What Makes Learning Second Language Grammar Difficult a Review of Issues DeKeyser 2005

What Makes Learning Second-LanguageGrammar Difficult? A Review of Issues

Robert M. DeKeyserUniversity of Pittsburgh

If the ability to use language in the restricted sense (i.e., acommunication system characterized by double articulation) isquintessentially human, then explaining this ability is a crucialtask for cognitive science, and explaining its acquisition is acrucial task for developmental psychology. If the difficulty ofacquiring a second language (L2), at least at a later age, standsin sharp contrast to the childs celebrated accomplishments, thenexplaining this contrast is equally important for developing acomplete understanding of humans abilities to use and acquirelanguage. In fact, it can be argued that it is the enormouscontrast between the two phenomena that needs explaining,rather than either of the two phenomena per se. One way totackle this problem is the social science approach of correlatingage and many other demographic variables with success inacquisition: to disentangle design features of the species fromaccidental characteristics of the environment. Another approachconsists of investigating what elements or characteristics of anL2 are hard to acquire: to understand better how weaknesses inthe acquisition process interact with the design features of humanlanguages. And of course, one can look at the two variables ininteraction with each other: Which problematic elements of the

Correspondence concerning this article should be addressed to RobertDeKeyser, Department of Linguistics, University of Pittsburgh, PittsburghPA 15260, USA. Internet: [email protected]

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language are an issue in L2 learning at any age, and whichare mostly a problem for later acquirers only? Or even better,how do five different variables interact in L2 acquisition: thecharacteristics of the L2, the influence of the first language (L1),the role of age, the role of individual differences in cognitive andaffective aptitudes, and the role of learning context, be it thenative-speaking environment or the classroom, the latterrepresenting, of course, a wide variety of learning contextswith different degrees of emphasis on form and meaning?

The focus of this introductory review article is on the char-acteristics of the L2 itself (and its differences from L1) that makeits acquisition difficult. Given the very broad nature of the topic,I will touch on the issues of age, other individual differences, andlearning context only to the extent that they cannot be ignoredbecause nothing can be generalized without taking them intoaccount. I also restrict discussion to morphosyntax rather thanphonology or the lexicon and to the acquisition of competencerather than processing, recognizing here too that all suchseparations are to some extent superficial because the meaningof morphemes and the distribution of their allomorphs cannot beacquired without the phonological capacity to extricate them fromthe flood of sounds in every sentence, and because competence isonly a (some would say fictional) abstraction of what humans dowhen they understand or produce language, and acquiring thiscompetence necessarily happens through processing input(cf., esp., Pienemann, 2003; Truscott & Sharwood Smith, 2004).Finally, I emphasize publications from the past 5 years in keepingwith the criteria for selecting articles for the Best of LanguageLearning series.

Broad Definitions of Difficulty

Even a cursory glance at some well-known discussions of whatis difficult in L2 acquisition shows how tricky this concept is.Krashen (1982) and R. Ellis (1990), for instance, at first sightappear to agree that one needs to make a distinction between

2 What Makes Learning L2 Grammar Difficult?

formal and functional complexity. But the same structure, thirdperson s in English as a Second Language (ESL), was classifiedby Krashen (1982) as easy to learn because it is simple, and byEllis (1990) as hard to learn because it is complex. One mightthink that the reason for this discrepancy is that Krashen wasdealing with learning in the narrow sense here (as opposed toimplicit acquisition) and Ellis with a broader meaning of learning,but when one looks at their reasons for classifying this structureas easy or difficult, it is clear that they used different criteria fordeciding on the complexity of s: Krashen pointed to the simpledichotomous choice between supplying this simple morpheme ornot, whereas Ellis, referring to Pienemann (1984), pointed to thelong-distance relationship between the grammatical number ofthe subject and the presence or absence of s on the verb. Nor is thedisagreement due to amere focus on formal complexity by Krashenversus a broader look at the form-function relationship by Ellis:The latter actually goes beyond Krashen by considering even theform-function relationship for s to be simple (transparent); it isonly because of the processing operations required that Ellisconsidered the structure to be complex (1990, p. 167).

