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Transcript of Explicit Memory Bias
8/3/2019 Explicit Memory Bias
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BEHAVIOR THERAPY 31,745-756,2000
E x p lic it M e m o r y B i a s fo r T h r e a t W o r d s inG e n e r a l i ze d A n x ie t y D is o r d e r
BRUCE H . FRIEDMAN
Virginia Polytechnic Institute and State University
JULIAN E THAYER
University of M issouri-Columbia
THOMAS D. BORKOVEC
The Pennsylvania State University
Although findings of an implicit memory bias for threat words in generalized anxi-
ety disorder (GAD) are fairly robust, the data regarding an explicit bias in this disor-
der are less consistent. This issue was investigated in the context of two studies
directed primarily at the examination of attentional and physiological underpinnings
of GAD. In these experiments , GAD clients and nonanxious control participants (35
and 29 in Study 1, and 22 and 31 in Study 2, respectively) engaged in an S1-$2 con-
ditioning procedure that involved the presentation of a series of neutral stimuli(colored dots) paired with threat and nonthreat words , followed by a free recall test.
Instructions were to simply look at the dot and read the word silently. A free recall
task was administered at the end of each experimental session. Contrary to previous
trends in the literature, a marked bias in the GAD group toward recall of the threat
words emerged in both studies. These results are considered in the light of method-
ological differences with previous research, information processing characteristics
of GAD, and the role of physiological assessment in cognitive studies of anxiety.
I n f o r m a t i o n p r o c e s s i n g a p p r o a c h e s t o a n x i e t y h a v e y i e l d e d n u m e r o u s
ins igh t s in to the cogn i t ive mechan isms tha t opera te in genera l i zed anx ie ty
d i so rder (GA D) . In pa r ti cu la r , examina t ion o f me m ory b iase s fo r d i so rder -
cong ruen t in fo rmat ion sugges t s tha t charac te ri s ti c cogn i t ive s ty les can d i s tin -
Preparation of this manuscript was supported in part by National Institute of Mental Health
Grant MH-39172 to the third author. The authors would like to thank Mary Borkovec, Holly
Hazlett-Stevens, Jim Lyonfields, Katie Peasley, and the late Silvia Molina for assistance in data
collection and quantification. These data were collected at the Stress and Anxiety Disorders
Institute, Department of Psychology, The Pennsylvania State University.
Address correspondence to Bruce H. Friedman, Department of Psychology, Virginia Polytech-
nic Institute and State University, Blacksburg, VA 24061--0436; e-mail: [email protected].
745 005-7894/00/07454)75651.00/0Copyright 2000 by Association or Advancementof BehaviorTherapy
All rights for reproduction n any form reserved.
8/3/2019 Explicit Memory Bias
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746 FRIEDMAN ET AL.
g u i s h a m o n g v a r i o u s p s y c h o p a t h o l o g i e s . F o r e x a m p l e , a n i m p l i c i t m e m o r yb i a s ( e n h a n c e m e n t o f s t i m u l u s r e c o g n i t i o n b y p r i o r s t i m u l u s e x p o s u r e o r" p r i m i n g , ' w i t h o u t c o n s c i o u s r e c o l l e c t i o n o f t h e e x p o s u r e ; s e e S q u i r e , 1 9 9 2)
h a s b e e n t y p i c a l l y as s o c i a t e d w i t h a n x i e t y , a n d a n e xp l i c i t m e m o r y ( a v a i l a b l eto c onsc ious re c a l l) b i a s ha s be e n fou nd m ore c ha ra c t e r i st i c o f de pre s s ion ( seeW i l li a m s , W a tt s, M a c L e o d , & M a t h e w s , 1 99 7, f o r re v i ew ) . I m p l i c it m e m o r yp r o c e s s e s a c t i v a t e s t o r e d i n f o r m a t i o n , t h e r e b y i m p r o v i n g i t s a c c e s s i b i l i t y ,
t hough no t ne c e ssa r i l y a f fe c t ing i t s d i re c t r e t r i e va b i l i t y (G ra f , 1994) . Con-v e r s e ly , e x p l i c it m e m o r i e s i n v o l v e c o n s c i o u s , d e li b e r a te r e c a ll o f i n f o r m a t i o n
t h a t w a s e l a b o r a t e d a t t h e t i m e o f e n c o d i n g , a n d a re t h e r e f o r e m o r e a v a i l a b led u e t o e m b e l l i s h m e n t f r o m c o n t e x tu a l c u es . A n x i e t y is m a r k e d b y a n o n c o n -
sc ious , a u tom a t i c , p re -a t t e n t ive b i a s tow a rd th re a t c ue s (M a the w s , 1990) t ha tm a y p r i m e s u c h i n f o r m a t i o n i n i m p l i c i t m e m o r y t e s t s . H o w e v e r , t h i s d e f e n -s i v e a t t e n t i o n a l m e c h a n i s m t h w a r t s f u r t h e r p r o c e s s i n g o f a n x i e t y - p r o v o k i n gs t i m u l i , a n d s o n o e x p l i c it m e m o r y b i as a p p e a r s f o r s u c h m a t e r i a l. I n c o n t r a s t,
d e p r e s s i o n i s c h a r a c t e r i z e d b y c o n s c i o u s e l a b o r a t i o n o f s a d m a t e r i a l , w h i c hinc re a se s i ts a v a i l a b i l i ty fo r e x p l i c i t, d i re c t e d re c a l l.
