Prosodic focus marking in Seoul Korean-speaking children: the use of prosodic phrasing

Abstract

Introduction
Prosodic focus marking in Seoul Korean is known to be achieved primarily through prosodic phrasing, different from the use of prosody for this purpose in many other languages. This study investigates how children use prosodic phrasing for focus-marking purposes in Seoul Korean, compared to adults.

Methods
Using a picture-matching game, we elicited semi-spontaneous production of SOV sentences in various focus conditions from monolingual Seoul Korean-speaking children aged 4 to 11 years.

Results
We found that the children varied prosodic boundaries to distinguish narrow focus from pre-focus and broad focus in a largely adult-like manner at the age of 4 to 5; at this age, they did not distinguish narrow focus from post-focus or contrastive focus using prosodic boundaries, similar to the adults. Their use of the prosodic boundaries in distinguishing the focus conditions was not fully adult-like in terms of frequency until the age of 10 to 11.

Discussion
In conjunction with the findings of previous studies on the acquisition of focus marking in Germanic languages, performed using a similar experimental method, our findings suggest that Seoul Korean-speaking children acquire the use of prosodic phrasing earlier than Dutch-speaking children acquiring the use of pitch accent but slightly later than Stockholm Swedish-speaking children acquiring the use of a prominence-marking high tone. These findings imply that the rate of focus-marking acquisition depends on the transparency of the form-meaning mapping between the phonological cue and focus.

Full text

Frontiers in Psychology 01 frontiersin.org
Prosodic focus marking in Seoul
Korean-speaking children: the
use of prosodic phrasing
AnqiYang
1
*, TaehongCho
2, SahyangKim
3 and AojuChen
4*
1 School of Foreign Languages, Tianjin University, Tianjin, China, 2 Hanyang Institute for Phonetics and
Cognitive Sciences of Language, Hanyang University, Seoul, Republic of Korea, 3 Department of
English Education, Hongik University, Seoul, Republic of Korea, 4 Institute for Language Sciences,
Utrecht University, Utrecht, Netherlands
Introduction: Prosodic focus marking in Seoul Korean is known to be achieved
primarily through prosodic phrasing, dierent from the use of prosody for this
purpose in many other languages. This study investigates how children use prosodic
phrasing for focus-marking purposes in Seoul Korean, compared to adults.
Methods: Using a picture-matching game, we elicited semi-spontaneous
production of SOV sentences in various focus conditions from monolingual
Seoul Korean-speaking children aged 4 to 11 years.
Results: We found that the children varied prosodic boundaries to distinguish
narrow focus from pre-focus and broad focus in a largely adult-like manner at
the age of 4 to 5; at this age, they did not distinguish narrow focus from post-
focus or contrastive focus using prosodic boundaries, similar to the adults. Their
use of the prosodic boundaries in distinguishing the focus conditions was not
fully adult-like in terms of frequency until the age of 10 to 11.
Discussion: In conjunction with the findings of previous studies on the acquisition
of focus marking in Germanic languages, performed using a similar experimental
method, our findings suggest that Seoul Korean-speaking children acquire the use
of prosodic phrasing earlier than Dutch-speaking children acquiring the use of
pitch accent but slightly later than Stockholm Swedish-speaking children acquiring
the use of a prominence-marking high tone. These findings imply that the rate
of focus-marking acquisition depends on the transparency of the form-meaning
mapping between the phonological cue and focus.
KEYWORDS
acquisition, focus, prosodic phrasing, prosodic marking of focus, Seoul Korean
1 Introduction
Previous studies on the acquisition of prosodic focus marking in various languages have
revealed that children acquiring a language that relies on prosody or both prosody and syntax
for focus marking show adult-like use of at least some language-specic prosodic focus-
marking cues by the age of 5 and further develop this ability until the age of 10 or 11 (e.g.,
Hornby and Hass, 1970; MacWhinney and Bates, 1978; Wells et al., 2004; orson and
Morgan, 2020, on English; Chen, 2009, 2011a,b; Romøren, 2016, on Dutch; Grünloh etal.,
2015, on German; Romøren and Chen, 2021, on Stockholm Swedish, hereaer Swedish; Yan g
and Chen, 2018, on Mandarin). However, the specic developmental trajectory diers for
children acquiring dierent languages due to typological dierences in prosodic system and
prosodic focus marking (Chen, 2018). e present study is concerned with children learning
Seoul Korean (hereaer Korean), a language that diers from more widely studied languages
OPEN ACCESS
EDITED BY
Joseph V. Casillas,
Rutgers, The State University of New Jersey,
UnitedStates
REVIEWED BY
Yong-cheol Lee,
Hannam University, Republic of Korea
Hyunah Baek,
Ajou University, Republic of Korea
Hanyong Park,
University of Wisconsin–Milwaukee,
UnitedStates
*CORRESPONDENCE
Anqi Yang
anqi.yang@tju.edu.cn
Aoju Chen
aoju.chen@uu.nl
RECEIVED 07 December 2023
ACCEPTED 30 May 2024
PUBLISHED 31 July 2024
CITATION
Yang A, Cho T, Kim S and Chen A (2024)
Prosodic focus marking in Seoul
Korean-speaking children: the use of
prosodic phrasing.
Front. Psychol. 15:1352280.
doi: 10.3389/fpsyg.2024.1352280
COPYRIGHT
© 2024 Yang, Cho, Kim and Chen. This is an
open-access article distributed under the
terms of the Creative Commons Attribution
License (CC BY). The use, distribution or
reproduction in other forums is permitted,
provided the original author(s) and the
copyright owner(s) are credited and that the
original publication in this journal is cited, in
accordance with accepted academic
practice. No use, distribution or reproduction
is permitted which does not comply with
these terms.
TYPE Original Research
PUBLISHED 31 July 2024
DOI 10.3389/fpsyg.2024.1352280

