EXAMINING IMPOVERISHED INPUT:
VIEWING THE CRITICAL PERIOD AS A PERIOD OF FORMALIZATION*
Jeffrey L. Bernath
University of Connecticut

1. Introduction
Examining cases of impoverished input can allow us to see into the tendencies of
Universal Grammar in ways that regular acquisition often cannot. Children, who have somespecial kind of access to UG that adults lack, appear to have the ability to deviate from their
input, and specifically formalize that input. In this paper I will propose that only children havethe ability to formalize language into features and projections, and adults lack this ability.
Below we will see evidence of children reorganizing inconsistent data, reliably outperforming
their models in areas specifically associated with formal syntactic features.
2. Nativization as Formalization – Aspect in ASL
To begin we will examine a case study of a child formalizing his language. While
linguists like Bickerton (1984) have certainly observed children organizing and in many cases
restructuring inadequate input, I will be using the term formalizing to describe situation inwhich children are augmenting the formal features of their input, to create consistent patterns
that were absent in their input. To make such a claim we will need to focus on individualacquisition, and for this I have chosen the case of Simon.
Simon is the pseudonym used by Singleton (1991) and Newport (1999) for a particular
Deaf child of Deaf parents. This child is of particular interest as his parents were extremelylate learners of ASL. English was their only language for the first 20 years of their lives, andonly later did they discover ASL and begin to use it as their primary mode of communication,
between each other and with Simon. Singleton asserts that Simon did not have any access to
ASL apart from his parents. He went to a school that did not use ASL, and none of his otherclassmates had Deaf parents. Because Simon only had access to ASL from his non-native
parents, he is in many ways like a creolizing child. His parents’ use of ASL was rule-based
but imperfect, and he was faced with input very similar to children in a pidgin-speaking
community.

*

I would like to thank Diane Lillo-Martin for her continued advice and support in this project, as wellas the attendees of the Linguistic Consortium at Nanzan and the UConn-UMass-Smith Language
Acquisition Workshop, as well as Sandra Wood and my other classmates for their advice andsuggestions on this work.
Nanzan Linguistics: Special Issue 3, Vol. 1, 23-33© 2007 Jeffrey L. BernathNanzan Linguistics: Special Issue 3, Vol. 1

Newport (1999) examined Simon and his parents in their use of ASL number andaspectual morphology. ASL morphology can become somewhat cumbersome in this domain,as the language contains dozens of aspectual morphemes, and can inflect for single, dual,
multiple, and exhaustive numbers (Klima & Bellugi 1979). Both kinds of inflection include achange in the movement of the sign, and multiple inflections can overlap to create complex
movements that are difficult to master for the non-native. A small sample of a verb inflectedin various ways is shown in figure 1.

Figure 1. Examples of the ASL sign GIVE (a) uninflected, (b) with a number marking, (c)with an aspect marking, and (d) with both. (Reprinted from Klima & Bellugi 1979.)
Simon’s parents’ use of ASL aspectual and number inflection was rather poor. Whilethey performed reasonably well at adding a single inflection to a verb stem, they failed rather-24-

