79612940

Evidence for Website Claims aboutthe Benefits of Teaching SignLanguage to Infants and Toddlerswith Normal Hearing

Lauri H. Nelson*, Karl R. White and Jennifer GreweUtah State University, Logan, Utah USA

The development of proficient communication skills in infantsand toddlers is an important component to child development.A popular trend gaining national media attention is teachingsign language to babies with normal hearing whose parentsalso have normal hearing. Thirty-three websites were identifiedthat advocate sign language for hearing children as a way ofpromoting better developmental outcomes. These sites makeseveral claims about the positive benefits of teaching hearinginfants and toddlers to sign, such as earlier communication,improved language development, increased IQ, reduced tan-trums, higher self-esteem, and improved parent–child bonding.Without endorsing or disparaging these claims, the purpose ofthis article was to evaluate the strength of evidence cited onwebsites that promote products to teach young children to usesign language. Cumulatively, 82 pieces of evidence were citedby the websites as supporting research. However, over 90% ofthese citations were opinion articles without any supportingdata or descriptions of products and only eight were empiricalresearch studies relevant to the benefits of teaching sign lan-guage to young children with normal hearing. Unfortunately,there is not enough high-quality evidence cited on these web-sites to draw research-based conclusions about whether teach-ing sign language to young children with normal hearingresults in better developmental outcomes. Copyright © 2012John Wiley & Sons, Ltd.

Key words: baby sign language; sign language for hearing toddlers

*Correspondence to: Lauri H. Nelson, PhD, Utah State University, 2620 Old Main Hill,Logan, UT 84322, USA. E-mail: [email protected]

Infant and Child DevelopmentInf. Child Dev. 21: 474–502 (2012)Published online 10 January 2012 in Wiley Online Library(wileyonlinelibrary.com). DOI: 10.1002/icd.1748

Copyright © 2012 John Wiley & Sons, Ltd.

INTRODUCTION

Communication, or the ability to participate in a meaningful exchange of informa-tion with another person, is a fundamental component of human interactions.Developing proficiency in communication skills during early childhood is univer-sally regarded as an important outcome in child development (Luze et al., 2001).Because communication is an exchange of both the expression of one’s thoughtsor ideas (expressive language) and the ability to understand the thoughts or ideasexpressed by someone else (receptive language), most parents are eager to witnessthe emergence of these skills in their children beginning in early infancy.

Typically developing infants show evidence of a natural emergence of expressiveand receptive communicative behaviours. Most infants follow a predictable patternof speech development, including babbling at 5–10months of age, comprehensionof words and concepts at 8–10months of age, productions of words or word approx-imations beginning near 12months of age, and the production of word combina-tions emerging at 14–24months of age (Coplan, 1995; Oller et al., 2006).

As children enter their second year of life, generally, they understand more thanthey can verbally express. Contributing to this disparity is the physical motor skilldevelopment necessary for expressive speech productions, which occurs later thancognitive development needed for receptive speech comprehension skills. For ex-ample, growth within the respiratory system is required to generate adequate airpressure and for respiratory action to be sufficiently coordinated with the anatomyof the larynx. The size and position of the larynx undergo significant changes duringthe first and second years of life along with neurological maturation of the speechand language centers of the brain. All of these mechanisms must experience suffi-cient growth and development for a child to produce early verbal productionsand, ultimately, understandable speech (Kent, 1999). This physiological processoccurs within the developmental time frame in which toddlers are beginning todevelop distinct preferences for what they desire, with the common theory thatthe inability to express these desires can precipitate tantrum behaviours. However,until these anatomical and neurological processes are poised for the onset of speechproduction skills, the communication capabilities of most toddlers are limited.Therefore, many parents strive to identify methods or strategies to assist their childin achieving or accelerating optimal expressive and receptive communication skills.

A popular trend gaining national media attention is teaching sign language tobabies with normal hearing whose parents also have normal hearing (e.g.,Anthony & Lindert, 2005; Azar, 1998; Ladino, 2003; Sanchez, 2001; Snoddon,2000). The premise of this strategy is to provide infants and toddlers with the skillsto communicate their needs or desires prior to the natural emergence of the motorand linguistic development required to produce verbal speech. The popularity ofusing sign language with normal-hearing infants is considerable. The use of signlanguage with hearing infants has been featured on popular TV shows (e.g.,Oprah, Dateline, Good Morning America, Today Show) and in general circulationmagazines and newspapers (e.g., Parenting, Newsweek, Los Angeles Times, TheWashington Post, U.S. News, USAToday). Hundreds of baby sign language booksare available that advocate the practice of using signed representations of words toincrease communication skills in infants and toddlers. An internet search yieldednumerous advertisements with directives to several different websites. As shownin the results section of this article, specific claims of direct benefits of teaching signskills to infants and young children are promoted on these websites, such as anincreased ability to communicate; improved language, literacy, and cognitiveskills; reduced frustration; and better parent–child bonding.

Baby Sign Language Website Claims 475

Copyright © 2012 John Wiley & Sons, Ltd. Inf. Child Dev. 21: 474–502 (2012)DOI: 10.1002/icd

To achieve the benefits and outcomes described on baby sign language websites,a variety of teaching tools, such as DVDs, audio tapes, instructional books, elec-tronic books, and flashcards are advertised for purchase. These websites promoteeither their own products or they refer consumers to the products of others. Inaddition, some websites promote their product or program by networking withprivate individuals as a business opportunity, such as becoming a trained instructorof a particular technique or program of infant sign language. Some websites havededicated sections for daycare providers and preschool instructors.

Purpose of the Study

The popularity of this trend has become so widespread that the benefits describedon sign language websites may be accepted as fact without substantiation.Although website businesses designed to attract internet consumer spendingclearly are not new, sites targeted to parents that advertise products that promisepositive outcomes for their children are more emotionally charged than generalproducts available for purchase. Therefore, the goals of this study were to (1) iden-tify websites that promote the practice of teaching sign language to hearing infantsand toddlers and identify the number and type of claims that websites makeregarding the benefits of this practice; (2) analyze the accuracy of these claimsbased on supporting research listed on websites; and (3) evaluate the methodo-logical quality of the empirical research listed on websites as support for statedclaims. This content analysis was not intended to either endorse or discouragethe practice of teaching sign language to hearing infants. Rather, the goal was toevaluate the credibility of evidence used to support the claims made on the web-sites so that parents and consumers can make informed decisions regarding theaccuracy and validity of these claims and the potential benefit to their child.