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 02 frontiersin.org
such as Dutch, English, Finnish, German, Swedish, and Mandarin in
that it primarily uses prosodic phrasing in focus marking (Jun, 1993,
2007b; Jun and Lee, 1998).
Focus is prosodically encoded in many languages (e.g., Vallduví
and Engdahl, 1996; Gussenhoven, 2007; Kügler and Calhoun, 2021).
Among the most frequently studied focus types in literature, narrow
focus (i.e., focus on a word of a syntactic constituent, like “the bread”
in (1B)) diers from narrow contrastive focus (i.e., narrow focus
carrying contrast1, hereaer contrastive focus, like “the bread” in (2B))
in contrastivity, and diers from broad focus (i.e., focus over a
constituent larger than a word, like (3B)) in size of focal constituent.
Generally, a word is realized with more prosodic prominence in
narrow focus and contrastive focus than when not focused or in broad
focus. Contrastive focus can berealized with additional prosodic
prominence, compared to non-contrastive narrow focus, in certain
speech styles in some languages (e.g., read speech in Mandarin) (Chen
and Braun, 2006).
(1) A: Look! e dog2, and it holds a painting brush. It looks like
the dog draws something. What does the dog draw?
B: 개가 [빵을]3 그려요.
kɛka p*aŋɨl kɨljʌjo.
e dog [the bread] draws.
(2) A: Look! e bear. e bear looks a bit puzzled. It looks like the
bear looks for something. Iwill make a guess: e bear looks
for the egg.
B: 곰이 [빵을] 찾아요.
komi p*aŋɨl tʃʰatʃajo.
e bear [the bread] looks for.
(3) A: Look! My picture is very blurry. I cannot see anything
clearly. What happens in your picture?
B: [말이 빵을 그려요].
mali p*aŋɨl kɨljʌjo.
[e horse the bread draws].
Regarding the precise prosodic means for achieving prominence,
wedistinguish phonetic implementation (hereaer phonetic means) and
phonological means, following Chen (2009, 2011b, 2018). Specically,
some languages (e.g., Mandarin and Cantonese) rely on phonetic
means. Speakers of these languages vary the phonetic implementation
1 Focus can carry contrastive information, e.g., a correction to a certain piece
of information introduced previously or an alternative to what has been
mentioned already. While the focal items are regarded as being in contrastive
focus in both conditions, the former is also referred to as corrective focus
(Gussenhoven, 2004, 2007). In the present study, weuse “contrastive focus”
instead of “corrective focus” to refer to the former condition.
2 The examples are from the experimental materials of the present study.
The referents are referred to with the definite article in the English glossary
because they had been introduced in a picture-naming task before the
production experiment.
3 The focused constituents are in square brackets in the examples.
of phonological categories such as lexical tones in the dimensions of
duration, pitch, and intensity for focus-marking purposes, without
changing the tonal identity of relevant words (e.g., Xu, 1999, on
Mandarin; Wu and Xu, 2010, on Cantonese). For example, in
Mandarin, a word in narrow focus is produced with a longer duration,
wider pitch span, and higher intensity than the same word in
non-focus, while its tonal category remains intact (e.g., Shih, 1988; Xu,
1999). Other languages (e.g., English, German, Dutch, Swedish, and
Korean) primarily use phonological means to realize prosodic
prominence. at is, speakers make coarse-grained changes in
duration, pitch, and intensity that lead to a change in the phonological
category of prosody. For example, in English, German, and Dutch,
speakers can either accent words with certain types of pitch accents
(e.g., rising vs. falling) or not accent words to distinguish narrow focus
from non-focus (e.g., Gussenhoven, 2004, 2007; Baumann etal., 2006;
Hanssen etal., 2008; Chen, 2009, 2011b); in Swedish, speakers can
either assign or not assign a prominence-marking high tone to the end
of a word for this purpose (Bruce, 2007; Romøren and Chen, 2021).
However, these languages can dier in the transparency of the form-
meaning mapping between the phonological cue and focus, i.e., how
consistent the mapping is. For example, in Swedish, only focused
words are produced with a word-nal high tone. e mapping
between the placement of the prominence-marking high tone and
focus is thus highly transparent. By contrast, in Dutch, both focused
and non-focused words can beaccented with the same type of pitch
accent, e.g., a falling accent in sentence-initial subject-noun phrases
and a downstepped falling accent in sentence-nal object-noun
phrases, regardless of focus status. ere is thus no consistent or
transparent mapping between accentuation and focus (Chen, 2018).
In such cases, speakers vary the phonetic implementation of pitch
accents to distinguish focus and non-focus (Chen, 2009).
Dierences in the transparency of the form-meaning mapping
between the phonological cue and focus can lead to dierences in the
rate of acquisition in prosodic focus marking across languages (Chen,
2018). Previous studies on children acquiring a West Germanic
language, which is relatively less transparent as discussed above, have
shown that while children can already use accentuation to mark focus
by the age of 5, their choice of accent type is not fully adult-like until
the age of 7 or 8 (e.g., Hornby and Hass, 1970; MacWhinney and
Bates, 1978; Wells etal., 2004; orson and Morgan, 2020, on English;
Grünloh et al., 2015, on German; Chen, 2011a,b, on Dutch). In
contrast, in Swedish, which is more transparent in the form-meaning
mapping, phonological focus-marking is acquired earlier (Romøren,
2016; Romøren and Chen, 2021). at is, Swedish-speaking children
are by and large adult-like at the age of 4 or 5 in assigning a
prominence-marking high tone to the end of the word in narrow focus
and contrastive focus conditions. e earlier acquisition of
phonological focus marking in Swedish than in the West Germanic
languages has been attributed to the more transparent form-meaning
mapping between the phonological cue and focus in Swedish
(Chen, 2018).
In the present study, weaim to extend the current understanding
of the eect of transparency of form-meaning mapping by
investigating how Korean-speaking children acquire the use of the
phonological cue for focus-marking purposes. Korean is dierent
from the previously studied languages in both prosodic system and
prosodic focus marking. Regarding prosodic system, Korean has no
word-level use of prosody. It is oen classied as an edge-prominence