Examining Impoverished Input (J. L. Bernath)dramatically at combining two such morphemes on to a single stem. In such cases Simon’s
mother added inflections to the verb correctly only 25% of the time, while his father neverdid, and both preferred periphrastic strategies to express the relevant concepts. However, on
the same task Simon added two inflections to the verb stem correctly 100% of the time. He
did not mimic his parents’ periphrastic strategies, nor their limit of one bound morpheme perverb stem. Singleton (1989) pointed out that a very similar pattern was observed by
Muhlhauser (1980) for Tok Pisin; in this case, pidgin-speakers (adults) were limited to asingle inflectional morpheme per verb stem, while creole speakers (children) use any numberof morphemes quite productively, as Simon did.
Under my hypothesis of formalization, Simon’s parents, as extremely late learners of
ASL, were not able to integrate ASL number and aspect morphology into their syntax asformal features or structure. They were forced to co-opt some other (non-linguistic)mechanism to inflect their verbs, perhaps other cognitive modules, or a strategy ofmemorization of each inflected form they were exposed to. Simon, however, as a natively
exposed child, not only had the ability to formalize his language into formal features, but
integrated the data into his grammar despite its high inconsistency. He was able to combine
morphemes in a productive, native-like way. He not only has an ability to formalize thelanguage that his parents lack, but was obliged to use it even in the face of other patterns.
3. Nativization as Formalization – Agreement in NSL
Nicaraguan Sign Language (NSL) began with the opening of a school for the Deaf inManagua, which brought together a critical mass of Deaf people for the first time in
Nicaragua. Although the school there did not advocate the use of sign language, thecommunity of Deaf people there quickly began communicating manually, and over the
decades this has been recognized as a true situation of language genesis by Anne Senghas andher colleagues (Senghas 2003; Kegl, Senghas & Coppola 1999).
Senghas tested several Deaf users of NSL that had entered the school in different years.
In this way, she is able to track the progress of the language as older language users havetransmitted it to younger users. This could be seen as another type of creolization situation,
however there is no target or superstrate language in this case; it could be said that theevolution of NSL is driven strictly by innate linguistic constraints. Either way, it can be seen
as an ideal case for us to examine in our investigation of nativization as formalization.
In Senghas’ study of verb agreement in NSL, she asked for grammaticality judgmentsfrom each signer about whether, in specific contexts, a verb is obliged to show agreement. In
most developed sign languages there exists at least a subclass of verbs for which agreement in
obligatory, suggesting that, for those classes of verbs, syntactic features are at work in themanner described for spoken language in the generative tradition (as in Chomsky 1995).

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Figure 2. Results for the acceptability of inflected vs. uninflected verbs for NSL users.
‘Rotated’ here means inflected, ‘unrotated’ means uninflected. (Reprinted from Senghas
2003).
Figure 2 shows an interesting pattern with respect to which informants accepted verb
agreement. All the informants in the first cohort (those entering the school before 1984)
accepted either an inflected or uninflected verb in most situations. Being exposed to very
early, rudimentary forms of the language, they perhaps did not have sufficiently regular input
to produce agreement. However, informants from the second cohort (those entering the school
after 1984) almost always required verbs to be inflected. This is interesting because membersof the first cohort are older, and have been using the language longer than those in the second
cohort. However it is the younger, second cohort signers that have a restriction which theolder, first cohort signers lack. Those in the second cohort appear to have the additional
requirement that verbs be inflected for person, despite the fact that we would not expect thisto be consistently modeled in their input, which came from the first cohort.
If we assume that the members of the first cohort sometimes used agreement andsometimes lacked agreement, then we can come up with a nativization story just like the oneused for Simon. It would seem that, while the input from the first cohort was inconsistent, it
had hints of agreement, and the learners in the second cohort had sufficient input to develop a
syntactic system that required agreement. Figure 3 shows that, in fact, the first cohort did
sometimes use agreement, albeit inconsistently. That being the case, the second cohort had
sufficient input to create a paradigm, and because they have been using this language from ayoung age, they were able to formalize this paradigm with syntactic features, which creates
the necessity of agreement associated with such features. Interestingly, the older first cohort
signers are using their version of the language concurrently with this more complex version,
yet have not changed with the times. This is because they are now older, and lack themechanism to transform their agreement paradigm into syntactic features.

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Examining Impoverished Input (J. L. Bernath)

Figure 3. Elicited NSL verbs with or without inflection. ‘Rotated’ here means inflected,‘unrotated’ means uninflected (reprinted from Senghas 2003).
4. Verb Types in ASL – Where Formalization is Unnecessary
Our final investigation of formalization comes from a case that is in many ways the
opposite of the creolizing child. Below we will examine the acquisition of ASL verb
agreement by late learners of the language, and we will see that they have trouble with formalfeatures, but not other aspects of the language. We will examine their performance withrespect to ASL verb agreement, which is of particular interest because formal features playdifferent roles in different kinds of verbs.
4.1. The ASL Verb Agreement Paradigm
The paradigms involved in ASL verb agreement paint a large and complex picture, so wewill examine the adult patterns before discussing acquisition. ASL, like many other sign
languages, has a verb agreement paradigm that is divided into three groups (Sandler & LilloMartin 2006, Padden 1983).
•••

Plain verbs do not undergo any kind of regular agreement process.
Person-agreeing verbs agree specifically with animate referents.
Spatially agreeing verbs agree with loci in space, which may or may not be associatedwith animate referents.

