![| Typical intonational display of the antecedent clause of an ISL counterfactual conditional and its change in the consequence clause, in a sentence meaning, "If the goalkeeper had caught the ball, the team would have won the game" and glossed [GOALKEEPER HE CATCH-BALL] [WIN]. The figure shows the underlined signs.](https://www.researchgate.net/publication/330192686/figure/fig1/AS:712973945421825@1546997643900/Typical-intonational-display-of-the-antecedent-clause-of-an-ISL-counterfactual_Q320.jpg)
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fpsyg-09-02202 December 13, 2018 Time: 14:3 # 1
ORIGINAL RESEARCH
published: 13 December 2018
doi: 10.3389/fpsyg.2018.02202
Edited by:
Judit Gervain,
Centre National de la Recherche
Scientifique (CNRS), France
Reviewed by:
Antonio Benítez-Burraco,
Universidad de Sevilla, Spain
*Correspondence:
Rose Stamp
rose_stamp@hotmail.com
Specialty section:
This article was submitted to
Language Sciences,
a section of the journal
Frontiers in Psychology
Received: 04 January 2018
Accepted: 24 October 2018
Published: 13 December 2018
Citation:
Dachkovsky S, Stamp R and
Sandler W (2018) Constructing
Complexity in a Young Sign
Language. Front. Psychol. 9:2202.
doi: 10.3389/fpsyg.2018.02202
Constructing Complexity in a Young
Sign Language
Svetlana Dachkovsky, Rose Stamp*and Wendy Sandler
Sign Language Research Laboratory, University of Haifa, Haifa, Israel
A universally acknowledged, core property of language is its complexity, at each level of
structure – sounds, words, phrases, clauses, utterances, and higher levels of discourse.
How does this complexity originate and develop in a language? We cannot fully
answer this question from spoken languages, since they are all thousands of years
old or descended from old languages. However, sign languages of deaf communities
can arise at any time and provide empirical data for testing hypotheses related to
the emergence of language complexity. An added advantage of the signed modality
is a correspondence between visible physical articulations and linguistic structures,
providing a more transparent view of linguistic complexity and its emergence (Sandler,
2012). These essential characteristics of sign languages allow us to address the issue
of emerging complexity by documenting the use of the body for linguistic purposes. We
look at three types of discourse relations of increasing complexity motivated by research
on spoken languages – additive, symmetric, and asymmetric (Mann and Thompson,
1988;Sanders et al., 1992). Each relation type can connect units at two different levels:
within propositions (simpler) and across propositions (more complex).1We hypothesized
that these relations provide a measure for charting the time course of emergence
of complexity, from simplest to most complex, in a new sign language. We test this
hypothesis on Israeli Sign Language (ISL), a young language, some of whose earliest
users are still available for recording. Taking advantage of the unique relation in sign
languages between bodily articulations and linguistic form, we study fifteen ISL signers
from three generations, and demonstrate that the predictions indeed hold. We also find
that younger signers tend to converge on more systematic marking of relations, that
they use fewer articulators for a given linguistic function than older signers, and that the
form of articulations becomes reduced, as the language matures. Mapping discourse
relations to the bodily expression of linguistic components across age groups reveals
how simpler, less constrained, and more gesture-like expressions, become language.
Keywords: language complexity, language emergence, sign languages, discourse relations, gesture, use of body,
compositionality
1Propositions are semantic constructs that usually represent meaning of sentences and discourse, and are subject to truth
conditions. They consist of a predicate, a number of arguments and one or more modalities (e.g., Goddard, 2011).
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
INTRODUCTION
The form of language is complex at each level of structure – the
word, the phrase, the clause, and higher units in the linguistic
hierarchy. And at each level, language is compositional – building
up complex structures by combining and recombining simpler
meaningful units. Children inevitably acquire this complex
system, but not all at once. The gradual, step-by-step process
of acquisition offers insight into the relative complexity of
different language structures and their interaction (Brown, 1973;
Barrett, 2016;Dromi, 2016;Tomasello and Brooks, 2016). The
contribution of the child’s mind to this process is clearly
impressive, but the process always occurs in the presence of adult
models, which also contribute to acquisition. How does a new
language accrue linguistic complexity from scratch? What are the
characteristics of language emergence de novo in a community?
Sign languages offer an opportunity to watch this phenomenon
unfold.
This opportunity is unique to sign language in two ways: (1)
they are young languages, and new ones can arise at any time
and (2) there is often a direct correspondence between visible
physical articulations and linguistic structures, providing a more
transparent view of the emergence of complexity. The emergence
of complexity with no model in spoken languages cannot be
traced, because spoken languages are all thousands of years
old or descended from old languages with complete linguistic
structures. However, sign languages arise spontaneously in a
community of signers, and if linguists are in the right place at
the right time, they can observe the emergence of language.
It is generally assumed that sign languages begin life as
gestural systems (Janzen and Shaffer, 2002;Goldin-Meadow,
2003;Meir et al., 2016) and interact with gesture even as they
transform into linguistic systems (Liddell, 2003;Padden et al.,
2013). Gestures are used by all of us, and they accompany spoken
language. However, they are unlike language because they are less
conventionalized and less systematic (McNeill, 1992). Established
sign languages are clearly fully linguistic systems (Sandler and
Lillo-Martin, 2006;Pfau et al., 2012). But how did they get that
way?
A good deal of research has described the home sign system
created by deaf children without a language model (Goldin-
Meadow, 2003), and compared it with established sign language
or with spoken language. Though most studies of the gestures
that accompany speech are restricted to manual gestures, it has
long been noted in studies of co-speech gesture that actions of
the whole body accompany linguistic interaction (Kendon, 1972;
Kidwell, 2013). But no study to date has attempted to combine
measures of discourse complexity and bodily systematicity in
order to map the emergence of language in a community, as we
do here.
As will become clear, unlike the relation between form and
meaning in spoken languages, many linguistic structures in
sign languages have overt physical form, so that actions of
different articulators – the hands, face, head, and torso – convey
particular linguistic information. This is another advantage for
our pursuit, as we explain. We do not claim that all aspects of
sign language structure have overt physical correlates. We accept,
for example, that syntactic, semantic, and other relations and
properties can be covert, and that evidence for them can be
attained through linguistic analysis of the same kind that applies
to spoken language (Sandler and Lillo-Martin, 2006;Pfau et al.,
2012). However, the unique kind of direct mapping that we will
demonstrate offers an opportunity to observe particular linguistic
properties directly as they unfold.
One study to date has adopted the strategy of matching
bodily form to linguistic function in a newly emerging language,
Al Sayyid Bedouin Sign Language (ABSL). This language was
formed in a Bedouin village in present day Israel, after four
deaf children were born in a single household, and deafness
began to proliferate throughout the village (Sandler et al., 2005).
The study showed that with each new generation of signers,
additional articulators were recruited to convey increasing
linguistic complexity as the language developed (Sandler et al.,
2011;Sandler, 2012). In particular, Sandler (2016) found that
the first overt markings to appear served to organize discourse
functions, such as topic-comment structure, referent perspective,
and topic continuity across a discourse – and in that order. This
approach and its preliminary findings motivate the current study,
and we describe it in more detail in Emerging Sign Languages:
Use of Body Articulators.
We investigate the emergence of complexity in a different sign
language of the same age as ABSL, Israeli Sign Language (ISL).
This language has developed under different social conditions
from those of ABSL (described briefly in The ISL Community
and the Formation of the Language), leading to certain
differences in the path of emergence (Meir et al., 2012;Meir and
Sandler, in press). In more than a decade of research on ABSL,
the research team refrained from attributing complex syntactic
structure to utterances without overt evidence, and instead based
their analyses primarily on the meaning and prosodic structure
of the productions, and their interaction (Padden et al., 2010b;
Sandler et al., 2014, 2005). We follow that strategy in the present
study of ISL as well.
We adopt the theory of discourse relations proposed by
Mann and Thompson’s (1988) and Sanders et al.’s (1992), laid
out in Measuring Relations and Complexity in Discourse, to
investigate the degree of complexity of utterances, and to measure
the frequency and systematicity of the discourse relations they
convey, including, for example, dependency between clauses.