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 03 frontiersin.org
language (Jun, 2014). at is, pitch movement in this language is
aligned to prosodic phrases (Jun, 1993, 1998, 2000, 2005, 2014).
Accentual Phrase (AP) is the smallest unit carrying a phrasal tone
sequence, THLH, with the initial tone (T) being realized as either a
high tone (H) or a low tone (L) at the le edge, depending on the
laryngeal feature of the initial segment of the AP. e second H tone
is generally realized on the second syllable of an AP, but is sometimes
realized on the third syllable when an AP is longer than four syllables;
when an AP contains fewer than four syllables, one or both of the two
middle tones may beundershot, with the choice of tones undershot
varied across speakers, discourse contexts, and other linguistic factors
(Jun, 2005). e nal H tone is realized on the last syllable and marks
the right edge of an AP. In addition to the tonal marking at both edges,
AP is also marked by domain-initial (segmental) strengthening at the
le edge (Cho, 2022; Kim et al., 2024). An AP consists of one or more
Phonological Words (PWs). An Intonational Phrase (IP) consists of
one or more APs and is marked by a phrase-nal boundary tone and
phrase-nal lengthening (or pre-boundary lengthening) at the right
edge (Cho, 2022; Kim et al., 2024).4
Regarding prosodic focus marking, past work based on read
speech shows that Korean primarily uses prosodic phrasing for this
purpose (e.g., Jun, 1993, 2007b). A word in a narrow focus or
contrastive focus condition typically initiates a prosodic phrase, which
can beeither an AP or an IP, with the following words tending to
beintegrated into the same phrase as the focused word, resulting in
dephrasing (Jun, 1993; Jun and Lee, 1998; Oh, 1999; Jun and Kim,
2007; Jeon and Nolan, 2017). Given that a phrasal boundary is either
present or not (i.e., a discrete concept), the use of prosodic phrasing
can beconsidered a phonological means of focus marking, like accent
placement and choice of accent type in Dutch and the placement of a
prominence-marking high tone in Swedish. However, prosodic
phrasing, including dephrasing, can beinuenced by factors other
than focus marking, such as speech rate, rhythm, semantic weight,
length and syntactic structure of the utterance (cf. Jun, 1993, 2011).
For example, when a short syntactic phrase (e.g., a verb phrase or
noun phrase) or a short sentence as a whole is focused, each word in
it tends to form an AP (Jun etal., 2006; Kim etal., 2006; Jun and Kim,
2007; Jun, 2011). Dephrasing does not play a role in focus marking in
this case. Hatcher etal. (2023) have also demonstrated instances where
focus realization can occur phrase-medially in Korean, notably
without resorting to phrasing. e transparency of the form-meaning
mapping between phonological cues and focus conditions in Korean
can thus be considered lower, compared to Swedish. It may not
be dierent from that in a West Germanic language, like Dutch,
5
because both phrasing (in Korean) and pitch accent (in a West
Germanic language) can occur in non-focused contexts.
4 An Intermediate Phrase (ip), which is larger than an AP but smaller than an
IP, was added in a later version of the Korean prosodic hierarchy (Jun, 2007b,
2014). However, as ip is not clearly defined, transcribing ips in speech data is
not straightforward, and its role in focus marking is not examined in the
present study.
5 The present study was done using an adapted method from Chen (2011a,b),
parallel to Romøren and Chen (2021). The results may thus bemore comparable
to Chen (2011a,b) on Dutch and Romøren and Chen (2021) on Swedish than
to other previous studies.
However, prosodic phrase boundaries, especially IP boundaries,
appear to berelatively easy to perceive in continuous speech streams,
compared to the perception of prosodic prominence associated with
pitch accent. is has been shown to bethe case of both linguistically
trained adult listeners (e.g., Grice etal., 1996, on German; Jun etal.,
2000, on Korean; Escudero etal., 2012, on Catalan) and naïve adult
listeners with no prior linguistic knowledge presented with an
unfamiliar language for the rst time (Cole and Shattuck-Hufnagel,
2016; Cole etal., 2017; Bishop etal., 2020). Development literature
suggests a very early ability to perceive and process prosodic phrase
boundaries. For example, French-learning infants exhibit sensitivity
to prosodic boundaries at birth (Christophe etal., 1994, 2001). Infants
learning a West Germanic language change from relying on all
possible cues in perception of major prosodic phrase boundaries to a
subset of the cues between 4 and 8 months, partially reecting the
relative importance of the cues in the target language (Seidl, 2007;
Johnson and Seidl, 2008; Seidl and Cristià, 2008). ey exhibit adult-
like processing of major prosodic phrase boundaries in the brain at
6 months (Holzgrefe-Lang etal., 2018). ese ndings suggest that a
prosodic boundary may bea perceptually more recognizable cue to
focus than accentuation, making the mapping between a prosodic
phrase boundary and focus possibly more transparent in Korean than
the mapping between accentuation and focus in a West Germanic
language to young language learners. Notably, children appear to
besimilar in their development in the production of pitch accents in
a West Germanic language and the production of AP pitch patterns
and IP-nal boundary tones in Korean, independent of the mapping
with meaning like focus. For example, by the age of 2, children
acquiring a West Germanic language can produce the core of an adult-
like inventory of pitch accents (Chen etal., 2020); Korean-speaking
children can produce certain AP pitch patterns and IP-nal boundary
tones (Jun, 2007a).
According to Chen’s (2018) cross-linguistic model of acquisition
of prosodic focus marking, higher transparency of the form-meaning
mapping between focus and the phonological cue will lead to a faster
rate of acquisition in prosodic focus marking. If this holds,
wehypothesize that Korean-speaking children will exhibit adult-like
phonological focus marking in some or all aspects relatively later than
their Swedish-speaking peers, who are adult-like at the age of 4 to
5 years, but earlier than their Dutch-speaking peers, who are not fully
adult-like yet at the age of 7 to 8 years.
To test this hypothesis, wehave examined how Korean-speaking
children aged 4 to 11 vary prosodic phrasing to distinguish (1) Narrow
focus from non-focus (Eect of focus); (2) Narrow focus from broad
focus (Eect of focal constituent size); and (3) Narrow focus from
contrastive (narrow) focus (Eect of contrastivity), in comparison to
Korean-speaking adults. Regarding the eect of focus, wepredict that
Korean-speaking children will befully adult-like at the age of 7 to
8 years or later in more frequently using an AP and/or IP boundary
before a word and a PW boundary aer it when the word is in the
narrow focus condition than in the non-focus conditions (i.e.,
pre-focus or post-focus). Regarding the eect of focal constituent size,
wepredict that the children will befully adult-like at the age of 7 to
8 years or later in frequently using an AP and/or IP boundary before
a word in both the narrow and broad focus conditions, and in more
frequently using a PW boundary aer a word when it is under narrow
focus than broad focus. Regarding the eect of contrastivity, as
previous studies on Korean reveal no evidence for the use of prosodic

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 04 frontiersin.org
phrasing to mark contrastivity and there is no language-independent
reason to use prosodic phrasing to mark a contrast, wepredict that
Korean-speaking children will not vary prosodic boundaries to
distinguish narrow focus from contrastive focus, like adults and this
may beobservable at the age of 4 to 5 years.
2 Method
2.1 Participants
ree groups of children participated in the experiment, including
six 4- to 5-year-olds (average age: 5;3, range: 4;10–5;10), eight 7- to
8-year-olds (average age: 8;0, range: 7;4–8;10), and eight 10- to
11-year-olds (average age: 10;10, range: 10;3–11;11). ey were
recruited via Hanyang Institute for Phonetics and Cognitive Sciences
of Language in Seoul, and came from diverse social-economic
backgrounds. Twelve adults (six females and six males, average age:
24 years, range: 19–28 years) participated as a control group. ey were
students of Hanyang University at the time of testing. All participants
spoke Seoul Korean as their native language and did not have any
known language and/or cognitive impairment.
2.2 The picture-matching game
We adapted the picture-matching game used in Chen (2011b) to
elicit semi-spontaneous production of sentences. e same game was
used in recent studies on prosodic focus marking in children
acquiring other languages (Romøren, 2016; Liu, 2017; Yang and
Chen, 2018; Romøren and Chen, 2021). In this game, the child was
supposed to help the experimenter put pictures in matched pairs
(Figure1). ree piles of pictures were used. e experimenter and
the child each held a pile of pictures. e third pile lay on the table in
a seemingly messy fashion. e experimenter’s pictures always missed
some information (e.g., the subject, the action, the object, or all
three). e child’s pictures always contained all three pieces of
information. On each trial, the experimenter showed one of her
pictures to the child, described the picture and asked a question about
it or made a remark about the missing information (in the contrastive
focus condition). e child then took a look at the corresponding
picture in his/her pile and responded to the experimenter’s question
or remark. e experimenter then looked for the right picture in the
messy pile and matched it with her own picture to form a pair.
As rules of the game, the child was asked to answer the
experimenter’s questions in full sentences and not to reveal his/her
pictures to the experimenter. Weconstructed an experiment protocol
outlining each step of the game, specifying the experimenter’s
instructions and responses for each trial. is protocol ensured
consistent conduct of the experiment for all children and the
provision of sucient background information before each question
or remark. e experimenter was instructed to follow the protocol
closely but was encouraged to make spontaneous remarks that did
not aect the information structure of the child’s responses for the
purpose of facilitating the interaction. Prior to the picture-matching
game, a picture-naming task was conducted to ensure that the child
would use the intended words to refer to the entities in the pictures.
is procedure also rendered all the entities in the pictures
referentially accessible.
2.3 Experimental materials
Sixty question-answer dialogues were embedded in the picture-
matching game to elicit 60 SOV sentences with the sentence-medial
target object-nouns in ve focus conditions, as given below:
FIGURE1
Illustration of the experimental setup.