I will not be discussing plain verbs in this paper, but rather will focus on the distinction
between person-agreeing and spatially agreeing verbs. This distinction has not always beenclear in the literature, as the process of agreement for the two types of verbs is phonologicallyvery similar. In both cases, the beginning and/or end point of a verb is modulated so that it isassociated with a specific point in space. Ambiguity arises because person-agreeing verbs
show agreement with a referent by agreeing with a spatial locus that is associated with thatreferent, while spatially agreeing verbs agree directly with a spatial locus.

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Liddell (2003) perhaps made this distinction in the clearest manner. Rather than using
features like person and number, which are common in spoken language agreement processes,
verbs in ASL either agree with specific, unique, animate referents (for person-agreeing verbs),
or directly with semantically relevant points in space (for spatially agreeing verbs), which areoften co-indexed with other specific, unique entities. Liddell points out that, while personagreeing verbs (and pronouns) in ASL might seem to be undergoing agreement with spatialloci, on an abstract level they are agreeing with specific referents, and only using space as a
medium to express this idea. Spatially agreeing verbs are the only ones that agree directlywith spatial loci.
An example of Liddell’s will be illustrative in distinguishing between agreement with aspatial locus, and person agreement. If my friend has a box of mine, and asks where I would
like the box to be put, I can answer in different ways. If I respond, “on the lawn,” then myfriend accesses her abstract representation of the lawn and can choose any place within thatspace to place the box. This is analogous to the case of the person-agreeing verb; an abstractreferent is referred to in both cases, and it is merely a phonological accident that it looks likespatial agreement in ASL. However, if I respond to my friend by pointing to a specific placeon the lawn, my friend can refer to the spatial locus I indicated in deciding where to place thebox. This is like a spatially agreeing verb, where a specific spatial locus is referred to, andwhatever abstract entity the locus refers to can be seen as irrelevant for communication. The
reader can see here that, while all referents we make mention of exist at particular points inspace, and it may even be those points in space that we use to refer to them, we can make thedistinction between referring to spatial loci and the entities that occupy them
The distinction between referents and spatial loci is directly observable across the two
ASL verbs types in question. In much the same way that the pointing gesture in the example
above makes a finer spatial distinction than words, spatially agreeing verbs also make finer
spatial distinctions compared to person-agreeing verbs. Figure 4 contrasts agreement withmultiple objects for a person-agreeing verb (GIVE) and a spatially agreeing verb (PUT).
While smaller changes in location do not change meaning for person-agreeing verbs (as thegloss shows), specific changes of spatial loci are meaningful for spatially agreeing verbs.
What I take this asymmetry to reflect is the fact that spatial verbs are, in the case of theiragreement process, regulated by the gestural component of the mind in a way that personagreeing verbs are not (Berk 2003). While both verb types, and indeed the entire language,
exists in space to some degree, spatially agreeing verbs need to refer to that space directly inorder to agree, as do other constructions like classifier predicates. Reference to real space isnecessary for the kinds of agreement used with spatially agreeing verbs, like the kind ofagreement seen in figure 4, and while we label this as agreement, the mechanism behind it is
not syntactic in nature. Person-agreeing verbs, on the other hand, refer to abstract referents
rather than actual space, and as such are not mediated by the gestural component in this way. I
will be assuming that person-agreeing verbs agree in the usual syntactic manner, throughfeatures and movement, in the tradition of Chomsky (1995) and others.

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Examining Impoverished Input (J. L. Bernath)

There is some evidence for this particular division between spatially agreeing andperson-agreeing verbs. Lillo-Martin (1991), in her investigation of null arguments in ASL,
found that person-agreeing verbs, and not other verb types, licensed Italian-type argument
drop, commonly called pro-drop. This pattern of argument drop is of the type associated with,and licensed by, rich overt agreement, and is not available for those verbs in the language
which lack agreement. While this supports the idea that person-agreeing verbs are operatingwith formal features in the usual way, we unfortunately do not have information on spatiallyagreeing verbs, as Lillo-Martin excluded them from her analysis. While more research isneeded in this area, the current evidence is in line with the division we will use here.

