the relationship of iq to effort test performance
TRANSCRIPT
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The Relationship of IQ to Effort Test PerformanceAndy C. Dean a; Tara L. Victor b; Kyle B. Boone a; Ginger Arnold ca Harbor-UCLA Medical Center, Torrance, CAb California State University—Dominguez Hills, Carson, CAc Kaiser Permanente-Sunset, Los Angeles, CA, USA
First Published: July 2008
To cite this Article: Dean, Andy C., Victor, Tara L., Boone, Kyle B. and Arnold,Ginger (2008) 'The Relationship of IQ to Effort Test Performance', The ClinicalNeuropsychologist, 22:4, 705 — 722
To link to this article: DOI: 10.1080/13854040701440493URL: http://dx.doi.org/10.1080/13854040701440493
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THE RELATIONSHIP OF IQ TO EFFORT TESTPERFORMANCE
Andy C. Dean1, Tara L. Victor2, Kyle B. Boone1,and Ginger Arnold3
1Harbor-UCLA Medical Center, Torrance, CA, 2California StateUniversity—Dominguez Hills, Carson, CA, and 3Kaiser Permanente–Sunset,Los Angeles, CA, USA
The relationship between IQ and nine effort indicators was examined in a sample of 189
neuropsychology clinic outpatients who were not in litigation or attempting to obtain
disability. Participants with the lowest IQ (50–59) failed approximately 60% of the effort
tests, while patients with an IQ of 60 to 69 failed 44% of effort indicators, and individuals
with borderline IQ (70 to 79) exhibited a 17% failure rate. All patients with IQ <70 failed
at least one effort test. Cutoffs for the Warrington Recognition Memory Test (Words) and
Finger Tapping maintained the highest specificities in low IQ samples.
Keywords: Effort; IQ; Malingering; Mental retardation; Specificity; Validity.
INTRODUCTION
Incentives abound for the production of suboptimal effort during neuropsycho-logical assessment. Ostensible impairment can lead to the allocation of disabilitymonies or worker’s compensation benefits, and the landmark Atkins vs. Virginia(2002) Supreme Court decision prohibits individuals with mental retardation fromreceiving the death penalty during criminal sentencing. This will likely increase thenumber of requests for forensic neuropsychological assessment in these cases, whichwill require inclusion of tests of effort=motivation to ensure that the results are accu-rate. However, are commonly used effort tests appropriate for use with individuals inthe borderline or extremely low ranges of intellectual functioning? How common iseffort test failure in low IQ groups? Given the stakes involved in some forensic cases(e.g., death penalty sentencing), examination of the relationship between intellectualabilities and effort test performance becomes a critical step in assuring that effort testsare valid across populations.
Address correspondence to: Andy C. Dean, Harbor-UCLA Medical Center, Box 495, Torrance,
CA 90509, USA. E-mail: [email protected]
Accepted for publication May 7, 2007. First published online: July 24, 2007.
# 2007 Psychology Press, an imprint of the Taylor & Francis group, an Informa business
The Clinical Neuropsychologist, 22: 705–722, 2008
http://www.psypress.com/tcn
ISSN: 1385-4046 print=1744-4144 online
DOI: 10.1080/13854040701440493
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REVIEW OF THE LITERATURE
Most existing effort measures have only limited data regarding the relationshipbetween test performance and IQ. Table 1 summarizes the available research relatingIQ to a variety of effort measures, with particular emphasis on samples=subsamplesin the ‘‘mentally retarded,’’ or extremely low (i.e., Full Scale IQ�70), range of func-tioning. Specificity estimates (i.e., the percentage of credible individuals appropri-ately passing the effort test) are reproduced when available or if they could becalculated from article data. Correlations between IQ and effort test performanceare also provided where available. Samples in which participants may have hadincentive to feign cognitive impairment are identified.
Initial examination of the table reveals that only a small subset of effort measureshave been evaluated in more than one study in low IQ populations, and many studieshad small sample sizes. In addition, several of the studies either included patients forwhom an incentive to feign was present (e.g., disability evaluations, evaluations inlegal arenas, etc.), or did not identify whether such external incentives were ruledout. Thus, specificity estimates in these populations may be deflated by inadvertentinclusion of true positives (individuals performing with poor effort) in the samples.
Correlations between IQ and effort test performance have generally been signifi-cant and within the small to moderate range (i.e., r ¼ .25 to .55), although because sev-eral of these analyses were conducted in low IQ samples, restriction of IQ range couldhave suppressed the extent of the correlations. Further, relationships may be underesti-mated on measures with non-normal distributions (e.g., forced-choice tests). On theother hand, it should also be noted that studies that did not exclude individuals withincentives to feign might have erroneously inflated correlations due to similar poor effortdisplayed during both IQ and effort testing. Only two studies investigating populationswithout an identifiable incentive to feign found nonsignificant correlations, both ofwhich involved forced-choice measures: the Test of Memory Malingering (TOMM;Hurley & Deal, 2006) and the Word Memory Test (WMT; Green & Flaro, 2003).
Examination of the table reveals that the vast majority of studies documentedunacceptable specificity rates (i.e., <90%; Baker, Donders, & Thompson, 2000) inlow IQ groups for commonly used cutoffs. For example, the four studies providingspecificity information for the standard Rey 15-item administration in groups withIQ <80 reported false positive identification rates of 31% to 79% (weightedmean ¼ 54%; Goldberg & Miller, 1986; Hurley & Deal, 2006; Marshall & Happe,in press; Spiegel, 2006). While two reports indicated that specificity for the TOMMranged from 90% (Kennedy et al., 2005) to 100% (W. R. Drwal, personal communi-cation, August 29, 2005) in low IQ samples, three other studies found false positiverates of 31% to 50% (Graue et al., in press; Hurley & Deal, 2006; Weinborn, Orr,Woods, Conover, & Feix, 2003). Specificity of the E-score for the Dot Counting Testwas only 21% (Marshall & Happe, in press) to 54% (W. R. Drwal, personal com-munication, August 29, 2005), while specificity for Digit Span cut-offs ranged from15% (Graue et al., in press) to 69% (Axelrod, Fichtenberg, Millis, & Wertheimer,2006). Similarly, specificity for the Victoria Symptom Validity Test (VSVT) was mea-sured at only 40% (Loring, Lee, & Meador, 2005), while a 95% false positive identi-fication rate for the Validity Indicator Profile (VIP) has been reported (Frederick,1997)! In contrast, better specificity rates were found for Vocabulary minus Digit