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Frontiers in Psychology 05 frontiersin.org
▪ Narrow focus condition: when narrow focus was on the sentence-
medial target object-noun, responding to a what-question, as
illustrated in (1) in the introduction;
▪ Pre-focus condition: when narrow focus was on the sentence-
nal verb, responding to a what-does-X-do-to-Y-question, as in
(4) below;
▪ Post-focus condition: when narrow focus was on the sentence-
initial subject-noun, responding to a who-question, as in
(5) below;
▪ Contrastive focus condition: when contrastive focus was on the
sentence-medial target object-noun, correcting the experimenter’s
remark about the object, as in (2) in the introduction;
▪ Broad focus condition: when broad focus was over the whole
sentence, responding to what-happens questions, as in (3) in
the introduction.
(4) A: Look! e rat, and the bread. It looks like the rat does
something to the bread. What does the rat do to the bread?
B: 쥐가 빵을 [만져요].
tʃwika p*aŋɨl mantʃʌjo.
e rat the bread [touches].
(5) A: Look! e bread, and someone looks a bit puzzled. It looks
like someone looks for the bread. Who looks for the bread?
B: [소가] 빵을 찾아요.
soka p*aŋɨl tʃʰatʃajo.
[e cow] the bread looks for.
Note that narrow focus was included in three sentence-positions to
make it possible to examine the eect of narrow focus on the sentence-
medial object-nouns compared to the same words in the pre-focus and
post-focus conditions, following previous studies on prosodic focus
marking (e.g., Chen, 2009). Moreover, comparing the object-nouns in
the narrow focus, contrastive focus and broad focus conditions allowed
us to examine the prosodic dierence between dierent focus types.
e 60 SOV sentences were unique combinations of ve subject-
nouns, 12 target object-nouns, and three verbs (Table1). Each subject-
noun was a monosyllabic lexical word followed by a nominative case
marker,6 /ka/ or /i/. e target object-nouns included six two-syllable
(or “short”) words and six four-syllable (or “long”) words, because APs
with two to four syllables tend to occur frequently in Korean. e
length of the target object-nouns was thus systematically varied to
control for any potential eects. Each “short” word was a monosyllabic
lexical word followed by an accusative case marker, /ɨl/ or /lɨl/. As for
the “long” words, except for /k*amakwilɨl/ (crows), which consisted of
a three-syllable lexical word and the accusative case marker /lɨl/, each
of the other words consisted of a disyllabic lexical word, a monosyllabic
sux /tɨl/ indicating the plural form of the lexical word, and the
accusative case marker /ɨl/. Each target word was initiated with either
a high-tone-triggering aspirated stop (i.e., /pʰ/ or /kʰ/) or fortis stop
6 There are two nominative case markers (i.e., /ka/ and /i/) and two accusative
case markers (/ɨl/ and /lɨl/) in Korean. The choice between each two variants
depends on the presence of a coda consonant in the preceding noun.
(i.e., /p*/ or /k*/) or a low-tone-triggering lenis stop (i.e., /p/ or /k/) or
a vowel (i.e., /a/), so that there would bevaried AP tonal patterns in
the data. Each target word appeared once in ve focus conditions (12
target words × ve focus conditions), leading to 60 “sentences” but
without subject-nouns and verbs. e ve subject-nouns and three
verbs were then nearly evenly distributed to the “sentences,” forming
60 SOV sentences. Each sentence was completed with the particle /jo/,
a common verb-nal politeness marker in informal Korean.
e 60 sentences were elicited in two experimental sessions: the
30 sentences with “short” target words in Session A and the 30
sentences with “long” target words in Session B. e trials in each
session were pseudo-randomized in such a way that trials from the
same focus condition did not appear next to each other, and the
focused constituent of a trial was not mentioned on its preceding trial.
2.4 Experimental procedure
e participants were tested individually upon being given
consent by their parents in Hanyang Institute for Phonetics and
Cognitive Sciences of Language at Hanyang University. A female
native speaker of Seoul Korean administered the experiment aer
having received intensive training on how to conduct the experiment
following the protocol. e experiment lasted about 60 min, including
a short chat between the experimenter and the child before the rst
experimental session, and a short break between the two sessions.
Audio recordings were made for each child in each session with a
sampling rate of 44.1 kHz with 16-bit resolution. Video recordings
were also made for some of the children for training purposes.
2.5 Prosodic annotation
e audio recordings from the participants were rst
orthographically annotated in Praat (Boersma and Weenink, 2013).
en, usable sentences were selected (1,602 or 83% from all the
participants in the four age groups; 64% from the 4- to 5-year-olds,
70% from the 7- to 8-year-olds, 80% from the 10- to 11-year-olds, and
91% from the adults), and unusable ones were excluded from further
analysis. A target sentence was considered unusable in any of the
following cases: (1) the participant produced the target sentence
before the experimenter asked the question, (2) the experimenter
asked a dierent question than the intended question on that trial, (3)
the experimenter did not provide an adequate description of the
picture before she asked a question, (4) the sentence was produced
with strong background noise, (5) the sentence was produced with
word insertion, deletion or replacement, (6) the sentence was
produced with self-repair or clearly perceivable hesitation, or (7) the
sentence was produced with perceivable irregular voice quality or
intonation caused by cold or unstable emotion.
e usable sentences were then annotated for phrasing, following
the Korean Tones and Break Indices (K-ToBI) transcription conventions
(Jun, 2000, 2005). at is, the boundaries immediately before the target
words (i.e., between the subject-noun and object-noun) and aer the
target words (i.e., between the object-noun and verb) were annotated as
an AP boundary, an IP boundary, or a phrase-internal phonological
word boundary (hereaer PW boundary) by combining auditory
impression and close inspection of prosodic cues to phrasing (e.g., tonal