METHODS

Sample

A detailed examination of the website claims, using content analysis, provided theframework for this study. Content analysis is a research technique for making infer-ences through objective, quantitative, and systematic analysis of a communication orconsumer message (Barr & Linebarger, 2010; Fenstermacher et al., 2010; Kassarjian,1977; Vaala et al., 2010). The first step in the analysis required a comprehensive inter-net search to identify all of the websites whose primary purpose was to promote theuse of sign language with pre-linguistic normal-hearing children of hearing parents.Non–English-speaking websites and blogs that discussed using sign language withchildren with normal hearing were excluded from the review. Sites were identifiedby entering ‘baby’, ‘sign language’, ‘infant’, and ‘gesture’ into a Google Internetsearch engine. Thirty-threewebsiteswere found, and each sitewas evaluated to iden-tify the specific outcomes the websites claim that parents can expect when infantsand toddlers with normal hearing are taught to communicate using sign language.1

Analysis of Website Claims

Next in the content analysis was the compilation of outcome statements listed on thewebsites, which yielded a variety of similarly worded promises of positive impact inareas of communication, language, cognition, and behaviour. Each statement of

476 L. H. Nelson et al.


benefit was documented in a spreadsheet and analyzed by the authors to identifycommon content areas. For instance, some websites stated that young childrenwho learn to sign will experience feelings of satisfaction, accomplishment, and em-powerment. Other websites described an increase in self-esteem and self-confidence.These descriptors were viewed as similar claims and categorized together. Similarly,websites used various phrases relative to cognitive benefits, such as acceleratedbrain development, enhanced memory, increased speed of spatial reasoning, andincreased IQ. These descriptors also were viewed as comparable and were categor-ized together. From this analysis, six categories of ‘claims’ were identified that web-sites make about the benefits to children that result from sign language instruction.Table 1 describes the claims and lists the number of websites making each claim.

To further illustrate, www.signbabies.com states on their website that teachingbabies to sign will ‘stop tantrums and start conversations; sign language helpsteach toddlers to talk and improve IQ scores’; www.signingtime.com states that‘baby sign language reduces frustration and tantrums; you can strengthen yourchild’s speaking, reading, writing, and spelling; you can build strong parentalbonds as you focus on language with your child; using sign language, childrencan develop literacy skills before they start school’; www.babysigningtime.comstates that ‘no more tantrums; stimulate early learning, language skills, and largervocabulary; create a window into your child’s mind and heart; and instill confi-dence and security through understanding’; and www.kindersigns.com states that‘baby signing will result in earlier verbal language, will reduce frustration betweenparents and their babies, will enhance receptive and expressive vocabulary, willhelp children learn to read more easily, will enhance a baby’s creative ability, willresult in a higher IQ of 10–12 points, and will help promote a closer parent/child/caregiver bond’. The analysis of claims made on these websites revealed a greatdeal of consistency in the claimed benefits, with almost all websites saying thathearing children who are taught sign language will be able to communicate theirneeds better, develop language faster, have a higher IQ, and have fewer tantrums.All websites were checked twice for accuracy, with additional random checks tomonitor potential website content changes. The URLs of the sites included in theanalysis and the claims made on each website are shown in Appendix A.

Analysis of Claims Based on Supporting Research

Even though there is consistency among the websites in the claims being made, itis important to know how credible the evidence is which is cited to support theseclaims. Therefore, the third step in the content analysis involved a comprehensivesearch and documentation of all the research cited on the websites. Each website

Table 1. Claims made by 33 websites about teaching sign language to children with normalhearing

Description of claim Frequency cited

1) Earlier communication of needs and thoughts 332) Increased language or speech development, improved literacy skills 293) Increased IQ or cognitive skills 274) Reduced frustration, tantrums, or emotional outbursts 275) Increased parent/child bonding 226) Increased self-esteem, feelings of satisfaction, accomplishment 19



http://www.kindersigns.com

was searched at least two times on different days to obtain a combined listing of allof the research evidence cited to support the claims made by that website. A var-iety of evidence types were found, including journal articles, book chapters, books,newspaper articles, online articles, professional conference presentations, andopinions by alleged experts. Each source of evidence was categorized accordingto research type (e.g., empirical studies, opinion articles, sign language instructionbooks, articles not relevant to teaching sign language to infants and toddlers).Personal anecdotal experiences or testimonials that did not cite evidence wereexcluded from the analysis. Evidence about the benefits of teaching sign languageto children with disabilities was not included in this review.

Studies documenting the natural emergence of gestures, if there was no teach-ing of sign language, were excluded from the analysis. An example of such a studywas reported by Iverson and Goldin-Meadow (2005), who examined the linkbetween naturally emerging gestures and early language development. In thisstudy, 10 typically developing infants with normal hearing were followed longitu-dinally between the ages of 10 and 24months. The researchers videotaped the chil-dren with a primary caregiver in the home during play or snack time to evaluatewhether the child’s natural use of gestures to refer to specific objects was relatedto the emergence of verbal labels for those objects. The researchers reported thatnine of the 10 children produced a majority of object references using gestures atthe beginning of the study and that none of the children used gestures for themajority of their communications at the final session. The authors concluded thatgesture both precedes and is tightly related to language development and mayfacilitate future learning. Although some researchers may hypothesize thatexpanding natural gestures by teaching sign language will result in improved lan-guage development, studies of naturally emerging gestures are not evidence thatthis will occur. Therefore, this article or others similarly designed (e.g., Acredolo& Goodwyn, 1988; Vallotton, 2008), when no sign language was purposefullytaught, is not relevant as evidence of the benefits to teaching sign language toinfants and toddlers.

Some websites referenced research studies of school-aged children (Bonvillianet al., 1988; Daniels, 2004; Felzer, 1998; Griffith, 1985). Such studies may explorethe efficacy of implementing sign language instruction into the educational cur-riculum but do not provide support toward the claims made by websites whensign language is taught to infants and toddlers.

Evaluation of Methodological Quality of Empirical Evidence

The fourth step in the content analysis involved a detailed evaluation of the meth-odological quality of the eight empirical articles cited on the websites that studiedwhether teaching sign language to hearing infants and toddlers leads to better out-comes. Articles were identified and included in this category based on the followinginclusion criteria:

(1). a research question was asked and data were collected;(2). sign language, symbolic gestures, or other manual communication method

was purposefully taught to some or all children in the study before60months of age;

(3). the article was printed in the English language.

Each empirical study that met inclusion criteria was coded with regard to thestudy design, characteristics of participants, outcomes reported as a standardized



mean difference effect size (SMDES) whenever possible, and the methodologicalquality of the study (i.e., the degree to which credible evidence was given to sup-port conclusions). Methodological quality was rated using a five-point scale(1 = good, 3 = fair, 5 = poor) by evaluating the threats to internal validity, such assubject selection, test instrumentation, history, maturation, regression, and statis-tical procedures (Appendix C). All three authors coded each article, and any dis-agreement on coding of the evidence was discussed until agreement was reached.