(i)

(ii)

Figure 4. (i) GIVE, a person-agreeing verb, conveys the same exhaustive meaning in (a) and(b). Both mean “give to each person.” (ii) PUT, a spatially agreeing verb, conveys
different meanings in (a) and (b). In particular, (a) means “put three objects in a row atequal distances from each other,” and (b) means “place two objects close together and
one further away.” (Reprinted from Padden 1983).
Given the division between person-agreeing and spatially agreeing verbs as we haveoutlined it, we can look for the effects of the use of formal features in acquisition. We haveseen above that the active organization of formal features is something that is unique to-29-

Nanzan Linguistics: Special Issue 3, Vol. 1

children, and as such they should be able to use person-agreeing verbs in a way late learners
cannot. Spatial verbs, however, being mediated by the gestural component for their agreement
processes, should pose no problem to adults (assuming the have the same kind of access tothis non-linguistic module).
4.2. How Late Learners Manage with ASL Agreement
Berk (2003), in her dissertation, examined the ASL acquisition of two Deaf children,
called CAL and MEI, who were first exposed to ASL at ages 5;9 and 6;1, respectively. These
children had not been exposed to regular linguistic input before those ages, but at that time
were completely immersed in an ASL environment. Berk hypothesized that the delay of input
to these children would have an affect on their verb agreement systems, and her hypothesis
was borne out.
Berk observed CAL and MEI, as well as a native signer, JIL, in a naturalistic setting forsome months to study their use of verb agreement. She examined each of their uses of plain,
spatially agreeing, and person-agreeing verbs, and paid particular attention to where thechildren made agreement errors. The native signer, JIL, showed almost no errors in verb use
and inflection, as expected (see figure 5a). She had no trouble with the gestural elements ofspatially agreeing verbs, nor with the formal features of person-agreeing verbs, being exposedto the language from birth. CAL and MEI, however, showed a particular error rate, which wasitself very regular. In particular, they almost always made some error when producing aperson-agreeing verb, but erred rarely with plain or spatial verbs (see figure 5b-c). While thegestural component of spatial verbs posed no problem for these late learners, verbs which
required the manipulation and expression of formal syntactic features were a problem forthem. In addition, this error pattern did not decrease over time.
It should also be noted that Berk found that all three children attempted similar
proportions of the verb types; that is to say, there was no difference between the children as totheir preference for one type of verb over another. Each child used person-agreeing verbs alittle more than half the time, and plain verbs less than 15% of the time. Their congruence on
this measure shows that elevated errors rates in one category or another would not bereasonably attributable to avoidance or preference for that category.
Person-agreeing verbs are most clearly set apart from plain and spatial verbs by the factthat person-agreeing verbs involve the overt realization of formal syntactic features. Plainverbs do not require the same amount of morphological synthesis, and spatial verbs have thebenefit of being mediated through a non-linguistic component. If we assume that the ability tomanipulate formal features within one’s language is only held by the youngest language
learners, then this result is expected and explained.

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(a)

(b)

(c)

Figure 3. Berk’s subjects’ errors by verb types. JIL (a), a native signer with Deaf parents,
produced almost no errors. CAL (b) and MEI (c), late learners, produced many errors
with person-agreeing verbs (called “agreeing” by Berk), but not with plain or spatial
verbs. (Reprinted from Berk 2003).

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5. Conclusions and Future Directions
We have seen here that person agreement and other features of verbal inflection are notmerely morphological reflexes of syntactic processes. Universal Grammar has a bias toward
their use, which is reflected in children’s acquisition of language and their penchant forformalizing language. Other logical options exist, such as stripping out agreement processes
from the language when they are imperfect. However, given sufficient exposure to partial or
degraded agreement paradigms, children seem to reorganize and even add to their input andproduce a language that has true agreement.
However, the behavior of the children in Berk’s (2003) study shows us that suchreorganization is restricted to the proficient, child language learner. It is critical that input bepresent at this stage, whatever its form. It seems ironic that, at the youngest ages children
obligingly restructure their input, such as in the cases of Simon and NSL, while afterward
children like MEI and CAL cannot even copy the language around them accurately. Their useof the linguistic system is limited, and may depend in a large way on other mechanisms likethe gestural component.
Of course, many unanswered questions remain in this domain. The most glaring is thequestion about the nature of the gestural component, and how it interacts with the linguistic
module. Linguistic forms that are grounded in real space, such as classifier predicates andspatially agreeing verbs, necessitate some kind of link between a gestural/spatial component
and language. However the nature of the relationship between this component and otheraspects of linguistic competence remains unclear. In a similar vein, we may ask the question,
what other mechanisms does the late learner use, and in what fashion, to produce some correct
agreement forms in the midst of her errors? While we often focus on the shortcomings of nonnatives, we need to remember that in nearly all cases, they are not wholly incompetent. MEI
and CAL, for example, still produced correct agreement forms about 20% of the time. But ifthey lack formal organization necessary for such structures, how do these utterances surface?
This is a question not only for the field of verb agreement in ASL, but for any linguist that
attempts to explain the nature of non-native output.
A final issue relates to the observed proclivity of young language learners to regularize
their input, and even enhance paradigms that were incomplete (as in the case of Simon and
NSL). This idea predicts that languages should not lose their agreement patterns, despite thefact that this is a process that does occur over time. While this is an issue, a positive aspect isthat we do predict upkeep of weaker agreement patterns. While many people learning English
as a second language could find it a wonder that English actively maintains the lone third
person singular –s morpheme, UG’s penchant for agreement would predict its maintenance.
(Indeed, when the language is used by a large amount of non-native speakers, such as pidginspeakers, this morpheme is the first thing to go. It can do so because these adult users do nothave the same ear for agreement that children seem to have.) However, the proposal in thispaper does not predict that an agreement paradigm should so weaken in the first place.