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 06 frontiersin.org
patterns, boundary tones and breaks). e AP boundary is “a minimal
phrasal disjuncture, with no strong subjective sense of pause” and is
associated with AP tonal patterns as described in K-ToBI (Jun, 2005,
p.219). Word-nal (i.e., pre-boundary) high tone and word-initial (i.e.,
post-boundary) low tone are taken as the typical AP boundary markers.
e absence of voicing in word-initial lenis stops is also an informative
indicator of an AP boundary (e.g., Jun, 1993; Cho etal., 2002). Moreover,
word-initial (or post-boundary) strengthening in terms of perceptual
clarity in the initial segment or syllable may also indicate an AP
boundary, unless this cue contradicts another important cue such as a
tonal cue. e IP boundary refers to phrasal boundaries that are
demarcated by boundary tones and “a strong phrasal disjuncture, with
a strong subjective sense of pause,” that is, either an “objective visible
pause” or a “virtual pause” cued by nal lengthening, as described in
K-ToBI (Jun, 2005, p.219). e PW boundary refers to word boundaries
that are not demarcated by perceivable prosodic disjunctures in
K-ToBI. It is worth noting that dephrasing does not consistently occur
immediately aer a focused word in Korean. In such a case, the AP
boundary between the focused word and the post-focal word remains,
but the pitch span of the post-focal word can bereduced (e.g., Jun and
Lee, 1998; Kim etal., 2006; Lee and Xu, 2010). In the present study, when
a boundary displayed the above-mentioned features of an AP boundary,
but the post-boundary pitch span was noticeably reduced as compared
to the pre-boundary pitch span, weannotated this boundary as an AP
boundary instead of a PW boundary.
We conducted three rounds of annotation to maximize the
reliability and agreement of the annotation. In the rst round, the
usable sentences were annotated by one transcriber (the rst author)
without access to information on the experimental conditions,
following the above-described K-ToBI conventions, while a portion of
the sentences (i.e., 81 sentences produced by two randomly selected
participants) were jointly transcribed by two expert K-ToBI transcribers
who were native speakers of Korean (the second and third authors),
again without access to information on the experimental conditions.
e two expert transcribers reached full agreement on the transcription
of the 81 sentences. e Cohen’s Kappa test on the annotation of the
rst transcriber and the expert transcribers for the 81 sentences
revealed a very good inter-rater agreement for the boundaries before
the target words (K = 0.811, p < 0.0005), and a good inter-rater
agreement aer the target words (K = 0.644, p < 0.0005) (Landis and
Koch, 1977). e cases of disagreement were primarily concerned with
the distinction between the AP boundary and the PW boundary. In the
second round, the rst transcriber and the expert transcribers discussed
the cases of disagreement, and agreed that the rst transcriber should
give more weight to three of the cues in her decision on AP and PW
boundaries; namely, the word-initial and word-nal tones and word-
initial strengthening. e rst transcriber then re-annotated all the
usable sentences without access to the rst-round annotation. e
expert transcribers then jointly transcribed 23% of the usable sentences
(i.e., 10 sentences randomly selected from each participant). e two
expert transcribers reached full agreement on the transcription of the
23% sentences. e Cohen’s Kappa test on the second-round annotation
for 23% of the usable sentences revealed a very good inter-rater
agreement between the rst transcriber and the expert transcribers for
the boundaries before the target words (K = 0.924, p < 0.0005), and aer
the target words (K = 0.897, p < 0.0005) (Landis and Koch, 1977). To
reach a nal agreement, a third-round annotation was conducted
without access to the previous two rounds of annotation by two
additional K-ToBI transcribers, who were native speakers of Korean
and did not participate in previous rounds of annotation. e two
expert transcribers subsequently examined the ambiguous ones
reported by the two additional transcribers, and reached a full
agreement on each boundary. e rst transcriber then went through
the third-round annotation and reached a nal agreement with the
expert transcribers and the additional transcribers. In this paper,
wepresent an analysis of the data based on the third-round annotation.
3 Statistical analyses and results
Having annotated the prosodic boundaries before and aer the
sentence-medial target words in the sentences, we found that a large
proportion of the sentences were produced as three separate APs in
all age groups (57.8%
7
for the 4- to 5-year-olds; 65.7% for the 7- to
8-year-olds; 62.2% for the 10- to 11-year-olds; 46.7% for the adults).
To statistically examine whether and how the children’s use of
phrasal boundaries before and aer the target words may dier across
focus conditions and age groups, we conducted mixed-eects
multinomial logistic regression analyses using R Statistical Soware
7 The percentages provided in the parentheses were calculated based on
raw data.
TABLE1 Words that occurred in the SOV sentences.
Subjects 개가
/kɛka/
“dog”
쥐가
/tʃwika/
“rat”
곰이
/komi/
“bear”
말이
/mali/
“horse”
소가
/soka/
“cow”
Short objects
발을
/palɨl/
“foot”
비를
/pilɨl/
“rain”
불을
/pulɨl/
“r e”
팔을
/pʰalɨl/
“ar m”
빵을
/p*aŋɨl/
“bread”
알을
/alɨl/
“eg g”
Long objects
가방들을
/kapaŋtɨlɨl/
“ba gs”
기둥들을
/kituŋtɨlɨl/
“pillars”
구두들을
/kututɨlɨl/
“shoes”
카드들을
/kʰatɨtɨlɨl/
“ca rd s”
까마귀를
/k*amakwilɨl/
“crow”
안경들을
/ankjʌŋtɨlɨl/
“pairs of glasses”
Verbs
그려
/kɨljʌ/
“draw”
만져
/mantʃʌ/
“touch”
찾아
/tʃʰatʃa/
“look for”

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 07 frontiersin.org
(R Core Team, 2015) and the package Brms (Bürkner, 2017, 2018,
2021). Brms adopts a Bayesian approach with the Markov chain
Monte Carlo (MCMC) method.
e random factors were  (i.e., the participants) and
 (i.e., the target sentences). e dependent variable was
 with three categories: AP boundary (reference category),
IP boundary, and PW boundary. e independent variables (or xed
eects) were  and .  referred to the focus conditions.
For each analysis, we compared narrow focus to another focus
condition to address a specic research question, so  always
had two categories.  referred to the four age groups, with the
adult group set as the reference category.
Three models were built using the aforementioned factors.
Starting from an “empty” model (or Model 0) containing only the
random factors, weadded the effects of  and  to form
Model 1, following Struiksma et al. (2022). The interaction
between  and  was then added, forming Model 2. The
method leave-one-out cross-validation (LOO) was used to
evaluate model fit (Vehtari et al., 2017). The model with the
lowest estimated looic was regarded as the best-fit model. The
boundaries before and after the target words were
analyzed separately.
As the model summary of the best-t model does not
straightforwardly show the dierence between two focus conditions,
or the dierence between two focus conditions in each age group in
the use of prosodic boundaries, wedid follow-up analysis to answer
the research questions. When the best-t model was Model 2,
containing the two-way interaction of focus and , weexamined
the main eect of  in each age group, in order to address
whether and how the speakers in each age group used prosodic
boundaries to distinguish two focus conditions. When the best-t
model was Model 1 containing the main eects of  and ,
webuilt and summarized a variant of model 1 containing only 
as the xed factor, in order to address how the speakers varied prosodic
boundaries to distinguish two focus conditions, regardless of age. For
concision, wereport the co-ecient (B) and odds ratio (Exp (B)) from
the models in the text; for transparency, wereport summaries of these
models and the best-t models in Supplementary Tables 1–12.
3.1 Narrow focus vs. pre-focus
Analyzing the boundaries before the target words in the narrow
focus and pre-focus conditions (Figure2), wefound that the best-t
model was Model 1 containing the eects of  and 
(looic = 861.1) (Supplementary Table1).  thus had a similar eect
on the use of boundaries before the target words across age groups. A
summary of the model containing only  (Supplementary Table2)
showed that the odds of the boundary before the target word being an
IP boundary rather than an AP boundary in the narrow focus condition
were 3.13 times as high as in the pre-focus condition (B = −1.13, Exp
(B) = 0.32). e odds of the boundary before the target word being an
PW boundary rather than an AP boundary in the pre-focus condition
were 2.53 times as high as in the narrow focus condition (B = 0.93, Exp
(B) = 2.53). In other words, the speakers were more likely to use an IP
boundary, but less likely to use a PW boundary before the target word
in the narrow focus condition than in the pre-focus condition,
regardless of age.
Analyzing the boundaries aer the target words, wefound that the
best-t model was Model 2, containing the interaction of  and
 (looic = 578.3) (Supplementary Table3). Subsequent analysis on
each age group showed that the model containing  was the
best-t model for each age group (looic = 242.3 for the adults; looic = 84.3
for the 4- to 5-year-olds; looic = 111.1 for the 7- to 8-year-olds;
looic = 143.0 for the 10- to 11-year-olds) (Supplementary Tables 4–7).
For the adults, the odds of the boundary aer the target word
being an IP boundary rather than an AP boundary in the pre-focus
condition were 1.89 times as high as in the narrow focus condition
(B = 0.64, Exp (B) = 1.89). e odds of the boundary aer the target
word being an PW boundary rather than an AP boundary in the
narrow focus condition were 110559.84 times as high as in the
pre-focus condition (B = −11.61, Exp (B) = 0.00). In other words, the
adults were less likely to use an IP boundary, but more likely to use a
PW boundary aer the target word in the narrow focus condition than
in the pre-focus condition.
For the 4- to 5-year-olds, the odds of the boundary aer the target
word being an IP boundary rather than an AP boundary in the
pre-focus condition were 10.30 times as high as in the narrow focus
condition (B = 2.33, Exp (B) = 10.30). e odds of the boundary aer
the target word being an PW boundary rather than an AP boundary
in the narrow focus condition were 7131.28 times as high as in the
pre-focus condition (B = −8.87, Exp (B) = 0.00). In other words, the
4- to 5-year-olds were less likely to use an IP boundary, but more likely
to use a PW boundary aer the target word in the narrow focus
condition than in the pre-focus condition.
For the 7- to 8-year-olds, the odds of the boundary aer the target
word being an IP boundary rather than an AP boundary in the
pre-focus condition were 28984.8 times as high as in the narrow focus
condition (B = 10.27, Exp (B) = 28984.8). e odds of the boundary
aer the target word being an PW boundary rather than an AP
boundary in the narrow focus condition were 33.33 times as high as
in the pre-focus condition (B = −3.50, Exp (B) = 0.03). In other words,
the 7- to 8-year-olds were less likely to use an IP boundary, but more
likely to use a PW boundary aer the target word in the narrow focus
condition than in the pre-focus condition.
For the 10- to 11-year-olds, the odds of the boundary aer the
target word being an IP boundary rather than an AP boundary in the
pre-focus condition were 9.79 times as high as in the narrow focus
condition (B = 2.28, Exp (B) = 9.79). e odds of the boundary aer
the target word being an PW boundary rather than an AP boundary
in the narrow focus condition were 64533.95 times as high as in the
pre-focus condition (B = −11.07, Exp (B) = 0.00). In other words, the
10- to 11-year-olds were less likely to use an IP boundary, but more
likely to use a PW boundary aer the target word in the narrow focus
condition than in the pre-focus condition.
As an interim summary, the children used IP boundaries more
frequently but used PW boundaries less frequently before the target
words in the narrow focus condition than in the pre-focus condition,
similar to the adults. ese results indicated that the children preferred
inserting a large prosodic boundary (IP) immediately before the word in
the narrow focus condition, similar to the adults; they also preferred
deleting the boundary between the two pre-focal words and producing
them as one larger AP or IP when the sentence-nal verb was focused,
similar to the adults.
As for the boundaries aer the target words, the speakers in all age
groups used IP boundaries less frequently but used PW boundaries