RESULTS

Research to Support Website Claims

As shown in Table 2, a total of 82 sources of evidence were cited by these websitesas support for the claimed benefits of teaching sign language to hearing infantsand toddlers (citations for each source of evidence are shown in Appendix B). Onlyeight of the 82 sources of evidence were empirical research studies that evaluatedthe benefits of teaching sign language to young children with normal hearing. Ofthe eight empirical studies cited on the websites, four articles focused on whetherthere is an increase in communicative exchanges and signed vocabulary wheninfants are purposefully taught to sign, three articles focused on receptive vocabu-lary development, and one article focused on outcomes related to IQ. None of thewebsites listed any research at all to support claims of reduced tantrums, increasedparent–child bonding, or increased feelings of self-esteem.

Methodological Quality of Empirical Evidence

Table 3 summarizes key information about each of the empirical studies that wereused to support the claims made on the websites. Of the eight studies coded, fivearticles were authored by researchers Acredolo and Goodwyn and three articleswere authored by Daniels. These researchers advocate the use of symbolic gesturesand sign language to improve communication and language development ininfants. Acredolo and Goodwyn are the founders of Baby Signs, Inc.©, a compre-hensive baby signs website that offers sign language books, DVDs, and other

Table 2. Sources of evidence for claims made by websites regarding the benefits of teachingsign language to young children with normal hearing

Sources of evidenceTotal number

cited

Empirical studies that evaluated the benefits of teaching sign language to youngchildren with normal hearing

8

Article, book, or book chapter that gave an opinion but did not include empiricalevidence not previously reported

41

Articles or empirical studies on a topic not related to the benefits claimed on signlanguage websites

10

Descriptions of sign language training programs for school-aged children 11Sign language instructional books 4Empirical studies of how children naturally acquire gestures but not studies of thebenefits of sign language instruction

3

Articles that could not be located 5Total sources of evidence 82



Table3.

Cha

racteristics

ofresearch

stud

iescitedto

supp

ortbe

nefits

ofteaching

sign

lang

uage

toyo

ungch

ildrenwithno

rmal

hearing

Stud

ydescription

andch

aracteristics

Metho

dolog

ical

quality

Article

(date)

Design

Age

atstart

ofstud

yAge

aten

dof

stud

yPu

rposeof

stud

yCon

clus

ions

ofau

thor(s)

SMDES

Validity

rating

(1=go

od!

5=po

or)

Validity

threatscoded

Com

men

tsof

metho

dolog

ical

quality

Acred

olo&

Goo

dwyn

(1985)

Casestud

y(n

=1)

12.5mon

ths

17.5mon

ths

Todocum

entthe

dev

elop

men

tof

spon

tane

ousan

dpu

rposefully

taug

htge

stures

inahe

aring

infant

ofhe

aring

parents.

Gesturals

igns

increased

this

child

’svo

cabu

lary

andwereapo

sitive

additionto

her

commun

icative

expe

rien

ces.

SMDES

:(couldno

tcalculate)

Validity

rating

:n/a

Validity

threatsc

oded

:other

•Su

bjectwas

thech

ildof

oneof

theau

thorsof

thestud

y•Sign

lang

uage

taug

htby

know

ledg

eableresearchers

•Itis

prob

lematic

toextend

conc

lusion

sfrom

acase

stud

yto

thege

neralp

opulation

Acred

olo&

Goo

dwyn

(1990)

Pre–po

stpilotstud

y(n

=6)

11mon

ths

(five

subjects)

13.75–21.5

Toevalua

teifpa

rents

canteachtheirinfants

symbo

licgestures

and

toexploretherelatio

nship

betw

eensymbo

licgesturingan

dverbal

lang

uage

developm

ent

Itispo

ssibleto

train

parentsto

teachgestures

toinfants.Su

bjectsshow

edlargeindividu

aldifferen

cesin

vocala

ndgestural

deve

lopm

ent,

with

ade

pend

ence

ofon

eon

theothe

r.

SMDES

:cou

ldno

tcalcu

late

Validity

rating

:4Validity

threatscode

d:selection,

instrumentatio

n,testing,other

8mon

ths

(one

subject)

•Non

-ran

dom

ized

participan

tselection

•The

rewas

nostud

ycontrolg

roup

•Pa

rticipan

tswereno

tblindas

tostud

ypu

rpose

(Contin

ues)



Table3.

(Con

tinu

ed)

Stud

ydescription

andch

aracteristics

Metho

dolog

ical

quality

•Pa

rent

repo

rtof

child

prog

ress;h

ighprob

ability

forrepo

rtingbias

•Po

tentialfor

large

variab

ility

inho

wpa

rents

interpretedchild

respon

ses

•Stud

ydid

notdescribeif

sign

swereus

edin

afunc

tion

alway

orifthey

werebo

undto

asing

lecontext

Goo

dwyn

Acred

olo&

Brow

n(2000)

Prospe

ctive

coho

rt11

mon

ths

36mon

ths

Eva

luated

theeffect

onve

rbal

lang

uage

dev

elop

men

tof

purposefully

encourag

ing

hearinginfantsto

use

simplege

stures

assymbo

ls.

Childrenareab

leto

use

gestures

whe

ntaug

htby

theirpa

rentsto

agreater

degree

than

whe

nthey

areno

ttaug

ht.Children

intheST

grou

pha

dexpressive

lang

uage

scores

that

were

high

erthan

theNIg

roup

at15

and24

mon

thsbu

twereno

thighe

rwhe

ntested

at19,30,or

36mon

ths.

SMDES:

0.34

Validityrating

:3ST

:(n=32)

Validity

threatscode

d:selection,

instrumentatio

n,testing,

other

•Non

-ran

dom

ized

participan

tselection

NI:(n

=39)

VT:

(n=32)

•Pa

rticipan

tswereno

tblindas

tostud

ypu

rpose

•Allou

tcom

esscores

from

verbaltraining

grou

pwere

notreported

•Po

tentialfor

large

variab

ility

inho

wpa

rents

interpretedchild

respon

ses

Goo

dwyn

&Acred

olo

(1993)

Prospe

ctive

coho

rt(n

=22)

11mon

ths

App

roximately

15mon

ths

Com

paredag

ewhe

nthe

firstan

dfifthve

rbal

orge

stural

symbo

l

Onav

erag

e,ba

bies

develope

dsymbo

lsab

out

thesametim

ein

both

SMDES:

0.56

Validityrating

:3 (Contin

ues)



Table3.

(Con

tinu

ed)

Stud

ydescription

andch

aracteristics

Metho

dolog

ical

quality

(sub

jects

draw

nfrom

pilota

ndlong

itudinal

stud

ies)

dev

elop

edto

determine

whe

ther

commun

ication

occu

rsearlierin

the

gestural

mod

alityor

the

vocalm

odality

mod

alities,w

itha

tend

ency

fortheon

seto

fgestural

symbo

lsto

appe

arfirst.

