Language is the basis for all human connection. It allows us to communicate our ideas, express our feelings, and have discussions with the people in our lives. The language skills we develop as children lay the foundation for how we communicate as adults. Typically developing children begin speaking between 12-18 months and start regularly incorporating verbs around the age of 2. Research suggests that the number of verbs a child knows at age 2 is an indicator of their grammar skills at age 3. But what happens when these language skills are delayed?  

In this episode, Dr. Sabrina Horvath an assistant professor of rehabilitation sciences in the College of Health Professions at MUSC shares her research in childhood language development. Horvath is the Principal Investigator for the MACAW Lab, which stands for Methods of Acquiring Concepts and Words. Horvath leads research in child language development and disorder, late talkers, and vocabulary development. 

Episode Links:

The MACAW Lab

Have an idea for an episode of Science Never Sleeps? Send us an email at ScienceNeverSleeps@musc.edu.

1

From the Medical University of South Carolina,

this is Science Never Sleeps, a show that explores

2

the science, the people, and the stories behind

the scenes of biomedical research happening

3

at MUSC. I'm Gwen Bouchie. Have you ever stopped

to think about the role language plays in our

4

lives? From casual greetings to public speeches,

language shapes our interactions, perceptions,

5

and identities. The language skills we use as

adults begin to form in our earliest years.

6

and we carry these skills with us throughout

our lifetimes. But what happens when children

7

have delays in language development during those

formative years? How can we course correct

8

to make sure that children develop language

skills that will set them up for a future of

9

success? In this episode of Science Never Sleeps,

we're joined by Dr. Sabrina Horvath, an assistant

10

professor of rehabilitation sciences in the

College of Health Professions at MUSC. Dr.

11

Horvath is also the principal investigator for

the MACAW Lab. standing for methods of acquiring

12

concepts and words. The MACAW Lab explores

how children develop their vocabularies and

13

broader language skills and the importance of

verbs in later language development. Stay with

14

us.

15

Dr. Horvath, welcome to Science Never Sleeps.

Thank you so much for having me. It's a real

16

pleasure. So you are a speech pathologist. And

I want to really jump in first. One of the

17

things we talk about on Science Never Sleeps

are researchers' journeys. How do they get

18

where they are? And you have this really fascinating

journey of starting in your early career, your

19

early college career. just in linguistics and

history, just sort of immersed in language,

20

and then that brought you to where you are now.

So I would love to hear you talk a little bit

21

about what that journey has been like for you

and how you got to where you are today. Absolutely.

22

Well, as you mentioned, I started my undergraduate

career as actually a history major and a Spanish-German

23

double minor. But more broadly, I've just always

loved and been fascinated by languages. I grew

24

up just outside of Washington, D.C., which is

a beautifully diverse area to live, and had

25

several friends growing up who spoke languages

other than English at home. And it's the sort

26

of place where you go to the grocery store and

hear half a dozen different languages on your

27

way to get eggs. So I've always been exposed

to this idea of the richness of language and

28

the variability of language, and the idea that

language connects us to others, to our own

29

culture, and... through language we can experience

other cultures and other ideas that we might

30

not be familiar with from our own particular

experiences. So that was my motivation for

31

studying two languages as minors, but I very

quickly found and fell in love with linguistics,

32

which is the study of language in a scientific

way. How do we put words together and make

33

sentences, and how might that look different

from one language to another? What are the

34

rules that govern how we... can use and formulate

sentences socially, structurally in the language

35

itself. And importantly to my future work, how

do children ever seem to figure this out? Because

36

it's a very complicated system. And yet so many

children seem to do it effortlessly without

37

any sort of direct instruction. So this was

kind of the beginning of my journey. And speech

38

pathology, of course, is one very obvious pathway

from linguistics and one that I was drawn to

39

because of those clinical implications of helping

children for whom this process is not unfolding

40

as it should, for whom there are challenges.