H o w e v e r , t h e s e s p e c i f i c m e m o r y e f f e c t s i n a n x i e t y m a y n o t g e n e r a l i z ea c r o s s d i a g n o s t i c c a t e g o r i e s . F o r e x a m p l e , a l t h o u g h t h e p r e d i c t i o n o f a n
i m p l i c i t b u t n o t e x p l i c i t m e m o r y b i a s f o r d i s o r d e r - c o n g r u e n t m a t e r i a l h a sb e e n r e p li c at e d in G A D ( M a c L e o d & M c L a u g h l i n , 1 9 9 5) , o t h er s h a v e f o u n dbo th impl i c i t a nd e xp l i c i t me mory b i a se s fo r r e l e va n t s t imul i i n pa n ic d i so r -
d e r ( C l o i tr e & L e i b o w i t z , 1 99 1 ) . A d i r e c t c o m p a r i s o n b e t w e e n p a n i c d i s o r d e ra n d G A D r e v e a l e d a n e x p l i c i t m e m o r y b i a s i n t h e f o r m e r , b u t n o t t h e l a t t e r
( B e c k e r , R o t h , A n d r i c h , & M a r g r a f , 1 9 9 9 ) . B e c k e r e t a l. s u g g e s t e d t h a t m e t h -o d o l o g i c a l i n c o n s i s t e n c i e s a cr o s s s t u d i e s m i g h t a c c o u n t f o r t h e s e d i s c r e p a n t
m e m o r y e f f e c t s i n t h e a n x i e t y l i t e r a t u r e , a n d a d v o c a t e d t h e c o m b i n a t i o n o finc ide n ta l l e a rn ing a nd f re e re c a l l a s t he op t ima l pa ra d igm fo r de t e c t ingm e m o r y b i a s e s i n c l in i c a l a n x ie t y . T h e y f u r t h e r p r o p o s e d t h a t t h i s p a ir i n g i s
e n h a n c e d w i t h c o m p a t i b l e l e a r n i n g a n d r e tr ie v a l ta s k s ; t h a t is , b o t h s h o u l d b ee i t h e r c o n c e p t u a l o r p e r c e p t u a l ( e .g . , E y s e n c k & B y r n e , 1 9 9 4) .
A n o p p o r t u n i t y t o m e e t t h e s e s t a n d a r d s a n d t h u s c o n c e p t u a l l y r e p l i c a t eB e c k e r e t a l . ' s ( 1 9 9 9 ) i n v e s t i g a t i o n o f e x p l i c i t m e m o r y b i a s f o r t h r e a te m e r g e d i n tw o o f o u r o n g o i n g s t u d ie s t h a t w e r e d i r e c t e d p r i m a r i l y a t at te n -t i o n a l a n d p h y s i o l o g i c a l e l e m e n t s o f G A D . A n S 1 - $ 2 p a r a d i g m , w h i c he n ta i l s t he p re se n ta t ion o f a s e r ie s o f pa i re d s t imul i s e pa ra t e d b y a f i xe d in te r -s t imu lus i n t e rva l (B oh l in & K je lbe rg , 1979) , w a s us e d in t he se tw o s tud ie s t oe x a m i n e h i g h e r o r d e r c o n d i t io n i n g t o t h re a t in G A D c l ie n ts a n d m a t c h e d c o n -t ro l g roups . In t he f i r s t s tudy , a c o lo re d d o t (S 1 ) w a s c on s i s t e n t ly pa i re d w i the i the r t h re a t o r non th re a t w ords ($2) ove r mul t ip l e t r i a l s ( s e e Tha ye r , F r i e d -
m a n , B o r k o v e c , J o h n s e n , & M o l i n a , 2 0 0 0 , f o r d e t a i l s ) . I n d i v i d u a l s w e r e
ins t ruc t e d to s im ply look a t t he do t a nd the n re a d the w ord s i l e n tly . Th e se c -o n d s t u d y w a s a n e x a c t r e p l ic a t io n o f t h e f i rs t: th e p h y s i o l o g i c a l a n d a t te n -t i o n a l d a t a f r o m E x p e r i m e n t 2 h a v e n o t y e t b e e n r e p o r t e d ( T h a y e r , F r i e d m a n ,& B o r k o v e c , 2 0 0 0 ) . T o a d d r e s s t h e i s s u e o f a p o t e n t i a l m e m o r y b i a s , a f r e e
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MEMORY BIAS IN GE NER ALI ZED ANXIETY DISORDER 747
r e c a ll t e s t o f t h e s t im u l u s w o r d s w a s g i v e n f o l l o w i n g t h e c o n d i t i o n i n g p r o c e -
d u r e . T h u s , t h e p a i r i n g o f th e S 1 - $ 2 p r o c e d u r e ( a n i n c i d e n ta l l e a r n i n g t a s k )
a n d f r e e r e c a l l ( b o t h t a s k s a r e a l s o c o n c e p t u a l ) , u t i l i z e d i n b o t h s t u d i e s , c o n -
f o r m s t o t h e r e c o m m e n d a t i o n s o f B e c k e r e t al . ( 1 9 9 9 ) . Im p o r t a n t l y , h o w e v e r ,t h e c o n d i t i o n i n g t a s k i n v o l v e d e x t e n d e d e x p o s u r e ( 8 s e c o n d s ) t o t h e t h r e a t
w o r d s , w h i c h m a y b e m o r e l i k e l y t o e l i c i t a n e x p l i c i t m e m o r y b i a s t h a n t h e
b r i e f e x p o s u r e t i m e s t h a t t y p i f y m o s t s t u di e s ( e . g ., S t r o o p p a r a d i g m s ) o f t h is
p h e n o m e n o n ( B o r k o v e c , R a y , & S t o b e r , 1 9 9 8 ). F u r t h e r m o r e , r e t e n t i o n is
g e n e r a l l y e n h a n c e d f o r e m o t i o n a l l y a r o u s i n g s ti m u l i ( M c G a u g h , 1 9 9 2 ) , a n d
t h r e a t w o r d s w o u l d p r e s u m a b l y b e e s p e c i a l l y a r o u s i n g t o G A D c l ie n t s. B a s e d
o n t h e s e n o t i o n s , t h e f o l l o w i n g h y p o t h e s e s w e r e g e n e r a t e d a n d t e s t e d i n t h e
p r e s e n t s t u d ie s : ( a ) G A D c l ie n t s w i ll r e c a ll m o r e t h r e a t t h an n o n t h r e a t w o r d s ,
( b ) t h e s e i n d i v i d u a l s w i l l r e c a l l m o r e t h r e a t w o r d s w h e n c o m p a r e d t o a
m a t c h e d c o n t r o l g r o u p , ( c ) r e c a l l f o r t h r e a t w o r d s w i l l b e g r e a t e r t h a n n o n -
t h r e a t w o r d s i n th e c o n t r o l g r o u p , a s w e l l , b e c a u s e o f th e a r o u s i n g n a t u r e o f
t h r e a t w o r d s , a n d ( d ) t h e re w i l l b e n o d i f f e r e n c e s b e t w e e n t h e g r o u p s o n
r e c a l l o f n o n t h r e a t w o r d s .