Validitythreatscoded

:selection,

instrumentatio

n,testing,

othe

r•Non

-ran

dom

ized

participan

tselection

•Validity

threatsof

instrumentatio

n,testing,

potentialreportin

gbias

are

perpetua

tedfrom

thepilot

andlong

itudina

lstudies

Acred

olo&

Goo

dwyn

(2000)

Prospe

ctive

coho

rt1–

3ye

ars

8ye

ars

Com

pare

IQscores

ofchild

renwho

weretaug

htsign

asinfantsor

todd

lers

Childrenin

theST

grou

pha

dhigh

erscores

onthe

WISC-IIIthan

child

renin

theNIg

roup

.Nosign

lang

uage

interven

tion

occu

rred

betw

eeninitial

testingan

dthe

assessmen

tata

ge8.

SMDES:

0.80

Validityrating

:5ST

:(n=19)

Validitythreatscoded

:history,

maturation,

selection,

instrumentatio

n,testing,

mortality,othe

r

NI:(n

=24)

(sub

jects

draw

nfrom

long

itudinal

stud

y)•Stud

ymetho

dolog

yno

tclearlydescribed

•Non

-ran

dom

ized

stud

ygrou

pselectionan

dassign

men

tpe

rpetua

ted

from

original

stud

y•Verba

ltraininggrou

pno

tinclud

edin

this

stud

y•Noindicationthat

data

colle

ctorswereblindto

purposeof

stud

y•Noinform

ationab

out

educationaltrainingdu

ring

(Contin

ues)



Table3.

(Con

tinu

ed)

Stud

ydescription

andch

aracteristics

Metho

dolog

ical

quality

timebetw

eenthisstud

yan

dtheoriginal

stud

y•Sign

ificant

attritionfrom

original

stud

yDan

iels,M

.(1993)

Cross-

sectiona

l2.10–1

3.6

2.10–1

3.6

Evalua

tedvo

cabu

lary

performan

cein

hearing

child

renof

deaf

parents

who

learne

dASL

beginn

ingin

infancyan

dused

ASL

regu

larlyin

the

home

Vocab

ularystan

dard

scores

high

erin

stud

ygrou

pthan

publishe

dstan

dardized

norm

s,as

measu

redov

erbroa

dag

erang

e.

SMDES:

0.64

Validityrating

:4Validitythreatscoded

:selection,

instrumentatio

n,testing,

statistic

alproced

ures,o

ther

•Non

-ran

dom

ized

participan

tselection

•Pa

rticipan

tswereno

tblindas

tostud

ypu

rpose

orhy

pothesis

•Scores

averag

edov

era

broa

dag

erang

e•Nocontrolg

roup

(autho

rused

assessment

stan

dardizationsampleas

thecompa

rativ

emeasure)

Dan

iels,M

.(2004)

Prospe

ctive

coho

rt(n

=60)

Treatm

ent

n=30

Con

trol:

n=30

Startof

pre-Kye

arEnd

ofpre-Kye

arEva

luated

vocabu

lary

performan

cein

child

ren

who

weretaug

htsign

compa

redwithch

ildren

ofthesameag

ewho

did

notreceivesign

instruction.

The

grou

pthat

received

sign

lang

uage

instructionscored

high

eron

avo

cabu

lary

test

than

theno

n-sign

grou

p.

SMDES:

1.30

Validityrating


:selection,

instrumentatio

n,testing,

statistic

alproced

ures,o

ther

•Non

-ran

dom

ized

participan

tselection

(Contin

ues)



Table3.

(Con

tinu

ed)

Stud

ydescription

andch

aracteristics

Metho

dolog

ical

quality

•Noba

selin

escores

for

controlg

roup

priorto

interven

tion

•Pa

rticipan

tswereno

tblindas

tostud

ypu

rposeor

hypo

thesis

Dan

iels,M

.(1996)

Prospe

ctive

coho

rt(n

=19)

N/A

End

ofKye

arFo

llow-upvo

cabu

lary

measu

refrom

same

subjects

who

received

sign

lang

uage

instructionas

repo

rted

inDan

iels,1

994.

Nosign

lang

uage

instruction

occu

rred

duringthe

kind

erga

rten

year.

Vocab

ularyscores

were

repo

rted

tobe

high

erthan

norm

ative

stan

dardizationsample,

withconc

lusion

that

the

sign

ingbe

nefitha

dbe

enmaintaine

d.

SMDES

:cou

ldno

tcalcu

late

Validityrating


:history,

maturation,

selection,

instrumentatio

n,testing,

statistic

alproced

ures,o

ther

Same

subjects

asthosein

1994

stud

y(intervention

grou

pon

ly)

•Non

-ran

dom

ized

participan

tselection

perpetua

tedfrom

original

stud

y•Scores

from

control

grou

pwereno

tobtaine

d•Did

nota

ccou

ntforothe

rinstructiona

lvariables

that

may

have

influe

nced

vocabu

lary

performan

ce

ST=sign

training

grou

p;NI=

non-interven

tioncontrolg

roup

;VT=ve

rbaltraining

controlg

roup

;SMDES

=stan

dardized

meandifferen

ceeffectsize;W

ISC-III=Wechsler

IntelligenceScaleforChildren,

3rdEd

ition

.



similar products for sale, business opportunities for becoming a baby signsinstructor or consultant, classroom baby signs training kits, and information onhow interested organizations can become a certified baby sign center. Acredolo,Goodwyn, and Daniels have authored several articles, sign language books, andAmerican Sign Language (ASL) training workshops.

Empirical support for claim no. 1: increased ability to communicate needs and thoughtsFour studies were identified that evaluated the impact on communication and

signed vocabulary in infants and toddlers with normal hearing who are taughtto sign. In a case study, Acredolo and Goodwyn (1985) described the communica-tion behaviours of a female child named Kate from 12.5 to 17.5months of age, whowas the daughter of Linda Acredolo, one of the authors of the study. The studyevaluated both naturally emerging gestures and symbolic gestures that were pur-posefully taught. Study results indicated that Kate learned 29 signs between theages of 12.5 and 17.5months and that her vocabulary development was higherwhen compared with normative vocabulary milestones reported by Nelson(1973). The authors concluded that the use of gestural signs was a positiveaddition to this child’s communicative experiences. They reported that a directcorrelation between sign language and increased verbal language skill develop-ment could not be determined based on this single case study but that the resultsargue against the theory that the development of a gestural system delays vocallanguage acquisition. Although case studies can provide helpful descriptive infor-mation relative to the experiences of an individual, it is always problematic toextend conclusions drawn from a case study to the general population.