706 ANDY C. DEAN ET AL.
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Tab
le1
Stu
die
so
fef
fort
mea
sure
per
form
an
cea
nd
IQ,
incl
ud
ing
effo
rtte
stcu
toff
s,sa
mp
lesi
zes,
effo
rt=IQ
corr
ela
tio
ns,
an
def
fort
test
Sp
ecif
icit
ies
inlo
wIQ
sam
ple
s
Mea
sure=
stu
dy
Cu
toff
NIQ
ran
ge
Sa
mp
leco
mp
osi
tio
n
Ince
nti
ve
tofe
ign
?aIQ
corr
elati
on
bS
pec
ific
ity
c
Rey
15
-Ite
m
Go
ldb
erg
&
Mil
ler
(19
86
)
<9
16
40
to6
9P
atie
nts
ina
MR
un
it
of
ap
sych
iatr
ich
osp
ita
l
No
n=a
62
.5%
Sch
retl
en,
Bra
nd
t,
Kra
fft,
&
Va
nG
orp
(19
91)
<9
14
8M
ean¼
87
.1
SD¼
14
.0
(po
ole
d
nu
mb
ers)
Neu
rolo
gic
al(T
BI,
dem
enti
a,
am
nes
tic)
an
dp
sych
iatr
ic
Un
kn
ow
n.5
5(i
ncl
ud
ing
no
rma
lco
ntr
ols
N¼
19
3)
73%
Ha
yes,
Ha
le,
&
Go
uv
ier
(19
97)
n=a
37
n=a
MR
pa
tien
tsin
faci
lity
for
crim
ina
lly
insa
ne,
som
ecr
edib
le,
som
em
ali
ng
erin
g(N¼
6)
Yes
n=a
Ma
lin
ger
s
per
form
ed
bet
ter
tha
n
cred
ible
pa
tien
ts
Ha
ys,
Em
mo
ns,
&
Law
son
(19
93)
n=a
30
0U
nk
no
wn
WA
IS-R
an
dS
hip
ley
IQsIn
pa
tien
tsin
a
psy
chia
tric
ho
spit
al
Un
kn
ow
n.6
0n=a
Hu
rley
&D
eal
(20
06)
<9
39
50
to7
8P
atie
nts
ina
resi
den
tia
l
faci
lity
for
MR
No
.31
20
.5%
Ma
rsh
all
&H
ap
pe
(in
pre
ss)
<9
69
51
to7
4
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
ts
wit
hd
ocu
men
ted
dev
elo
pm
enta
ld
isab
ilit
y
No
n=a
45%
Ma
rsh
all
&H
ap
pe
(in
pre
ss);
wit
h
reco
gn
itio
ntr
ial
�2
06
95
1to
74
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
tsw
ith
do
cum
ente
d
dev
elo
pm
enta
ld
isab
ilit
y
No
n=a
17%
Sp
eig
el(2
00
6)<
93
9<
70
Cli
nic
al
ou
tpati
ents
,
psy
chia
tric
an
d
neu
rolo
gic
al
No
.53
(in
clu
din
g
IQ>
70
,
N¼
24
5)
69%
TO
MM
Ken
ned
yet
al.
(20
05)
Tri
al
2o
r
Ret
enti
on<
45
60
Mea
n¼
62
.2
SD¼
.1
Psy
chia
tric
ho
spit
al
pa
tien
ts,
mix
edM
Ra
nd
psy
chia
tric
Yes
.55
90%
(Co
nti
nu
ed)
707
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Tab
le1
Co
nti
nu
ed
Mea
sure=st
ud
yC
uto
ffN
IQra
nge
Sam
ple
com
po
siti
on
Ince
nti
ve
tofe
ign
?aIQ
corr
elati
on
bS
pec
ific
ity
c
W.
R.
Drw
al(p
erso
na
l
com
mu
nic
ati
on
,
Au
gu
st2
9,
20
05)
Tri
al2<
45
19
57
to7
0M
Rp
ati
ents
ind
isab
ilit
y
eva
luat
ion
,p
re-s
cree
ned
for
feig
nin
g
Yes
n=a
10
0%
Wei
nb
orn
,O
rr,
Wo
od
s,C
on
ove
r,
&F
eix
(20
03)
Tri
al2
or
Ret
enti
on<
45
6n=
aM
R(m
ild
an
dm
od
era
te)
fore
nsi
cp
ati
ents
,ci
vil
ly
com
mit
ted
or
no
t
gu
ilty
by
rea
son
of
insa
nit
y
Po
ssib
lyn=a
3fa
lse
po
siti
ve
fail
ure
s
Hu
rley
&D
eal
(20
06)
Tri
al2<
45
39
50
to78
Pati
ents
ina
resi
den
tial
faci
lity
for
MR
No
-.0
35
9%
Gra
ue
eta
l.
(in
pre
ss)
Tri
al2
or
Ret
enti
on<
45
26
Mea
n¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
dd
evel
op
men
tal
dis
ab
ilit
yw
ho
wer
e
pa
idfo
rst
ud
yp
art
icip
ati
on
No
n=a
Tri
al2¼
69%
Ret
en.¼
89%
Do
tC
ou
nti
ng
Ha
yes
eta
l.(1
99
7)n=a
37
n=
aM
Rp
ati
ents
infa
cili
tyfo
r
crim
ina
lly
insa
ne,
som
ecr
edib
le,
som
e
(N¼
6)
ma
lin
ger
ing
Po
ssib
lyn=a
Mali
nger
s
per
form
ed
bet
ter
tha
n
cred
ible
pa
tien
ts
W.
R.
Drw
al(p
erso
na
l
com
mu
nic
ati
on
,
Au
gu
st2
9,
20
05)
esco
re�
17
24
57
to7
0M
Rp
ati
ents
ind
isab
ilit
y
eva
luat
ion
,p
re-s
cree
ned
for
feig
nin
g
Yes
n=a
54%
Hu
rley
&
Dea
l(2
00
6)
To
tal
tim
e
�1
80
seco
nd
s
39
50
to78
Pati
ents
ina
resi
den
tial
faci
lity
for
MR
No
n=a
97%
Ma
rsh
all
&H
ap
pe
(in
pre
ss)
esco
re�
17
69
51
to7
4
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
tsw
ith
do
cum
ente
d
dev
elo
pm
enta
ld
isab
ilit
y
No
n=a
21%
708
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WM
T
Gre
en,
All
en,
&
Ast
ner
(19
96)
n=a
12
4V
IQ,
ran
ge
un
kn
ow
n
Mix
edn
euro
log
ica
la
nd
psy
chia
tric
sam
ple
,
all
att
emp
tin
g
toget
fin
an
cial
com
pen
sati
on
Yes
.26
to.3
1
on
WM
T
ind
ices
n=a
Ger
ma
nW
MT
ad
ap
tati
on
;
Bro
ckh
au
s&
Mer
ten
(20
04)
;
R.