We look at three types of relations of increasing complexity,
motivated by research on spoken languages. In the spirit of
Mann and Thompson (1988) and Sanders et al. (1992, 1993), we
adopt the following terms: additive, symmetric and asymmetric
(see Types and Levels of Discourse Relations and Their
Relative Complexity). Each of these types of relations can
occur at two different levels: within propositions (simpler) and
across propositions (more complex). We hypothesized that these
constructions provide a measure for charting the emergence of
complexity in a young language, from simplest to most complex,
and tested the hypothesis on ISL.
By studying the recruitment of articulators to express
linguistic form in fifteen ISL signers from three generations,
we show in the section Discussion: Bodily Marking Emerges
Gradually that this is indeed the case. In other words, the
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
emergence of constructions reflects the degree of complexity
in terms of relation type and level. We also find evidence for
increasing systematicity and automaticity of form as the language
matures. Our conclusions and suggestions for future research
comprise the Conclusion.
The ISL Community and the Formation of
the Language
Israeli Sign Language is the established language of the deaf
community in Israel (Meir and Sandler, 2008). It is a young
sign language, roughly about 90 years old, which arose with the
formation of the deaf community in Israel around the 1930s,
beginning with the establishment of the first Israeli School for
the Deaf in 1932 in Jerusalem. Immigrants from all over the
world contributed to the signing used by a small number of
deaf Jews and Arabs already in Jerusalem. Vocabulary items have
been traced to a small number of immigrants from Germany,
and immigrants from elsewhere in Europe, North Africa, and
the Middle East also brought their sign languages or home sign
systems with them. A conventional local sign language evolved,
and today, ISL is used in a wide range of settings including
the educational system, deaf social and cultural institutions,
interpreting programs, and the media.
The linguistic structure of ISL is investigated in earlier work
(e.g., Meir, 1998, 2010;Meir and Sandler, 2008;Meir and Sandler,
in press) and its emergence has recently become the object of
study, briefly noted in The Body as a Marker of Linguistic
Complexity below.
The Body as a Marker of Linguistic
Complexity
Signers exploit the use of the hands, torso, head and
facial expression to convey linguistic information. Early sign
language research demonstrated that non-manual signals play
important roles in American Sign Language (ASL) grammar
by systematically co-occurring with various linguistic structures:
questions, topics, conditionals, and others (e.g., Baker and
Padden, 1978;Liddell, 1978, 1980;Baker-Shenk, 1983;Reilly
et al., 1990). Later, similar phenomena were demonstrated in
other sign languages (Bergman, 1984, Swedish Sign Language;
Engberg-Pedersen, 1990, Danish Sign Language; Coerts, 1992,
Sign Language of the Netherlands (NGT); Nespor and Sandler,
1999, Israeli Sign Language; Sutton-Spence and Woll, 1999,
British Sign Language; Herrmann and Steinbach, 2013, German
Sign Language). Although most of this research studied facial
expressions, a few studies focused on the role of other articulators,
such as the head (Sandler et al., 2011;Dachkovsky et al., 2013;
Lackner, 2013;Puupponen et al., 2015) and torso (Wilbur and
Patschke, 1998;Ormel and Crasborn, 2012); also see Pfau and
Quer (2010) and Sandler (2010) for overviews of non-manuals
in sign languages.
While early work on the role of non-manual markers in
various structures such as interrogatives, topics, and relative
clauses attributed them to the syntactic level of analysis (e.g.,
Liddell, 1978, 1980;Neidle et al., 2000), other researchers have
argued that facial expressions and head movements are driven
by various information structure and discourse considerations,
such as topic continuity, foregrounding-backgrounding in
subordinate constructions and others (Dachkovsky et al., 2013;
Sandler et al., in press). For example, Figure 1 below illustrates
the marking of a neutral conditional in ISL. It typically consists of
raised eyebrows and forward movement of the head (Dachkovsky
and Sandler, 2009).
Moreover, those signals can co-occur with other signals to
create a more complex grammatical meaning. Thus, raised
brows and forward head movement signaling conditionality can
combine with squinted eyes to create a more complex linguistic
form – together they systematically mark counterfactual
conditionals in ISL (Dachkovsky, 2008). An example of this
subordinate construction using a complex array of facial
expressions and head movements is presented in Figure 2.
The antecedent, or ‘if’ clause, in this example comprises an
intonational phrase, and the head position and facial intonation
align with the timing of the hands to mark the phrasal boundary.
Thus, the head posture (head movement forward) and facial
expression (raised brows and squinted eyes) change between the
last sign of the first clause and the first sign of the second clause.
This change follows the manual cue at the intonational phrase
boundary – the hold in position of the last sign CATCH-BALL of
the first clause.
These findings motivated a study of a newly emerging
Bedouin sign language, which we discuss below. The study
demonstrated that, in addition to the hands, head, and face,
the torso and the non-dominant hand independently can be
recruited for discourse organization. Since each articulator
contributes additional linguistic information, recruitment of
more articulators for different functions implies more complexity
of language structure.
Taking the findings across sign languages into consideration,
we arrive at a very general model that relates bodily articulators
to linguistic roles across sign languages (see Sandler, 2018
FIGURE 1 | Typical intonational display of the antecedent clause of an ISL
neutral conditional in a sentence meaning, “If you eat now, you won’t be
hungry for lunch.” The image was captured while the signer was producing
the underlined sign.
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
FIGURE 2 | Typical intonational display of the antecedent clause of an ISL counterfactual conditional and its change in the consequence clause, in a sentence
meaning, “If the goalkeeper had caught the ball, the team would have won the game” and glossed [GOALKEEPER HE CATCH-BALL] [WIN]. The figure shows the
underlined signs.
for more details). This sort of correspondence is derived
from a range of data and methods of analysis in different
sign languages, and awaits statistical confirmation. Here our
point of departure is that reliable correspondences between
articulator activation and linguistic roles exist, and we test them
statistically across different generations of signers in a young sign
language.
Emerging Sign Languages: Use of Body
Articulators
The new field of emerging sign languages has laid the foundation
for understanding how language arises. Yet, in most cases, these
studies evaluate particular structures at the level of the word, the
clause, or the sentence, without generalizing across levels. Since
sign languages are transmitted in the visual modality and use
multiple articulators, the findings of most earlier studies do note
the role of the body in the process of the emergence of complex
grammatical distinctions, but only indirectly.
Here we aim to overcome these limitations. First, the theory
of discourse relations that we adopt allows us to make broader
generalizations about the emergence of complexity across the
clause and the sentence levels. Second, we exploit the direct
relation between bodily action and linguistic structure to evaluate
the emergence of complexity and systematicity.
Senghas (1995) and Senghas et al. (1997) were pioneers in
this field. They have claimed rapid language development and
change between cohorts of children in a deaf school in Nicaragua.
In their work, the researchers focused on the development of
temporal and spatial devices in this rapidly developing language
(Senghas and Coppola, 2001;Kocab et al., 2016). Assignment to
a cohort reflects both the age at which the signers arrived at the
newly established school, and whether or not they had signing
models in the environment. Members of the first cohort were
older when they arrived at the school, and had no models for
creating a language, while the second cohort were younger and
had the advantage of the older cohort as a language model.
In their work, the researchers examined the emergence of
particular discourse signals, often called referential shift devices –
that is, devices, which shift the perspective of the discourse. In
addition to lexical labels, sign languages can mark the shift with
a manual point or with a movement of the body to a specified
location in the three-dimensional space in front of the signer,
capitalizing on the spatial affordances of the visual modality.
While there was no significant difference between age cohorts
of Nicaraguan Sign Language (NSL) in the use of neutral lexical
signs and indexical points, there was a difference in the use
of spatial devices (e.g., indexical points to space, body shifts
and spatially modulated signs), with second-cohort signers using
them significantly more (Kocab et al., 2015).
Ergin (2017) investigated the development of a recently
discovered young sign language – Central Taurus Sign Language
(CTSL), which emerged in the 1960s in a remote village situated
in the mountainous region of Southern Turkey. The researcher
reported on the emergence of a phonological system, handshape
classifiers and argument structure in this village sign language,
with a special focus on the way the semantic complexity in various
different scenarios is realized on the surface structure of such a
young language. In her study of the word order in this language,
the author also demonstrated that the more specified use of
body articulators (‘body segmentation’) in signaling reciprocal
argument relations in a sentence is more characteristic of the
younger signers’ production (Ergin, 2017).