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Examining Impoverished Input (J. L. Bernath)

Perhaps at least this final issue can be twisted into a positive. Work on diachronicchanges in agreement, launched largely by Givón (1976), has shown that languages will bothbuild up and tear down their agreement paradigms over time. If we are trying to explain whyboth kinds of changes occur, then this paper gives us half of the explanation. We know thatchildren will build agreement up, given the opportunity, as part of a larger formalization
mechanism. This mechanism operates, even in the face of contrary input, to maintainlanguage as the ordered entity linguists know it to be. As for why an agreement paradigm
might atrophy over time, that is a problem I will generously donate to my colleagues.

References
Berk, S. B. (2003) Sensitive Period Effects on the Acquisition of Language: A study of Language
Development, Doctoral Dissertation, University of Connecticut, Storrs.
Bickerton, D. (1984) “The Language Bioprogram Hypothesis.” The Behavioral and Brain Sciences 7,
173-221.
Chomsky, N. (1995) The Minimalist Program, MIT Press, Cambridge, Mass.
Givón, T. (1978) “Topic, Pronoun, and Grammatical Agreement.” In C. Li, ed., Subject and Topic,
Academic Press, New York, 151-188.
Kegl, J., Senghas, A. & Coppola, M. (1999) “Creation through Contact: Sign Language Emergenceand Sign Language Change in Nicaragua.” In M. DeGraff, ed., Language Creation andLanguage Change: Creolization, Diachrony, and Development, MIT Press, Cambridge,
Mass., 179-237.
Klima, E. S. & Bellugi, U. (1979) The Signs of Language, Harvard University Press, Cambridge, Mass.
Liddell, S. K. (2003) Grammar, Gesture, and Meaning in American Sign Language, Cambridge
University Press, Cambridge, U.K.
Lillo-Martin, D. C. (1991) Universal Grammar and American Sign Language: Setting the Null
Argument Parameters, Kluwer Academic Publishers, Dordrecht, The Netherlands.
Muhlhauser, P. (1980) “Structural Expansion and the Process.” In A. Valdman & A. Highfield, eds.,
Theoretical Orientation in Creole Studies, Academic Press, New York.
Newport, E. L. (1999) “Reduced Input in the Acquisition of Signed Languages: Contributions to the
Study of Creolization.” In M. DeGraff, ed., Language Creation and Language Change:
Creolization, Diachrony, and Development, MIT Press, Cambridge, Mass., 161-178.
Padden, C. A. (1983) Interaction of morphology and syntax in American Sign Language, Doctoral
Dissertation, University of California, San Diego.
Sandler, W. & Lillo-Martin, D. C. (2006) Sign Language and Linguistic Universals, Cambridge
University Press, Cambridge, Mass.
Senghas, A. (2003) “Intergenerational Influence and Ontogenetic Development in the Emergence of
Spatial Grammar in Nicaraguan Sign Language.” Cognitive Development 18, 511-531.
Singleton, J. L. (1989) Restructuring of Language from Impoverished Input: Evidence for Linguistic
Compensation, unpublished doctoral dissertation, University of Illinois, Urbana-Champaign.

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