Bro
ckh
au
s(p
erso
na
l
com
mu
nic
ati
on
,
Ma
y1
8,
20
06)
IR,
DR
,a
nd
Co
n.
all
>8
2.5%
32
Un
kn
ow
nG
erm
an
MR
ad
ult
s
pre
scre
ened
for
a
‘‘te
sta
ble
’’
lev
elo
fco
gn
itiv
e
com
pet
ence
an
dem
oti
on
al
sta
bil
ity
,so
me
wit
h
beh
avio
rp
rob
lem
s
un
kn
ow
nn=a
97%
Gre
en&
Fla
ro
(20
03)
IR,
DR
,a
nd
Co
n.
all>
82
.5%
13
Mea
nV
IQ¼
64
.0
SD¼
4.5
Ch
ild
ren
,m
ean
ag
e1
1.7
yrs
wit
ha
va
riet
yo
f
neu
rolo
gic
al
an
dp
sych
iatr
icd
iag
no
ses
No
Co
rrel
ati
on
sn
ot
sig
nif
ica
nt
wit
h
WM
TIR
,D
R,
an
dC
on
sist
ency
ind
ices
,to
tal
sam
ple
(N¼
13
5)
Mea
nIR
,D
R,
an
d
Co
nsi
sten
cy
sco
res
wer
e
ab
ov
e
cuto
ffs,
spec
ific
ity
un
kn
ow
n
MS
VT
Ric
hm
an
eta
l.(2
00
6)
IRa
nd
DR
>8
5%
7M
ean¼
65
SD¼
5
Ch
ild
ren
of
un
kn
ow
n
ag
ea
nd
dia
gn
osi
s
un
kn
ow
nn=a
Mea
nIR
an
d
DR
wer
e
ab
ov
e
cuto
ffs,
spec
ific
ity
un
kn
ow
n
Rel
iabl
eD
igit
Sp
an
Bab
ikia
n,
Bo
on
e,
Lu
,&
Arn
old
(20
06)
�6
56
Mea
n¼
90
.1
SD¼
16
.6
Cli
nic
al
ou
tpa
tien
ts,
psy
chia
tric
an
d
neu
rolo
gic
al
No
n=a
Fa
lse
po
siti
ves
mo
reli
kel
y
wit
hlo
w
IQ(e
.g.,
70
s)
Ma
rsh
all
&H
ap
pe
(in
pre
ss)
<6
70
51
to7
4
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
tsw
ith
do
cum
ente
d
dev
elo
pm
enta
ld
isab
ilit
y
No
n=a
31%
(Co
nti
nue
d)
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Ta
ble
1C
on
tin
ued
Mea
sure=st
ud
yC
uto
ffN
IQra
ng
eS
am
ple
com
po
siti
on
Ince
nti
ve
tofe
ign
?aIQ
corr
elati
on
bS
pec
ific
ity
c
Gra
ue
eta
l.(i
np
ress
)�
62
6M
ean¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
dd
evel
op
men
tal
dis
ab
ilit
yw
ho
wer
ep
aid
for
stu
dy
pa
rtic
ipa
tio
n
No
n=a
15%
Dig
itS
pan
AC
SS
Ba
bik
ian
eta
l.(2
00
6)
<5
56
Mea
n¼
90
.1
SD¼
16
.6
Cli
nic
al
ou
tpa
tien
ts,
psy
chia
tric
an
dn
euro
log
ica
l
No
n=a
Fa
lse
po
siti
ves
mo
reli
kel
y
wit
hlo
w
IQ(e
.g.,
70
s)
Axel
rod
,F
ich
ten
ber
g,
Mil
lis,
&W
erth
eim
er
(20
06)
�7
29
Mea
n¼
86
.0
SD¼
16
.5
TB
Ip
ati
ents
ina
no
utp
ati
ent
reh
ab
ilit
ati
on
pro
gra
m,
wit
hin
itia
l
GC
So
f<
15
or
15
wit
h
po
siti
ve
neu
roim
ag
ing
No
n=a
69%
Gra
ue
eta
l.(i
np
ress
)<
52
6M
ean¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
dd
evel
op
men
tal
dis
ab
ilit
yw
ho
wer
ep
aid
for
stu
dy
pa
rtic
ipa
tio
n
No
n=a
19%
Vo
cab
ula
ry-
Dig
itS
pa
n
Sca
led
Sco
re
Gra
ue
eta
l.(i
np
ress
)�
42
6M
ean¼
0.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
dd
evel
op
men
tal
dis
ab
ilit
yw
ho
wer
ep
aid
for
stu
dy
pa
rtic
ipa
tio
n
No
n=a
10
0%
Mit
ten
ber
gD
iscr
imin
an
t
Fu
nct
ion
Gra
ue
eta
l.(i
np
ress
)>
.21
26
Mea
n¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
d
dev
elo
pm
enta
ld
isab
ilit
y
wh
ow
ere
pa
idfo
r
stu
dy
pa
rtic
ipa
tio
n
No
n=a
65%
710
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008
VIP
Fre
der
ick
(19
97)
�‘‘
Vali
d’’
40
Un
kn
ow
nU
nk
no
wn
gro
up
of
MR
ind
ivid
uals
Un
kn
ow
nn=a
5%
VS
VT
Lo
rin
g,
Lee
,&
Mea
do
r(2
00
5)
<2
1o
nH
ard
item
s
15
60
to6
9E
pil
epsy
pa
tien
t
clin
ical
sam
ple
,so
me
of
wh
ich
lik
ely
pro
vid
ed
sub
op
tim
al
effo
rt
No
ne
ob
vio
us
.43
wit
hH
ard
VS
VT
item
s,
tota
lIQ
sam
ple
(N¼
12
0)
40%
(so
me
pa
tien
ts
lik
ely
no
tcr
edib
le)
CA
RB
All
en,
Co
nd
er,
Gre
en&
Co
x(1
99
9)
n=a
25
6V
IQ,
ran
ge
un
kn
ow
n
Mix
edn
euro
log
ica
la
nd
psy
chia
tric
sam
ple
,a
ll
att
emp
tin
gto
get
fin
an
cial
com
pen
sati
on
Yes
.26
wit
hC
AR
B
tota
lsc
ore
n=
a
Fin
ger
Tap
pin
g
Arn
old
eta
l.(2
00
5)
Do
m.
