L1 Acquisition of Tense-Aspect Markers -ess (Past-Perfective)and -ko iss (Imperfective) in Korean

Ju-Yeon Ryu and Yasuhiro Shirai

1. Introduction

In cross-linguistic research on the acquisition of tense-aspect marking, it has

been observed that children associate past-perfective marking with telic verbs

(i.e. accomplishments and achievements), general imperfective marking with

atelic verbs (states and activities), and progressive marking with activity verbs in

the early stages of development. Although researchers generally agree on this

observation (e.g. Shirai, Slobin and Weist, 1998), the reason for this observation

is not fully understood. One important hypothesis appeals to a universal

predisposition (e.g. Bickerton, 1981), which argues that children have a bias to

map tense-aspect markers with particular temporal-semantic distinctions.

Meanwhile, the Distributional Bias Hypothesis (e.g. Shirai and Andersen, 1995)

argues that children make these particular associations based on input frequency.

In this paper, we will report on a study that looked at Korean data to test whether

Korean children follow the acquisition pattern that was described as a universal

tendency. We will also look at the relation between caretakers’ speech and

children’s speech from the point of view of the Distributional Bias Hypothesis to

gain a better understanding of the sources of universal tendencies.

2. Background 2.1. The Aspect Hypothesis

We first go over the notion of lexical aspect, which is used to categorize the

semantics of verb phrases and their relationship with tense and aspect

morphology. Vendler (1957) categorized temporal semantic of verbs into four

classes. “State” terms describe a situation that continues to exist without any

additional input of energy. “Activity” terms describe a dynamic and durative

situation that has an arbitrary endpoint. In contrast, “accomplishment” terms

describe a situation that is dynamic and durative, but has a natural endpoint.

* Ju-Yeon Ryu, Aichi Shukutoku University, juyeonryu@gmail.com. Yasuhiro Shirai,

Case Western Reserve University, yasuhiro.shirai@case.edu. This work was partially

supported by JSPS KAKENHI Grant Number JP18K12384 awarded to the first author,

which is gratefully acknowledged. We wish to thank all the children and their caretakers

who participated in this study. This research would not have been possible without their

contributions.

© 2019 Ju-Yeon Ryu and Yasuhiro Shirai. Proceedings of the 43rd Boston University Conference on Language Development, ed. Megan M. Brown and Brady Dailey, 561-572. Somerville, MA: Cascadilla Press.

Finally, “achievement” terms describe a situation that can be reduced to a point

on a time axis, that is, it is instantaneous and punctual (e.g. Andersen and Shirai,

1994).

L1 acquisition researchers have observed an interesting correlation between

tense-aspect markers and temporal semantics of verbs. This observation, which

is often called the Aspect Hypothesis (Andersen and Shirai, 1994; Shirai and

Andersen, 1995), can be summarized as follows:

1. Learners first use past marking or perfective marking on achievement and

accomplishment verbs, eventually extending its use to activities and stative

verbs.

2. In languages that encode the perfective/imperfective distinction,

imperfective past marking begins with stative verbs, then extends to activity

and accomplishments verbs.

3. In languages that have progressive aspect, progressive marking begins with

activity verbs, then extends to accomplishment or achievement verbs.

4. Progressive markings are not incorrectly overextended to stative verbs.

(Andersen and Shirai 1996: 533)

2.2. Tense-Aspect Markers -ess (past-perfective) and -ko iss (imperfective) in Korean

Korean has the morpheme -ess expressing past tense, perfect, and perfective

aspect, although we refer to it as past tense marker in this paper. Examples (1) to

(3) are children’s utterances. These are the first sentences each child used with

past tense marking in our data.

(1) tway-ss-ta. (JONG 1;7)

do-Past-Dec

“I am done.”

(2) neynney hay-ess-e? (JOO 2;2)

sleeping do-Past-Dec

“Did he (or she) sleep?”

(3) ta ilk-ess-ta. (YUN 2;3)

all read-Past-Dec

“I read it all.”

There are two major Korean imperfective aspect markers: -ko iss and -a iss.

When expressing progressive meaning, Korean uses -ko iss as the progressive

marker, attached to activity and accomplishment verbs. When expressing a

resultative state meaning, Korean takes -ko iss or -a iss, attached to achievement

verbs. Syntactically, when expressing a resultative state, -ko iss co-occurs with

transitive verbs, whereas -a iss co-occurs with intransitive verbs (Lee, 1991).