It appears, then, that at least three factors are involvedin determining grammatical difficulty: complexity of form,complexity of meaning, and complexity of the form-meaningrelationship. Even this picture, however, is not complete; itactually leaves out the core psycholinguistic difficulty ofacquisition, that is, the difficulty of grasping the form-meaningrelationship while processing a sentence in the L2. Rather thanforms, meanings, or form-meaning relationships, it is the trans-parency of form-meaning relationships to a learner who isprocessing language for meaning that determines the difficultyof acquisition, at least for learners who are left to their ownresources instead of presented with a reasonably complete setof rules about form-meaning relationships.

Part of what determines this transparency is the degree ofimportance of a linguistic form for the meaning it expresses:Certain morphemes are the one and only clue to the meaning

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they express; others are largely or completely redundant, becausethey mark grammatical agreement with meanings whose primaryrepresentations are elsewhere in the sentence or the discourse.VanPatten (e.g., 1990) has therefore emphasized the distinctionbetween meaningful and redundant for predicting what will beeasy or hard to acquire, especially in early stages of L2 development.

Some researchersmost notably Stockwell, Bowen, andMartin (1965)have drawn up elaborate hierarchies of difficultyof acquisition based on form-meaning mapping. But the work ofStockwell, Bowen, and Martin (1965) focused primarily onSpanish, put more emphasis on L1L2 surface differences thanis warranted by more recent research on the role of L1, and waslargely nonempirical. They also left out completely the notion ofsalience in the input, presumably because they were thinking ofinstructed learning contexts, in which salience is less of an issuethan in naturalistic L2 acquisition, a phenomenon that was notyet a topic of research at that time.

Other researchers, recognizing the difficulty of definingdifficulty, have avoided a theoretical conceptualization altogether.When structures needed to be classified according to difficulty,they chose to ask teachers to rate L2 structures for the level ofdifficulty they seemed to present intuitively (e.g., Robinson, 1996).While such an approach may be a useful operationalization,depending on the nature of the study, it still leaves us with thequestion of what constitutes difficulty.

In what follows, I present various components of grammaticaldifficulty, with at least a modest amount of empirical evidence fortheir importance in acquisition or lack thereof and for how they fitinto the broader picture of interaction with each other and withindividual and contextual factors (the latter including L1 as wellas instruction). One way of isolating components of difficulty is tolook separately at problems of meaning, problems of form, andproblems of form-meaning mapping.


Problems of Meaning

Regardless of the form used to express a meaning, the meaningitself can constitute a source of difficulty, because of novelty,abstractness, or a combination of both. Articles, classifiers,grammatical gender, and verbal aspect are notoriously hard toacquire for native speakers of L1s that do not have them or thatuse a very different system (for articles in ESL, see, e.g., Jarvis,2002; Liu & Gleason, 2002; Robertson, 2000; Tarone & Parrish,1988; Thomas, 1989; Young, 1996; cf. also Celce-Murcia & Larsen-Freeman, 1999, chap. 15; for classifiers in Japanese and Chinese,see, e.g., Hansen & Chen, 2001; for grammatical gender in avariety of languages, see, e.g., Carroll, this volume; Kempe &Brooks, this volume; Taraban, 2004; Williams & Lovatt, thisvolume; for aspect in Romance or Germanic languages, see, e.g.,Andersen & Shirai, 1994, 1996; Bardovi-Harlig, 1998, 1999, 2000;Collins, 2002; Dietrich, Klein, & Noyau, 1995; Lee, 2001; Montrul& Slabakova, 2003; Salaberry, 2000).