Ha
nd
�3
5m
en;
�2
8w
om
en
17
�7
0C
lin
ica
lo
utp
ati
ents
,n
o
neu
rolo
gic
ald
iso
rder
or
ob
vio
us
mo
tor
pro
ble
ms
No
n=a
78%
men
87%
wo
men
Dig
itM
emo
ryT
est
(sh
ort
form
)
Gra
ue
eta
l.(i
np
ress
)<
90%
26
Mea
n¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
h
do
cum
ente
d
dev
elo
pm
enta
ld
isab
ilit
y
wh
ow
ere
pa
idfo
r
stu
dy
pa
rtic
ipa
tio
n
No
n=a
85%
Let
ter
Mem
ory
Tes
t
Gra
ue
eta
l.(i
np
ress
)<
93%
26
Mea
n¼
60
.0
SD¼
5.5
Mil
dM
Rp
ati
ents
wit
hd
ocu
men
ted
dev
elo
pm
enta
ld
isab
ilit
y
wh
ow
ere
pa
idfo
r
stu
dy
pa
rtic
ipa
tio
n
No
n=a
58%
CV
LT
-2R
eco
gn
itio
n
Ma
rsh
all
&H
ap
pe
(in
pre
ss)
�3in
corr
ect
10
05
1to
74
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
tsw
ith
do
cum
ente
d
dev
elo
pm
enta
l
dis
abil
ity
No
n=a
89%
(Co
nti
nue
d)
711
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Ta
ble
1C
on
tin
ued
Mea
sure=st
ud
yC
uto
ffN
IQra
ng
eS
am
ple
com
po
siti
on
Ince
nti
ve
tofe
ign
?aIQ
corr
elati
on
bS
pec
ific
ity
c
Log
ica
lM
emo
ryR
are
ly
Mis
sed
Item
s
Ma
rsh
all
&H
ap
pe
(in
pre
ss)
�1
36
10
05
1to
74
Mea
n¼
63
Mil
da
nd
Mo
der
ate
MR
pa
tien
tsw
ith
do
cum
ente
d
dev
elo
pm
enta
l
dis
ab
ilit
y
No
n=
a9
1%
Ma
lin
geri
ngS
cale
Sch
retl
en&
Ark
ow
itz
(19
90
)
n=a
20
Mea
n¼
47
SD¼
12
Aco
mm
un
ity
sam
ple
of
MR
men
No
n=
aP
oo
r(t
rue
MR
sco
red
low
er
tha
nin
ma
tes
told
tofa
ke
MR
(N¼
20
))
TO
MM¼
Tes
to
fM
emo
ryM
ali
nger
ing;
WM
T¼
Wo
rdM
emo
ryT
est;
MS
VT¼
Med
ica
lS
ym
pto
mV
ali
dit
yT
est;
Dig
itS
pa
nA
CS
S¼
Dig
itS
pa
nA
ge
Co
rrec
ted
Sca
led
Sco
re;
VIP¼
Va
lid
ity
Ind
icat
or
Pro
file
;V
SV
T¼
Vic
tori
aS
ym
pto
mV
ali
dit
yT
est;
CA
RB¼
Co
mp
ute
rize
dT
est
of
Res
po
nse
Bia
s;C
VL
T-2¼
Cali
forn
iaV
er-
ba
lL
earn
ing
Tes
t;a
Ince
nti
ve
tofe
ign
wa
ses
tim
ate
da
sa
ccu
rate
lya
sp
oss
ible
ba
sed
on
av
ail
ab
lea
rtic
led
ata
;bC
orr
elati
on
sw
ere
oft
eno
bta
ined
wit
hla
rger
sam
ple
size
sth
an
tha
tu
sed
toa
sses
ssp
ecif
icit
y—
this
isin
dic
ated
wh
ere
ap
pli
cab
le;
c Sp
ecif
icit
yw
as
oft
end
eriv
edb
yth
ecu
rren
tau
tho
rsfr
om
avail
ab
leart
icle
data
.
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Span (100%; Graue et al., in press), Logical Memory Rarely Missed Items (91%;Marshall & Happe, in press), California Verbal Learning Test – 2 (CVLT-2) recog-nition (89%; Marshall & Happe, in press), dominant finger tapping (78% to 87%;Arnold et al., 2005), and a short form of the Digit Memory Test (85%; Graue etal., in press). While high specificity was reported for a German version of theWMT, only participants who were judged to be ‘‘testable’’ (less than half of availableparticipants) were included (97%; Brockhaus & Merten, 2004; R. Brockhaus, per-sonal communication, May 18, 2006), raising questions regarding the representative-ness of the sample. In summary, existing research suggests that several commonlyused effort cutoffs are likely inappropriate for patients with low IQs; however, thefew studies available require replication due to methodological limitations and=orsmall sample sizes, and no data are available for several effort indicators.
The current study evaluated the relationship between Full Scale IQ and testperformance on nine different effort measures=indices (Digit Span Age CorrectedScaled Score, Reliable Digit Span, Rey 15-item plus recognition, Rey Word Recog-nition Test, Warrington Recognition Memory Test – words, Rey Osterreith EffortEquation, Rey-Osterreith=Rey Auditory Verbal Learning Test discriminant func-tion, Dot Counting Test, Finger Tapping Test), as well as the impact of IQ on efforttest specificity, in a heterogeneous clinic sample without external incentive to feign.
METHOD
Participants
Participants were 189 outpatients who presented to one of two SouthernCalifornian outpatient psychiatry clinics for neuropsychological assessment.1 Poten-tial participants were excluded from the original pool if there was indication of ident-ifiable motive to feign (i.e., applying for disability compensation or in litigation attime of testing). Patients with history or current evidence of dementia, amnestic dis-order, or somatoform disorder were also excluded. Lastly, one participant wasexcluded because her performance on a forced-choice effort measure was grosslyimprobable, raising questions regarding her effort (Warrington Recognition Mem-ory Test—Words ¼ 14 of 50). No other patient given a forced-choice test performedat or below chance levels (after the excluded patient above, the lowest WarringtonRecognition Memory Test score was 32 of 50). Further, none of the participantsretained in the study was determined to be malingering or otherwise noncrediblefrom a clinical standpoint, and any observed low IQ scores were entirely consistentwith behavioral observations and referral questions.
Primary diagnoses of the sample included depressive disorders (N ¼ 49), headinjury (penetrating and closed; N ¼ 22), psychosis=schizoaffective=schizophreniadisorders (N ¼ 20), seizures=epilepsy (N ¼ 13), anxiety=panic=PTSD (N ¼ 10), cog-nitive disorder NOS (N ¼ 8), bipolar disorder (N ¼ 8), stroke (N ¼ 7), HIV (N ¼ 6),substance abuse (N ¼ 6), learning disability (N ¼ 4), multiple sclerosis (N ¼ 3),Klinefelter’s syndrome (N ¼ 3), and a variety of conditions with N�2 (ADHD,
1It is estimated that 40% or less of the current sample was present in the Arnold et al. (2005) study,
while 30% or less was present in the Babikian et al. (2006) study.
IQ AND EFFORT TEST PERFORMANCE 713
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aneurysm, Asperger’s disorder, meningitis, Behcet’s disease, brain tumor, carotidstenosis, cerebral palsy, encephalitis, epidural abscess, heart attack=complications,hydrocephalus, lupus, mental retardation, neurosyphilis, personality disorder, Tourette’sdisorder, Turner syndrome, intermittent explosive disorder, and neurosurgery [nototherwise specified]; N ¼ 30). Mean age was 43.6 (SD ¼ 14.1), and mean educationwas 12.8 years (SD ¼ 2.8), and 53% were female. Approximately 51% of the samplewas Caucasian, while 19% were Hispanic, 16% were African American, 10% wereAsian, 1% were Middle Eastern, and 3% were other. FSIQ ranged from 56 to133, with a mean of 87.9 (SD ¼ 15.1). All patients were fluent in English; a minorityof the sample (22%) was raised bilingual or spoke English as a second language.ESL=bilingualism was equally distributed across the range of IQ. Of those patientswith IQs less than 70, mean educational level was 11.5 years (SD ¼ 2.0), and 53%reported a history of special education and=or learning disability. Diagnoses in thissubset included epilepsy (N ¼ 4), depression (N ¼ 4), head injury (N ¼ 2), mentalretardation (N ¼ 1), schizophrenia (N ¼ 1), neurosyphilis (N ¼ 1), lupus (N ¼ 1),and cognitive disorder NOS (N ¼ 1).