Therefore, -ko iss can refer to both progressive meaning (with dynamic atelic

verbs) and resultative meaning (with transitive achievement verbs). In this study,

562

we focus on the imperfective (i.e. progressive/resultative) -ko iss and do not deal

with the resultative imperfective -a iss.1

Table 1. Imperfective Aspect Markers -ko iss and -a iss Meaning Progressive Resultative

Lexical Aspect Activity

Accomplishment Achievement

Markers -ko iss -a iss

Transitivity Transitive

Intransitive Transitive Intransitive

2.3. Previous Studies

One previous study that focused on the development of past tense marker

-ess in L1 Korean acquisition was Gökmen and Lee (2002). They found that

Korean children use past marking -ess predominantly with accomplishment and

achievement verbs, supporting the Aspect Hypothesis. However, they were not

able to analyze input from their caretakers, because they analyzed longitudinal

diary data of three Korean children based on notes taken by their parents.

Another study, Ryu and Shirai (2014), investigated the L1 acquisition of the

Korean imperfective aspect markers -ko iss and -a iss by three children. The

results indicated that there was no clear association found between children’s use

of -ko iss and -a iss and progressive meaning or activity verbs, and that there

was no common pattern in the three children’s acquisition. In other words,

individual variation was observed.

In sum, the acquisition of Korean tense-aspect markers so far shows a

mixed picture: acquisition of past tense marker supports the Aspect Hypothesis,

while that of imperfective aspect markers is inconclusive. We also do not know

much about the effect of input distribution for the acquisition of these

grammatical markers. We address these questions in the present study.

The research questions addressed are:

(1) Is the Aspect Hypothesis supported in the L1 acquisition of Korean

tense-aspect markers?

(2) Is there a relation between child-directed speech and children’s speech in

the distributional pattern of tense-aspect markers?

Based on previous cross-linguistic research, we hypothesize that the Aspect

Hypothesis holds for the L1 acquisition of Korean tense-aspect markers. Thus,

we predict that the acquisition proceeds as follows:

1 It is not conventional to treat resultative as imperfective. Here, we follow Shirai (1998),

which is based on Smith’s (1997) two-component theory.

563

State Activity Accomplishment Achievement

Past -ess 4 � 3 � 2 � 1

Imperfective -ko iss 1 � 2 � 3

We also hypothesize that there is a close relationship between child-directed

speech and children’s speech, supporting the Distributional Bias Hypothesis.

3. Method

We used the Korean corpus, called the Ryu-Corpus, which was contributed

by the first author to the CHILDES database (MacWhinney, 2000). The data

consist of longitudinal video-recorded interaction from three children (two boys

and one girl) and their caregivers (see Table 2). The length of the collected

video-recordings for each child is between 20 and 31 hours, totaling about 81

hours of data.

Table 2. Children in the Longitudinal Data Sample

Child Age Sex and Sibling Length of data

JONG 1;3~3;5 M, no siblings 31hr37min

JOO 1;9~3;10 F, 1 older sister 29hr 2min

YUN 2;3~3;9 M, no siblings 20hr 36min

Total length: 81hr 15min

Ryu-Corpus consists of video-recording data collected every two weeks for

30 minutes, starting with a book-reading, followed by natural interaction such as

everyday conversation, describing pictures, playing with toys, and eating snacks.

The data were recorded at the children’s homes. Table 3 represents token counts

of -ess and -ko iss produced by the children and their caretakers. As for the past

marker -ess, three children produced 1,491 predicate tokens, and their caretakers

produced 12,556 tokens. As for imperfective (i.e., progressive/resultative) -ko iss,

three children produced 163 predicate tokens and their caretakers produced

2,092 tokens. In total, 16,302 tokens were analyzed.

Table 3. Tokens of -ess and -ko iss Produced by Children and Caretakers

-ess (past) -ko iss (imperfective)

Child Caretaker Child Caretaker

JONG (1;3~3;5) 782 5,498 34 329

JOO (1;9~3;10) 496 3,761 21 639

YUN (2;3~3;9) 213 3,297 37 418

Total 1,491 12,556 92 1,386

564

4. Results

Table 4 shows the emergence of past tense and imperfective markers. JONG

starts to use past marker -ess at 1 year 7 months and uses imperfective -ko iss at

1 year 11 months. However, JOO and YUN start to use past markers after

crossing 2 years (2;2 and 2;3, respectively), and imperfective -ko iss at 3;3 and

2;7. Therefore, there was a large difference among the three children regarding

the age of emergence of tense-aspect markers. In particular, JONG and YUN

started to use the imperfective markers -ko iss four months after the past marker

first emerged in their speech, whereas JOO took more than a year before she

started using -ko iss after she first used past marker -ess. Looking at these results,

it appears that there is no direct correlation between the age of the emergence of

the tense-aspect markers and their later course of development.