These elements of grammar are even strongly resistant toinstructional treatments (for aspect see, e.g., Ayoun, 2004; Ishida,2004; for gender see, e.g., Leeman, 2003; for articles see, e.g.,Butler, 2002; Master, 1997). What they all have in common isthat they express highly abstract notions that are extremely hardto infer, implicitly or explicitly, from the input. Where thesemantic system of the L1 is different from that of the L2, as isvery often the case for aspect, or where equivalent notions do notget expressed overtly in L1, except through discourse patterns, asmay be the case for ESL articles for native speakers of most Slaviclanguages or Chinese, Japanese, or Korean, the learning problemis serious and long-lasting.

Problems of Form

Difficulty of language form is largely an issue of complexity.Assuming the learner knows exactly the meanings that need to beexpressed, difficulty of form could be described as the number of

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choices involved in picking all the right morphemes andallomorphs to express these meanings and putting them in theright place. Clearly, this problem is most complex in richlyinflected languages, whether they be agglutinative, polysynthetic,or inflectional in the narrow sense. Everything else (such assemantic difficulty) being the same, the more that needs to beexpressed overtly, the more choices need to be made aboutmorphemes, allomorphs, and their position. Morphology in L2 ishard: Basic word order is typically nonproblematic past the initialstages of acquisition, but even the most basic morphology is oftenlacking from the speech of untutored immigrants (see, e.g., Klein& Dittmar, 1979) and of classroom learners who are not able tomonitor themselves effectively (see, e.g., Krashen & Pon, 1975;Tarone, 1985). Morphology is even shakily represented inlearners intuitions, even after many years of exposure to the L2(e.g., DeKeyser, 2000; Johnson & Newport, 1989).

Much ink has been spent discussing whether continuingfailure to supply these morphemes systematically is truly aproblem of competence or one of mere performance. Given thepoor scores of adult immigrants on grammaticality judgment testson this point (in ESL, e.g., third person s, articles, or plurals inDeKeyser, 2000; Johnson & Newport, 1989; Yeni-Komshian,Robbins, & Flege, 2001) and the failure of intermediate English-speaking foreign language students even to take into account themeaning of elementary morphology in order to come to the correctunderstanding of a sentence (see, esp., VanPatten, 2004; cf. alsoMacWhinney, 2001, in press), it seems safe to conclude that morethan processing is at stake. Jiang (2004), in particular, showedconvincingly that errors of verb agreement with complex nounphrases in ESL were due to lack of sensitivity to plural markingon the noun, not to problems with processing agreement.

This problem of L2 users failing to use morphology, even incomprehension, is so fundamental that it has by itself spawnedentire bodies of literature. The research on processing instructionhas showed that students benefit from intensive training in payingattention to elements of morphology for comprehension, because


without such practice they tend to gloss over the morphology(especially students of a morphology-poor language like Englishacquiring a relatively morphology-rich language like Spanish).The interpretation of various aspects of the processing-instructionliterature has been controversial (see, e.g., DeKeyser, Salaberry,Robinson, & Harrington, 2002; VanPatten & Wong, 2002). Butnobody doubts that L2 students need to have their attentiondrawn to morphology while processing input, because otherwisethey tend to ignore the morphological cues to sentence meaning.

The research within the framework of the competition model,on the other hand, has shown repeatedly, with speakers of avariety of L1s and L2s, that morphology is a weak cue in initialstages of language learning, at least for English L1 speakers, andthat if it becomes stronger over time, this only happens in a veryslow and gradual fashion (cf., esp., MacWhinney, 2001, in press;see, e.g., Hertel, 2003; Kempe & MacWhinney, 1998; McDonald,1987).

More formal approaches to morphosyntax, however differentthey may be in other respects, coincide in singling out morphologyas hard to acquire in comparison with syntax. Lardiere (1998),Prevost and White (2000), and Sprouse (1998) provide evidencethat morphological and syntactic features that are closely linkedin syntactic theory (verb raising and inflection) are not acquiredtogether. One way out of this problem, from the point of view of atheory in which such a link is seen as crucial, is the view thatlearners acquire the syntactic features easily but continue to haveproblems with their morphological instantiation (cf. Sorace, 2003,and Lardieres summary of several of her own articles in Long,2003).