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 08 frontiersin.org
more frequently in the narrow focus condition than in the pre-focus
condition. e results indicated that they frequently dephrased the
post-focal word in the narrow focus condition, and frequently inserted
a large prosodic boundary (IP) immediately before the focused
sentence-nal word in the pre-focus condition. However, the children
diered from the adults in absolute frequency in their use of prosodic
boundaries aer the target words. e 7- to 8-year-olds were least
similar to the adults. To distinguish the narrow focus and pre-focus
conditions, while the other age groups seemed to rely more on the use
of PW boundaries (or post-focus dephrasing) rather than the use of IP
boundaries aer the target words, the 7- to 8-year-olds relied more on
the use of IP boundaries than the use of PW boundaries aer the target
words. e 10- to 11-year-olds were most similar to the adults in their
use of prosodic boundaries in terms of absolute frequency.
3.2 Narrow focus vs. post-focus
Analyzing the boundaries before the target words in the narrow
focus and post-focus conditions, wefound that the best-t model was
Model 0 containing only the random eects (looic = 863.2), indicating
that the speakers did not vary the boundaries before the target words
to distinguish narrow focus from post-focus, regardless of age.
Analyzing the boundaries aer the target words, wefound that the
best-t model was Model 0 containing only the random eects
(looic = 659.7), indicating that the speakers did not vary the
boundaries aer the target words to distinguish narrow focus from
post-focus, regardless of age.
As an interim summary, the children did not vary the boundaries
before or aer the target words to distinguish narrow focus from post-
focus, similar to the adults. As the speakers tended to insert an AP or
IP boundary before the sentence-medial target word and dephrase its
following word when the target word was under narrow focus, this
part of the results indicated that they also did so when the target word
was post-focus.
3.3 Narrow focus vs. broad focus
Analyzing the boundaries before the target words in the narrow
focus and broad focus conditions (Figure3), wefound that the best-t
model was Model 2, containing the interaction of  and 
(looic = 782.3) (Supplementary Table8). Subsequent analysis on each
age group showed that the model containing  was the best-t
model for the 10- to 11-year-olds (looic = 205.8) and the adults
(looic = 258.6) (Supplementary Tables 9–10), but the model
containing only the random eects was the best-t model for the 4- to
5-year-olds (looic = 154.6) and 7- to 8-year-olds (looic = 165.9). In
other words, the 10- to 11-year-olds varied prosodic boundaries
before the target words to distinguish narrow focus from broad focus,
similar to the adults, but the 4- to 5-year-olds and 7- to 8-year-olds
did not.
For the adults, the odds of the boundary before the target word
being an IP boundary rather than an AP boundary in the broad focus
condition were 4.08 times as high as in the narrow focus condition
(B = 1.41, Exp (B) = 4.08). e odds of the boundary before the target
word being a PW boundary rather than an AP boundary in the
narrow focus condition were 26041.80 times as high as in the broad
focus condition (B = −10.17, Exp (B) = 0.00). In other words, the adults
were more likely to use an IP boundary, but less likely to use a PW
boundary before the target word in the broad focus condition than in
the narrow focus condition.
For the 10- to 11-year-olds, the odds of the boundary before the
target word being an IP boundary rather than an AP boundary in the
broad focus condition were 4.31 times as high as in the narrow focus
condition (B = 1.46, Exp (B) = 4.31). e odds of the boundary before
the target word being an PW boundary rather than an AP boundary
in the narrow focus condition were 3.13 times as high as in the broad
condition (B = −1.15, Exp (B) = 0.32). In other words, the 10- to
11-year-olds were more likely to use an IP boundary, but less likely to
use a PW boundary before the target word in the broad focus
condition than in the narrow focus condition, similar to the adults.
Analyzing the boundaries aer the target words, wefound that the
best-t model was Model 1 containing the eects of  and 
(looic = 670.1) (Supplementary Table11).  thus had a similar
eect on the use of boundaries aer the target words across age groups.
A summary of the model containing only 
(Supplementary Table12) showed that the odds of the boundary aer
the target word being an IP boundary rather than an AP boundary in
the broad focus condition were 5.58 times as high as in the narrow focus
condition (B = 1.72, Exp (B) = 5.58). e odds of the boundary aer the
target word being an PW boundary rather than an AP boundary in the
narrow focus condition were 5.56 times as high as in the broad focus
condition (B = −1.70, Exp (B) = 0.18). In other words, the three groups
of children used IP boundaries more frequently but used PW boundaries
less frequently aer the focal words in the broad focus condition than in
the narrow focus condition, similar to the adults.
As an interim summary, the adults used IP boundaries more
frequently before and aer the target words in the broad focus
condition than in the narrow focus condition, indicating their
preference for producing the words as separate IPs when the sentence
was in broad focus. e adults used PW boundaries more frequently
aer the target words in the narrow focus condition than in the broad
focus condition, indicating their preference for post-focus dephrasing
in the narrow focus condition. e 10- to 11-year-olds were adult-like
in distinguishing narrow focus from broad focus. However, the two
younger groups of children only varied the boundaries aer the target
words in the same way as the adults did.
3.4 Narrow focus vs. contrastive focus
Analyzing the boundaries before the target words in the narrow
focus and contrastive focus conditions, wefound that the best-t
model was Model 0 containing only the random eects (looic = 854.6),
indicating that the speakers did not vary the boundaries before the
target words to distinguish narrow focus from contrastive focus,
regardless of age.
Analyzing the boundaries aer the target words, wefound that the
best-t model was Model 0 containing only the random eects
(looic = 716.7), indicating that the speakers did not vary the
boundaries aer the target words to distinguish narrow focus from
contrastive focus, regardless of age.
As an interim summary, the children did not vary the boundaries
before or aer the target words to distinguish narrow focus from
contrastive focus, similar to the adults. In other words, the children
and adults marked contrastive focus similarly to narrow focus via
prosodic phrasing.