E x p e r i m e n t 1
Method
Participants. T h i r t y -f i v e t r e a tm e n t - s e e k in g G A D c l ie n ts a n d 2 9 m a t c h e d
c o n t r o l p a r ti c i p a n ts c o m p l e t e d t h e l a b o r a t o r y s e s si o n . A g e n c y - r e f e r r e d a n ds e l f - re f e r r e d c l ie n t s w e r e f ir st g iv e n a 3 0 - m i n u t e p h o n e i n t e r v ie w b y c l in i c a l
g r a d u a t e s t u d e n t a s se s s o rs t o d e t e r m i n e w h e t h e r G A D w a s t h e li k e l y d i a g n o -
s i s . S u b s e q u e n t l y , t h e a s s e s s o r c o n d u c t e d a d i a g n o s t i c i n t e r v i e w u s i n g t h e
A n x i e t y D i s o r d e r I n te r v ie w S c h e d u l e - R e v i s e d ( A D I S - R ; D i N a r d o & B a r l ow ,
1 9 8 8 ) . C l i e n t s w e r e a d m i t t e d t o a t h e r a p y t ri a l i f t h e y m e t c r i t e r i a f o r a p r i n c i -
p a l DSM-III-R ( A m e r i c a n P s y c h i a t r i c A s s o c i a t i o n , 1 9 8 7) d i a g n o s i s o f G A D
w i t h a n a s s e s s o r s e v e r i t y ra t in g o f 4 (moderate anxiety) o r g r e a t e r o n a 0 - t o -
8 - p o i n t s e v e r i ty s c a l e , a n d i f t h e y d i d n o t m e e t c r i t e ri a f o r p a n i c d i s o r d e r w i t h
o r w i t h o u t a g o r a p h o b i a , o r g a n i c b r a i n s y n d r o m e , s u b s ta n c e a b u s e , o r m e d i c a l
c o n d i t i o n s t h a t m a y c o n t r i b u t e to a n x i e ty . T h e A D I S - R w a s c o n d u c t e d a s e c -o n d t i m e b y a P h . D . c l i n i c a l p s y c h o l o g i s t . It w a s r e q u i r e d t h a t b o t h d i a g n o s t i c
i n t e r v i e w e r s a g r e e t h a t t h e c r it e r ia w e r e m e t . C o n t r o l s u b j e c ts w e r e r e c r u i t e d
b y n e w s p a p e r a d v e r t i se m e n t s a n d w e r e a s s e s s e d b y th e p h o n e i n t e r v i e w a n d a
s i n g le a d m i n i s tr a t io n o f t h e A D I S - R c o n d u c t e d b y o n e o f th e c l in i c a l a ss e s -
s o rs . T h e s e i n d i v id u a l s w e r e i n c l u d e d i n t h e s t u d y i f t h e y d i d n o t m e e t d i a g -
n o s t i c c r i t e r i a f o r a n y d i s o r d e r a t e v e n m i l d s e v e r i t y l e v e l s a n d i f t h e y
r e p o r te d n o p r i o r h is t o ry o f p s y c h o p h a r m a c o l o g i c a l o r p s y c h o l o g i c a l t re a t-
m e n t o f a n y k in d . P h y s i o l o g i c a l d a t a f r o m t h is s t u d y a r e r e p o r t e d i n T h a y e r e t
a l . ( 2 0 0 0 ) .T h e d i st r ib u t i o n o f g e n d e r a c ro s s g r o u p s w a s 2 2 w o m e n a n d 1 3 m e n f o r
G A D a n d 1 8 w o m e n a n d 11 m e n f o r c o n t ro l . T h e d i st r ib u t i o n o f r a c e w a s 3 1
C a u c a s i a n , 1 A f r i c a n A m e r i c a n , 2 H i s p a n i c , a n d 1 M i d d l e E a s t e r n f o r t h e
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748 F R I E D M A N E T A L .
T A B L E 1
C O M O R B I D D I A G N O S E S F O R G A D C L IE N T S
E x p e r i m e n t I E x p e r i m e n t 2
S o c i a l p h o b i a 1 9 1 5
S p e c i f i c p h o b i a 1 2 3
A g o r a p h o b i a 3 2
M a j o r d e p r e s s i o n ( r e c u r re n t ) 3 0
M a j o r d e p r e s s i o n 2 0
D y s t h y m i a 1 2
M a j o r d e p r e s s i o n ( p a r ti a ll y r e m i t t e d ) I 1
O b s e s s i v e - c o m p u l s i v e d i s o rd e r 1 0
P o s t t r a u m a t i c s t re s s d i s o r d e r 1 0
S e a s o n a l a f f e c t i v e d i s o r d e r 1 0
G A D g r o u p , a n d 2 6 C a u c a s ia n , 1 A f r i c a n - A m e r i c a n , 1 H i s p a n i c , a n d 1 M i d d l e
E a s t e r n f o r t h e c o n t r o l g r o u p . A v e r a g e a g e s o f t h e c l ie n t s a n d c o n t r o l s w e r e
3 6 . 9 (SD = 1 1 . 8 ) a n d 3 3 . 8 (SD = 1 0 .9 ) y e a r s , re s p e c t i v e l y , a n d a v e r a g e y e a r s
o f e d u c a t i o n w e r e 1 5.7 (SD = 2 .6) and 16 .1 (SD = 2 . 3 ) , r e s p e c t i v e l y . T h e
g r o u p s d i d n o t d i f f e r s i g n i f i c a n t l y o n a n y o f t h e s e v a r i a b l e s . T h e a v e r a g e
d u r a t i o n o f t h e c l i e n t s ' d i s o r d e r w a s 1 2 .5 y e a r s (SD = 1 2 .6 ) . S e v e n t y - s e v e n
p e r c e n t h a d a t l e a s t o n e c o m o r b i d d i a g n o s i s ( s e e T a b l e 1 ) a n d 5 w e r e t a k i n g
p s y c h o t r o p i c m e d i c a t io n ~ a t t h e t i m e o f t h e s e ss i o n.