The youngest reported sign language – the Sao Tome and
Principe Sign Language (LGSTP) – started to emerge just a
few years ago and is still in its first age cohort. The research
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
group investigating this language conducted a longitudinal study
through a few successive sessions of video recordings. One of
their findings is that the earlier stages of language development
are characterized by larger signing space than subsequent, later
stages (Mineiro et al., 2017), measured according to the size of
the joints involved in sign production.
By and large, all the studies mentioned so far have traced the
emergence of the signed word, morphological complexity, and
syntax within the sentence. As noted above, their findings related
to the use of the body were an artifact of studying languages
conveyed by corporeal articulators. Taking linguistic functions
as the point of departure, their strategy can be summarized as a
function-to-body approach.
A different perspective has arisen in the studies investigating
a young sign language that emerged in a Bedouin village in
the Negev desert of present day Israel. ABSL has been the
object of study for over a decade by Aronoff et al. (2008) and
Sandler et al. (2014, for an overview). ABSL began with four
deaf children in a single family about 90 years ago, and the
deaf population has since spread throughout the village, now
numbering about 150 deaf people in a village of 4,000. ABSL has
been developing across generations of signers. In their work on
this young language, the team has been especially interested in the
externalization by the body of the emergence and development
of grammatical functions. The researchers paid special attention
to manual timing and to use of the face and head in order to
understand the structuring of sentences in ABSL (Sandler et al.,
2005, 2011;Padden et al., 2010a).
Taking those studies as a basis, Sandler (2012) explicitly
addressed the emergence of ABSL from a body-to-function
perspective. With this approach, she investigated broader
discourse functions, such as the discourse topic. This
preliminary study traced the step-by-step recruitment of
different articulators – the face, the head, the torso, and the non-
dominant hand – to create an increasingly complex linguistic
system in ABSL. In this way, a correlation was found between the
increase in language complexity and the affordances of multiple
bodily articulators participating in language expression at higher
levels of discourse.
Two observations emerge from this work, which are relevant
for the present study. The first is that there is often a direct
correspondence between linguistic and bodily complexity. The
second is that the body traces the order of emergence of linguistic
structure, such that words on the hands are first; propositions and
links between them, signaled by the head and face, are next; and
broader discourse organization, embodied in movement of the
torso and independent spatial placement of the non-dominant
hand, is last. Details of this emergence are expanded in Sandler
(2012, 2013).
Although ABSL studies rely on a small number of participants,
due to the exigencies of fieldwork in a community of this kind,
ISL offers a field that is much less limited, both in the size of
the deaf population (estimated at about 10,000) and in their
availability. At the same time, ISL arose under very different
conditions, and can be considered a creole of many substrates
but no superstrate (Meir and Sandler, 2008), so that the stages of
its emergence may be less crisply defined. Nevertheless, concrete
results about the emergence of this language have been reported.
For example, conventionalization of the use of space was studied
in Padden et al. (2010a). Another study found consistent and
quantifiable relations between the increasing organization of
bodily articulators and of linguistic structure in this language
(Stamp and Sandler, 2016). Specifically, younger signers are
more likely than older signers to use the head and the body
simultaneously for separate linguistic functions.
In a study of relative clauses across age groups, Dachkovsky
(2017) found that younger signers, unlike older signers,
consistently organize this construction by aligning the noun
and predicate of the relative clause with characteristic head
positions and facial expressions. In the youngest group,
the bodily markers are phonetically reduced, indicating the
increased automaticity and conventionalization typical of
grammaticalization (Dachkovsky, 2017). In general, these
studies point to increased language complexity tied to increased
articulatory complexity, as well as increased efficiency in use of
different parts of the body as a language matures.
Here we develop the body-to-function approach and
investigate the emergence of complexity and conventionalization
in finer resolution. Specifically, we trace the relationship
between the recruitment of bodily articulators and
the complexity of discourse relations both within and
across propositions. We adopt a particular measure
of discourse relations and complexity, described in
Measuring Relations and Complexity in Discourse, and
investigate their emergence by tracking actions of the
body for different linguistic units across age groups. We
review relevant properties of language change, such as
convergence as well as reduction of form in the process of
conventionalization.
Measuring Relations and Complexity in
Discourse
We approach the study from the perspective of relations
among constituents in a discourse, and their relative complexity.
By discourse, we mean a coherent multi-utterance dialog
or monolog text. Discourse contains propositions, where
propositions are usually understood to be truth bearing
statements denoting states of affairs (e.g., Wittgenstein, 1961;
Krifka, 2001;Cristofaro, 2003), but it is more than a sequence
of propositions. Despite some key differences, all definitions
view discourse structure as the conceptual organization of a
text, driven by the communicative goals of language users, the
direction of information flow and considerations of common
ground.
Discourse structure subsumes such notions as segmentation,
anaphoric relations, and relations between segments (Kruijff-
Korbayová and Steedman, 2003). As a result, stretches of
discourse are analyzed as connected to each other through a
range of discourse relations (see, among others, Gernsbacher and
Givon, 1995;Graesser et al., 1997;Noordman and Vonk, 1997).
In the present study we are concerned only with relational
aspects of discourse organization. Discourse relations usually
connect events and situations described in propositions, and,
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therefore, cross the bounds of isolated propositions (cf.
Hobbs, 1979;Mann and Thompson, 1986;Sanders et al.,
1992, 1993). Yet, elements at a lower discourse level, within
propositions, also contribute to discourse connectivity. For
example, relations between topic and comment contribute
substantially to information packaging.
In discourse, both explicit and implicit devices signify links
between propositions, and between groups of propositions (e.g.,
Mann and Thompson, 1988;Kruijff-Korbayová and Steedman,
2003). Our approach encompasses both conceptual relations in
discourse connectivity and overt linguistic signals. This approach
is especially appropriate in the signed modality, where formal
syntactic machinery for signaling these relations may be missing,
controversial, and/or lacking empirical support, particularly in
new sign languages.
Not all discourse relations contribute to complexity in the
same way. In Types and Levels of Discourse Relations and Their
Relative Complexity and Increasing Complexity in Language
Ontogeny, Diachrony, and Typology, we introduce the types
and levels of discourse organization that we adopt in terms of
complexity, and briefly survey empirical evidence.
Types and Levels of Discourse Relations and Their
Relative Complexity
A significant part of the discourse literature has focused on the
question of how various sets of relations should be organized
and what principles guide their groupings. Sanders (1997,
121) determined the properties common in all relations, in
order to define “the relations among the relations” relying on
the assumption that some discourse relations are more alike
than others (see also Mann and Thompson, 1988). Within an
organized system of discourse, its segments2may bear relation
to the system as a whole, or to each other, or to both. On these
grounds, some discourse relations are described as more basic
and others as more complex. We adopt here the general principles
of an approach that distinguishes relations based on two criteria:
types and levels (Sanders et al., 1992;Givón, 1995).
The first criterion, relation type, distinguishes between degrees
of connection between the units of discourse, ranging from
additive (weakly connected) to asymmetric (strongly connected)
relations. In additive3relations, basic units bear relations to the
system as a whole but not to each other (Sanders et al., 1992).
A more complex type of relation is symmetrical (e.g., Cristofaro,
2008;Givón, 2009a;Nir and Berman, 2010): units of the same
rank are related both to the system as a whole, and to each other.
Symmetric type relations can involve either coordinate (e.g., I
walk to work and also walk back home) or contrastive relations
(e.g., I walk to work but drive back home). In a third type of
organization, known as asymmetric relations, the units are not
of the same rank; one unit is dependent on another unit in the
system (e.g., Cristofaro, 2008;Givón, 2009a;Langacker, 2009;Nir
and Berman, 2010; see Table 1).
The units in example (1) in Table 1, show additive relations
within a proposition, where the only relation between them is
2Discourse segments can be characterized as formally distinct units of discourse.
3Additive relations are also known as iterative (Givón, 2009b).
TABLE 1 | Examples from our data for each relation.
Within proposition Across proposition
Additive (1) My father was
[hammering], [sawing], [and
painting].
(4) [I talked with Dani], [Kate
danced with Peter], [and
Sveta ate her sandwich].
Symmetric (2) [As well as sign
language (being important)],
[I don’t rule out the
importance of spoken
language].
(5) (The basketball game), it
was [Tel Aviv] vs. [Haifa].
Asymmetric (3) [My father and his wife]
[they both had to stay].
(6) (Doctor said). . .
[because you’re not getting
vitamin B12], [you need
injections].
that they belong to the same whole. The order of items in additive
relations does not change the meaning of the proposition.