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Frontiers in Psychology 09 frontiersin.org
4 General discussion
To further the current understanding of the eect of transparency
of phonological form-meaning mapping on the acquisition of
prosodic focus marking, wehave examined how Korean-speaking 4-
to 5-year-olds, 7- to 8-year-olds, and 10- to 11-year-olds varied
prosodic boundaries to distinguish narrow focus from non-focus (i.e.,
pre-focus and post-focus) and two other types of focus (i.e., broad
focus and contrastive focus) in semi-spontaneous production of SOV
sentences, as compared to adults.
Regarding the prosodic realization of narrow focus as compared to
non-focus, we rst compared narrow focus to pre-focus and found that
the children in all age groups preferred inserting a large prosodic
boundary (i.e., IP boundary) immediately before the focused target
word in the narrow focus condition, similar to the adults, and in line
with previous ndings on Korean-speaking adults’ read speech (e.g.,
Jun, 1993; Jun and Kim, 2007; Jeon and Nolan, 2017). ey also
preferred deleting the boundary between the pre-focal words and
producing them as one larger AP or IP when the sentence-nal verb was
focused, similar to the adults. is observation coincides with an earlier
nding that pre-focal words tend to bedephrased in adults’ production
of read speech (Oh, 1999). Regarding the use of prosodic boundaries
aer the target words, the children in all age groups frequently used a
PW boundary (i.e., dephrasing the post-focal word) in the narrow focus
condition, and frequently inserted a large prosodic boundary (IP)
immediately before the focused sentence-nal word in the pre-focus
condition, similar to the adults. However, while the other age groups
seemed to rely more on the use of PW boundaries (or post-focus
dephrasing) rather than the use of IP boundaries aer the target words,
the 7- to 8-year-olds relied more on the use of IP boundaries than the
use of PW boundaries aer the target words, and thus were least similar
to the adults. e 10- to 11-year-olds were most similar to the adults in
their use of prosodic boundaries in terms of absolute frequency.
Regarding the comparison between narrow focus and post-focus, we
found that while the children tended to use an AP or IP boundary
before the sentence-medial target word and dephrase its following
word when the target word was under narrow focus, they also did so
when the target word was post-focus, similar to the adults.
us, our prediction that Korean-speaking children will befully
adult-like at the age of 7–8 years or later in more frequently using an
AP and/or IP boundary before a word and a PW boundary aer it in
the narrow focus condition than in the non-focus conditions
(i.e., pre-focus or post-focus) is only partly borne out. We have
unexpectedly observed a protracted developmental path in Korean-
speaking children, as the 7- to 8-year-olds relied more on the use of
large prosodic boundaries (i.e., IP boundaries) than PW boundaries
(related to post-focus dephrasing) to distinguish the narrow focus and
pre-focus conditions, dierent from the other age groups. Wesuggest
two speculations for this nding. First, as the 7- to 8-year-olds start to
take read-aloud practice in primary school, their preference to large
prosodic boundaries might befrom the inuence of read speech.
However, as previous studies on adults’ read speech usually analyzed
dierent focus conditions separately, welack comparable ndings on
how prosodic boundaries are used to distinguish focus conditions in
read speech. Moreover, wedid not observe a similar pattern in the
10- to 11-year-olds, who had an equal chance of being inuenced by
read speech in class. Second, the 7- to 8-year-olds might have been
more engaged in the picture-matching game, and thus put in more
eort in providing answers to the experimenter, compared to the 10-
to 11-year-olds and the adults. We speculate that in an edge-
prominence language like Korean, more eort in marking focus might
lead to more frequent use of prosodic phrasing related to large
prosodic boundaries in distinguishing focus conditions. e game was
designed in such a way that it would suit the youngest children in the
study. It is thus plausible that the oldest children and the adults did not
put in more eort in production than needed in encoding focus. A
similar observation about 10- to 11-year-olds engaging less with the
game and making less eort to answer questions than younger
children was reported in Romøren and Chen (2021).
As for the distinction between narrow focus and broad focus, only
the 10- to 11-year-olds were fully adult-like. ey preferred producing
the words as separate IPs when the sentence was in broad focus, and
preferred post-focus dephrasing in the narrow focus condition.
However, the two younger groups of children only varied the
boundaries aer the target words in the same way as the adults did to
distinguish the two focus conditions. ese results largely support our
prediction concerning the eect of focal constituent size.
Regarding the comparison between narrow focus and contrastive
focus, wedid not nd any evidence of the speakers distinguishing the
two types of focus using prosodic boundaries, regardless of age. e
results fully support our prediction regarding the eect of contrastivity.
In previous studies on the acquisition of phonological focus
marking, Dutch-speaking children used accentuation close to the
ceiling across narrow focus, broad focus, and contrastive focus
conditions, showing no evidence of using accent placement in
distinguishing focus types, similar to Dutch-speaking adults
(Romøren, 2016), although the exact accent types used for marking
the three types of focus were not reported in Romøren (2016).
Swedish-speaking children used the prominence-marking high tone
more frequently in narrow focus than in broad focus, but did not
distinguish narrow focus from contrastive focus using this cue, similar
to Swedish-speaking adults (Romøren, 2016). us, the current
ndings, along with those from previous studies, imply that languages
dier both in whether and how focus types are distinguished by
language-specic phonological cues, and in the acquisition of
phonological marking of these focus types.
Based on the ndings of the present study, wecan depict Korean-
speaking children’s developmental path of phonological focus marking
from the age of 4 to 11 as follows: At the age of 4 to 5, Korean-speaking
children use prosodic phrasing to mark focus and distinguish dierent
types of focus in a largely adult-like manner, though their use of prosodic
boundaries for focus-marking purposes is not fully adult-like in terms
of absolute frequency. In contrast, 4- to 5-year-old Swedish-speaking
children were fully adult-like in the use of the prominence-marking high
tone in sentence-nal position, and largely adult-like in sentence-medial
position in terms of manner and frequency (Romøren, 2016; Romøren
and Chen, 2021). e dierence between Korean-speaking and Swedish-
speaking children is further evident at later stages. For example, at the
age of 7 to 8, Korean-speaking children tend to rely more on the use of
large prosodic boundaries (i.e., IP boundaries) than PW boundaries (or
dephrasing) when distinguishing narrow focus from pre-focus, dierent
from adults. At the age of 10 to 11, they exhibit fully adult-like abilities
in distinguishing focus conditions. e results in general support our
hypothesis regarding Korean-speaking children’s rate of acquisition of
phonological focus marking, compared to that of Swedish-speaking
children and Dutch-speaking children.