A t t h e e n d o f th e d i a g n o s t ic i n t e rv i e w u s i n g t h e A D I S - R , t h e H a m i l t o n
A n x i e t y R a t i n g S c a l e ( H A R S ; H a m i l t o n , 1 9 6 0 ) a n d t h e H a m i l t o n R a t i n g
S c a l e f o r D e p r e s s i o n ( H R S D ; H a m i l t o n , 1 9 5 9 ) w e r e a l so a d m i n i s t e r e d . I n a
s e p a r a t e s e l f - r e p o r t s e s s i o n , c li e n t s ( b e f o r e t h e r a p y b e g a n ) a n d c o n t r o l s c o m -
p l e t e d t h e S t a t e -T r a i t A n x i e t y I n v e n t o r y - T r a i t ( S T A I ; S p i e lb e r g e r , G o r s u c h ,
L u s h e n e , V a g g , & J a c o b s , 1 9 8 3) ; th e R e a c t i o n s t o R e l a x a t i o n a n d A r o u s a l
Q u e s t i o n n a i r e , a f a c t o r a n a l y t i c a l l y d e r i v e d m e a s u r e o f f e a r o f r e l a x a t i o n
( R R A Q ; H e i d e & B o r k o v e c , 1 9 8 3) ; t h e P e n n S t a t e W o r r y Q u e s t i o n n a i r e
( P S W Q ; M e y e r , M i l le r , M e t z g e r , & B o r k o v e c , 1 9 9 0 ) , a m e a s u r e o f w o r r yt h a t d i s t in g u i s h e s G A D f r o m a ll o t h e r a n x i e ty d i s o rd e r s ( B r o w n , A n t o n y , &
B a r l o w , 1 9 9 2) ; a n d t h e B e c k D e p r e s s i o n I n v e n t o r y ( B D I ; B e c k , W a r d , M e n -
d e l s o n , M o c k , & E r b a u g h , 1 9 6 1 ).
T h i s r e s e a r c h w a s a p p r o v e d b y t h e I n s t i t u t i o n a l R e v i e w B o a r d a n d
i n f o r m e d c o n s e n t w a s o b t a i n e d f r o m e a c h p a r t i c i p a n t p r io r t o th e s t a rt o f t h e
e x p e r i m e n t .Procedure. F u l l d e t a i l s o n t h e S 1 - $ 2 t a s k a n d p h y s i o l o g i c a l r e c o r d i n g
p r o c e d u r e c a n b e f o u n d i n T h a y e r e t a l . ( i n p r e s s ) ; i n c l u d e d h e r e i s a n o v e r -
v i e w o f t h e S 1 - $ 2 p r o c e d u r e a n d d e t a i l s o f th e f r e e r e c a ll t es t . E a c h p a r t ic i -
p a n t r e c e i v e d a t o u r o f t h e l a b o r a t o r y a n d a d e s c r i p t i o n o f t h e r e c o r d i n g m e t h -
O n e w a s t a k i n g P r o z a c , 2 w e r e t a k i n g h y p n o t i c - s e d a t i v e s , 1 w a s t a k i n g L i s i n o p r il ( f o r h i g h
b l o o d p r e s s u r e ) , a n d 1 w a s t a k i n g S y n t h r o i d ( a t h y r o i d m e d i c a t i o n ) .
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MEMORY BIAS IN GENERALI ZED ANXIETY DISORDER 749
o d s a n d t a s k s p r i o r t o t h e a c t u a l s e s s i o n . A t t h e e x p e r i m e n t a l s e s s i o n a n d a f t e r
e l e c t r o d e a t t a c h m e n t , t h e p a r ti c i p a n t w a s s e a t e d i n a r e c l i n e r c h a i r i n a s m a l l
s o u n d - a t t e n u a t e d r o o m a d j a c e n t t o t h e e q u i p m e n t r o o m a n d l e f t a l o n e w i t h
d o o r c l o s e d ; th e e x p e r i m e n t e r c o m m u n i c a t e d w i t h th e p a r t ic i p a n t v i a in t e r-c o m . T h e i n i t i a l p h a s e o f t h e e x p e r i m e n t i n v o l v e d p h y s i o l o g i c a l r e c o r d i n g
d u r i n g p e r i o d s o f q u i e t r e s t i n g , s e l f - r e l a x a t i o n , a n d w o r r y i n g ( s e e T h a y e r ,
F r i e d m a n , & B o r k o v e c , 1 9 9 6 ). A f t e r a f in a l 5 - m i n u t e b a s e l i n e , t h e S 1 - $ 2
t a s k w a s i n i t ia t e d , w h i c h i n v o l v e d t h e p r e s e n t a t i o n o f a c o l o r e d d o t ( S 1 ) d i s -
p l a y e d a t t h e c e n t e r o f a c o m p u t e r m o n i to r . T h e c o l o r o f th e d o t ( y e l lo w o r
g r e e n ) w a s c o n s i s t e n t l y p a ir e d w i t h e i t h e r t h r e a t o r n o n t h r e a t w o r d s ( $ 2 ) ; t h is
a s s o c i a t i o n w a s c o u n t e r b a l a n c e d a c r o s s s u b j e c t s w i t h i n b o t h G A D a n d c o n -
t r o l g r o u p s . T h i s c o n t i n g e n c y w a s n o t m a d e e x p l i c i t , w h i c h a l l o w e d f o r t h e
a s s e s s m e n t o f h i g h e r o r d e r c o n d i t i o n i n g . T h e i n s t r u c ti o n s s i m p l y r e q u i r e d
t h a t e a c h w o r d b e r e a d s i le n t ly a s i t a p p e a r e d o n t h e s c r e e n . T h e S 1 a n d $ 2
s t i m u l i w e r e s e q u e n t i a l l y p r e s e n t e d f o r 8 s e c o n d s e a c h , w i t h a n i n t e r t r i a l
i n t e r v a l o f 3 0 s e c o n d s . A t o t a l o f 2 0 t r ia l s ( 1 0 t h r e a t , 1 0 n o n t h r e a t ) w a s p r e -
s e n t e d . A s i n g l e o r d e r w a s u s e d w i t h a l l p a r t i c i p a n t s ; t h e o r d e r o f t h e w o r d s
h a d b e e n r a n d o m l y d e t e r m i n e d b e f o r e t h e e x p e r i m e n t , w i t h t h e c o n s t r a i n t
t h a t n o m o r e t h a n 2 c o n s e c u t i v e t r i a l s c o n t a i n w o r d s o f o n e t y p e . T h e 2 0
w o r d s w e r e t a k e n f r o m M a t h e w s a n d M a c L e o d ( 1 9 86 ) . F o l l o w i n g t h e S 1 - $ 2
p r o c e d u r e , s u b j ec t s w e r e a s k e d t o w r it e d o w n a s m a n y w o r d s f r o m t h e p r e v i-
o u s t a sk t ha t t h e y c o u l d r e m e m b e r . T h e n u m b e r o f c o r re c t l y r e c a ll e d t h r ea t
a n d n o n t h r e a t w o r d s s e r v e d a s t h e d e p e n d e n t v a r ia b l e .