Table 4. Emergence of -ess and -ko iss

Child -ess (past) -ko iss (imperfective)

JONG 1;7 Achievement + -ess 1;11 Activity + ko iss (Prog)

JOO 2;2 Achievement + -ess 3;3 Activity + ko iss (Prog)

YUN 2;3 Accomplishment + -ess 2;7 Achievement+-ko iss (Result)

Table 5 shows the usage of -ess and -ko iss by the children and caretakers.

Looking at the data, we can see the longitudinal development of past marker -ess

and imperfective markers -ko iss over time. We divided the whole period into

three stages to investigate the developmental patterns. Stage 1 is the period from

the emergence of past -ess to the emergence of imperfective -ko iss. Stage 2 is

the period from the emergence of imperfective -ko iss to its stable usage. Stage 3

is the stable usage period of both -ess and -ko iss. Therefore, there is no Stage 1

for imperfective -ko iss.

565

Tabl

e 5.

The

Per

cent

age

of U

sage

of -

ess

(pas

t) an

d -k

o is

s (im

perf

ectiv

e) b

y th

e C

hild

ren

and

Car

etak

ers (

toke

n co

unt)

JON

G

JOO

Y

UN

st

age

1

stag

e 2

st

age

3

care

taker

s st

age

1

stag

e 2

st

age

3

care

taker

s st

age

1

stag

e 2

st

age

3

care

taker

s

(1;7

~1;1

0) (

1;1

1~

2;9

) (2

;10

~3;5

) (a

ver

age)

(2;2

~3;2

) (3

;3~

3;6

) (3

;7~

3;1

0)

(aver

age)

(2;3

~2;6

) (2

;7~

3;1

) (3

;2~

3;9

) (a

ver

age)

-ess

S

tate

3

3

0

24

3

74

9

1

0

3

33

3

0

1

14

3

79

Act

ivit

y

24

1

46

6

0

18

58

4

6

67

4

5

97

5

2

3

31

5

91

Acc

om

p.

8

79

3

1

96

1

18

5

9

33

6

28

1

8

2

0

45

5

Ach

iev

emen

t 6

1

19

5

12

1

23

05

5

5

95

5

6

18

25

5

2

6

10

2

18

72

Su

m

96

4

50

2

36

5

49

8

12

8

23

1

13

7

37

61

8

3

8

16

7

32

97

-ko

iss

Sta

te

Act

ivit

y

4

9

22

2

5

10

4

89

5

11

2

75

Acc

om

p.

3

2

37

1

4

0

6

4

36

Ach

iev

emen

t

8

8

7

0

1

4

11

0

9

2

10

7

Su

m

15

1

9

32

9

7

14

6

39

2

0

17

4

18

566

All three children used past marker -ess most frequently with the

achievement verbs. Therefore, results indicate that in the early stages of

development, the three Korean children used past marking -ess predominantly

with telic verbs, supporting the Aspect Hypothesis. To investigate the influence

of input, we calculated the Kendall rank correlation coefficient, commonly

referred to as Kendall's tau-b, between caretakers’ usage and children’s usage of

each stage. Figure 1 suggests that all children’s usage closely reflects the

frequency of usage of their caretakers.

Regarding the acquisition of imperfective marker -ko iss, we hypothesized

that the Aspect Hypothesis would be supported for the acquisition of Korean

tense-aspect markers, predicting that the Korean imperfective marker -ko iss

would be used with activity verbs first, describing the progressive meaning

rather than with transitive achievement to denote resultative state. However, as

Figure 2 indicates, only JOO, who used 71% of her -ko iss with activity verbs at

stage 2, followed this prediction. JONG and YUN used transitive achievement

verbs (53% and 45%, respectively) at stage 2, expressing resultative meaning

(such as riding a car, holding something, wearing clothes/hats), which was more

frequent than their use of activity verbs (27% and 25%, respectively) to denote

progressive meaning. Thus, the acquisition of Korean imperfective marker -ko iss does not seem to follow the Aspect Hypothesis.