Problems of Form-Meaning Mapping

Even assuming that neither form nor meaning is particularlyproblematic according to the criteria mentioned in the previoustwo sections, acquiring the form-meaning mapping can still bedifficult if the link between form and meaning is not transparent.

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Such lack of transparency can be due to at least three factors:redundancy, optionality, or opacity.

Redundancy means that the form at issue is not semanti-cally necessary because its meaning is also expressed by at leastone other element of the sentence; for example, a verb endingcan be redundant because the subject is explicit, whether it be afull noun phrase or a pronoun, which makes person and numberinformation redundant, and because adverbs or other lexicalitems make information such as tense or aspect redundant(cf., e.g., VanPatten, 1990). When the redundant element is alsoabstract and novel, then the learning problem is particularlysevere: Robinson (2002), for instance, showed that learners ofSamoan L2 had more trouble with the ergative marker thanwith the locative or noun incorporation, because the ergativemarker (both novel for learners of L1 English and abstract) wassemantically redundant, which the other two structures were not.

Optionality of certain elements, such as null subjects inSpanish or Italian (see, e.g., Herschensohn, 2000; Liceras, 1989)or case marking in Korean, only makes matters worse. Not onlydoes the optional character of the case marking or the overtsubject pronoun suggest it is redundant, but its alternatingpresence or absence in the presence of the same meaning,except for subtle aspects of pragmatics, makes the form-meaning link even harder to establish. (This optionality in theL2 as a cause of acquisition problems is not to be confused withoptionality in the sense of interlanguage variability, which is aconsequence of a variety of problems with the acquisition offeatures that are not variable in the L2; cf. Papp, 2000; Prevost& White, 2000; Robertson, 2000; Sorace, 2000, 2003.)

Opacity is a complex form of the problem of low form-meaningcorrelation. When a morpheme has different allomorphs, and atthe same time it is homophonous with other grammaticalmorphemes, then the correlation between form and meaningbecomes very hard to detect: Different forms stand for the samemeaning, and the same form stands for different meanings. This,of course, is exactly the case for s in English, which can be the


third-person singular of the verb, the plural of the noun, or thegenitive of the noun and in each case has the same threeallomorphs. Where third-person singular is concerned, thisproblem of low correlation between form and meaning is furthercompounded by the so-called morphemes really being a morph (achunk of sound isolated in morphological analysis, but without aone-to-one mapping with any meaning), in this case conflatingthree different meanings (singular, third person, present tense),all of which are expressed by separate morphemes in manylanguages, and all of which have to be present at the same timefor s to appear, and all of which are rather abstract and thereforedifficult by themselves. More generally, instances of morphologicalirregularity, such as irregular plurals and irregular past tenses, allfall into this category: The problem is not so much a problem ofform (an irregular is not necessarily more formally complex); it isthe form-meaning mapping that becomes more opaque and/orcomplex.

Other examples of opaque form-meaning mappings can befound in syntax, such as the relationship between the order ofsubject and verb in Spanish, on the one hand, and the lexicalsemantics of the verb and the discourse functions of subject-verbinversion, on the other hand. Hertel (2003) showed how learnersof L2 Spanish do not use much verb-subject (VS) order till theyare quite advanced in their L2 proficiency and that eventhe advanced learners do not make any distinction betweenunergatives and unaccusatives when it comes to VS order, eventhough native speakers clearly do. The optional nature of the VSorder makes it even harder to acquire its correlation with theabstract semantic elements that favor its appearance. DeKeyser(2005) also documents a virtual total absence of VS order forany kind of verb in declarative sentences among intermediateSpanish learners during a 6-week stay in Argentina. Jungs(2004) finding that English speakers did not acquire topicprominence in Korean L2 till the advanced level, in spite of thehypothetical universal nature of topic prominence in early inter-language, can be seen as another example of how difficult it is to

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map a variable phenomenon to abstract discourse-dependentsemantics. To the learner, many cases of opacity probably appearto be instances of optionality.