In a pilot study as a precursor to a longitudinal study, Acredolo and Goodwyn(1990) evaluated the efficacy of teaching infants to use idiosyncratic gestures tofacilitate vocabulary development and communication. The parents of six infantseach taught their child five specific gestures associated with a toy object and wereencouraged to develop any other object–gesture associations in which their childappeared to show interest. It is unclear if these subjects were a subset of the longi-tudinal study or how subjects were recruited or selected for study participation.Data collection consisted of weekly telephone interviews with parents to deter-mine the child’s progress in development of vocal words and in symbolic gesturesand to determine the point at which a label was being used in a meaningful orsymbolic way. Results of this study indicated that the six participants learnedan average of 20 signs each and that they developed verbal vocabulary in advanceof what would be expected based on previously published normative data(Nelson, 1973; Rescorla, 1980).

This study was rated as ‘fair–poor’ in terms of methodological quality (a ratingof 4 in the coding system that was used). Findings were based entirely on parentreport, and parents were informed of the purpose of the study and knew that itwas desirable for their child to develop as many signs and words as possible,resulting in a high probability for reporting bias. Study results do not describe aprotocol to ensure consistency in how parents interpret meaningful use of wordsof gestures, nor the degree to which study participants used the gestures in afunctional or truly symbolic way as opposed to being bound to a single context.Furthermore, there was not a control group of subjects who were not exposed togestural training, which by the authors’ own report, renders it impossible to deter-mine with any certainty that gestural training was the variable that had a positiveeffect on verbal language acquisition.



Acredolo and Goodwyn began data collection in 1989 for a longitudinalcohort study funded by the National Institutes of Child Health and HumanDevelopment. The purpose of the study was to evaluate the effects on vocabu-lary and verbal language development when hearing infants are taught to usesimple gestures for communication. Data from this study were reported acrossseveral years and in a number of different publications. The study conductedby Goodwyn, Acredolo, and Brown (2000) is one of the articles that describesthe study outcomes and is referenced on several websites. This longitudinalstudy involves one experimental group and two control groups. The experimen-tal group was a Sign Training group (n= 32) in which parents were instructed tomodel symbolic gestures and to encourage their child to use them. Parents wereinformed of the study purpose, viewed a training video, and were made awareof the specific interest on documenting use of signs or gestures in infants. Thefirst control group was composed of parents of infants in a non-interventiongroup (n= 39) who received no instructions specific to using verbal or signedprompts with their children and who were not informed of the purpose of thestudy. The second control group was composed of parents of infants in a verbaltraining group (n= 32) who were encouraged to model verbal labels, but it is notclear if these parents were informed of the purpose of the study. Procedures forsubject recruitment were not described, and group assignment did not appear tobe randomized. Data were collected via telephone interview with parents every2weeks to report on the communicative progress of their child. The researchersreported using strategies in the telephone interview to ‘jog the memories’ of theparents; therefore, it is unclear if a systematic method of documenting thechild’s signed or verbal communications that occurred between each biweeklyreport was used.

Based on the parent interviews, it was reported that children in the sign lan-guage training group acquired an average of 20.4 signs or gestures. The research-ers compared these findings with an earlier study (Acredolo & Goodwyn, 1988) inwhich children who were not specifically taught to sign acquired an average offive gestures or signs, suggesting that children are able to use gestures and signswhen specifically taught by their parents to a greater degree than when they arenot taught. These data are relevant to the question of whether young children withnormal hearing can be taught sign language but do not address the claim that chil-dren who are taught sign language will have better developmental outcomes thanchildren who are not taught sign language. Furthermore, despite research byAcredolo and Goodwyn advocating the importance of naturally emerginggestures (Acredolo and Goodwyn, 1998; Acredolo and Goodwyn, 1988), no datawere collected on the spontaneous or naturally acquired use of gestures in eithercontrol group.

In addition to parent interviews to obtain data on vocabulary progress, theparents completed the MacArthur Communicative Developmental Inventory (Fensonet al., 1993) at 11, 15, 19, 24, and 30months of age. Expressive and receptivelanguage skills were evaluated at 15 and 19months using the Sequenced Inventoryof Communicative Development (Hedrick, Prather, & Tobin, 1984), as measuredthrough a variety of behavioural responses to verbal questions and commands.At 24, 30, and 36months of age, receptive and expressive language skills weremeasured using the Receptive- and Expressive-One-Word-Picture-Vocabulary Tests(Gardner, 1985). To measure receptive language with this assessment, four picturesare presented on each trial and the child is asked to point to the picture that depictsthe meaning of the word. Expressive language is measured by presenting a differ-ent picture on each trial and asking the child to label the picture. At 24months of



age, a free play session was completed to obtain Mean Length of Utterance, and aPhonemic Discrimination Taskwas completed at age 30months. Children in the signtraining group had expressive language scores that were statistically significantlyhigher than the non-intervention control group at 15 and 24months, but outcomeswere not statistically significantly higher for the experimental group when testedat 19, 30, or 36months. Children in the sign training group had receptive languagescores that were statistically significantly higher than the non-intervention controlgroup at 19 and 24months but showed no statistically significant differences at 15,30, and 36months.

A treatment effect size was calculated for the analysis reported in this article byaveraging the results for each outcome variable for the scores that were reported,resulting in a SMDES of 0.33. However, these comparisons are only between thesign training group and the non-intervention control group because Goodwynand her colleagues did not report scores from the verbal training group that wouldhave been the best comparison to determine whether teaching sign language toyoung children results in better developmental outcomes.

The study was rated as ‘fair’ with respect to methodological quality. The omis-sion of scores from the verbal language control group is perplexing. The research-ers offered only the vague explanation that the results of the non-interventioncontrol group and the verbal training control group were not statistically signifi-cantly different and suggested that this provides evidence that ‘training effects’had been controlled for in the sign training group. However, full analysis of theverbal training group comparison at each test interval would have strengthenedthe study findings. Furthermore, the fact that subjects were not randomly assignedto groups means that selection bias is a strong alternative explanation for thedifferences in outcomes between groups. Finally, the way in which outcomedata were collected created moderate threats to internal validity with respect toinstrumentation and testing.

In a prospective cohort study reporting outcomes from a subset of 22 partic-ipants drawn from the longitudinal study and from the original pilot study,Goodwyn and Acredolo (1993) compared onset of the symbolic use of signsand words in infants to determine whether communication with true symbolsoccurs earlier in the gestural modality than the vocal modality. Study resultsrevealed that on average, infants in this study developed symbols aboutthe same time in both modalities, although there was a small tendency forthe onset of gestural symbols to first appear earlier than vocal symbols. Thereported average age when the first symbol appeared was 11.9months forgestures and 12.6months for vocal words, resulting in an average gesturaladvantage of slightly more than 2weeks. Goodwyn and Acredolo stated intheir conclusions that the size of gestural advantage was not as great as hadbeen hypothesized, that there were significant individual differences seen inthe language acquisition patterns among all participants, and that the basicbuilding blocks for language must be in place before symbolizing of any typecan effectively be used for purposeful communication. This finding may fur-ther illustrate the fundamental principle described by Piaget that cognitivedevelopment is at the center of the human organism and language is contin-gent on cognitive development (Russell, 1999). The methodological quality ofthis study was rated as ‘fair ’ because subjects were not randomly assigned togroups and problems about instrumentation and testing perpetuated fromthe original pilot and longitudinal studies. The treatment effect size comparingage at first onset of gestural use with age at first onset of vocal word useresulted in a SMDES of 0.56.