Regarding the Distributional Bias Hypothesis, Figures 1 and 2 also compare

the relationship between children and caretakers’ use of past (-ess) and

imperfective (-ko iss) markers, respectively, by reporting correlation coefficients.

Regarding past -ess, Kendall's tau-b has a perfect correlation (1.0) for all

comparisons except one for all three children (see Figure 1). More specifically,

the frequency ranking was achievement > activity > accomplishment > state,

except for one coefficient (correlation between YUN’s Stage 2 and his

caretaker’s speech, which was 0.67). In contrast, the correlation is far from

perfect for imperfective -ko iss, ranging from 0.33 to 1.00 for JONG and YUN,

and 0.82 to 1.00 for JOO (see Figure 2). Thus, we conclude that the caretakers’

input did not have a strong influence on the children’s use of the imperfective

aspect marker -ko iss in Korean.

567

JON

G

JOO

YU

N

τb=

1.0

0

τb=

1.0

0

τb=

1.0

0 τb

= 0

.67 τb

= 1

.00

τb=

1.0

0

Figu

re 1

. The

Per

cent

age

of U

sage

of -

ess b

y th

e C

hild

ren

and

Car

etak

ers

568

JON

G

τb=

0.3

3

τb=

1.0

0

τb=

0.3

3

JOO

τb=

0.8

2

τb=

1.0

0

τb=

1.0

0

YU

N

τb=

-0

.33

τb

= 0

.33

τb

= 1

.00

Figu

re 2

. The

Per

cent

age

of U

sage

of –

ko is

s by

the

Chi

ldre

n an

d C

aret

aker

s

569

5. Discussion and Conclusion

Research question 1 was on whether the Aspect Hypothesis is supported by

the data from L1 acquisition of Korean tense-aspect markers. In the case of the

past marker, the answer is yes. Our results indicate that L1 acquisition of Korean

past marker -ess follows the universal pattern predicted by the Aspect

Hypothesis. However, in the case of the imperfective marker, the answer appears

to be negative. Our results suggest that JONG and YUN did not associate

imperfective -ko iss more with activity verbs.

Research question 2 addressed the influence of input. In the case of past

marking, all children’s usage closely reflects the frequency of usage of their

caretaker. This suggests that child-directed speech influenced the distributional

pattern of past marking in the children’s speech, supporting the Distributional

Bias Hypothesis. However, in the case of imperfective marking, our results did

not show an influence of input directly. Figure 3 is the scatter diagrams of past

and imperfective marker. These scatterplots are calculated based on the token

frequencies of each stage, with each data point representing the total token

frequency of a verb type (e.g. achievement) produced by a child and his/her

caretakers. Thus, there are only 9 data points for -ko iss since it did not appear

with stative verbs in our data. Figure 3 shows that the frequency of past marking

in caretaker speech has a strong association with the frequency of past marking

-ess in children’s speech, as shown by the high correlation coefficient, Kendall's

tau-b (.79). On the other hand, the correlation coefficient of the imperfective

aspect -ko iss was low (.40).

Past marking ( =0.79) Imperfective marking (Tb=0.40)

0

100

200

300

400

500

600

0 5 10 15 20

Car

etak

er's

use

Children's use

0

500

1000

1500

2000

2500

3000

0.0 100.0 200.0 300.0 400.0

Car

etak

er's

use

Children's use

Tb

Figure 3. The Scatter Diagrams of Past and Imperfective markers

Therefore, our results regarding the influence of input are not very clear.

According to our data, the children’s usage pattern of past marker was similar to

that of their caretakers, but their usage pattern of imperfective marker was not.

Thus, it is difficult to argue that the Distributional Bias Hypothesis can fully

explain the L1 acquisition of the Korean tense-aspect markers.

How then, can we interpret the results? To see the difference in input

frequency between past tense -ess and imperfective -ko iss, we calculated the

percentages of each marker relative to the total number of caretaker utterances.

As Table 6 indicates, past tense -ess is much more frequent, used nearly 10 times

570

more than imperfective marker -ko iss. High-frequency input may have a strong

influence on children’s speech, and we suspect that this could be the reason for

past tense usage following the Aspect Hypothesis, while the imperfective aspect

does not.

Table 6. The Usage Percentage of -ess and -ko iss in Caretakers’ Utterances

Target utterances Total utterances Percentage (%)

Past tense -ess 12,556 98,378 12.8%

Imperfective -ko iss 1,386 98,378 1.4%

Another possibility is the language-specific system of aspectual semantics.