Procedure/measures
Approval to utilize archival neuropsychological data was obtained from bothclinic institutional review boards. FSIQ and effort indicator performance was selec-ted from more comprehensive neuropsychological assessments (typically coveringmultiple domains including language, visuospatial functioning, memory, executivefunctioning, motor function, and personality=mood). FSIQ was measured via theWechsler Adult Intelligence Scale–III (WAIS-III), and all participants completeda minimum of five Verbal subtests and four Performance subtests. Table 2 lists
Table 2 Effort indices used in the current study
Effort indicator Cutoff
WAIS-III Digit Span Age-corrected scaled score (ACSS) �5
Babikian, Boone, Lu, & Arnold (2006)
WAIS-III Reliable Digit Span �6
Babikian et al. (2006)
Rey 15-Item Test plus recognition combination score (REY-15) <20
Boone, Salazar, Lu, Warner-Chacon, & Razani (2002)
Rey Word Recognition Test Men�5
Nitch, Boone, Wen, Arnold, & Alfano (2006) Women�7
Warrington Recognition Memory Test - Words �33
Iverson & Franzen, 1994
Rey-Osterreith Effort Equation (RO) ��47
Lu, Boone, Cozolino, & Mitchell (2003)
Rey-Osterrieth=RAVLT Effort Equation (RO=RAVLT) ��.40
Sherman, Boone, Lu, & Razani (2002)
Dot Counting Test E-score �17
Boone, Lu, Back, King, Lee, et al. (2002)
Finger Tapping Test Men�35
Arnold et al., (2005) Women�28
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the effort measures and the cutoffs used for determination of suboptimal effort.Given the clinical setting of the assessments, not all tests were administered to allparticipants.
RESULTS
Kolmogorov-Smirnov analyses indicated that the following measures deviatedfrom the normal distribution: Digit Span–Age Corrected Scaled Score (ACSS),D(189) ¼ 1.86, p ¼ .00; Reliable Digit Span, D(102) ¼ 1.73, p ¼ .01; Rey-15D(143) ¼ 1.92, p ¼ .00; and the Dot Counting Test D(135) ¼ 1.46, p ¼ .03. Thuscorrelations with these measures were conducted nonparametrically with Spearman’srho. With the exception of the Rey–Osterreith=Rey Auditory Verbal Learning Test(RO=RAVLT) discriminant function (r ¼ �.01; p > .05), all effort measures weresignificantly correlated with FSIQ. Furthermore, of those that were correlated withIQ, all but the Warrington Recognition Memory Test (r ¼ .31; p ¼ .02) and FingerTapping Test (r ¼ .21, p ¼ .01) were significant at the p < .01 level (RO Effort Equa-tion, r ¼ .32; Dot Counting Test, rho ¼ �.36; Rey 15-item, rho ¼ .31; Rey WordRecognition Test, r ¼ .39; Reliable Digit Span, rho ¼ .58; Digit Span ACSS,rho ¼ .63). It should be noted that the Digit Span correlations are spuriously inflatedbecause digit span performance is included in the calculation of FSIQ.
The mean number and range of effort tests failed by each IQ band is displayedin Table 3. As can be seen, test failure was inversely related to FSIQ (i.e., the likeli-hood of effort test failure became more likely as FSIQ declined), with those patientswith FSIQ <70 failing three to four effort indicators on average, those with border-line IQ (70 to 79) failing an average of one effort measure, and those with FSIQ� 80averaging <1 failure. Of particular note, in the extremely low range of IQ (<70),100% of patients failed at least one effort test. Because all patients did not receiveall effort measures (rendering calculation of mean number of failures problematic),Table 3 also presents the average percentage of effort indicators failed by each IQband. This again demonstrates a linear relationship between IQ and effort test per-formance. While those participants with IQ� 80 failed fewer than 10% of adminis-tered tests, individuals with borderline IQ failed 17%, those with IQ 60–69 failed44% of the indicators, and those with IQ 50–59 failed 60% of tests.
The specificity, means, and standard deviations for each effort measure accord-ing to IQ band are presented in Table 4. Although caution should be used in
Table 3 Number of effort indices failed by IQ band: Mean, range, and mean percent
FSIQ band N Mean tests failed Range failed Mean percent tests failed (%)
50–59 3 4.0 1 to 6 60
60–69 12 2.9 1 to 6 44
70–79 48 1.1 0 to 4 17
80–89 44 0.5 0 to 4 8
90–99 39 0.3 0 to 2 7
100–109 27 0.2 0 to 1 4
110–119 11 0.4 0 to 2 6
�120 5 0.2 0 to 1 5
IQ AND EFFORT TEST PERFORMANCE 715
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Ta
ble
4M
ean
s,st
an
da
rdd
evia
tio
ns,
an
dsp
ecif
icit
ies
of
effo
rtin
dic
ato
rsb
yIQ
ba
nd
IQB
an
dD
S-A
CS
SR
DS
Rey
-15
RW
RT
aR
MT
RO
RO=R
AV
LT
DC
TF
TT
a
50
–5
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
3
5.0
(2.6
)
33
n¼
3
5.3
(2.5
)
33
n¼
3
16
.0(1
0.4
)
33
n¼
1
7.0
0
n¼
1
37
.0
10
0
n¼
3
40
.8(1
3.0
)
33
n¼
3
0.1
6(2
.2)
67
n¼
3
16
.2(7
.5)
33
n¼
2
45
.5(5
.0)
10
0
60
–6
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
12
5.3
(1.9
)
33
n¼
12
5.9
(1.8
)
33
n¼
11
19
.4(5
.6)
45
n¼
7
8.6
(2.7
)
57
n¼
3
35
.7(4
.7)
67
n¼
11
48
.3(1
3.2
)
64
n¼
12
0.5
3(.
96)
75
n¼
7
15
.9(5
.2)
71
n¼
6
44
.0(8
.0)
10
0
70
–7
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
48
7.0
(1.9
)
81
n¼
32
7.7
(1.5
)
81
n¼
37
22
.2(6
.6)
68
n¼
13
9.0
(2.9
)
85
n¼
16
45
.4(3
.6)
10
0
n¼
37
53
.8(1
1.8
)
81
n¼
44
1.2
(.8
8)
93
n¼
39
13
.7(5
.3)
85
n¼
36
39
.9(8
.7)
83
80
–8
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
44
7.9
(1.6
)
98
n¼
22
8.4
(1.3
)
10
0
n¼
32
24
.9(5
.1)
84
n¼
7
7.9
(1.2
)
71
n¼
13
45
.5(4
.4)
10
0
n¼
39
56
.4(7
.8)
85
n¼
37
1.1
(.8
5)
95
n¼
33
11
.8(3
.0)
88
n¼
28
44
.1(9
.3)
93
90
–9
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
39
9.0
(1.9
)
97
n¼
19
8.8
(1.5
)
10
0
n¼
29
24
.7(4
.4)
90
n¼
10
10
.2(1
.8)
10
0
n¼
11
45
.4(3
.9)
10
0
n¼
30
58
.1(7
.5)
93
n¼
28
0.9
7(.