The acquisition problem is compounded even further whenoptionality and discourse-motivated preferences for one of theoptions interact with arbitrary or semantically obscure subcat-egorization restrictions, such as, in Japanese L2, the restriction ofgoal PPs to directed-motion verbs (Inagaki, 2001) or the restrictionof quantifier floating to unaccusatives (Sorace & Shomura, 2001),and in English L2, the restriction of agentive use to manner-of-motion verbs as opposed to change-of-state verbs (Montrul, 2001),the restrictions on dative alternation (see esp. Inagaki, 1997;Whong-Barr & Schwartz, 2002), and those on locative alternation(see esp. Bley-Vroman & Joo, 2001; Joo, 2003; Juffs, 1996). Thepossibility of alternation seems to be motivated by semanticcriteria, but according to Pinker (1989), at least 14 semanticallydefined verb classes need to be distinguished for locativealternation and 10 for dative alternation. When, on top of that,relevant input is very limited in ESL materials (Juffs, 1998) andprobably even in more natural input, it is clear that acquisition isa challenge, to say the least. Even simpler subcategorizationrestrictions, such as which English verbs take an infinitive andwhich a gerund, appear to be problematic, even after decades ofexposure to the language (DeKeyser, 2000; Flege, Yeni-Komshian,& Liu, 1999; Johnson & Newport, 1989; McDonald, 2000).

Finally, an important factor that helps determine ease ordifficulty of learning form-meaning mappings is, of course,frequency. N. Ellis (2002, 2003) provided evidence from a varietyof sources on the role of frequency in L2 learning. He argued thatthe typical route of acquisition of grammar structures is fromformulae through low-scope patterns to constructions and thatthe abstraction of regularities within these constructions isfrequency-based. In principle, the importance of frequency isindependent of semantic transparency, but how importantfrequency is depends to some extent on the transparency of themapping. If the mapping is very clear, minimal exposure may be


enough for acquisition; if it is very obscure, the structure may wellnever be acquired by adults. If the transparency of the mapping isin between these two extremes, frequency may largely determinewhether the mapping is acquired or not, in further interaction, ofcourse, with the learners aptitude and (methods of) instruction.Hansen and Chen (2001), for instance, provided a clear example ofa set of morphemes in which frequency played a very importantrole: classifiers in Chinese and Japanese L2. As the structure isfairly salient and its function is clear, but the choice of the rightform is based on semantic criteria that are hard to define, the levelof difficulty is such that the role of frequency is maximized.

Where to Look for Direct Evidence on What Is Difficult?

I have presented a number of factors that make theacquisition of L2 grammar difficult, attempting to organizeevidence from a wide variety of studies which addressed allkinds of narrowly focused questions about the acquisition ofgrammar, but in the process I have also documented aspectsof the difficulty of specific language structures. Relatively fewstudies have actually attempted a systematic empirical investi-gation of difficulty by comparing acquisition for a broad range oflanguage structures. The vast majority of studies either have anarrow linguistic focus or a very wide linguistic scope with littleor no interest in comparing acquisition of different structuressystematically. In principle, there are several research areas inwhich one could look for systematic evidencedocumentation offossilization, ultimate attainment studies with adult learners, andresearch on order of acquisitionbut not all of these areas haveyielded much that can help answer the question of what makes anL2 structure difficult.

Fossilization is a concept that has been around for decades,but the concept has remained rather vague. If one uses a narrowdefinition, such as that of Long (2003), requiring that learnershave been fully exposed to the L2 for at least 10 years and thatlack of change for a specific structure has been systematically

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documented for at least 5 years, then it turns out that onlya handful of studies have met this criterion. Long (2003) citedHan (2000), Lardiere (1998, 2000), and Long (1997), which havedocumented fossilization of, respectively, nontarget unaccusa-tive verbs, missing verb morphology, and lexically determinedinflection on nouns and verbs.