Example (2) is different because the units of the same rank
are related symmetrically to each other through contrast. In
(3), the elements of the utterance are not of the same rank so
that the topic, ‘My father and his wife,’ serves as an anchor for
the subsequent predication. We can see that they are related
asymmetrically, since the former serves as a background for the
latter, and their order cannot be reversed without changing the
meaning of the utterance.
The second criterion relates to the level of language items
across which the relations hold. Thus, the same major types of
relations exemplified in 1–3 can also hold across propositions,
exemplified in examples 4–6, resulting in more complexity within
the same types of relations.
Asymmetrical relations across propositions are prototypically
signaled by syntactically subordinate constructions, as in
(6), where the asymmetric temporal relations between two
propositions are manifested explicitly by the subordinating
conjunction and different tense agreement in the English
translation.
If categorization of discourse relations in terms of complexity
is significant apart from purely descriptive considerations, it
should prove relevant in areas such as language development,
both synchronically (language acquisition) and diachronically
(language change). In both areas, there is substantial supporting
evidence for the increasing complexity of these relations.
Increasing Complexity in Language Ontogeny,
Diachrony, and Typology
The increasing complexity of discourse relations is reflected in the
order of development of its markers, both in ontogeny (language
acquisition) and in diachrony (e.g., grammaticalization, pidgin
and creole studies). Such general trends are reported in the works
of Bloom (1973),Bowerman (1973),Bates (1976),Scollon (1976),
Givón (1979,1987,2009a), Bickerton (1981),Bickerton (1990),
Heine and Kuteva (2007),orSanders et al. (2009), and others.
In stages of child language development, increasing
complexity is well documented (Bloom, 1973;Bowerman,
1973;Scollon, 1976;Ochs and Schieffelin, 1979;Givón,
2009b). The focus has typically been on the use of connectives
such as conjunctions reflecting age-related command of
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complex syntax (e.g., Jisa, 1987;McCabe and Peterson, 1991;
Berman, 1996;Akinci and Jisa, 2000;Diessel, 2004), where
syntactic development progresses from linear juxtaposition.
Relations between clauses are first implicit (e.g., Hobbs,
1979;Diessel, 2004) then coordination is acquired, followed
by subordination and embedding (Verhoeven et al., 2002).
This progression corresponds to additive, symmetrical, and
asymmetrical relations, within and across propositions in the
Type and Level Approach adopted in this study.
Similarly, in historical change, in both established languages
and in creole genesis, the development from additive relations
to asymmetric relations across propositions has gained extensive
empirical support (e.g., Heine and Kuteva, 2007;Hilpert
and Koops, 2009;Koops and Hilpert, 2009). In addition,
connective devices initially used at the level of the proposition
often grammaticalize into various types of connectors
across propositions. For example, the clause-final locative
demonstrative ia ‘here,’ originally characterizing a location in a
single proposition in Tok Pisin, developed to signal particular
relations across propositions – between relative and main clauses
(Sankoff and Brown, 1976).4
Conventionalization, Convergence, and Reduction
A critical part of language emergence and change is
conventionalization. Through conventionalization, a language
community converges on a consensus about the relationship
between forms and their meanings. In a comparison of two
young sign languages, ABSL and ISL, Meir and Sandler (in press)
showed that language begins with extensive variation at all levels
of structure, before gradually converging on conventionalized
forms. They also showed that different parts of the grammar (e.g.,
phonology and different kinds of morphology) conventionalize at
different paces, so that different aspects of linguistic organization
should be evaluated in their own right, a direction that we take
here.
In established languages, diachronic changes are sometimes
driven by a tendency to distinguish grammatical meanings
with distinctive forms, to make language more precise and, as
a result, more explicit. For example, the Latin subordinating
concessive conjunction quamvis started out as a clause-internal
marker of speech-situation evocation meaning something like
‘as you want’ and grammaticized to a marker of concessive,
adversative relations between propositions. As often happens in
grammaticalization, at the beginning of this process, quamvis
occurred interchangeably with other conjunctions, but gradually
became the most frequent marker of the concessive/adversative
relation in Latin, interpreted as ‘although,’ while the usage of
other variants for this function decreased drastically. We will
report a similar process of convergence and conventionalization
in ISL.
4Sociolinguistic factors can affect the degree of language complexity in young
and emerging languages. This is mostly as a result of external factors, such as
the degree of contact with other languages, the size and social structure of the
language population, and the number of second language users (Bolender, 2007;
McWhorter, 2007;Wray and Grace, 2007;Lupyan and Dale, 2010;Meir et al., 2012;
Trudgill, 2012;Meir and Sandler, in press in signed and spoken language research).
The comparison of ISL with other languages using the same criteria is a topic for
future research.
In the process of conventionalization and specialization,
the form of quamvis was also phonetically reduced – another
measure of language emergence and conventionalization. The
principle of economy (reduction of effort in the production of
form) constantly interacts with the frequency of a language item,
as demonstrated for example by Bybee (2010, 2013) in a series
of studies on spoken languages. It is well known that the most
frequent expressions tend to be reduced phonetically (see Zipf,
1935). In other words, information that is redundant because it is
recoverable and/or predictable, either due to frequency of use or
grammatical redundancy, tends to be reduced.
In sum, increase in complexity is accompanied by the
development of linguistic signals specialized for a particular
discourse function in a systematic (conventionalized) way, as well
as by the reduction of articulatory effort (Lehmann, 2008;Bybee,
2010). It should be emphasized that language changes do not
happen overnight; old forms do not give way to new without
oscillation or variation. Changes occur gradually, as “orderly
heterogeneity” is a fundamental characteristic of language (e.g.,
Weinreich et al., 1968;Labov, 1981). For example, in Labov’s
(1981) discussion of the asplit (i.e., tense/lax) in Philadelphia
there is a steady movement from 0% tense ain the oldest speakers,
a slight tendency toward tensing in speakers 40–60 years
old, about 30% tensing among speakers in their twenties and
thirties, and almost 50% among pre-adolescents and adolescents.
Moreover, this growth in the tensing pattern does not occur
evenly across the gamut of lexical items, but rather progresses
incrementally by particular lexical items. Similar patterns of
change have been observed for sign languages (Meir and Sandler,
in press).
Research Questions and Hypotheses of
the Present Study
The present study elaborates and further supports the Type
and Level Approach to understanding linguistic complexity and
its emergence. We extend the approach to a language in a
different physical modality from that of spoken language – a sign
language. As ISL is a young language and some of its earliest
users can still be recorded, we can track the development of
complexity over time. We take advantage of the unique relation
in sign languages between bodily articulations and linguistic
forms, to investigate the accumulation of more complexity, more
convergence in form, accompanied by reduction in this young
language.
We hypothesize that the Type and Level Approach predicts
the course of emergence of linguistic complexity in ISL – from
more basic additive relations to the more complex asymmetric
relations, and from the lower, within-proposition discourse level
to a higher, across-proposition level, as schematized in Figure 3
below.
In addition to increased complexity, we hypothesize that
markings will become more systematic (i.e., more frequently used
in the expected context), that signers will converge on fewer
types of marking for a particular relation (like quamvis in Latin
described above), and that their form will be reduced as the
language matures.
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FIGURE 3 | Schema of complexity cline.
METHODOLOGY
This project follows the approach introduced in Sandler (2012),
by analyzing language from the outside in, paying particular
attention to the bodily articulators in sign languages and
evaluating the linguistic structures that they manifest according
to their meaning and discourse relations. Here we present
evidence from ISL, a young sign language (about 90 years old)
for the gradual emergence of linguistic complexity – from basic
to complex language forms – through the gradual increase in
systematicity and specificity of bodily signals.
To this end, we investigate the emergence of three relations,
varying in terms of relation type (additive, symmetric, and
asymmetric) and level (within or across propositions). We
compare the frequency and systematicity of each relation
produced by fifteen signers of different ages in 2 min each
of spontaneous narrative. While spontaneous data are less
controlled than elicited data, spontaneous data have the
advantage of being natural and more ecologically sound than
elicited data in terms of information structuring and the relations
among constituents.
We adopt the apparent time hypothesis (Labov, 1963;Sankoff,
2006), which holds that language users do not change their
language significantly after young adulthood, so that the language
of older generations is a reflection of the state of the language
in their youth. A comparison between older and younger signers
enables us to make inferences about language emergence from
the outset, since the language analyzed in this study is less than
100 years old.
