Brain Development: Normal Processes and the Effects of Alcohol ...

compromising executiv e function. Investigators have
approached thi s construc t fro m severa l theoretica l
positions. Som e investigator s aggregate measure s t o
obtain a n estimat e o f executive function (e.g. , Samp -
son et al, 1997 ; Connor et al, 2000), whereas other s
evaluate specific area s thought t o represent aspects of
executive functio n (e.g. , Kern s et al, 1997 ; Mattso n
et al, 1999 ; Schonfel d e t al, 2001) . It is difficult t o
compare studie s becaus e th e construc t pe r s e is no t
well defined. Therefore, th e followin g review will examine
the effec t o f prenatal alcoho l exposur e o n various
component s tha t ar e usuall y understoo d t o b e
part of executive functioning.
Memory an d Metamemory . Memor y i s a broa d
field o f study, and onl y some aspect s o f memory ar e
considered to be part of executive function. Childre n
with FAS exhibit deficits in memory skills, but the im -
pairments are not always stable and their extent seems
to be influence d b y modality of the tas k used an d b y
the specifi c cognitive demands of tasks (Mattson an d
Roebuck, 2002) . For instance , a n interactio n o f age
and tas k characteristic s ma y determin e whethe r
effects ar e shown . Usin g th e McCarth y Scale s o f
Children's Abilitie s (McCarthy , 1972) , Janze n an d
colleagues (1995 ) do not find difference s i n memory
function betwee n youn g childre n diagnose d wit h
FAS and a contrast group selected fro m day-car e settings.
This finding contrasts with a study by Coles and
colleagues (2004) , wh o use d a differen t test . The y
find that children in the same age range do have spe -
cific memory deficits.
The effec t o f presentation modalit y (i.e. , visualauditory)
on memory has been investigated. Learnin g
and recal l o n task s presented visuall y o r i n narrative
form w ; ere compared (Platzma n et al., 2001). Adolescents
with FA S have poorer recall of visual elements
than control s and age mates in special education pro -
grams, wherea s long-ter m recal l o f auditoril y pre -
sented item s i s not impaired . Short-ter m memor y for
auditorily presented item s (i.e., random string s of digits;
Wechsler Intelligenc e Scal e for Children-Revised,
Digit Span) is also similar to that of contrast groups. In
a different sampl e o f clinically referred children, age s
3 to 9 years old, wit h a diagnosis o f FASD, a similar
auditory tas k an d a visual/spatia l analo g wer e contrasted.
Relativ e deficit s for spatial spa n ar e evident ,
whereas performance on th e digi t span task is consistent
wit h overal l abilit y leve l (Cole s e t al , 2004) .
These findings suggest specific deficits in memory with
PRENATAL ALCOHOL EXPOSURE AND HUMAN DEVELOPMENT 13 1
language-related or auditorily presented materials relatively
spared . Thi s patter n o f performanc e i s als o
noted b y Mattson and Roebuck (2002) among schoolaged
an d adolescen t childre n diagnose d wit h FA S or
having ha d heav y prenata l exposure . I n thi s group ,
memory performance is compared t o that o f normal
controls o n fiv e standardize d measure s o f learnin g
and memory: a verbal learning task (California Verbal
Learning Test-Children' s Versio n [CVLT-C] ; Deli s
et al., 1987) , the Biber Figure Learning Test, and three
subtests from th e Wid e Rang e Assessment o f Memory
and Learnin g (WRAML ; Sheslow an d Adams , 1990) .
These subtest s ar e Verbal Learning , Visua l Learning ,
and Soun d Symbol . The constructio n o f the CVLT- C
is important for understanding the result s of these studies.
This test i s a verbal learning tas k with orall y pre -
sented lists of words in several categories (i.e., clothing,
fruits, an d toys). Due t o the lis t structure, a n effectiv e
memory strategy (grouping by semantic category) can
be used to aid learning and recall .
Through th e use of tests of verbal and visual memory,
it has been show n that alcohol-affected childre n
learn fewe r item s (bot h word s an d figures ) overal l
than control s (Mattso n an d Roebuck , 2002) . After a
standard dela y period , however , th e percentag e re -
called (o f the materia l that ha d bee n learned ) i s not
different betwee n th e group s for verbal material. O n
the nonverba l material , th e alcohol-affecte d grou p
show 7 relativ e deficits in delaye d recall . Thus , verbal
memory i s les s affecte d tha n nonverba l memory .
Data fro m thes e studie s hav e been reanalyze d t o examine
the effec t o f stimulus differences i n two of the
verbal memory tasks (Roebuck-Spencer an d Mattson ,
2004). Accordingly, children with FASD demonstrat e
semantic clusterin g on th e CVLT-C , indicatin g tha t
they are able to take advantage of the list characteris -
tics t o ai d recall . The y perfor m bette r o n thi s tas k
than o n th e WRAM L verba l memor y task , whic h
does no t offe r th e sam e opportunit y t o us e th e "im -
plicit" memor y strateg y inherent i n the stimulu s material.
O n th e basi s o f thes e findings , th e author s
argue tha t previousl y observe d difference s in verba l
and nonverba l memory ma y result from us e of more
effective memor y strategie s o n verba l learning tasks .
Other work (i.e., Platzma n e t al, 2001; Coles et al.,
2004, se e discussion above) does not suppor t this explanation
becaus e visuall y and auditoriall y presente d
materials are equivalent in these studies.
Various studie s repor t tha t childre n with FAS D
have memory deficits on verbal learning tasks (Mattson