So I got actually the history and linguistics

41

double major. The history has not served me

particularly well moving forward, but I went

42

straight into a master's program in speech language

pathology. did a little bit of research as

43

part of that because I was interested in the

how and the why and worked clinically for a

44

couple of years before deciding that research

was really where I wanted to be. So went back,

45

got my PhD, did a postdoc and was very, very

lucky to end up here at MUSC for a faculty

46

position. And here you are. And you're working

now with children, particularly toddlers. talking

47

about your work today, I wanted to define a toddler.

So when we talk about toddlers and the kids

48

that you're working with, what does that mean?

What is that age range? What are we looking

49

at? Absolutely. Most of my research is from

the two to three age range. But I've run studies

50

with children as young as about 18 months as

part of my work. and as old as about seven

51

years of age, relevant to some of my, depending

on what the question is, of course. Right,

52

right, depending on the research. Yes. Yeah.

With two to three year olds, what we're seeing

53

a lot of is this rapid growth in vocabulary

development and the beginnings of putting words

54

and short sentences together. So I'm interested

in how this process is happening and why some

55

children might be struggling with this. And

the children who struggle with this, we typically

56

refer to as late talkers. And so we do, so many

of us have either children that we know in

57

our lives who have been late talkers or perhaps

ourselves we were late talkers. So this really

58

is sort of a common thing across lots of different

children, I would imagine. Absolutely. Late

59

talking impacts about 12 to 13 percent of kids.

And late talking itself is not a diagnosis.

60

However, children who are late talkers are at

increased risk for ultimately having a diagnosis

61

of something called developmental language disorder.

Developmental language disorder is a disorder

62

in which an individual has difficulty understanding

and using language. And that challenge is not

63

attributable to something like autism spectrum

disorder. or cerebral palsy, or an intellectual

64

disability. These challenges can manifest in

many ways, such as difficulty finding the words

65

that they want to say, being unspecific in their

word choices, or perhaps having difficulty

66

following complex directions or understanding

figurative language. And as I said, it's the

67

most common disorder you've probably never heard

of. It impacts about 7% to 8% of the population.

68

So this is. about three times more common than

autism spectrum disorder and about as common

69

as ADHD. Wow, yeah. So our goal in the McCall

lab is to first, help all late talkers who

70

could all benefit from therapy services, but

second, to try to identify which of our late

71

talkers are at greatest risk for ultimately

having developmental language disorder, so

72

that we know who needs the greatest support

in those preschool years. because early intervention

73

is critical in improving long-term outcomes.

And as part of your work, you really have this

74

focus on verbs. And so what is it about the

verb in language that makes it such a critical

75

piece of assessing language skill? That is such

a good question and one I love talking about.

76

Verbs are unique because they bridge the gap

between the vocabulary, words and their meanings,

77

and the structure of language itself. So it's

the verb that actually determines what a sentence

78

is going to look like. For example, the verb

sleep can only take a subject. I sleep, you

79

sleep, the dog sleeps. Comparatively, the verb

give. must take a subject and an object and

80

an indirect object. I give you the book, for

example. So the verb is really what dictates

81

what can and needs to appear in that larger

sentence structure. The reason I focus on verbs

82

is because this is potentially a very early

way of getting a sense of children's later

83

grammatical skills and development. And that

grammar piece is what children who have developmental

84

language disorder struggle most with. Unfortunately,

we can't back up our current age of diagnosis

85

for developmental language disorder, which is

about four to five, because we've traditionally

86

been waiting for these milestones that typically

developing children have to hit, where we can

87

then compare and say the child isn't doing X,

Y, and Z. Therefore, they have developmental

88

language disorder. I think if we focus on verbs,

we can predict which children are struggling,

89

even in the earliest stages, with what will

become their grammatical system. Verbs are

90

also interesting because learning verbs themselves

requires some knowledge of grammar. So we're

91

getting insight into their learning process,

their ability to use grammar at an early age,

92

and then when they learn verbs, they're reinforcing

what they know of grammar and expanding their

93

ability to use structure and language. So the

idea is then that if we provide intervention

94

focusing on verbs, we're supporting not only

vocabulary development. but some of those grammatical

95

skills as well. And it reminds me a little of,

if you think about the early primers, see,

96

spot, run, those type of things are very basic

sentence structure as children are learning.