According to the Type and Level Approach, we expect
additive constructions to be present in the earliest stages of
sign language emergence, as discussed in Research Questions
and Hypotheses of the Present Study. Therefore, we expect
signers of all ages to show similar frequency rates for additive
constructions. Conversely, since we expect constructions with
more complex relation types, such as symmetric and asymmetric
relations, to appear in later stages of language emergence, we
predict that younger ISL signers will show more examples of
these relations than older ISL signers. Assuming that relations
across propositions are more complex than relations within
propositions, we expect older signers to convey symmetric and
asymmetric relations within propositions more often than across
propositions, and younger signers are expected to mark more
across proposition relations than older signers.
Participants
Fifteen deaf ISL signers were filmed as part of this study. They
represent three age groups, five in each: younger (18–29), middle
(30–54), and older (55+years). Participants ranged in age from
18 to 68 years (mean age: 42 years, 6:9 male: female), and their
preferred language was ISL.
The oldest group of signers in our study have varied language
backgrounds. Some were born outside of Israel, immigrating to
Israel at a young age. Despite this, the first and most preferred
language for the older signers in our dataset was ISL. The
language of this group, like subsequent age groups, is by no
means a home sign system. It qualifies fully as a language,
since it has a large, conventionalized vocabulary and linguistic
organization; it is the preferred language of its users; and it fulfills
all communication and social functions of language throughout
the larger community of 10,000 (See Meir and Sandler, 2008 for
details). We did not control for heterogeneity (i.e., variation in
terms of education and literacy), because it is this sort of variation
that characterizes the language of this age group, and which was
the model for the younger groups. Younger signers in our dataset
are less heterogeneous than older signers, as they were exposed to
peers and adult models from a young age, and attended school in
deaf education frameworks.
All participants of all three age groups either grew up in
deaf families (70% participants in the two younger groups) or
have signed from a very young age, and all use sign language as
their primary means of communication. This was confirmed by
a detailed questionnaire containing information about language
use throughout the lifetime of the participants. Consent was
obtained from all participants for their involvement in the
filming, and signers were compensated for their time. Filming
took place at the University of Haifa Sign Language Research Lab.
Task Procedure
Participants were asked to tell a personal life story to a deaf
native signer research assistant of middle age. Narratives ranged
in length from 3–40 min. We extracted 2 min from the middle
of each narrative for this study (30 min of data in total). We did
not analyze the beginnings of narratives as our aim was to analyze
naturalistic signing, when the signer had become accustomed to
the presence of the camera.
Coding Units of Analysis and Discourse
Relations
Narratives were divided into intonational phrases based on
manual signals. Previous research has demonstrated that manual
signals, such as pause, hold and reduplication, correspond to
phrase-final lengthening in ISL, and are reliable signals of
intonational phrase boundaries, often accompanied by blinks in
ISL5(Nespor and Sandler, 1999). The intonational phrase is the
main domain of non-manual intonational contours. In other
words, facial expression and head movements, corresponding
to intonation, systematically align with intonational phrase
boundaries (Nespor and Sandler, 1999;Dachkovsky et al., 2013).
5Eyeblinks were also found to align with intonational phrase boundaries by Wilbur
(1994).
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As in spoken languages (e.g., Chafe, 1984;Du Bois, 1985),
intonational phrases can be considered as roughly corresponding
to thought units. In this study the intonational phrase was the
basic unit in the analysis of the distribution of non-manual
signals marking discourse relations. All coding was completed
using ELAN (Crasborn and Sloetjes, 2008), a video annotation
software.
Each discourse relation was identified based on reliable
markers in the sign language literature (see Table 2). The first
relation, additive, is often described in the sign language literature
as listing. It is expressed by a movement of the head, often in a
thrusting action, along the forward-back axis, with or without
movement of the torso. This has been noted in a number of
sign languages (Wilbur and Patschke, 1998 in ASL; van der Kooij
et al., 2006 in NGT; Sandler, 2012 in ABSL; Puupponen, 2017
in Finnish Sign Language). The second relation, the symmetric
relation, is marked by opposite torso or head leans (van der Kooij
et al., 2006 in NGT; Man, 2008 in Hong Kong Sign Language;
Crasborn and van der Kooij, 2013;Puupponen, 2017 in Finnish
Sign Language). A similar contrastive display has been noticed for
ISL (Meir and Sandler, 2008).
Finally, a number of articulations of the body have been
associated with asymmetric relations. For example, raised brows
has been shown to characterize subordinate constructions, such
as conditionals and temporal clauses, as well as asymmetric
relations within propositions such as between topic and
comment (Liddell, 1980;Cecchetto et al., 2006;Dachkovsky and
Sandler, 2009;Gökgöz, 2009;Fenlon, 2010). These relations are
by definition asymmetrical because one constituent provides
background information for the other constituent. Another
marker, forward torso lean and/or forward head movement,
marks asymmetric relations across the proposition, e.g., in
conditional and relative clause constructions (Dachkovsky and
Sandler, 2009;Dachkovsky et al., 2013;Dachkovsky, 2017).
Forward head movement commonly combines with raised brows
to mark dependent constructions (Nespor and Sandler, 1999;
Dachkovsky and Sandler, 2009;Dachkovsky et al., 2013).
In total, for the present study we coded 17 articulations. They
included movements of the torso (thrust, forward, back, tilt left,
tilt right, turn left, and turn right), and head (thrust, forward,
back, tilt left, tilt right, turn left, turn right, up, and down), as
well as eyebrow raises. We made the distinction between head or
torso thrusts or head and torso movements. The two share the
same direction, forward and back, while a thrust has a quicker
movement.
Data Analysis
From here on, we use the term ‘marking’ to refer to the
articulations of the body, which accompany a given construction.
We are aware that this term is traditionally restricted to
conventionalized grammatical units such as morphemes, but here
we follow the sign language literature which has long studied
‘non-manual markers,’ and we use the term in a broader sense,
to mean any articulatory action corresponding to a linguistic
unit, agnostic with respect to the degree of conventionalization.
Another caveat before we proceed: apart from brow raises, our
coding did not include facial expressions6, and this awaits future
research.
We investigate the frequency in the marking of three
different types of relations: additive, symmetric, asymmetric.
We follow these relations at two levels of discourse: within
and across propositions. Together with discourse relations, we
investigate three parameters that accompany the increase of
language complexity, as described in Measuring Relations and
Complexity in Discourse: (1) systematicity, (2) convergence
on a particular marker, and (3) articulatory reduction of these
markers, which is also an indication of their conventionalization.
We measure (1) systematicity in terms of frequency of marking
of these relations – we calculate the proportion of intonational
phrases marked with each relation during 2 min of narrative
and (2) convergence in terms of number of marker variants
for the same function. Finally, we measure (3) the reduction of
articulatory effort by (a) number of articulators and (b) type of
articulators, where a decline in the number of articulators as well
as a reduction in size of articulators is an indicator of a reduction
in marking. For example, the head is a smaller articulator and
its activation results in less muscular activity and displacement
in space than the torso. Each specific marking (e.g., torso thrust)
was calculated as a fraction of the total marked instances for each
relation (e.g., 20% of additive relations marked by a torso thrust).
The results of these analyses were further correlated with the
complexity of discourse relations in order to see if the changes in
the parameters of systematicity, convergence and reduction are
indicative of an increase in complexity.
A total of 1473 tokens were analyzed. For every intonational
phrase, we counted whether each relation was present, in order
to make the tokens binary. For our study, we were interested
in whether the frequency of each relation is predicted by the
signer’s age. To this end, we included age as an independent
and continuous variable (i.e., entering individual ages in years
rather than categorical age groups). We conducted multivariate
logistic regressions using a program known as Rbrul (Johnson,
2009) for each individual relation. Rbrul quantitatively evaluates
the influence of multiple factors on variation (Rand and Sankoff,
1990). We included participant as a random effect in order to
account for the effects of individual differences (Baayen, 2008;
Jaeger, 2008).
RESULTS
Relations per Intonational Phrase Unit
The total number of relations produced in our dataset was
755. On average, each signer produced 50 relations of varying
degrees of complexity during 2 min of spontaneous narrative. We
also found that on average signers across age groups produced
similar numbers of intonational phrases during 2 min of narrative
(O= 100, M= 95, Y= 100).
Table 3 presents the average percentage of all intonational
phrases containing each relation, displayed by each age group.