65)
93
n¼
32
11
.7(5
.8)
88
n¼
33
48
.0(8
.9)
97
10
0–
10
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
27
10
.3(3
.0)
10
0
n¼
10
10
.1(2
.9)
10
0
n¼
15
26
.6(2
.8)
10
0
n¼
4
11
.5(1
.7)
10
0
n¼
9
45
.6(5
.0)
10
0
n¼
17
58
.4(6
.7)
88
n¼
18
0.9
9(1
.0)
89
n¼
12
10
.0(2
.2)
10
0
n¼
19
46
.6(1
0.0
)
89
11
0–
11
9
Mea
n(S
D)
Sp
ecif
icit
y
n¼
11
12
.5(2
.1)
10
0
n¼
2
11
.5(.
71)
10
0
n¼
11
25
.1(3
.6)
91
n¼
6
10
.3(1
.9)
10
0
n¼
6
47
.0(2
.5)
10
0
n¼
10
56
.4(9
.2)
80
n¼
11
0.9
3(.
44)
10
0
n¼
5
9.9
(4.5
)
10
0
n¼
9
44
.9(1
2.3
)
89
�1
20
Mea
n(S
D)
Sp
ecif
icit
y
n¼
5
11
.0(2
.3)
10
0
n¼
3
11
.0(1
.7)
10
0
n¼
5
27
.6(3
.8)
10
0
n¼
1
14
.0
10
0
n¼
1
49
.0
10
0
n¼
5
65
.2(5
.1)
10
0
n¼
5
0.6
8(.
87)
80
n¼
4
10
.5(1
.7)
10
0
n¼
2
46
.7(8
.0)
10
0
Sp
ecif
icit
y¼
pro
po
rtio
no
fcr
edib
lep
ati
ents
ap
pro
pri
atel
yp
ass
ing
effo
rtcu
toff
;sp
ecif
icit
ies
inb
old
are
low
erth
an
the
acc
epte
d9
0%
lev
el.
aD
iffe
ren
tcu
toff
su
sed
acc
ord
ing
tog
end
er.
DS
-AC
SS¼
Dig
itS
pa
nA
ge
Co
rrec
ted
Sca
led
Sco
re;
RD
S¼
Rel
iab
leD
igit
Sp
an
;R
ey-1
5¼
Rey
15
Itemþ
Rec
og
nit
ion
Tes
t;R
WR
T¼
Rey
Wo
rdR
eco
gn
itio
nT
est;
RM
T¼
Wa
rrin
gto
nR
eco
gn
itio
nM
emo
ryT
est—
Wo
rds;
RO¼
Rey
-Ost
erre
ith
Eff
ort
Eq
uati
on
;R
O=R
AV
LT¼
Rey
-Ost
erre
ith=R
AV
LT
Eff
ort
Eq
ua
tio
n;
DC
T¼
Do
tC
ou
nti
ng
Tes
t;F
TT¼
Fin
ger
Tap
pin
gT
est.
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008
interpreting specificities with small sample sizes, Table 4 again illustrates that speci-ficity rates become unacceptable at lower levels of IQ for most measures. With somevariability, the tests with best specificity at recommended cut-offs in low IQ groupsappear to be the Warrington Recognition Memory Test and the Finger TappingTest.
Table 5 provides adjusted effort cutoffs for low IQ groups (<70; 70–79; 80–89)which maintain specificity above 90%. Although conclusions for the lowest IQgroup (<70) are tentative due to small sample size, the available data indicate thatmost effort cutoffs need considerable adjustment to maintain acceptable specificityin this IQ range. Unfortunately, small sample sizes precluded separate analysis ofeffort measures with different cut-offs for gender, but it should be noted that theexisting cut-off for women on Finger Tapping (�28) was very similar to the adjustedgenderless cut-off (�29), which would maintain acceptable specificity in the lowestIQ group (<70).
DISCUSSION
In a sample without identifiable incentive to feign deficits, moderate correla-tions were generally found between Full Scale IQ and performance on effort mea-sures. Further evidence of the relationship between IQ and effort test performancewas provided by examining effort test failures according to IQ band. While zero toone effort test was typically failed by those in the low average to superior range ofintellectual functioning, the likelihood of effort test failure increased regularly withdecreasing IQ scores. In the lowest range of IQ (50–59), patients failed an averageof four effort measures, or approximately 60% of the effort tests administered.Patients with an IQ of 60 to 69 averaged three effort test failures or 44% of effort indi-cators, and individuals with borderline IQ (70–79) failed a mean of one indicator andaveraged a 17% failure rate. Of particular concern is the fact that all patients withextremely low IQs (<70) failed at least one effort test. This contrasts with the<10% effort test failure rate in those with low average to superior range of IQ.
Examination of the various effort indicators in low IQ groups revealed that mostmeasures produced unacceptable specificity rates (i.e., <90%) when IQ droppedbelow 80, with the worst specificities found for the lowest IQ group (50–59). In the bor-derline IQ group, all specificities were �80% with the exception of Rey 15-Itemþ re-recognition test, which was associated with a 32% false positive identification rate. Inthe 60–69 IQ range, nearly all specificities were �75% (with the exception of FingerTapping at 100%), with Digit Span tasks showing the highest false positive rates(66%). In the 50–59 range, most specificities were �33%, with the exception of War-rington Recognition Memory Test (100%), Finger Tapping (100%), and RO=RAVLTdiscriminant function (67%), although these conclusions should be viewed as tentativedue to the very small sample size in this group (n ¼ 3). Although preliminary due tosmall N, the most robust effort tests across low IQ groups were the WarringtonRecognition Memory Test and the Finger Tapping Test.
Compared with previous studies in low IQ samples, current data regardingspecificity rates are somewhat higher for the Rey 15-item recognition (i.e., 33% to45%) than those reported previously (17%; Marshall & Happe, in press), while ratesfor the Dot Counting Test (33% to 71%), and Digit Span indices (33%) are grossly
IQ AND EFFORT TEST PERFORMANCE 717
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Ta
ble
5A
dju
sted
effo
rtcu
toff
sa
nd
corr
esp
on
din
gsp
ecif
icit
ies
for
low
IQg
rou
ps
IQB
an
dD
S-A
CS
SR
DS
Rey
-15
RW
RT
bR
MT
RO
RO=R
AV
LT
DC
TF
TT
b
<70
aN
ew
cuto
ffsp
ecif
icit
y
n¼
15
<3
10
0
n¼
15
<3
93
n¼
14
<9
10
0
n¼
8
<5
10
0
n¼
4
<3
2
10
0
n¼
14
<2
6
10
0
n¼
15
<�
1.0
7
93
n¼
10
>2
3.0
90
n¼
8
<2
9
10
0
70
–7
9N
ew
cuto
ffsp
ecif
icit
y
n¼
48
<5
90
n¼
32
<6
94
n¼
37
<1
2
92
n¼
13
<5
92
n¼
16
<3
9
94
n¼
37
<3
0
95
n¼
44
<�
.17
91
n¼
39
>2
2.0
92
n¼
36
<2
9
92
80
–8
9N
ew
cuto
ffsp
ecif
icit
y
n¼
44
<6
98
n¼
22
<7
10
0
n¼
32
<1
7
91
n¼
7
<7
10
0
n¼
13
<4
0
92
n¼
39
<4
6
92
n¼
37
<.1
8
92
n¼
33
>1
7.0
91
n¼
28
<3
4
93
aG
iven
smal
lsa
mp
lesi
zeb
elo
wa
nIQ
of
60
,ef
fort
cuto
ffs
for
the<
70
gro
up
are
lik
ely
tob
em
ost
ap
pro
pri
ate
for
pa
tien
tsin
the
IQ6
0–
69ra
ng
e;bS
epa
rate
cuto
ffs
by
gen
der
wer
en
ot
con
sid
ered
inth
ese
an
aly
ses.