Experiment 2
Method
Participants an d procedure. P a r t i c ip a n t s w e r e s e l e c t e d a l o n g t h e s a m e c r i -
t e r ia a s d e s c r i b e d i n E x p e r i m e n t 1 . T h e d i s t ri b u t io n o f g e n d e r a c r o s s g r o u p s
w a s 15 w o m e n a n d 7 m e n f o r G A D a n d 2 2 w o m e n a n d 9 m e n f o r t he c o n tr o l
g r o u p . T h e d i s t r ib u t i o n o f ra c e w a s 1 8 C a u c a s i a n , 1 A f r i c a n A m e r i c a n , 2 H i s -
p a n i c , a n d 2 I n d i a n f o r t h e G A D g r o u p , a n d 2 6 C a u c a s i a n , 1 A f r i c a n A m e r i -
c a n , 2 H i s p a n i c , 1 I n d i a n , a n d 1 A s i a n f o r t h e c o n t r o l g r o u p . A v e r a g e a g e s o f
t h e c l ie n t s a n d c o n t r o l s w e r e 3 5 . 8 1 (S D = 1 2 . 1 ) an d 3 9 . 6 0 (SD = 1 3 . 2 ) y ea r s ,
r e s p e c t i v e l y , a n d a v e r a g e y e a r s o f e d u c a t i o n w e r e 1 5 .9 (S D = 2 . 3 ) an d 1 6 . 8 0
(S D = 2 . 2 ) , r e s p e c t i v e l y . T h e g r o u p s d i d n o t d i f f e r s i g n i f i c a n t ly o n a n y o f
t h e s e v a r i a b le s . T h e a v e r a g e d u r a t i o n o f t h e c l i e n t s ' d i so r d e r w a s 1 0 .9 y e a r s
(S D = 9 . 8 ) . E i g h t y - s i x p e r c e n t h a d a t l e a s t o n e c o m o r b i d d i a g n o s i s ( s e e
T a b l e 1 ) a n d 2 w e r e t a k in g p s y c h o t r o p i c m e d i c a t i o n 2 a t th e t i m e o f t h e s e s -
s i o n . T h e G A D c l i e n t s a n d c o n t r o l p a r t i c i p a n t s c o m p l e t e d t h e s a m e s e l f -
r e p o r t m e a s u r e s o f a n x i e t y a n d d e p r e s s i o n t h a t w e r e a d m i n i s t e r e d in E x p e r i -
m e n t 1 ( s ee T a b l e 2 fo r m e a n s c o r e s ).T h e i n i ti a l p r o c e d u r e , w h i c h i n v o l v e d p h y s i o l o g i c a l r e c o r d i n g d u r i n g p e r i -
2 One was taking Xan ax and 1 was taking Buspar.
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750 FRIEDMAN ET AL.
T A B L E 2
G A D CLIENT AND CONTROL SCORES ON SELF-REPORT MEASURES OF
ANXIETY AND DEPRESSION
Experiment 1 Experiment 2
GAD Control GAD Control
Mean SD Mean SD Mean SD Mean SD
BDI 18.12 8.03 1.21 1.70 16.24 7.76 1.84 4.19
HARS 24.35 6.31 2.53 1.98 23.51 6.31 2.82 2.23
HR SD 14.10 7.32 1.47 1.27 10.26 4.89 1.29 1.21
RRAQ 28.15 7.12 12.92 3.99 28.29 6.54 13.10 4.47
STAI 59.03 7.56 27.69 4.89 55.82 8.23 25.45 5.43
PSWQ 68.58 7.72 28.07 6.31 67.05 8.36 28.55 9.41
Note. BDI - Beck Depress ion Inventory; HARS = Hamilton Anxiety Rating Scale; HRSD =
Hamilton Rating Scale for Depression; RRAQ = Reactions to Relaxation and Arousal
Questionnaire; STAI = State-Trait Anxiety Inventory-Trait: PSWQ = Penn State
Worry Questionnaire.
o d s o f q u ie t r e s t, s e l f - re l a x a t io n , a n d w o r r y , a n d s u b s e q u e n t S l - S 2 a n d f r e e
r e c a ll p r o c e d u r e s , w e r e i d en t ic a l to E x p e r i m e n t 1.