The Korean imperfective aspect system is complex, because it has two meanings

and two morphemes, -ko iss and -a iss. This may contribute to mapping

difficulty. Finally, we also need to consider individual variation, because our

participants showed clearly different patterns regarding the acquisition of the

imperfective aspect. Specifically, even though the three children received input

of –ko iss with the highest percentage of activity verbs (JONG, 67%; JOO, 77%;

YUN, 66%), only JOO followed the input distribution, with 71% activities in her

speech, while the other two children had a low ratio of activities (JONG, 27%;

YUN, 25%) and used achievements most frequently, denoting resultative

meaning. Thus, individual variation seems to be at work in the acquisition of

tense-aspect markers in Korean, analogous to Budwig (1996) in pronominal case

acquisition in English. Budwig found that of the six children who received

similar input patterns, three exhibited an acquisitional process different from that

of the other three. To conclude, we suggest that L1 acquisition of tense-aspect

markers may be dependent on multiple factors, such as a frequency-based

learning process, a language-specific system of aspectual semantics, and

individual variation.

References Andersen, Roger, and Yasuhiro Shirai. 1994. Discourse Motivations for Some Cognitive

Acquisition Principles. Studies in Second Language Acquisition 16: 133–156.

Andersen, Roger W., and Yasuhiro Shirai. 1996. The Primacy of Aspect in First and

Second Language Acquisition: The Pidgin-Creole Connection. In Handbook of Second Language Acquisition, ed. William C. Ritchie and Tej K. Bhatia, 527–570.

San Diego, CA: Academic Press.

Bickerton, Derek. 1981. Roots of Language. Ann Arbor, MI: Karoma.

Budwig, Nancy. 1996. What Influences Children’s Patterns of Forms and Functions in

Early Child Language? In Social Interaction, Social Context, and Language, ed. Dan

Isaac Slobin, Julie Gerhardt, Amy Kyratzis, and Jiansheng Guo, 143–156. Mahwah,

NJ: Lawrence Erlbaum Associates.

Gökmen, Seda, and Chungmin Lee. 2002. Aspects of the Acquisition of (Past) Tense and

(Telic) Aspect in Turkish and Korean. Language Research 38(4): 1317–1347.

571

Lee, Hyo Sang. 1991. Tense, Aspect and Modality: A Discourse-Pragmatic Analysis of

Verbal Suffixes in Korean from a Typological Perspective. Unpublished doctoral

dissertation, University of California, Los Angeles.

MacWhinney, Brian. 2000. The CHILDES Project: Tools for Analyzing Talk. Third

Edition. Mahwah, NJ: Lawrence Erlbaum Associates.

Ryu, Ju-Yeon, and Yasuhiro Shirai. 2014. The First Language Acquisition of the Korean

Imperfective Aspect Markers -ko iss-/-a iss-. In Japanese/Korean linguistics 21, ed.

Seungho Nam, Heejeong Ko and Jongho Jun, 265–279. Stanford, CA: CSLI

Publications

Shirai, Yasuhiro. 1998. Where the Progressive and the Resultative Meet: Imperfective

Aspect in Japanese, Korean, Chinese and English. Studies in Language 22: 661–692.

Shirai, Yasuhiro, and Roger W Andersen. 1995. The Acquisition of Tense-Aspect

Morphology: A Prototype Account. Language 71: 743–762.

Shirai, Yasuhiro, Dan Issac Slobin, and Richard M Weist. 1998. Introduction: The

Acquisition of Tense/Aspect Morphology. First Language 18: 245–253.

Smith, Carlota S. 1997. The Parameter of Aspect (2nd ed.) Dordrecht: Kluwer.

Vendler, Zeno. 1957. Verbs and Times. The Philosophical Review 66(2): 143–160.

572

Proceedings of the 43rd annualBoston University Conference on Language Development

edited by Megan M. Brown and Brady Dailey

Cascadilla Press Somerville, MA 2019

Copyright information

Proceedings of the 43rd annual Boston University Conference on Language Development© 2019 Cascadilla Press. All rights reserved

Copyright notices are located at the bottom of the first page of each paper.Reprints for course packs can be authorized by Cascadilla Press.

ISSN 1080-692XISBN 978-1-57473-096-8 (2 volume set, paperback)

Ordering information

To order a copy of the proceedings or to place a standing order, contact:

Cascadilla Press, P.O. Box 440355, Somerville, MA 02144, USAphone: 1-617-776-2370, sales@cascadilla.com, www.cascadilla.com