DS
-AC
SS¼
Dig
itS
pan
Age
Co
rrec
ted
Sca
led
Sco
re;
RD
S¼
Rel
iab
leD
igit
Sp
an
;R
ey-1
5¼
Rey
15
Itemþ
Rec
og
ni-
Rec
og
nit
ion
Tes
t;R
WR
T¼
Rey
Wo
rdR
eco
gn
itio
nT
est;
RM
T¼
Wa
rrin
gto
nR
eco
gnit
ion
Mem
ory
Tes
t—W
ord
s;R
O¼
Rey
-Ost
erre
ith
Eff
ort
Eq
uati
on
;
RO=
RA
VL
T¼
Rey
-Ost
erre
ith=R
AV
LT
Eff
ort
Eq
uat
ion
;D
CT¼
Do
tC
ou
nti
ng
Tes
t;F
TT¼
Fin
ger
Tap
pin
gT
est.
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similar to previous findings: Dot Counting Test ¼ 21% to 54% (W. R. Drwal, per-sonal communication, August, 29, 2005; Marshall & Happe, in press), Digitspan ¼ 15% to 69% (Axelrod et al., 2006; Marshall & Happe, in press; Graue et al.,in press). Finger tapping specificities in the current study (100%) were also similar toprevious findings in low IQ groups (78% to 87%, Arnold et al., 2005), although someoverlap was present in the participant pools between these two investigations.
To address the unacceptable specificities noted above, we created adjustedcutoffs for the effort indices by IQ band (see Table 5). The cut-off for the Rey 15-ItemþRecognition test needed to be lowered by three points to maintain acceptablespecificity (91%) in even the low average range of IQ. In contrast, the existing cutofffor the Warrington Recognition Memory Test was sufficient in all but the lowest IQrange (<70), in which the cutoff needed to be lowered by only one point to retainadequate specificity (100%). In fact, examination of the low average IQ rangerevealed that a few test cut-off scores were overly lenient at this level of IQ. Forinstance, the Warrington Recognition Memory Test maintained adequate specificity(92%) in the low average IQ range with a 7-point increase in the existing cutoff (from<33 to <40), and the RO=RAVLT discriminant function could be increased to apositive value at this IQ level (from ��.40 to < .18) while still maintaining accept-able specificity (92%).
While adjusted cutoffs will help to protect against the possibility of false posi-tive identifications in low IQ samples, the increase in specificity occurs at theexpense of sensitivity (the percentage of noncredible participants correctly identifiedas noncredible); for example, very few noncredible patients are likely to obtain aReliable Digit span <3, the cut-off required for adequate specificity in those withIQ <70. Thus, several of the effort indicators are unlikely to be useful in the dif-ferential between actual versus feigned low IQ due to negligible sensitivity atacceptable specificity levels. For this reason, different effort indices need to beemphasized, and perhaps new ones developed, for a low IQ population. In thisstudy, the Warrington Recognition Memory Test-Words was effective at low IQlevels, and the limited data available on other forced-choice tests in low IQ groupshas frequently been positive with respect to specificity (e.g., Logical MemoryRarely Missed Items Index ¼ 91%, Marshall & Happe, in press; GermanWMT ¼ 97%, Brockhaus & Merten, 2004; CVLT-2 Recognition ¼ 89%, Marshall &Happe, in press; TOMM ¼ 50–100%, W. R. Drwal, personal communication,August 29, 2005; Graue et al., in press; Kennedy et al., 2005; Hurley & Deal, 2006;Weinborn et al., 2003; Digit Memory Test ¼ 85%, Graue et al., in press). In addition,forced choice scores significantly below chance would not be plausible in any IQrange. Research is needed on other commonly administered forced-choice effort indi-cators (e.g., Portland Digit Recognition Test, Computerized Assessment of ResponseBias) to confirm the utility of forced-choice measures in a low IQ population, and todetermine if some forced-choice measures have higher specificity rates than others inthis context.
The Finger Tapping Test also was associated with relatively high specificityat low IQ levels; because the Finger Tapping Test does not rely on cognitive abili-ties, it would appear to be an appropriate effort measure in low IQ patients whohave no gross motoric problems. The effectiveness of the Finger Tapping Test inthis population raises the possibility that other motor tests, such as Grip Strength
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and Grooved Pegboard, may also be particularly appropriate for use as effortindicators in low IQ groups. Given the excellent specificity previously reportedfor Vocabulary minus Digit Span in a mild MR sample (100%, Graue et al., inpress), further examination of the use of this effort test in low IQ groups shouldalso be pursued.
In contrast, the current study suggests that effort tests with a premium onimmediate attention=encoding may be inadvisable for use in low IQ populations.Unacceptably low specificities were found on memory effort tests with single trialexposure (Rey-15, Rey Word Recognition Test) and effort tests of immediate atten-tion span (Digit Span-ACSS, Reliable Digit Span). The Dot Counting test is alsocontraindicated in groups with difficulties in basic calculation and multiplicationabilities. The RO=RAVLT discriminant function was the only measure in the currentstudy that did not significantly correlate with IQ. This is also evidenced by inspectionof means, in which higher mean scores were found on the RO=RAVLT function inborderline and low average IQ groups compared to average and high averagegroups. However, the mean performance did drop in the lowest IQ samples, as illu-strated by the adjustment to the cutoff needed in the IQ <70 group to maintainacceptable specificity. The lack of correlation between IQ and the discriminant func-tion is likely a byproduct of the manner in which it is calculated, i.e., weighted visualmemory performance is subtracted from weighted verbal memory performances. Inaverage and high average IQ groups, participants do well on both visual and verbalmemory measures, resulting in a smaller difference between verbal and nonverbaldomains. Similarly, patients in the extremely low range of IQ typically performpoorly on both the visual and verbal memory measures, again resulting in a smallerrelative difference between verbal and nonverbal scores.
It is recommended that the current data be used cautiously as a guide for devel-oping expectations as to how differing IQ groups perform on effort measures.Patients in the current study had various psychiatric and neurologic diagnosesand, as a result, their effort test performance may not be representative of the effectof lowered IQ in isolation. However, this sample does reflect the typical clinic popu-lation in which neuropsychologists must assess effort. Further limitations of the cur-rent study include the fact that sample sizes were small in the lowest and highest IQbands, raising concerns regarding reliability of the findings, and not all tests wereadministered to all participants due to the hetereogeneity of the clinical setting(i.e., various examiners, differing clinic locations). Finally, it is possible that someindividuals who were not performing with adequate effort were included in the sam-ple despite the fact that participants with obvious incentive to feign cognitive symp-toms were excluded. As a result, the false positive identification rate may have beenartificially raised, although this is not likely to be a major problem given that none ofthe participants retained in the study was determined to be malingering or otherwisenoncredible from a clinical standpoint, and low IQ scores were entirely consistentwith behavioral observations and referral questions.