Results
Statis t ical An alyses
A s a m a n i p u l a t i o n c h e c k , d i f f e r e n c e s b e t w e e n t h e c l i e n t s a n d t h e c o n t r o l s
o n th e s e l f - r e p o r t m e a s u r e s o f a n x i e t y a n d d e p r e s s i o n w e r e e x a m i n e d u s i n g t
t e s t s . I n b o t h e x p e r i m e n t s t h e c l i e n t s s c o r e d h i g h e r t h a n t h e c o n t r o l s o n a l l
m e a s u r e s ( al l p s < 0 . 0 0 0 0 1 ) . I n a d d i t io n , t h e t w o c l i e n t g r o u p s a n d t h e tw o
c o n t r o l g r o u p s d i d n o t d i f f e r s i g n if i ca n t ly o n a n y m e a s u r e s a f t e r c o n t r o l o f
T y p e I e r r o r r a t e s .
P l a n n e d t t e s t s w e r e c o n d u c t e d , b a s e d o n t h e p r e d i c t i o n s s t a t e d in th e i n t r o -
d u c t io n : m e a n n u m b e r s o f r e c a l le d w o r d s ( o u t o f 1 0 t h r e a t a n d 1 0 n o n t h r e a t
w o r d s ) a r e r e p o r t e d in T a b l e 3 . I n a d d i t i o n , e f f e c t s iz e s ( p o i n t - b i s e r i a l c o r r e l a -
t io n s ) a r e r e p o r t e d . A m o d i f i e d B o n f e r r o n i p r o c e d u r e ( S i m e s , 1 9 86 ) w a s u s e d
t o c o n t r o l h y p o t h e s i s - w i s e T y p e I e r r o r r a t e s . I n b o t h e x p e r i m e n t s , t h e G A D
g r o u p r e c a l le d s i g n i f ic a n t ly m o r e t h r e a t w o r d s t h a n n o n t h r e a t w o r d s [ E x p e r i -
m e n t 1: t ( 6 2 ) = 6 . 2 9 , p < . 0 0 1 , rp b = 0 . 6 2 ; E x p e r i m e n t 2 : t ( 5 1 ) = 3 . 6 9 , p <
.004 , one - t a i l ed , / ' i 0b = 0 . 4 6 ] . F u r t h e r m o r e , t h e G A D g r o u p r e c a l l e d s i g n i f i -
c a n t l y m o r e t h r e a t w o r d s t h a n t h e c o n t r o l g r o u p d i d i n b o t h s t u d i e s [ E x p e r i -
m e n t 1: t ( 6 2 ) = 3 .6 9 ,p < . 0 0 1 , r pb ---- 0 . 4 2 ; E x p e r i m e n t 2 : t (5 1 ) = 2 . 0 0 , p <
. 0 3 , o n e - t a i l e d , rpb ---- 0 . 2 7 ] . T h e r e w a s a m a r g i n a l l y s i g n i f i c a n t t r e n d i n t h ec o n t r o l g r o u p in E x p e r i m e n t 1 f o r r e c a ll o f m o r e t h r e a t t h a n n o n t h r e a t w o r d s ,
t ( 6 2 ) = 1 .4 6 , p < . 0 8 , o n e - t a i l e d , rp b ---- 0 .1 8 , t h a t r e a c h e d s i g n i f i c a n c e i n
E x p e r i m e n t 2 , t ( 5 1 ) = 1 . 9 1 ,p < . 0 3 , o n e - t a i l e d , rp b ---- 0 .2 6 , b u t d i d n o t su r -
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M E M O R Y B IA S I N G E N E R A L I Z E D A N X I E T Y D I S O R D E R 7 5 1
T A B L E 3
M E A N S A N D S T A N D A RD D E V IA T I O N S F OR N U M BE R O F T H RE A T A N D
N O N T H RE A T W O RD S RE CA L L E D
W o r d T y p e
G r o u p T h r e a t N o n t h r e a t
E x p e r i m e n t 1
G A D 4 . 6 ( 1 .5 ) 3 . 0 ( 1 .7 )
C o n t r o l 3 . 3 ( 1 . 3 ) 2 . 9 ( 1 . 2 )
E x p e r i m e n t 2
G A D 4 . 7 ( 1 .7 ) 3 . 5 ( 1 .7 )
C o n t r o l 3 . 7 ( 1 . 8 ) 3 . 0 ( 1 . 3 )
v i v e e r r o r c o r r e c t i o n . H o w e v e r , t h e e f f e c t s i ze s i n d i c a t e d t h a t t h e e f f e c t w a s
n o n t r iv i a l. T h e d i f f e r e n c e b e t w e e n G A D a n d c o n t r o l g r o u p s f o r r ec a l l o f n o n -
t h r ea t w o r d s d i d n o t a p p r o a c h s i g n if i ca n c e in e i t h e r e x p e r i m e n t ( E x p e r i m e n t
1: rpb = 0 . 0 2 ; E x p e r i m e n t 2 : rp b = 0 . 1 6 ) . T o e x a m i n e p o s s i b l e d i f f e re n t i a l
r e c a l l o f so c i a l t h r e a t v e r s u s p h y s i c a l t h r e a t w o r d s , a n a l y s i s o f v a r i a n c e u s i n g
g r o u p ( G A D v s . C o n t r o l ) a s a b e t w e e n - s u b j e c t s f a c t o r a n d w o r d t y p e ( s o c ia l
v s . p h y s i c a l th r e a t ) a s a w i t h i n - s u b j e c t s f a c t o r w a s c o n d u c t e d f o r e a c h e x p e r -
i m e n t . T h e r e w e r e n o s i g n i f i c a n t i n t e r a c t i o n s b e t w e e n g r o u p a n d w o r d t y p e
[ E x p e r i m e n t l : F ( 1 , 6 2 ) = 0 . 0 6 6 , p = 0 . 7 9 ; E x p e r i m e n t 2: F ( 1 , 5 1 ) =
2 . 3 5 , p -- 0 . 13 ] .