Ultimate attainment studies of adult learnerswith the goalof establishing age effectshave become popular in the last decadeor so, but again not many have engaged in a systematic comparisonof how well different aspects of grammar have been acquired. Theonly studies in the morphosyntax category that have exploreddifferential age effects for different language elements areBirdsong (1992), DeKeyser (2000), DeKeyser, Ravid, and Alfi-Shabtay (2005), Flege et al. (1999), Johnson and Newport (1989,1991), and McDonald (2000).

Both Birdsong (1992) and Johnson and Newport (1989, 1991)made a distinction between structures within and outside of therealm of universal grammar. Birdsong made a direct comparisonwithin his study and found that both categories of structures wereequally sensitive to age effects. Johnson and Newport carried outtwo studies, one with structures outside of Universal Grammar(UG; 1989), the other with structures exemplifying the subjacencyprinciple, assumed to be an element of UG (1991). They foundessentially the same strong age effect in both studies. It should bepointed out, however, that the UG/non-UG classification inBirdsong (1992) was tentative, as the author indicated himself,and that the classification of subjacency among the principles ofUG is not uncontroversial either (Huang, 1982; Pesetsky, 1987;Rizzi, 1982).

Flege et al. (1999) made a different kind of distinction. Theyadministered an ESL grammaticality judgment test, mostlydrawn from Johnson and Newport (1989), to speakers of KoreanL1 and found overall age-proficiency correlations of !.71 for ageon arrival (AoA)< 15 and !.23 for AoA>15. The researchersshowed, through analysis of a series of subsamples matched forAoA, that education was a significant predictor for performance


on rule-based items and use of English was a significant predictorfor performance on lexically based items.

Johnson and Newport (1989), DeKeyser (2000), and McDonald(2000), all using variants of the same grammaticality judgment testfor English L2, found a tendency for a few elements of morphosyn-tax to be resistant to age effects, especially basic word order andyes/no questions. Moreover, both Flege et al. (1999) and McDonald(2000) found that auxiliaries, subcategorization and wh-questionswere more sensitive to length of residence or other measures ofusage than AoA. On the basis of such patterns and further posthoc analyses of his own data (for instance, successful acquisition ofsubject-verb inversion in yes-no questions, but not in wh-questions),DeKeyser (2000) hypothesized a strong role of salience, in the sensethat this variable becomes increasingly important with age.

One more study to mention here is Yeni-Komshian et al.(2001). Among the Korean speakers of L2 English in this study,performance was markedly worse for plural s than for third-persons, and this difference became gradually larger with increasing AoA.The authors of this study attributed the difference in correctnessbetween noun phrase (NP) and verb phrase (VP) to the highersalience of the VP in Korean L1 and to a transfer of processingstrategies in this respect.

In contrast to ultimate attainment studies, research onacquisition order, of course, has made explaining difficulty intoan explicit goal, at least if one accepts that difficulty can beoperationalized as order of acquisition. This type of researchwas prominent from the early 1970s to the early 1980s, but whileresearchers eventually agreed on a more or less universal order ofacquisition of grammatical morphemes in ESL, they could notagree on an explanation for that order (cf., e.g., Gass & Selinker,2001; Larsen-Freeman & Long, 1991; Long & Sato, 1984). Thislack of explanatory adequacywas probably one of themain reasonswhy the order-of-acquisition question for morphemes faded fromthe published literature in the mid-1980s. Parallel work onacquisition order of syntactic patterns such as interrogativestructures (e.g., Eckman, Moravcsik, & Wirth, 1989) or relative

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clauses (e.g., Eckman, Bell, & Nelson, 1988; Gass, 1979), however,pointed to markedness as a potentially important factor indetermining order of acquisition/difficulty. Bardovi-Harlig (1987),on the other hand, showed that salience prevailed overmarkedness by comparing the acquisition of pied piping andpreposition stranding in ESL. Goldschneider and DeKeyser (thisvolume) returned to the issue of morpheme acquisition order andfound that saliencebroadly construed as a combination of phono-logical salience, semantic complexity, morphological regularity, andfrequencyaccounted for a large percentage of the variance in theorder of L2 acquisition. They found it impossible to tease out thecontribution of the various components of salience, however,because these factors are strongly intercorrelated in Englishmorphology.