When interpreting effort test performance in any population, it is important toconsider the cognitive abilities required by the measures (e.g., memory, attention,calculation, language abilities) in conjunction with the overarching clinical context(e.g., external incentives to feign; consistency between test scores and collateral infor-mation, observations of behavior, and performance of ADLs, etc.).
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REFERENCES
Allen, L. M., Conder, R. L., Green, P., & Cox, D. (1999). Computerized Assessment ofResponse Bias manual. Durham, NC: Cognisyst.
Arnold, G., Boone, K. B., Lu, P., Dean, A., Wen, J., Nitch, S., & McPherson, S. (2005).Sensitivity and specificity of Finger Tapping scores for the detection of suspect effort.The Clinical Neuropsychologist, 19(1), 105–120.
Axelrod, B. N., Fichtenberg, N. L., Millis, S. R., & Wertheimer, J. C. (2006). Detecting incom-plete effort with Digit Span from the Wechsler Adult Intelligence Scale—Third Edition.The Clinical Neuropsychologist, 20, 513–523.
Babikian, T., Boone, K. B., Lu, P., & Arnold, G. (2006). Sensitivity and specificity of variousDigit Span scores in the detection of suspect effort. The Clinical Neuropsychologist, 20,145–159.
Baker, R., Donders, J., & Thompson, E. (2000). Assessment of incomplete effort with theCalifornia Verbal Learning Test. Applied Neuropsychology, 7, 111–114.
Boone, K. B., Lu, P., Back, C., King, C., Lee, A., Philpott, L., et al. (2002). Sensitivity andspecificity of the Rey Dot Counting Test in patients with suspect effort and various clini-cal samples. Archives of Clinical Neuropsychology, 17, 1–19.
Boone, K. B., Salazar, X., Lu, P., Warner-Chacon, K., & Razani, J. (2002). The Rey 15-Itemrecognition trial: A technique to enhance sensitivity of the Rey-15 Item MemorizationTest. Journal of Clinical and Experimental Neuropsychology, 24, 561–573.
Brockhaus, R., & Merten, T. (2004). Neuropsychologische diagnostik suboptimalen:Leistungsverhaltens mit dem Word Memory Test [in German]. Nervenarzt, 75, 882–887.
Frederick, R. I. (1997). Validity indicator profile manual. Minneapolis, MN: NationalComputer Services.
Goldberg, J. O. & Miller, H. R. (1986). Performance of psychiatric inpatients and intellectu-ally deficient individuals on a task that assesses the validity of memory complaints.Journal of Clinical Psychology, 42, 797–795.
Graue, L. O., Berry, D. T. R., Clark, J. A., Sollman, M. J., Cardi, M., Hopkins, J., &Werline, D. (in press). Identification of feigned mental retardation using the new generationof malingering detection instruments: Preliminary findings. The Clinical Neuropsychologist.
Green, P., & Flaro, L. (2003). Word Memory Test performance in children. Child Neuropsy-chology, 19, 189–207.
Green, P. W., Allen, L. M., & Astner, K. (1996). The Word Memory Test: A user’s guide to theoral and computer-administered forms (U.S. Version 1.1). Durham, NC: Cognisyst.
Hayes, J. S., Hale, D. B., & Gouvier, W. D. (1997). Do tests predict malingering in defendantswith mental retardation? Journal of Psychology, 131, 575–576.
Hays, J. R., Emmons, J., & Lawson, K. A. (1993). Psychiatric norms for the Rey 15-ItemVisual Memory Test. Perceptual and Motor Skills, 76, 1331–1334.
Hurley, K. E. & Deal, P. (2006). Assessment instruments measuring malingering used withindividuals who may have mental retardation: Potential problems and issues. MentalRetardation, 44, 112–119.
Iverson, G. L. & Franzen, M. D. (1994). The Recognition Memory Test, Digit Span, andKnox Cube Test as markers of malingered memory impairment. Assessment, 1, 323–334.
Kennedy, C., Shaver, S., Weinborn, M., Manley, J., Broshek, D., & Marcopulos, B. (2005,November). Use of the Test of Memory Malingering (TOMM) in Individuals with FSIQbelow 70. Poster session presented at the 25th annual meeting of the National Academy ofNeuropsychology (NAN), Tampa, Florida.
Loring, D. W., Lee, G. P., & Meador, K. J. (2005). Victoria Symptom Validity Test perform-ance in non-litigating epilepsy surgery candidates. Journal of Clinical and ExperimentalNeuropsychology, 27, 610–617.
IQ AND EFFORT TEST PERFORMANCE 721
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nt] A
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Lu, P. H., Boone, K. B., Cozolino, L., & Mitchell, C. (2003). Effectiveness of the Rey Oster-reith Complex Figure Test and the Meyers and Meyers Recognition Trial in the detectionof suspect effort. Clinical Neuropsychologist, 17, 426–440.
Marshall, P. S., & Happe, M. (in press). The performance of individuals with mental retar-dation on cognitive tests assessing effort and motivation. The Clinical Neuropsychologist.
Nitch, S., Boone, K. B., Wen, J., Arnold, G., & Alfano, K. (2006). The utility of the Rey WordRecognition Test in the detection of suspect effort. The Clinical Neuropsychologist, 20,873–887.
Richman, J., Green, P., Gervais, R., Flaro, L., Merten, T., Brockhaus, R., et al. (2006). Objec-tive tests of symptom exaggeration in independent medical evaluations. Journal of Occu-pational and Environmental Medicine, 48, 303–311.
Schretlen, D. & Arkowitz, H. (1990). A psychological test battery to detect prison inmates whofake insanity or mental retardation. Behavioral Sciences and the Law, 8, 75–84.
Schretlen, D., Brandt, J., Krafft, L., & Van Gorp, W. (1991). Some caveats in using the Rey15-item memory test to detect malingered amnesia. Psychological Assessment: A Journalof Consulting and Clinical Psychology, 3, 667–672.
Sherman, D. S., Boone, K. B., Lu, P., & Razani, J. (2002). Re-examination of the Rey Audi-tory Verbal Learning Test=Rey Complex Figure discriminant function to detect suspecteffort. Clinical Neuropsychologist, 16, 242–250.
Speigel, E. (2006). The Rey 15-Item Memorization Test: Performance in under-representedpopulations in the absence of obvious motivation to feign neurocognitive symptoms. Unpub-lished doctoral dissertation, Fuller Theological Seminary, Pasadena, California.
Weinborn, M., Orr, T., Woods, S. P., Conover, E., & Feix, J. (2003). A validation of the Testof Memory Malingering in a forensic psychiatric setting. Journal of Clinical and Experi-mental Neuropsychology, 25, 979–990.
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