6For a study of the emergence of a particular structure in ISL that explicitly
incorporated facial expression, see Dachkovsky (2017).
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TABLE 2 | Marking for each relation in ISL.
Relation Gloss of ISL example
and translation
Marking in ISL Example of ISL marking
Additive within
proposition (no
examples of additive
across proposition)
[FATHER] [HAMMER]
[SAW] [PAINT]
My father was hammering,
sawing, and painting.
Head thrusts
HAMMER (head thrust)
Symmetric within
proposition
[TEL-AVIV] [HAIFA]
[COMPETE]
It was Tel Aviv vs. Haifa.
Contrasting head
and/or torso positions
TEL-AVIV (torso and head tilt right) HAIFA (torso and
head tilt left)
Symmetric across
proposition
[ALSO LANGUAGE
SIGN-LANGUAGE] [ALSO
ME NO RULE-OUT
IMPORTANT ORAL]
As well as sign language
(being important), I don’t
rule out the importance of
spoken language.
Contrasting head
and/or torso positions
ALSO (head tilt left) RULE-OUT (head tilt right)
Asymmetric within
proposition
[TWO-OF-THEM WIFE
FATHER] [TWO-OF-THEM
STAY]
My father and his wife they
both had to stay.
Head forward, brow
raise, and retraction
FATHER (head forward, brow raise) STAY (retraction)
Asymmetric across
proposition
[BECAUSE B-12 NO]
[NEED INJECTION]
(Doctor said). . .because
you’re not getting vitamin
B12, you need injections.
Head forward, brow
raise and retraction
NO (head forward, brow raise) INJECTION (retraction)
The underlined words are the signs represented in the images.
Some relations appear in similar distribution across all age
groups. For example, additive constructions are present in
0.12 for younger, 0.13 for middle and 0.10 for older signers.
Other constructions appear to be more frequent for some age
groups than for others. For example, asymmetric relations across
propositions (e.g., clausal dependencies) are more frequent in the
narratives of younger signers (0.08) compared to older signers
(0.01). We now present our statistical findings for types and levels
of relation, leading us to an interpretation of the data relative to
our hypotheses.
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TABLE 3 | Proportion of relations per intonational phrase.
Construction Older Middle Younger Total
Additive 0.098 0.13 0.118 0.346
Symmetric within
proposition
0.018 0.037 0.042 0.097
Symmetric across
propositions
0.03 0.061 0.108 0.199
Symmetry 0.146 0.228 0.268 0.642
Asymmetric within
proposition
0.116 0.12 0.074 0.31
Asymmetric across
propositions
0.018 0.04 0.076 0.134
Asymmetry 0.134 0.16 0.15 0.444
Total number of intonational
phrases
500 475 500 1475
Types of Relations
We investigated age-related differences for additive, symmetric
and asymmetric constructions, using statistical methods, to
see whether the presence of a particular relation type is
predictable by a signer’s age. The simple, additive type of
construction occurred at the within-proposition level only, and
was common across age groups. Multiple regression analysis
reveals no significant differences with age for additive relations
(p>0.05). However, presence of symmetric constructions (log-
odds7−0.029, p= 0.015) and asymmetric constructions (log-odds
−0.014, p= 0.0233) was significantly predicted by age. The results
show that these relations are used significantly more by younger
signers. The results are plotted as percentages in Figure 4 below.
Levels of Relations
For levels of relations (within or across propositions), we
investigated whether there were any age-related differences. Here
we found a difference between the two levels. The data show
similar numbers of symmetric and asymmetric relations within
propositions across all age groups – there were no significant
age-related results for symmetric or asymmetric relations within
propositions. While no significant age differences were found
for symmetric constructions across propositions (p>0.05),
we did observe a trend, such that younger signers mark
symmetric constructions across propositions more than older
signers (Y= 11%, >M= 6%, >O= 4%). We expect this result
to be significant with the addition of more tokens.
For asymmetric constructions across propositions (e.g.,
main/subordinate constructions, i.e., embedding), age was found
to be statistically significant. Multiple regression revealed that
presence of these relations was predicted by age (log-odds
−0.043, p<0.01), with significantly more relations found in the
signing of younger signers.
7Log odds measure the strength of the relationship between a factor (in this
case, age) and a dependent variable (in this case, presence of a relation type
in each intonational phrase). Results with positive log odds, above 0, indicate a
positive correlation and results with negative log-odds, below 0, indicate a negative
correlation between the variables - the higher the value the stronger the correlation.
Convergence in Marking of Relations
Our results point to increasing convergence; that is, there is
less variation in the ways in which relations are marked in
the younger signers. The findings for each relation are as
follows:
(a) For the marking of additive relations, older signers mark
these relations with a number of coexisting variants, with
similar frequencies (torso thrust 30%, head and torso thrust
19%, head thrust 25%, etc.) Younger signers employ the
same variants as the older signers, but they show clear
convergence in the direction of one variant for the marking
of additive relations: head thrust 41%.
(b) For asymmetric relations within the proposition, the main
marking used by older signers is manual timing, i.e., phrase
final lengthening (32%), followed by a number of other
frequent variants (brow raise and forward head movement
18%, brow raise alone 15%, and forward head movement
alone 12%). Younger signers, however, converge toward
two main signals making up the majority of the marking
(brow raise and forward head movement 35% or forward
head movement alone 38%).
(c) While 44% of asymmetric relations across propositions are
marked with a brow raise and forward head movement
by older signers, the majority of the marking (56%)
is randomly divided among other unrelated signals
represented by single occurrences (e.g., head tilt, head turn,
or brow lower). Younger signers again show more efficient
and systematic use of the body, using only two major
variants in equal distribution, one a reduced version of
the other (brow raise and forward head movement 34% or
forward head movement alone 34%).
(d) For symmetric relations within propositions, older signers
use three distinct variants (torso and head tilt 50%, torso tilt
25%, and head tilt 25%) while all of the marking for younger
signers is attributed to two variants, i.e., articulation by one
articulator or the other (head tilt 53% and torso tilt 47%).
(e) For symmetric relations across propositions, we find no
clear reduction in the number of variants used across age
groups. That is, we do not see convergence on particular
variants. Instead, we see a reduction in the number and type
of articulators used (reported in Changes in Number and
Type of Articulators below).
Changes in Number and Type of
Articulators
Further analyses of the data reveals differences in the number and
type of articulator activated. We find three main age differences;
the marking of relations by younger signers is characterized
by: (a) fewer articulators, (b) less use of the torso, and (c)
composites are split into individual markers. We present the
findings below:
(a) Fewer articulators – we collapsed our findings to consider
the average number of articulators used to mark a discourse
relation by signer age group (see Table 4). Younger signers
in all relation types and levels are more likely to use a single
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FIGURE 4 | Percentage of intonational phrases containing each relation, displayed by age group.
TABLE 4 | Average percentage of articulators per discourse relation.
Age group 1 Articulator 2 Articulators 3 Articulators Manual
timing
Older 38.6% 45.2% 7.4% 6.6%
Middle 47.2% 45% 5.2% 2.6
Younger 63.8% 33.8% 2.4% 0%
articulator to mark a relation (64%) than older signers
(39%). Older signers favor the use of two articulators in
most cases.
(b) Less use of the torso – in additive relations and symmetric
relations across propositions we see a reduction in the use of
the torso across age groups, with younger signers using the
torso less than older signers. Asymmetric relations, within
and across propositions, rarely use the movement of the
torso and therefore we do not see any change across the age
groups for this parameter.
(c) Composites split into individual markers – in nearly
all relations, older signers tend to use a composite of
articulators simultaneously for the same relation (e.g.,
torso and head tilt simultaneously for symmetric within
proposition). Younger signers, rather than simply moving
toward the use of one dominant marker exclusively, split
the composite into individual articulators and use either
one of the articulations used in the composite (e.g., torso
tilt or head tilt for symmetric within proposition). We
discuss the implications of this trend in the Discussion:
Bodily Marking Emerges Gradually. In Figure 5 below,
FIGURE 5 | Decrease in multiple marking of symmetric relations within
propositions.
we categorize the use of head and torso movements
in symmetric relations and demonstrate the reduction
in composites and the increase in individual head
or torso use (composities: O= 67%>,M= 22%>,
Y= 5%).
While the patterns across age groups are clear, we do find
some variation at the level of individual signers, as shown
in Figure 6. Despite this individual variation, results were
significant at the age group level, a finding to which we return
below, in Convergence: Increased Systematicity of Bodily
Marking.