97

So it really is, they're learning from that

very young age, the sentence structure of how

98

to tie the action of something or someone together

through language. And your hope is to try to

99

assess their skill or ability to be able to

do that or not do that much earlier so that

100

they can get intervention sooner. One of the

things we do know about verb learning is that

101

at very, very young ages, children are sensitive

to these patterns in language and use those

102

patterns to make predictions about what new

words will mean. So this is a process for verb

103

learning known as syntactic bootstrapping. Children

will assume if we teach them a made up verb

104

that the duck is gorping the bunny means something

very different from the duck and the bunny

105

are gorping. And so this attention to early

structure is really important in them being

106

able to build their verb vocabularies. or I

should say, typically developing children,

107

being able to build their verb vocabularies,

because we don't know if late talkers can use

108

this skill or not. So talk a little bit about

your work in terms of the specificity around

109

typical development versus some development

that falls outside of that typical range. So

110

we would be thinking about children with autism,

perhaps other disorders. Can you talk a little

111

bit about what you're exploring in that space?

Absolutely. Most of my work is comparing typically

112

developing children to late talkers, but I've

also done some work with children on the autism

113

spectrum as well. Autism is a unique disorder

to look at when we think of language because

114

language challenges are no longer part of the

diagnosis itself. However, the majority of

115

children on the autism spectrum do have some

challenge with language. We are interested

116

in the relationship between those characteristic

features of autistic children, like the challenges

117

they have with joint attention and social engagement,

and what those implications might be for the

118

language learning process. I'm sure a day in

your lab or in your study environment is wildly

119

fun because I can't imagine, you know, having

these toddlers coming in and their families.

120

So let's talk a little bit about what is a typical

study visit look like for the kids who are

121

coming in to work with you? Well, as you said,

we try to make it as fun as possible for the

122

families and their children. We know it can

be a challenge to drive into downtown Charleston,

123

but we want to make sure that the visit is enjoyable

and a positive experience for everyone. We

124

always start with a little play to make sure

that the child feels comfortable in the space

125

and with the research team. And we also take

that time to sign consent forms, which are

126

always important, and gather any additional

information that we might need from the family,

127

such as completing a vocabulary checklist of

the words that they know, or maybe providing

128

some demographic information for us. The actual

study will vary based on our particular research

129

questions and goals, but a lot of our studies

use eye tracking methodology, which is a lot

130

of fun for children and their families. Our

children sit in our special race car chair

131

in front of an eye tracking machine where we

display videos and it captures in real time

132

the exact coordinates on the screen where the

child is looking. And we can analyze this data.

133

to get a lot of information about language skills,

language processing, language knowledge, and

134

really a far more robust data set than we would

get from just pointing, for example. Yeah,

135

the eye tracking is really interesting because

it does give you that extra set of data. And

136

what are we really looking for when we're looking

at eye tracking? That's a great question. One

137

thing we can look at is accuracy. So when we

run studies that have made up verbs, we can

138

look at whether the child can, for example,

find groping when we ask them to do so. Another

139

thing we can look at is something called language

processing speed. And for these, we're using

140

familiar words. We might display a picture of

a ball and a shoe and say, find the ball. And

141

what's very interesting is the speed at which

a child will look to the ball is predictive

142

not only of their concurrent vocabulary size,

but also their language growth and later language

143

outcomes. At least if you're looking at nouns,

we've been exploring this in verb vocabulary

144

as well. So how is it that you can tie those

things together in terms of it being predictive

145

of a future vocabulary? Well, these have been

longitudinal studies traditionally, where the

146

children who are faster to find the item have

better language scores on standardized tests

147

to age eight. We have worked on how to quantify

processing speed when children are watching

148

videos of verb actions, as opposed to looking

at static images, because eye behaviors will

149

change if you're looking at a video versus an

image. Right now we've only done concurrent

150

studies. We've done one with late talkers and

one with autistic children. But our hope in

151

the future is to do some longitudinal work to

see if this processing of verb vocabulary also

152

predicts later language outcomes. One of the

things that we found is that late talkers and

153

typically developing children have different

types of verbs in their early verb vocabularies.