Given the evidence for the importance of salience in both theultimate-attainment and the order-of-acquisition literatures, onthe one hand, and the lack of systematic research on the role ofsalience in ultimate attainment by adult learners, on the otherhand, DeKeyser, Ravid, and Alfi-Shabtay (2005) decided toinvestigate the role of salience in the acquisition of Hebrewmorphology by adult immigrants. They found not only a strongeffect of salience in determining difficulty (as measured bya grammaticality judgment test), but also a significant interactionwith age in the sense that the role of salience grew more importantwith increasing age of acquisition. Further analysis of the data(DeKeyser, Alfi-Shabtay, Ravid, & Shi, 2005) showed that severalcomponents of salience played an independent role in determiningdifficulty for all learners: phonological salience (length in phonesand /!syllabic character of the morpheme) and /!homonymywith other morphemes. Two other components of salience didnot show a main effect but interacted with age in the sensethat they were an important predictor of learning for olderlearners only: distance (between morphemes in agreementpatterns) and stress.

In conclusion, there is increasing evidence from both theorder-of-acquisition literature and the ultimate-attainment


literature that lack of salience plays an important role inacquisition difficulty. Much remains to be done in this area,however. On the one hand, it is much harder to agree on anoperationalizaton of salience in syntax as opposed to morphologyor phonology. On the other hand, even for morphology, there is stilla lack of systematic, let alone cross-linguistic, research comparingacquisition difficulty for morphemes with different degrees ofsalience or different degrees of other factors mentioned above, forthat matter, such as redundancy, optionality, and opacity of form-meaning mapping, novelty and abstractness of meaning, and sheercomplexity of form. As research on ultimate attainment effects isaccumulating, there is hope, however, that a meta-analysis of thatliterature may soon be able to help determine the characteristics ofconsistently poorly learned L2 structures.

Mitigating Factors

Meanwhile, additional insights on what is difficult and whycome from studies that have investigated the interactionbetween characteristics of the L2 structures being learned andindividual learner or contextual factors. While a substantialliterature exists on individual differences, not much work hasaddressed the question of the differential impact of factors suchas aptitude and motivation on specific elements withinmorphology and syntax, in other words, on elements char-acterized by specific types of difficulty. Two recent studies thatstand out in this area, however, are Willliams (1999) andWilliams and Lovatt (this volume).

The findings of both studies are complex, but Williams (1999)showed that meaningful form-function mapping (in Italian L2)resulted from conceptually driven, explicit learning (a function ofaptitude in the sense of grammatical sensitivity), whereas seman-tically redundant agreement rules were largely the result of data-driven, implicit learning (a function of memory). DeKeyser (2003)argued that this is because the agreement rules amounted toconcrete sound-sound correspondences (even euphony), whereas

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the meaningful form-function mappings required associating anelement of the noun phrase with an element of the verb phrase,each element taking a very different concrete form. Associatingnonmeaningful co-occurrence of concrete elements logically drawsmore on memory, whereas establishing meaningful relationshipsbetween abstract entities draws more on insight (cf. Gomez, 1997;Perruchet & Pacteau, 1990, 1991; Reed & Johnson, 1998). Williamsand Lovatt (this volume) found that even for more abstractpatterns of morpheme agreement, not involving euphony, phono-logical short-termmemory played an important role; there was alsoevidence, however, that explicit processes were strongly involved inlearning these patterns.

It is interesting to compare these findings to those ofTaraban (2004), who studied induction of gender-like categoriesin miniature linguistic systems. He did not take individualdifference measures but found that learning was greatlyfacilitated either by providing explicit instruction or by drawinglearners attention to the correlated sets of grammaticalmorphemes by means of blocking trials as a function of nouncategory. When time is limited and the pattern is made salient,explicit learning (presumably drawing on aptitude) is clearlyimportant; when there is more time and when the pattern is farless salient, as would be the case in naturalistic languageacquisition, the role of more implicit learning, relying moreheavily on mere associative memory, is likely to increase.