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FIGURE 6 | Variability of the marking of symmetric relations within proposition.
Signer 1, 2, 8, and 15 showed no examples for this relation.
DISCUSSION: BODILY MARKING
EMERGES GRADUALLY
Our results suggest that a signer’s age – and according to our
analysis, the age of the language – is an important predictor
of frequency, systematicity, and complexity of relation marking.
Frequency of marking varies depending on relation type and
level. Our results indicate that younger signers mark more
symmetric and asymmetric relations than older signers, despite
the fact that all signers produced similar numbers of intonational
phrases. There were no significant differences in the frequency of
marking for simple additive relations, however. We also found a
difference between the frequency of asymmetric relation marking
depending on whether they were relations within or across
propositions, with younger signers marking more asymmetric
relations across propositions than older signers. Systematicity of
marking differed across age groups. While older signers used
larger articulators (the torso) and often redundantly marked
relations with combinations of articulations, younger signers
used the torso less, and they used fewer articulators, and often
fewer composites, for a given relation. In the next sections, we
discuss how our findings may be interpreted in terms of language
emergence.
Similarity in Number of Thought Units
Across Age Groups
Interestingly, we found no difference in the numbers of
intonational phrases produced across age groups. All signers
produced roughly 100 intonational phrases during the 2-min
narrative. Similar results were found for ABSL (Sandler et al.,
2011). The number of signs in an intonational phrase and the
internal complexity increased for younger signers, as did the
speed of signing, but the number of intonational phrases was
constant. In this study, we found that propositions produced by
older signers consisted of fewer signs than propositions produced
by younger signers. Based on the proposed correspondence
between intonational phrases and thought units (Chafe, 1984;
Du Bois, 1985), this finding suggests that humans generally
conceive of and express thought units at the same rate, regardless
of the internal linguistic complexity of each unit and of their
interrelations.
This finding is important in verifying our results as it indicates
that older signers are not simply marking fewer relations because
they produce fewer or less complex thought units – instead, it
strengthens our finding that older signers simply do not have
the linguistic means for marking relations. The recruitment of
different bodily articulators for different linguistic purposes takes
time to emerge in a young sign language.
Simple Adjacency Emerges Before
Dependency
We suggest that those relations that are marked statistically more
frequently by younger signers are undergoing change; that is,
these relations are increasing as the language matures, while those
used similarly across age groups are not undergoing change.
In terms of language emergence, relations that are no longer
undergoing change with age but show a stable use across all
age groups (e.g., additive relations, see Types of Relations) may
reflect earlier constructions that have stabilized in the language
development process. Signals which are still undergoing change
may reflect constructions that conventionalize later, that take
time to emerge in a language. Therefore, since we find no
age differences for additive relations, we propose that additive
relations emerge before symmetric and asymmetric relations,
and that relations within proposition (both symmetric and
asymmetric) emerge before relations across propositions (i.e.,
symmetric and asymmetric across propositions). This supports
our hypotheses, as schematized in Figure 3. Importantly, this
shows that not all relations are marked from the outset of
language emergence, and furthermore, that both the type and
level of relation are important predictors in the ordering of
emergence.
Since the relations that appear in the earliest stages of
language emergence – additive type relations and relations
within propositions – are less complex, we conclude that
simple discourse relations emerge before more complex ones,
as hypothesized. This directionality of language development –
from additive relations to more dependent relations – has
been attested in numerous studies in the framework of
grammaticalization, in well-researched European languages, like
Latin (Lehmann, 2008), and also in less studied languages, such
as Saliba, an Oceanic language (Bril, 2007). Similar findings have
been shown in the development from pidgins to creoles (e.g.,
Bruyn, 1995). However, since all of these studies involve old,
well established languages or languages descending from them,
conclusions could not be drawn regarding the emergence of a
language from scratch. The current study fills this gap.
Convergence: Increased Systematicity of
Bodily Marking
In most types of relations that we analyzed, the marking becomes
more convergent as the language matures. In other words, signers
gradually converge on one or two signals to mark a specific
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
relation from a larger number of signals. In doing so, the degree
of variation decreases over time, with fewer coexisting variants
observed in the signing of later generations (i.e., younger signers).
In some cases, we see that signers in the older generation fail to
explicitly mark the relation at all, only using manual signals to
mark the intonational phrase boundary, or mark relations with a
number of coexisting variants, with no indication of convergence
among older signers toward a particular marker for each relation.
Increase in conventionalization has also been attested in
an earlier study on the grammaticalization of relative clause
constructions in ISL (Dachkovsky, 2017), as noted above. Similar
processes have been attested in child language acquisition in
a number of spoken languages (Berman, 1988, 1996;Givón,
2009b;Tomasello and Brooks, 2016). Results of experiments on
language acquisition point in the same direction. For example,
Hudson Kam and Newport (2009) investigated what learners
acquired when their input contained inconsistent grammatical
morphemes by manipulating the degree of input inconsistency
and the age of the learners (children vs. adult). They demonstrate
that only children, not adults, regularize inconsistent input and
make their output less variable and more systematic. These results
suggest that children may play a unique and important role
in creole formation by regularizing grammatical patterns. And
indeed, this is the trajectory of changes shown for pidgins and
creoles (e.g., Muysken, 2001;McWhorter, 2005;Plag, 2008).
Literature on conventionalization suggests that the effect of
regularization through repeated learning and use is amplified
more when measured at the level of the whole population, rather
than at the level of an individual language user (Smith and
Wonnacott, 2010). The study reported here comes to exactly
the same conclusions, but the evidence comes from a language
in the visual modality. Specifically, we demonstrate that the
convergence on specific articulators and increase in systematicity
are a cumulative result of comparison across the age groups (see
Figure 5 above), whereas individual signers display considerable
variability in their signing, as shown in Figure 6.
Reduction of Marking in Terms of
Number and Type of Articulators
So far we have demonstrated that as the language matures there
is an increase in the frequency and systematicity of marking
which directly corresponds to the degree of complexity of these
relations. In addition to this, our findings show a gradual
reduction in the number and type of articulators, in line with
grammaticalization studies in established languages, as outlined
below.
Type of Articulators
In addition to the number of articulators, we also find a change
in the type of articulator involved in marking. For symmetric
relations, older signers typically displace the head and torso
together (see Figure 7). Younger signers, however, in most cases
engage only the head or only the torso in the marking of relations
(see Figure 8). The former change, from head and torso to
only head, shows that the use of a larger, grosser articulator
(the torso) is replaced by a smaller, subtler articulator (the
head).
A comparable change has been observed in the use of different
arm joints – studies on sign language acquisition have found
that signers change from first using joints closer to the body
(e.g., movement of the shoulder) to using joints further from
the body (e.g., movement of the elbow) (Lavoie and Villeneuve,
1999;Takkinen, 2003), causing reduction in the overall size of
the sign. This also resembles findings by Mineiro et al. (2017),
in which signing size decreased in the early stages of a new
sign language. It may be that signers of a new language become
gradually more efficient in the use of their articulators and that as
a result signing becomes reduced as the signer is able to reduce
their production effort. This seems to hold true in studies on
young sign languages with later generations of signers using their
bodies in a less holistic way compared to earlier generations in the
marking of various linguistic functions (Kegl et al., 1999;Aronoff
FIGURE 7 | Marking of a symmetric relation by an older signer with opposite tilts of head and torso together.
head and torso tilt left head and torso tilt right
EXIST FOOD NOT-EXIST FOOD
Sometimes there was food and sometimes there wasn’t food (The underlined words in the glosses above are the words signed in the corresponding figures.).
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
FIGURE 8 | Marking of a symmetric relation by a younger signer with opposite head-only tilts.
head tilt right head tilt left
BEFORE DOCTOR HE REPLACE DIFFERENT NEW DOCTOR SHE SIGN GOOD
et al., 2003). Older signers in NSL and signers of ISL (compared to
ASL) typically used their whole bodies for representing character
viewpoint (i.e., overt constructed action, whole-body classifiers).
While reduced effort might account for this replacement of larger
articulators (e.g., torso) with smaller articulators (e.g., head), this
does not explain why younger signers in ISL continue to use the
torso as a relation marker, without moving the head. In the next
section, we propose that signers benefit by separating the use of
the torso and the head in order for one to be made available to
participate in other linguistic functions.