154

So I'll explain what that means. We've looked

at several different aspects of how verbs encode

155

meaning. And one that is important across the

world's languages is manner versus result verbs.

156

Manner verbs are verbs that encode how something

happens, like walk, run, jump, hop, skip. These

157

are all manners of motion. Result verbs, by

contrast, encode the end state of the event,

158

like open or close or finish. What we've found,

very interestingly, is that late talkers have

159

a preference for result over manner meanings

even from the earliest stages of development,

160

whereas typically developing children prefer

manner over result verbs. So this is a notable

161

difference. We've also found that irrespective

of whether a child is or is not a late talker,

162

Children who have proportionally more manner

than result verbs have larger vocabularies

163

overall. So this has opened up several interesting

lines of research for us in thinking about

164

why each group might prefer one verb type over

another and what it might mean for intervention

165

in terms of picking therapy targets. Another

notable finding that we have out of our lab

166

is actually publishing the first ever study

to look at verb learning mechanisms in late

167

talkers. In this particular study, we were considering

whether it was better for late talkers and

168

typically developing children when learning

a new verb to hear only content nouns, the

169

boy is daxing the balloon, the boy is daxing

the balloon, or to hear a mix of content nouns

170

and pronouns, the boy is daxing the balloon,

he is daxing it. We found, somewhat to our

171

surprise, that both typically developing children

and late talkers performed better given only

172

content nouns. But late talkers in particular

performed very poorly when they were given

173

the suboptimal content noun pronoun mix. So

this is evidence for the idea that when a verb

174

learning situation is suboptimal, late talkers

are particularly negatively impacted. And further

175

support. for the idea that we need to be conscientious

about how we're teaching new vocabulary items

176

to children who are already struggling with

vocabulary. So let's talk for a second about

177

these made up words. You have mentioned a few,

and so I just, it's so fascinating that there's

178

these, you know, just made up words that you're

working with in your lab. So what is the significance

179

of these words and working with the kids with

these particular words? Well, our purpose in

180

using made-up words is to make sure that the

child doesn't already know what that word is.

181

That way we can say confidently that when they

demonstrate knowledge of this made-up word,

182

it's not because they came in already knowing

what daxing or gorping or ziffing is. And in

183

the actual experiments, we're able to make subtle

changes to learning environments. For example.

184

comparing only content nouns versus content

nouns and pronouns, and make conclusions from

185

our experiment about which learning situations

are optimal or suboptimal. This is one of the

186

major goals of our research because identifying

what is optimal is necessary when we think

187

about designing efficacious interventions. Do

you think there are implications for this research

188

to... for... is generally the way we teach language

to children? Absolutely. And I think you're

189

tapping into a really interesting question about

our perceptions of how much teaching needs

190

to happen in the process of language development.

Interestingly, there are cultures across the

191

globe where it's inappropriate socially to talk

to a child before the child is at a stage where

192

they can be conversational in return. children

learn language beautifully in these cultures

193

as well. What we see is that the child mind,

whether it's pre-programmed for language or

194

not, a theoretical debate for another time,

is ready to embrace the rich complex system

195

that is language to work through it, make sense

of it, and then employ it themselves. in a

196

variety of circumstances and with a variety

of experiences. Our challenge, particularly,

197

is for those children who struggle with this

process and making sure that we can support

198

them as best we are able to improve their long-term

outcomes. With your study, you're looking at

199

things like verbal cues, various different methods

of doing this assessment. Can you tell us a

200

little bit about what that looks like and maybe

where that comes from? Figuring out what an

201

unfamiliar word means is actually an incredibly

difficult task. And sometimes we don't think

202

about how hard it is for children to make sense

of a word that they have never heard before.

203

There's been wonderful research over the past

60 to 70 years to identify some of the cues

204

that children use when making sense of an unfamiliar

word. One of the cues is visual information.