Empirical support for claim no. 2: earlier language, vocabulary, literacy skillsIn a cross-sectional study, Daniels (1993) reported receptive vocabulary profi-

ciency of 14 children between the ages of 2 and 13 years. The Peabody PictureVocabulary Test—Revised Edition (PPVT-R) was used to measure vocabularydevelopment in hearing children of deaf parents who reportedly had acquired pro-ficient skills in ASL as preschoolers. With no control group, Daniels used the nor-mative standardization sample from the PPVT-R as the comparative measure.Study participant standard scores were averaged across all 14 children, for a meanscore of 109.57, and a SMDES of 0.64. Daniels used these results as evidence thatASL proficiency accounted for the strong performance on the receptive vocabularyassessment. However, the study was rated as ‘fair–poor’ with respect to methodo-logical quality because there was no explanation for how subjects were recruitedor selected for participation, there is no evidence that data collectors were ‘blind’with regard to study hypotheses, and scores were averaged over a disproportion-ately broad age range. Because there is no comparison group, it is difficult to deter-mine if these children would have performed more poorly if they had not obtainedASL skills as preschoolers and there is no accounting for other educational vari-ables that may have contributed to this single measure of vocabulary proficiency.

In another study, Daniels (1994) reported findings from a longitudinal studythat evaluated receptive vocabulary using the PPVT-R in pre-kindergarten chil-dren who were taught sign language in the classroom compared with childrenof the same age who did not receive sign instruction in the classroom. Participantswere 60 students in four classes, two of which received sign instruction (n= 30)and two classes that did not receive sign language instruction (n= 30). A differentteacher taught the classes using sign language than the teacher who taught thenon-sign classes. Daniels reported the mean scores on the PPVT-R for the twoclasses that received sign language instruction were 94.6 and 92.3, compared withmean scores of 78.9 and 77.6 for the non-sign classes (an SMDES of 1.3). However,the methodological quality of this study was rated as ‘fair–poor’, with severalthreats to internal validity. The absence of baseline group vocabulary test perform-ance scores prior to receiving sign language instruction significantly weaken theconclusion that sign language was the variable that resulted in increased vocabu-lary in the non-sign classrooms. Furthermore, the non-randomized group assign-ment, having a different teacher for the sign classes than the non-sign classes, noevidence that data collectors were blind as to the purpose of the study, and the lackof controls to ensure that teachers in the sign language group were not ‘teaching tothe test’ contributed to concerns of internal test validity.

In a continuation of the longitudinal study described earlier, Daniels (1996)reported follow-up data of vocabulary performance on 19 of the original 30 sub-jects who received sign language instruction in the classroom during their pre-school year. These subjects did not receive additional sign language instructionduring their kindergarten year and were tested using the PPVT-R at the end ofthe kindergarten year. Daniels reported that the standard scores of this grouphad not significantly changed as compared with scores from the original studyobtained at the end of the preschool year. In other words, Daniels concluded thatthere was no decay in vocabulary proficiency over time and the benefit resultingfrom the signing treatment had been maintained. However, unlike the originalstudy, the follow-up study did not include scores from the group that did notreceive sign language instruction for comparison, data were reported for only 19of the original 30 subjects, and there was no accounting for other instructional vari-ables during the school year that may have influenced vocabulary performancethat had nothing to do with sign language instruction. Furthermore, threats to



internal validity because of non-randomized subject selection from the first studywould have been perpetuated into the follow-up study.

Empirical support for claim no. 3: increased IQ or cognitive skillsOf the 33 websites reviewed in this analysis, 27 sites reported improved IQ as an

outcome of sign language instruction. The only empirical study cited as evidence thatusing sign language as an infant or toddler improves IQ was a summary documentbriefly describing a conference presentation by Acredolo and Goodwyn (2000),which reported follow-up data using the same subjects as those in the originallongitudinal study. Children from the sign training experimental group and thenon-intervention control group participated in cognitive testing at 8 years of age,using the Wechsler Intelligence Scale for Children, 3rd Edition (WISC-III). However,there was significant attrition from the original data set (data were available for 19 ofthe original 32 subjects in the sign training group and 24 of the original 39 in the non-intervention control group). Children from the verbal training group were notincluded in this study for reasons that are not explained by the researchers. Childrenfrom the sign training group were reported to have higher scores on the WISC-IIIIntelligence Test than children from the non-intervention control group, as well asthose from the general population as reported in the normative WISC-IIIstandardization sample, with an SMDES of 0.80. However, the methodological qual-ity of this study was rated as ‘poor’ for several reasons. Because scores from theverbal training groupwere either not obtained or not reported, statistical comparisonamong all the original study groups is not available. There is no information aboutthe educational training that the children received during the time between theoriginal study and the follow-up study 5–6years later. The non-randomized methodof study group assignment is perpetuated from the original study into the IQ study,with no way of knowing how children were selected and if children from the signtraining groupwere cognitively stronger regardless of sign instruction. Furthermore,the only information about this study was based on a presentation at a professionalconference, the methodology is not clearly represented, and there is no indicationthat the data collectors were ‘blind’ with regard to the purpose of the study or theassignment of subjects to groups. Thus, there aremultiple and serious internal threatsto the validity of the conclusion in this study that teaching sign language to youngchildren results in higher IQ scores at age 8.

Empirical support for claims no. 4, no. 5, and no. 6: reduced frustration, tantrums, oremotional outbursts; increased parent/child bonding; and increased self-esteem, feelings ofsatisfaction, and accomplishment

None of the sources of evidence listed on the websites included empirical sup-port for claims that teaching sign language to hearing infants and toddlers resultsin reduced frustration and tantrums, better parent–child bonding, and increasedfeelings of self-esteem, satisfaction, and accomplishment.

CONCLUSIONS

At least 33 websites are now encouraging parents to teach sign language to theiryoung children with normal hearing. All of these websites claim that children withnormal hearing who are taught sign language will have better developmental out-comes than children who are not taught sign language. Based on anecdotal reportsand testimonials reported on these websites, it appears that many families find



that teaching sign language to their children is an enjoyable experience that theybelieve is beneficial for their child. We know of no evidence that refutes this pointof view, but it is equally important to be clear that there is no credible research evi-dence to support the frequent claims on these websites that teaching sign languageto young children with normal hearing will result in increased IQ, improved lan-guage development, reduced tantrums, improved self-esteem, earlier communica-tion, and increased parent–child bonding.