Discuss ion
A n e x p l i c it m e m o r y b i a s f o r th r e a t w o r d s w a s r e p l i c a t e d ac r o s s t w o s e p a -
r a te G A D s a m p l e s u n d e r c o n d i t io n s r e c o m m e n d e d a s i d ea l fo r d e t e c t i o n o f
m e m o r y b i a s e s i n s tu d i e s o f a n x i e ty : n a m e l y , i n c i d e n t a l l e a r n i n g a n d f r e e
r e c a l l ( B e c k e r e t a l ., 1 9 9 9 ) . I n d e e d , t h e o v e r a l l t o t al n u m b e r o f c o r r e c t l y
r e c a l l e d w o r d s w a s i n a c c o r d w i t h t h is r e s e a r c h . H o w e v e r , t h e p r e s e n t d a t a
c o n f l i c t w i t h a b o d y o f l it e r a tu r e t h a t h a s f a i l e d to f i n d a n e x p l i c i t m e m o r y
b i as i n G A D ( B e c k e r e t al .; B r a d l ey , M o g g , & W i l li a m s , 1 9 9 5; M a c L e o d &
M c L a u g h l i n , 1 9 95 ; M a t h e w s , M o g g , M a y , & E y s e n c k , 1 9 8 9) , t h o u g h e x c e p -
t i o n s t o t h i s t r e n d c a n b e f o u n d ( M o g g & M a t h e w s , 1 9 9 0 ; O t t o , M c N a l l y ,
P o l l a c k , C h e n , & R o s e n b a u m , 1 9 9 4 ). M o g g e t al . a t tr ib u t e d th e i r f in d i n g t o a
r e s p o n s e b i a s i n G A D t o w a r d m o o d - c o n g r u e n t w o r d s , r a t h e r t h a n a s e l e c t i v e
m e m o r y e f f ec t . H o w e v e r , p a r ti c ip a n t s i n t h is s t u d y w e r e a w a r e t h a t t h e y
w o u l d r e c e i v e a r e c a l l t e s t , a n d s o t h e t a s k d o e s n o t q u a l i f y a s i n c i d e n t a l
l e a r n i n g . T h i s d i f f e r e n c e r e n d e r s t h e f i n d i n g s l e s s d i r e c t l y c o m p a r a b l e t o
e i t h e r B e c k e t e t a l. o r t h e p r e s e n t s t u dy . O t t o e t a l. f o u n d a n e x p l i c i t m e m o r yb i as o n l y i n l e f t - h e m i s p h e r e - d o m i n a n t G A D s u b j ec t s; t h is e f f e c t i s co n s i d -
e r e d i n g r e a t e r d e t a i l b e l o w .
T h e h y p o t h e s i z e d m e m o r y b i a s f o r th r e a t i n th e c o n t r o l g r o u p w a s l es s
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752 FRIED MAN ET AL.
r o b u s t l y s u p p o r t e d , a s e v i d e n c e d b y s m a l l e r e f f e c t s i z es a n d t h e m a r g i n a l s i g -
n i f i c a n c e o f t h e e f f e c t . O n e l i k e l y e x p l a n a t i o n f o r t h i s d i f f e r e n c e i s t h a t t h e
t h r e a t w o r d s w e r e l e s s a r o u s i n g a n d s i g n i f i c a n t f o r t h e c o n t r o l g r o u p . T h i s
p o s s i b i l i t y i s s u p p o r t e d b y t h e c l e a r b i a s f o r t h e t h r e a t w o r d s b y t h e G A Dp a t ie n t s i n b o t h s t u d ie s w h e n c o m p a r e d t o t h e c o n t r o l g ro u p s . M o r e o v e r , as
p r e d i c t e d , t h e r e w e r e n o g r o u p d i f f e r e n c e s i n r e c a l l f o r n o n t h r e a t w o r d s ,
w h i c h f u r t h e r s u p p o rt s t h e s a l ie n c e o f th e t h r ea t w o r d s t o t h e G A D g r o u p .
I n g e n e r a l , th e p r e s e n t r e s u lt s h i g h l i g h t th e p o i n t s e m p h a s i z e d b y B e c k e r e t
a l . ( 1 9 9 9 ; i .e ., m e t h o d o l o g i c a l i n c o n s i s t e n c i e s a n d t h e r o l e o f p h y s i o l o g i c a l
a r o u s a l i n a n x i e t y ) i n t h e i r a t t e m p t t o a c c o u n t f o r i n c o n s i s t e n t m e m o r y b i a s
f i n d i n g s a c r o s s a n x i e t y s t u d i e s . O n e m e t h o d o l o g i c a l v a r i a n c e t h a t m a y
a c c o u n t f o r d i f f e r e n c e s i n f in d i n g s i n v o l v e s t h e n a t u r e o f t h e ta s k s . M a n y
s t u d ie s o f m e m o r y b i a s i n G A D h a v e u s e d v e r y b r i e f st im u l u s e x p o s u r e
t i m e s , t o w h i c h a n a c t i v e r e s p o n s e i s r e q u i r e d ( B o r k o v e c e t a i. , 1 9 9 8 ) . In c o n -
t r a st , t h e p r o t r a c t e d , p a s s i v e v i e w i n g o f t h e S 1 - $ 2 t a s k in t h e p r e s e n t s t u d y
m a y h a v e o v e r r i d d e n t h e a v o i d a n t a s p e c ts o f w o r r y , a n d s o r e s u l t e d i n
e n h a n c e d r e t e n ti o n o f t h r e at w o r d s .
A n o t h e r d i s t i n c ti o n c a n b e m a d e r e g a r d i n g t h e n a t u re o f t h e s ti m u l i . A
c o m m o n l y u s e d p r o c e d u r e i n v o l v e s t h e g e n e r a ti o n o f s e lf - r e fe r e n t i m a g e s t o
t h r e a t a n d n o n t h r e a t w o r d s ( e . g . , B e c k e r e t a l. , 1 9 9 9 ; M a t h e w s e t a l. , 1 9 8 9 ) .