205

It's a lot easier to figure out what a word

means if the referent of that word is visually

206

available to the child in real time. Children

also use social cues to figure out what words

207

mean. For example, a parent might point to an

item or direct the child's attention in some

208

other way to bring attention to the word that

they are teaching. One cue that's incredibly

209

important, but perhaps not so immediately obvious,

is using linguistic information to figure out

210

what that word means. And there are all sorts

of linguistic cues that children use. For example,

211

by about 18 months of age, children can reliably

class words into nouns or verbs based on how

212

they're used in a sentence. If they hear, a ziff, a mody, they know that that's probably

213

a noun. Whereas if they hear gorp-ing or zeb-ing,

they know that that's probably a verb. They're

214

also aware by this age that nouns denote objects

and verbs denote actions. So this is one way

215

they may narrow down their hypotheses of what

an unfamiliar word might mean. When we consider

216

verb learning specifically, Typically developing

children use a process known as syntactic bootstrapping.

217

This means they use the structure of the sentence

and the relationship of the nouns to the verb

218

to make inferences about the type of meaning

encoded by that verb. I'll give you an example.

219

Typically developing children by age two know

that the duck is groping the bunny means that

220

the duck is doing something to. a bunny. Conversely,

the duck and the bunny are groping means that

221

the duck is doing something and the bunny is

doing something separately from that duck.

222

We actually don't know if late talkers use syntactic

bootstrapping at all in their process of verb

223

learning. This is one of the studies we're running

right now in the lab, and I'm very excited

224

to see what the results are. There are different

implications about the verb learning process

225

and intervention techniques based on whether

this cue is available to late talkers in learning

226

new verbs. Do you have any tips for parents

of toddlers or even of really honestly parents

227

at any age probably, you know, kids sub five,

I guess, based on your work and what you know

228

particularly as a researcher and also as a speech

language pathologist? This is a question I

229

get asked a lot. The first recommendation I

make to any parent is to read to your child.

230

Reading is a wonderful way to expand a child's

vocabulary and their grammar skills, because

231

we use grammatical structures and vocabulary

items in literature, even children's literature,

232

that we don't use in our day-to-day conversation.

For example, ball means one thing when we're

233

playing outside and another thing altogether

when reading Cinderella. Another thing that

234

I encourage parents to do is to talk to and

with and around their children. You are enriching

235

their language environment by giving them exposure

to language even if you're not talking directly

236

to them. Narrating what you're doing or narrating

what you're seeing is a wonderful way to spark

237

their language growth. I also get a lot of questions

about language development from parents who

238

are concerned that their child might be a late

talker. It's hard to know what the milestones

239

are. To any parent who asks me, I always recommend

that they talk with their pediatrician. If

240

you have serious concerns, it is worth it to

follow up and potentially pursue an evaluation.

241

Why are things like the number of verbs that

a child knows and sentence structure important?

242

These are parts of language known as morphology

and syntax. And together, morphology and syntax

243

make grammar. They're so important because children

who have developmental language disorder struggle

244

with grammar particularly. We're interested

in verbs as an early predictor of where they'll

245

end up with their grammar skills and who might

struggle the most. But I've used these very

246

technical terms, morphology and syntax, and

I feel like I should define them a little bit

247

more. Syntax is essentially the word order of

a language. For example, in English, we have

248

a subject verb object word order. In other languages

like Hungarian, the verb goes at the end of

249

the sentence. Morphology are these little pieces

of language that let us know who did what to

250

whom and when it happened. They don't have any

meaning in and of themselves other than conveying

251

this information. Examples in English include

the progressive -ing, walking, eating, the past

252

tense -ed, walked, talked, or the plural s, shoes,

socks. What we've found is that the number

253

of verbs a child has at age two predicts how

many morphemes they know at age three and how

254

complex their sentences are. We find this very

suggestive of the role that verbs play in developing

255

grammar. So understanding how children learn

verbs and how to possibly improve that learning.

256

is key to their language success in the future.

Absolutely. We've been talking to Dr. Sabrina

257

Horvath about childhood language development.

Have an idea for a future episode of Science

258

Never Sleeps? Click on the link in the show

notes to share with us. Science Never Sleeps

259

is produced by the Office of the Vice President

for Research at the Medical University of South

260

Carolina. Special thanks to the Office of Instructional

Technology for support on this episode.