Because these are all outcomes that any parent would desire for their child, the fre-quent claims on multiple websites and in the popular media that research hasdemonstrated that there are benefits to teaching sign language to young childrenwith normal hearing may well lead to the general public accepting these claims asfact. Surprisingly, even though virtually all of the websites claim that their promisesare based on research (and 82 pieces of evidence were cited as if they were researchstudies), over 90% of these citations were opinion articles or descriptions of productsand only eight were empirical research studies relevant to the benefits of teachingsign language to young children with normal hearing. Furthermore, when the web-sites are read carefully, there was not even an attempt to provide research to supportclaims of reduced tantrums, better self-esteem, and improved parent–child bonding.

Relevant research that was cited to support claims about benefits related toearlier communication, improved language development, and increased IQ wasof only fair quality and not convincing. Research studies by Acredolo, Goodwyn,and Daniels are referenced numerous times in opinion articles or the popularmedia, yet without examination of the study purpose, design, or methodologicalquality. Hence, the conclusions drawn may not accurately represent outcomes par-ents might expect for their child. For example, none of the empirical studies ran-domly assigned subjects to groups, which creates the potential for a biasedparticipant sample. None of the studies described whether parents and childrenwere using sign language in a functional way in their daily activities, and the reli-ance on parent reports of their own child’s progress must be viewed with cautionbecause of the conscious or subconscious implications of a ‘value judgment’ par-ents might feel when reporting their child’s performance, particularly knowingthe researchers’ desired outcome. Daniels (1993, 1994, 1996) claimed to be evaluat-ing language development when the independent variable was a vocabularyassessment, a measure that does not equate to meaningful, cognitively based lan-guage integration. Five of the studies (excluding the case study) either lackedadequate data on comparison control groups or did not provide results for allstudy participants. None of the longitudinal studies adequately accounted forthe myriad of learning variables that could have impacted the development ofyoung children over the course of the study, rendering it difficult to validate therelationship between the independent and dependent variables of these studies

Despite the literature promoting the ease with which babies produce signed ges-tures relative to spoken language, even researchers who advocate signed communi-cation in infants reported that the intentional use of a sign in a truly symbolic fashionis directly impacted by the child’s cognitive development (e.g., memory capacity,object categorization skills, categorization perceptual skills, the understanding thatcommunication is a two-way encounter) (Goodwyn & Acredolo, 1993). Symbolicgesturing does not occur in isolation, and large individual differences in the develop-ment of both the gestural and vocal domains were reported (Acredolo & Goodwyn,1990). Furthermore, parents in these studies were taught sign language byknowledgeable researchers. This is very different from the products advertised forpurchase on the websites, which primarily requires parent self-instruction. Nostudies were available that evaluated outcomes when parents use the DVDs and



instructional products to teach their child, and no studies were cited that evaluatedoutcomes when children watch the signing videos on television.

In summary, parenting is naturally accompanied by some level of stress in navi-gating the daily demands of work, home, and child-rearing. Many parents experi-ence feelings of guilt and anxiety if they do not implement every strategy orprogram that is promoted to improve the well-being of their child and family. Theclaims made by numerous websites that if young children with normal hearing aretaught to use sign language, then theywill have better language and communicationdevelopment, higher IQs, fewer tantrums, higher self-esteem, and better parent–child bonding needs to be more carefully examined.2 The results of this study donot prove that these claims are false, but they certainly make it clear that we do notyet know from the information presented on the websites analyzed for this articlewhether there are benefits associated with teaching sign language to young childrenwith normal hearing. Before thousands of additional families spend the time andmoney to teach sign language to their young children with normal hearing, add-itional high-quality research should be done. Such research should employ randomassignment of subjects to appropriate comparison groups, collection of relevant out-come data by peoplewho are blind as to the purpose of the experiment, better controlof history, instrumentation and testing threats to internal validity, verification oftreatment implementation, and collection of data until children are at least in earlyelementary school. Until such research is completed, parents should understand thatexisting research cannot be used to reach definitive conclusions and that decisionsabout whether to teach sign language to their young children with normal hearingmust be based on opinions and beliefs but not on research.

Study Limitations

The purpose of this study was to identify all websites that claim there are benefitsfor teaching sign language to young children with normal hearing, identify thespecific claims made for sign language instruction, and evaluate the degree towhich those claims are supported by credible research. In interpreting the conclu-sions of this study, readers should keep the following limitations in mind:

1. Because websites evolve so rapidly, the results reported here represent a staticpoint in time. Because these datawere collected in 2010, otherwebsitesmay havebeen created and information on the websites cited here may have changed.

2. Only websites written in English were included so evidence from websites inother languages are not represented.

3. The content andmethodological quality of all the research studies cited by thesewebsites to support claims about the benefits of teaching sign language toyoung children with normal hearing were judged independently by the threeauthors, and any disagreements were resolved via discussion to produce thedata used in the final analysis. As valuable as it would have been to have kepttrack of the initial coding by each rater so that a measure of inter-rater reliabilitycould have been computed using a technique such as that recommended byHayes and Krippendorff (2007), that was unfortunately not done. Such calcula-tions should be included for similar studies done in the future.

Only information related to teaching sign language to young children with nor-mal hearing was considered for this study. Thus, the conclusions should not be ap-plied to other groups such as older children with normal hearing or children withother disabilities.



APP

ENDIX

ACLAIM

SON

WEBSITESREGARDIN

GBENEFITSOFTEACHIN

GSIGN

LANGUAGETO

YOUNG

CHILDREN

WITH

NORMALHEARIN

G

Increased

ability

tocommun

icate

need

san

dthou

ghts

Increasedab

ility

tocommun

icate

need

san

dthou

ghts

IncreasedIQ

orcogn

itive

skills

Red

uced

frus

tration

andtantrums

Parent–

child

bond

ing

Increasedself-

esteem

and

social

adjustmen

t

www.bab

ies-an

d-sign-lang

uage

.com

XX

XX

XX

www.bab

yseensign.com

XX

XX

www.bab

ysigna

cadem

y.com

XX

XX

Xwww.bab

ysigna

long

.com

XX

XX

Xwww.bab

ysigning

time.com

XX

XX

Xwww.bab

ysignlan

guag

e.ne

tX

XX

Xwww.bab

ysigns.com

XX

XX

XX

www.bab

ysignsrus.com

XX

XX

www.bab

ystrolog

y.com

XX

www.cyb

erpa

rent.com

/ba

by-sign-

lang

uage

XX

XX

XX

www.han

dsp

eak.com

XX

XX

www.kindercareers.com

Xwww.kindersign

s.com

XX

XX

Xwww.learnb

abysignlan

guag

e.com

XX

XX

XX

www.littlesign

ers.com

XX

XX

www.m

ybab

ycan

talk.com

XX

XX

XX

www.m

ybab

yfing

ers.com

XX

XX

www.m

ypreciou

skid.com

XX

XX

www.rmlearning

.com

/ba

bysign

lang

uage

XX

www.sign2

me.com

XX

XX

Xwww.signb

abies.com

XX

XX

www.signing

babies.net

XX

XX

www.signing

4bab

ies.com

XX

XX

XX

(Contin

ues)



