphosyntactic rules is highly skill-specific and that these skills developvery gradually over time, following the same power function learning curve as the acquisition ofother cognitive skills. These results are consistent with current skill acquisition theory.

This experimental study examines the extent to which 60 adult Japanese ESL learners wereable to acquire a rule regulating the argument structure frames of novel verbs of English afterexposure to grammatical examples of sentences containing the verbs. Training took place underconditions with no focus on form (implicit and incidental conditions) and with focus on form(enhanced and instructed conditions). The presentation of instances during training wasmanipulated as a test of predictions made by Logan's (1988, 1990, 1992) memory-basedinstance theory of automaticity. Results measured in reaction times show similarslopes for automaticity on trained examples in each condition but significant differences in theextent of learning, with the focus on form conditions outperforming the no focus on formconditions in transfer of learned knowledge to accurate judgments of new ungrammaticalsentences. Implications are drawn from the results regarding the acquisition of rule-based versusmemory-based knowledge from exposure to stimuli in each training condition and the influenceof this knowledge on decision-making about grammaticality during the transfer task.

Theories on the role of consciousness and the enhancement of noticing (Schmidt, 1990,1994; Sharwood Smith, 1993) predict a facilitative effect of explicit knowledge, as built up byexplicit instruction, on the acquisition of implicit second language (L2) knowledge. This studyinvestigates the interaction between the presence or absence of explicit instruction and thevariables complexity and morphology/syntax in the acquisition of four L2 structures. Twogroups of 27 university students, differing in the exposure to explicit instruction, followed acomputer-controlled self-study course in an artificial language. Results from computer-controlledposttests confirm the general hypothesis that explicit instruction facilitates the acquisition of L2grammar. However, no evidence could be reported for the hypotheses predicting a differentialeffect of explicit instruction depending on the variables complexity andmorphology/syntax.

The relation between experimental psychology and second language acquisition research hasgone through at least two major swings of the pendulum. During the heyday of behaviorism, thependulum swung strongly toward psychology. The behaviorist psychologists advised us to thinkof language learning as nothing more than habit formation (Mowrer, 1960), and second languagelearning materials reflected an emphasis on repetition, drill, rewards, practice, and conditioning.During the early years of the cognitive revolution, Chomsky (1959) argued that viewing languageas a conditioned response (Skinner, 1957) ignores the complexities of both language structureand cognition. Persuaded by these arguments, second language researchers turned away frombehaviorist psychology and sought the explanation for language acquisition in universals oflanguage structure (Dulay & Burt, 1974).