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 10 frontiersin.org
e results have further implications for understanding cross-
linguistic variation in the acquisition of focus marking. As discussed at
the outset of the paper, Swedish employs a highly transparent
phonological means of focus marking, so that words under narrow
focus are consistently assigned a word-nal high tone (Bruce, 2007;
Romøren, 2016). In other words, Swedish demonstrates a clear and
direct mapping between the phonological form and the focus-related
meaning. On the other hand, while focus marking in Korean is typically
achieved through phrasing (involving the initiation of a large prosodic
constituent such as an IP) (e.g., Jun, 1993, 1998, 2000, 2005), phrasing
is not exclusively used for focus marking, indicating a less transparent
form-meaning mapping compared to that observed in Swedish. Given
these cross-linguistic dierences between Swedish and Korean, our
results lend support to Chen’s (2018) view that the transparency of the
form-meaning mapping between phonological cues and focus
conditions inuences the rate of acquisition in prosodic focus marking
across languages.
Let us now compare our Korean results with those observed in
Dutch-speaking children. Recall that Dutch-speaking 4- to 5-year-olds
were not fully adult-like in their choice of accent type for focus-
marking purposes (Chen, 2011b). In contrast, at these ages (4 to
5 years), Korean-speaking children exhibited some phonological focus
marking patterns that were more adult-like than their Dutch-speaking
peers. us, our results suggest that Korean-speaking children tend to
acquire an adult-like way of focus marking relatively earlier than their
Dutch-speaking peers. However, the dierence between Korean-
speaking and Dutch-speaking children does not seem to befully in line
with the eect of transparency based on consistency in the association
between a form and a meaning. is is because there is no apparent
dierence in the consistency of the form-meaning mapping between
Korean and Dutch. In other words, phrasing and pitch accent, which
are used for focus marking in each language, respectively, can also
occur in various other non-focused contexts. However, our results are
compatible with a transparency hypothesis based on perceptual
FIGURE2
The use of boundaries after the object-noun in the narrow focus condition and pre-focus condition.
FIGURE3
The use of boundaries before the object-noun in the narrow focus condition and broad focus condition.

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 11 frontiersin.org
transparency between a form and a meaning. at is, if weextend the
notion of the degree of transparency in the form-meaning mapping to
include perceptual transparency of the cues to focus, the earlier
acquisition of focus marking by Korean-speaking children can still
be understood as a reection of cross-linguistic dierences in the
transparency of the form-meaning mapping.
5 Conclusion and limitations
In conclusion, our ndings on Korean-speaking children support
Chen’s (2018) view that a higher degree of transparency in the form-
meaning mapping between phonological cues and focus leads to a faster
rate of acquisition in prosodic focus marking. Further, wedemonstrate
that a greater diversity in phonological forms, such as the use of
phrasing for purposes other than focus marking in Korean, can slow
down the rate of acquisition. us, our study not only provides new
experimental evidence for the role of transparency in form-meaning
mapping as a determinant of children’s acquisition of focus marking, but
also expands our current understanding of the notion of the degree of
transparency in the form-meaning mapping to include perceptual
salience of the phonological cue.
Some important questions remain to beaddressed in future studies.
For example, wedid not observe evidence of Korean-speaking adults and
children distinguishing narrow focus from post-focus as well as narrow
focus from contrastive focus using prosodic phrasing. Given that these
focus conditions are distinguished phonologically and/or phonetically in
many other languages, they may be distinguished with pitch- and
duration-related phonetic cues as well as segmental cues in Korean. It will
be insightful to study whether and how other phonetic focus-marking
cues are used in Korean when the primary cue, prosodic phrasing, does
not suce to distinguish two focus conditions (but see Cho etal., 2011;
Hatcher etal., 2023, for related data), as well as how Korean-speaking
children acquire the use of the phonetic cues. Moreover, as Korean
utilizes both the le and right edges of prosodic phrases for phrasing and
focus marking, another interesting question for future research is whether
our ndings on the acquisition of prosodic focus marking in Korean-
speaking children can begeneralized to children acquiring other edge-
prominence languages, like Mongolian, in which prosodic phrasing and
focus are typically marked at the le edge of prosodic units (Karlsson,
2014). us, more studies under the same theoretical framework
adopting similar experimental methods need to bedone to broaden our
understanding of the acquisition of prosodic focus marking.
Data availability statement
e raw data supporting the conclusions of this article will
bemade available by the authors, without undue reservation.
Ethics statement
Ethical review and approval were not required for the study on
human participants in accordance with the local legislation and
institutional requirements at the time of testing. Written informed
consent for participation in this study was provided by the participants’
legal guardians/next of kin.
Author contributions
AY: Conceptualization, Data curation, Formal analysis, Funding
acquisition, Investigation, Methodology, Resources, Validation,
Visualization, Writing – original dra, Writing – review & editing. TC:
Conceptualization, Data curation, Funding acquisition, Investigation,
Methodology, Resources, Validation, Writing – review & editing. SK:
Conceptualization, Data curation, Funding acquisition, Investigation,
Methodology, Resources, Validation, Writing – review & editing. AC:
Conceptualization, Data curation, Funding acquisition, Investigation,
Methodology, Project administration, Resources, Supervision,
Validation, Writing – review & editing.
Funding
e author(s) declare nancial support was received for the
research, authorship, and/or publication of this article. is work was
supported by a VIDI grant awarded to AC by the Dutch Research
Council (NWO) (grant number 276-89-001). is work was also
supported in part by the Ministry of Education of the Republic of
Korea and the National Research Foundation of Korea
(NRF-2023S1A5A2A03084924) to TC and SK, and by the Independent
Innovation Fund of Tianjin University (2019XSC-0034; 2024XSC-
0023) to AY.
Acknowledgments
We would like to thank Hanyang Institute for Phonetics and
Cognitive Sciences of Language for its great help with the experiment.
Weexpress our special gratitude to the children and their parents for
their participation.
Conflict of interest
e authors declare that the research was conducted in the
absence of any commercial or nancial relationships that could
beconstrued as a potential conict of interest.
Publisher’s note
All claims expressed in this article are solely those of the
authors and do not necessarily represent those of their aliated
organizations, or those of the publisher, the editors and the
reviewers. Any product that may beevaluated in this article, or
claim that may bemade by its manufacturer, is not guaranteed or
endorsed by the publisher.
Supplementary material
e Supplementary material for this article can befound online
at: https://www.frontiersin.org/articles/10.3389/fpsyg.2024.1352280/
full#supplementary-material

Yang et al. 10.3389/fpsyg.2024.1352280
Frontiers in Psychology 12 frontiersin.org
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