http://www.babies-and-sign-language.com

http://www.kindercareers.com

http://www.kindersigns.com

http://www.learnbabysignlanguage.com

http://www.mybabycantalk.com

http://www.mybabyfingers.com

http://www.mypreciouskid.com

http://www.rmlearning.com/babysignlanguage

http://www.sign2me.com

http://www.signbabies.com

http://www.signingbabies.net

http://www.signing4babies.com

www.signing

baby

.com

XX

XX

XX

www.signing

smart.c

omX

XX

XX

www.signing

time.com

XX

XX

XX

www.signshine

.com

XX

XX

XX

www.signw

ithm

e.com

XX

XX

www.tiny

fing

ers.com

XX

XX

XX

www.tiny

talkersp

ortlan

d.com

XX

XX

XX

www.tiny

talkingh

ands.com

XX

XX

XX

www.to

ddlerinterpreter.com

XX

XX

Xwww.you

rtalking

baby

.com

XX

XX

XNo.

ofweb

sitesmak

ingeach

claim

3329

2727

2219



http://www.signingbaby.com

http://www.signingsmart.com

http://www.signingtime.com

http://www.signshine.com

http://www.yourtalkingbaby.com

APP

ENDIX

BCITATIO

NSFO

REACH

SOURCEOFEVID

ENCEFO

RCLAIM

STHATTEACHIN

GSIGN

LANGUAGETO

YOUNG

CHILDREN

IMPR

OVESDEVELOPM

ENTA

LOUTCOMES

Empiricals

tudiesthat

evalua

tedthebe

nefits

ofteaching

sign

lang

uage

toyo

ungch

ildrenwithno

rmal

hearing

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L.&

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dwyn

,S.(1985).Sy

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licge

sturingin

lang

uage

dev

elop

men

t:A

case

stud

y.Hum

anDevelopment,28

,40–

49.

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olo,

L.&

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dwyn

,S.

(199

0).Sign

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eof

symbo

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stur

ingforun

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(Ed.),

Ann

alsof

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7,1–

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:JessicaKingsleyPu

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long

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IQat

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toyo

ungchild

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,S.(1997).Fu

rthe

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Table.(C

ontinu

ed)

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tudiesthat

evalua

tedthebe

nefits

ofteaching

sign

lang

uage

toyo

ungch

ildrenwithno

rmal

hearing

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nk,H

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rdmoreite

(Con

tinu

ed)



http://www.sign2me.com

http://www.signingsmart.com/research.html

APP

ENDIX

CCODIN

GSH

EETFO

REMPIRIC

ALRESE

ARCH

ARTIC

LES

________________________

Date

______________________________________________

_______________________________

Autho

rs/Ye

ar

1.Stud

yID

2.ESno

.3.

Year

ofPu

blication

SubjectCha

racteristics

fortheTreatm

entGroup

4.Age

inmon

ths

5.%

Male

6.SE

S(1=low,2

=med

ium,3

=high

,4=mixed

)defi

ned?

7.Abilityleve

l(1=gifted

,2=no

rmal,3

=sp

eciale

duc

ation,

4=combina

tion

)8.

Samplesize

9.Is

sign

lang

uage

used

asregu

larmod

eof

commun

icationin

theho

me?

(1=no

,2=ye

s,3=ye

s,siblings,4

=ye

s,pa

rents/

siblings)

10.H

earing

status

(1=no

rmal,2

=assu

med

norm

al,3

=he

aringloss)

11.T

each

erexpe

rien

ceof

sign

lang

uage

(1=no

ne,2

=some,

3=expe

rt)

Treatm

ent

13.D

urationof

treatm

entin

weeks

14.H

ours

perweekof

directsign

lang

uage

instruction

15.H

ours

perweekus

ingsign

lang

uage

in‘in

structiona

l’16.H

owwas

thesign

lang

uage

taug

ht?(1=pa

rent/ch

ild,2

=profession

al/ch

ild,3

=video

,4=classroo

m–teach

er/ch

ild,5

=othe

r:____________)

17.S

ignlang

uage

system

(1=ASL

,2=sign

edEng

lish,

3=ge

stures

unique

tostud

y,4=othe

r)

(Contin

ues)



Dep

enden

tva

riab

le18.C

onstruct

ofinterest

1=Earlie

rab

ility

tocommun

icatene

eds,wan

ts,tho

ughts

2=Earlie

rlang

uage

,vocab

ulary,

literacyskills

3=IncreasedIQ

4=Red

uced

frus

tration/

tantrums(positiveES=reduc

edfrus

tration)

5=Increasedpa

rent–child

bond

ing

6=Self-esteem,satisfaction/

socially

adjusted

19.T

imeaftertreatm

entcompleted

,dep

enden

tva

riab

lemeasu

redin

mon

ths

20.T

ypeof

assessmen

t(1=stan

dardized

test,2

=cu

stom

mad

e,3=pa

rent

rating

,4=na

turalo

bserva

tion

,5=othe

r)21.G

eneral

valid

ityof

outcom

escores

(1=go

od,2

=fair,

3=po

or)

22.M

etho

dof

assign

ingsu

bjects

totreatm

ents

(1=rand

om,2

=match

ing,

3=no

nran

dom

,con

venien

ce,4

=pre/

post)

23.E

xperim

entalu

nits

(1=class,2=individua

l,3=sm

allg

roup

)24.T

hreats

tointernal

valid

ity(0=no

ne,1

=minor,2

=mod

erate,

3=major)

History

Maturation

Reg

ression

Selection

Instrumen

tation

Testing

Mortality

Inap

prop

riatestatisticalp

rocedure

Other

(spe

cify)

21.G

eneral

index

ofva

lidityforthis

effect

size

(1–5

;1be

st,5

worst)

Results

SMDES(referen

cegrou

p?__________________)

Other’sconc

lusion

s(five

-point

scale:

1=be

neficial

to5=detrimen

tal)



Notes

1. Because websites evolve rapidly, some changes may have occurred because thetime this analysis was completed.

2. The review of claims made and evidence cited on websites did not include arti-cles or information relative to the benefits of teaching sign language to childrenwith hearing loss, developmental delays, or other disabilities. The needs of suchchildren are complex and are not addressed by the information in this article.

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