Few researchers so far seem to have ventured further andinvestigated how linguistic characteristics of the patterns tobe acquired interact with both individual differences andinstructional conditions at the same time. Robinson (2002), forinstance, provided interesting data on the interaction betweenaptitudes, on the one hand, and linguistic characteristics of thestructures to be learned, instructional conditions, or testingconditions, on the other hand, but not on the three-wayinteraction between linguistic characteristics, instructionalconditions, and aptitudes. Robinson (1996), on the other hand,documented an interaction between linguistic characteristics


and instructional conditions (i.e., instructed learners outperformedothers in learning simple rules), but he did not investigate aninteraction with aptitude. Robinson (1997), however, diddocument a three-way interaction between structure, aptitude,and instructional condition, in the sense that the learning of easystructures was predicted by grammatical sensitivity but not bymemory and the learning of complex structures by memory butnot by grammatical sensitivity, for instance, and that this patternonly obtained for one of the four instructional conditions (rulesearch, i.e., inductive explicit learning).

Implications for Instruction

The nature and degree of difficulty of individual structureshave a range of potential implications for instructional decisionmaking. At the most basic level, one can argue that instruction isnot necessary for the easiest structures and doomed to failure forthe hardest, in particular where focus on form is concerned(cf. DeKeyser, 2003). Within form-focused instruction, however,whether it be characterized by traditional focus on forms or morenarrowly defined focus on form (cf. Long & Robinson, 1998),different activities are likely to have a differential impact ondifferent structures characterized by different learningproblems. Larsen-Freeman (2003, pp. 117120), for instance,made distinctions among three kinds of activities, aimed atassociation (e.g., through phrase combination tasks), frequentuse, and choice (e.g., in a fill-in-the blanks format). Sheassociated these three kinds of activities with the problems oflearning the meaning of a grammar structure, the form itself, orits use, respectively. Within the terminological framework I haveused in the present article, one could argue that associationactivities are particularly useful when the learning issue is oneof form-meaning mapping, that frequent use should be the goalwhen the problem is one of semantically redundant form-formmapping, and that choice among forms should be the focus of theactivity when novel meanings are at issue.

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Much empirical work needs to be done in order to testhypotheses such as these, but they should provide a usefulstarting point for research that goes beyond the simplisticquestion of whether explicit grammar teaching and systematicpractice are useful for L2 grammar learning.

The Articles in This Volume

The four articles that follow were all published in LanguageLearning between 1999 and 2003. They are all about theacquisition of L2 morphology. Three are about the acquisitionof gender in particular: Kempe and Brooks demonstrate howdiminutives facilitate gender acquisition in Russian L2 byeliminating nontransparent morphophonological marking. Carrollshows that gender acquisition in French L2 is largelydetermined by the semantic distinctions the learner makes onthe basis of previous linguistic experience. Williams and Lovattdocument the role of individual differences, in particular,phonological short-term memory, in the acquisition of genderin a semiartificial miniature linguistic system.

These three studies illustrate with different methodologiesand with different languages how factors such as consistency ofform-meaning mapping, semantically driven insights derivedfrom prior linguistic knowledge, and the learners phonologicalshort-term memory all play an important role in solving adifficult problem in acquisition: form-meaning mapping, in whichthe form is complex and the meaning redundant, abstract, andnovel. Together with Goldschneider and DeKeysers meta-analysisof a wider range of morphological elements, these studies showhow success in L2 acquisition is strongly influenced by (a) howtransparent the form-meaning link is to the learner, eitherbecause of the salience of the linguistic structure itself orbecause its apperception is facilitated by the structure or thefrequency of the input, or (b) the learners aptitudes andprevious linguistic experience.


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What Makes Learning Second Language Grammar Difficult a Review of Issues DeKeyser 2005