Number of Articulators
Generally, we see a decrease in the number of articulators
when we compare across the different age groups. Older signers
tend to use multiple articulators – for example, the signer
in Figure 9 moves her head forward, raises her eyebrows
and turns her head, compared to younger signers who use
a single articulator for the marking of asymmetric relations,
such as dependencies (typically, subordination, see Figure 10) –
for example, with only forward head movement. This change
across age groups reflects a diachronic change, such that
there is a decrease in the number of articulators used for
the marking of these discourse relations as the language
matures.
Less Is More: Implications for
Compositionality
In later stages of the language, signers use fewer articulators
to mark a single linguistic function. What we see here is a
reduction in redundancy of articulator marking as the language
evolves. During language emergence one might expect that
redundancy of feature marking may increase in order to improve
comprehensibility (e.g., Pinker and Jackendoff, 2005;Bazzanella,
2011). That said, languages must find a balance between
comprehension and economy (Zipf, 1949). ISL at only 90 years
of age is considered to be a young sign language8, and yet studies
of its development have shown that it has changed dramatically
relative to other sign languages of a similar age in villages and
towns in Israel (Padden et al., 2010a;Meir and Sandler, in press).
This has been attributed to the size and heterogeneity of the ISL
population, as well as to its use in a range of different domains
including education, interpreting programs and the media (Meir
et al., 2012). As a result, it is perhaps unsurprising that we see a
reduction in redundancy of features in this language, as we find
in spoken languages also (e.g., Jaeger, 2010;Bazzanella, 2011).
Considering the mixed backgrounds of older deaf signers in our
dataset, we might expect to find clearer patterns of reduction
in older signers of ABSL, where the sign language community
receives relatively little contact from other languages, spoken or
signed.
With decreased redundancy and increased systematicity come
a number of advantages. In the case of sign languages, by using
one fewer articulator in the marking of a specific function, the
signer is able to recruit that articulator to mark a different
function (Sandler, 2012, 2013 for ABSL). Simultaneous markings
of different functions by different articulators do not stand
out in our dataset, which we attribute in part to the fact that
we restricted our analysis to markers of a subset of discourse
relations. For example, markers of information status, indicated
by facial expressions (Dachkovsky et al., 2013) and independent
actions of the non-dominant hand (Liddell, 2003;Sandler, 2012,
under review), were not included in the analysis. We predict
that the inclusion of such structures in future research will show
8In comparison with British Sign Language, at 300 years old, which is considered
to be old among established sign languages (Kyle and Woll, 1985).
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
FIGURE 9 | Marking of an asymmetric relation across propositions shown by an older signer – torso shift, forward head movement, head turn, and eyebrow raise
accompanies the first part of this construction.
torso and head turn, brow raise, head forward head tilt left
FATHER SAY YOU TWO THREE ME ONE GO
My father said that if there had been two or three of us (girls), then I could have gone.
FIGURE 10 | Marking of an asymmetric relation across propositions shown by a younger signer – forward head movement accompanies the first proposition When
my mother needed urgent treatment and backward head movement accompanies the second proposition, we did not know what to do.
head forward head back
SHE MOTHER EMERGENCY PAST SHE WE THINK WHAT-TO-DO
When my mother needed urgent treatment we did not know what to do.
that increased linguistic complexity is reflected by increased
simultaneous activation of different articulators for different
functions, as demonstrated for ABSL.
However, in the present study, there are some examples of
such simultaneous complexity in young signers. For example, one
young signer produced an utterance containing two relations (see
Figure 11 above). The utterance can be translated as:
[[[When I was at that school,] [they closed the deaf program]],
[and I moved to another school.]]
In this example, the signer marks a symmetric (coordinate)
contrastive relation between the two main constituents by tilting
his torso to the right for ‘When I was at that school, they closed
the deaf program,’ and to the left for ‘and I moved to another
school.’ The first constituent has as its topic ’that school,’ and
topic continuity is marked by keeping the non-dominant hand
(‘nd’ – indexing the location of the school) in the signing space
throughout.
The information provided in the first constituent is further
subdivided into two clauses in an asymmetrical (dependent)
relation to one another (‘When I was at that school’ and ‘they
closed the deaf program’). Here the signer moves his head forward
for the dependent clause, ‘When I was at that school,’ and back for
the matrix clause, ‘they closed the deaf program’ – while keeping
the body position constant throughout this whole complex first
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
FIGURE 11 | Mapping between simultaneous discourse relations and simultaneous articulations. Opposite torso tilts signal the symmetric contrast between the two
major constituents (two different schooling situations); the non-dominant hand (=nd) marks topic continuity; and forward-backward head movement marks the
asymmetric relation between dependent and matrix clauses within the first coordinated constituent.
head forward head back
torso tilt right torso tilt left
[[ME GROW-UP SCHOOL THERE] [END SCHOOL THERE CLOSE DEAF INTEGRATE NO-MORE] [MOVE-HERE]]
[[When I was at that school,] [they closed the deaf program]], [and I moved to another school.]]
constituent, and changing it only for the second constituent, ‘I
moved to another school.’
By separating out articulators for different functions, two
discourse relations can be conveyed simultaneously – symmetry
by torso tilt and asymmetry by head movement – so that the
compositionality of the discourse relations is reflected in the
compositionality of bodily articulations.
CONCLUSION
Differences between the frequency of occurrence and the type
and consistency of marking of discourse relations by younger
and older signers reveal specifically how this young language
becomes increasingly complex over time. The most striking
finding in this regard is that the asymmetrical relations across
propositions – that is, typically, subordination – are significantly
more common in the younger than in the older signers. This
finding is commensurate with a more limited study on ABSL,
where dependent, subordinate structures were found only in
younger second generation signers (Sandler et al., 2011).
We also find here that the marking of the discourse relations
becomes more systematic over time, in that they become more
reliably marked by the same articulators. As the language
matures, the signals become more specialized, with fewer
articulators dedicated to a particular function, and with finer
movements, involving the head more than – and separately
from – the torso. Systematic use of the body for linguistic
organization mirrors the emergence of linguistic complexity.
The overall picture painted by these results is that of a system
that begins with simple relations, unconstrained, redundant
form, and high variability. Thus, while the system of older signers
clearly has linguistic properties, as we have explained, the aspects
of its organization uncovered here are less systematic. We see
gradual change in all of these parameters, resulting in a more
conventionalized, systematic, constrained, and compositional
sign language.
The previous work on ABSL has suggested that the markers
of different discourse functions do not appear all at once.
The present study on ISL expands and enriches that proposal
by demonstrating that the recruitment of the specific bodily
articulators follows a rule-governed functional trajectory – from
less complex to more complex discourse functions. Another
hypothesis put forward by the earlier study, that the earlier stages
of a sign language are characterized by a more holistic use of the
body, was also supported in the present study. The current study
suggests benefits that the specification of the articulators might
contribute in the process of language emergence. Moreover, the
findings here shed light on the complex tug of war between
conventionalization and regularization on the one hand and
variability and diversity on the other (see Meir and Sandler, in
press). A lower number of participants in the previous studies
might have obscured that issue. In addition, until now, little has
been reported at the level of discourse about the path from a
system with idiosyncratic characteristics to a more constrained
and complex sign language. The work we report here reveals steps
along that path.
ETHICS STATEMENT
All participants provided written informed consent to
participate in this study. The study was approved by
the Ethics Committee/IRB of the University of Haifa
(https://resau.haifa.ac.il/index.php/en/policy-requirement/
ethics-committee-institutional-review-board-irb).
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Dachkovsky et al. Constructing Complexity in a Young Sign Language
AUTHOR CONTRIBUTIONS
SD is the lead author. RS and SD completed the data coding
and analysis. RS contributed toward writing the paper. WS is the
principal investigator on the project and contributed toward the
writing and interpreting of the results.
FUNDING
This research has received funding from the European Research
Council (ERC) under the European Union’s Seventh Framework
Programme, grant agreement No. 340140. Principal Investigator,
Wendy Sandler.
ACKNOWLEDGMENTS
We wish to thank Shai Davidi for video and other technical
assistance, Shiri Barnhart for her administrative help, and
Debi Menashe for her ISL expertise. We are grateful to
the participants of GestComp 2017 and the 3rd Usage-based
Linguistics Conference, Jerusalem for their useful feedback.
Special thanks go to all of our deaf participants who were involved
in our study.
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