I n c o n t r a s t , i n s t r u c t i o n s i n t h e p r e s e n t t a s k w e r e t o s i m p l y r e a d t h e w o r d s
s i le n t ly . I t is p o s s i b l e t h a t t h e p r o c e s s o f i m a g i n i n g o n e s e l f i n a n a n x i e t y -
p r o v o k i n g s c e n a r i o e li c i ts g r e a t e r c o g n i t i v e a v o i d a n c e a n d t h e r e f o r e le s s s t ra -t e g i c e l a b o r a t i o n t h a n m e r e l y r e a d i n g a t h r e a t e n i n g w o r d . T h e l a t t e r t a s k m a y
i n f a c t b e b e t t e r m a t c h e d t o t h e c h a r a c t e r i s t i c t e n d e n c y t o w a r d w o r r y a n d
r u m i n a t i o n in G A D , w h i c h i s m a r k e d b y t h e d o m i n a n c e o f v e r b a l- l in g u i s t ic
p r o c e s s i n g o v e r i m a g e r y ( B o r k o v e c & I n z , 1 9 90 ; B o r k o v e c e t a l. , 1 9 9 8;
L y o n f i e l d s , B o r k o v e c , & T h a y e r , 1 9 9 5 ). F u r t h e r m o r e , th e u s e o f i m a g e r y i n
g e n e r a l m a y y i e l d n o p a r t i c u l a r a d v a n t a g e i n t e r m s o f a c q u i s i t i o n a n d r e t e n -
t i o n ( P o s t m a n , 1 9 7 4 ) . In s u m , t h e S 1 - $ 2 t a sk u s e d i n t h e p r e s e n t s tu d y m a y
b e s i n g u l a rl y c o n g r u e n t w i t h G A D in te r m s o f d e t e c ti n g a n e x p l ic i t m e m o r y
b i a s . O n t h e o t h e r h a n d , a l t h o u g h i m a g e r y t a s k s m a y b e c o n c e p t u a l l y c o m -
p a t ib l e w i t h f r e e r ec a l l ( B e c k e r e t al .) , t h e y m a y n o t b e w e l l m a t c h e d t o G A D .
I n d e e d , t he l o w c a p a c i t y f o r g e n e r a t i o n o f f e a r i m a g e r y i n G A D h a s b e e n
i n v o k e d t o e x p l a in t h e r a p y o u t c o m e d i f fe r e n c e s b e t w e e n G A D a n d o t h e r a n x -
i e t y d i s o r d e r s s u c h a s s p e c i f i c p h o b i a s , i n w h i c h v i v i d f e a r i m a g e s a r e m o r e
r e a d i l y p r o d u c e d ( L a n g , L e v i n , M i l l e r , & K o z a k , 1 9 8 3 ) . T h e f a c t t h a t t h e
e f f e c t s iz e s r e p o r t e d h e r e a r e t w o t o t h r e e t im e s g r e a t e r t h a n t h o s e r e p o r t e d i n
B e c k e r e t a l . l e n d s f u r t h e r s u p p o r t t o th e s e n o t i o n s .
T h i s r e a s o n i n g is c o n s i s t e n t w i t h t h e fi n d i n g o f a n e x p l i c i t m e m o r y b i a s i n
G A D i n d i v i d u a l s w h o d i s p l a y a l e f t - h e m i s p h e r i c b ia s ( O t t o e t a l ., 1 9 9 4 ) . T h e
l e f t c e r e b r a l h e m i s p h e r e is g e n e r a ll y d o m i n a n t f o r l an g u a g e a n d v e r b a l m e m -o r y , a n d t h e r ig h t h e m i s p h e r e f o r i m a g e r y a n d n o n v e r b a l m e m o r y ( B r a d s h a w ,
1 9 8 9 ; B r y d e n & L e y , 1 98 3 ; K o l b & W h i s h a w , 1 9 9 0 ). H e n c e , a m e m o r y b i as
i n v o l v i n g v e r b a l m a t e r i a l i s m o r e l i k e l y t o a p p e a r i n l e f t - d o m i n a n t i n d i v i d u -
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MEMORY BIAS IN G ENE RAL IZE D ANXIETY DISORDER 753
a l s . I n f a c t , t h e c h a r a c t e r i s t i c w o r r y o f G A D i s m a r k e d b y l e f t f r o n t a l h e m i -
spher ic ac t i va t ion (B orkovec e t a l ., 1998). T hus , bo th t he cen t ra l ne rvous sys t em
and i n fo rmat ion p roces s ing cha rac t e r i s t i c s o f GAD under sco re t he po t en t i a l
i n a p p r o p r i a t e n e s s o f i m a g e r y t a s k s f o r t h e d e t e c t i o n o f m e m o r y b i a s e s i n th i sd i so rde r .
P h y s i o l o g i c a l a r o u s a l h a s b e e n i n v o k e d l o o s e l y i n c a u s a l s p e c u l a t io n s o f
m e m o r y d i f f e re n c e s b e t w e e n p a n i c a n d G A D ( B e c k e r e t a l. , 1 9 9 9) . H o w e v e r ,
a m o d e l t h a t c a n m o r e s p e c i f ic a l l y r e l a te i n f o r m a t i o n p r o c e s s i n g t o p h y s i o -
l o g ic a l r e s p o n d i n g m a y b e m o r e u s e f u l th a n g l o b a l , n o n s p e c i fi c d e p ic t io n s o f
p h y s i o l o g i c a l a r o u s a l . T h e f o r m e r a p p r o a c h w a s t a k e n i n o u r i n v e s t i g a t i o n
( f r o m w h i c h t h e p r e s e n t d a t a w e r e o b t a i n e d ) o f p h a s i c h e a r t r at e ( H R )
r e s p o n s e s t o r e p e a t e d p r e s e n t a t io n o f t h r e a t w o r d s i n G A D ( T h a y e r e t a l ., i n
p r e s s) . In t h a t r e p o r t , t h e G A D g r o u p d e v e l o p e d a c o n d i t i o n e d H R d e c e l e r a -
t i o n i n a n t i c i p a t i o n o f t h r e a t w o r d s , a p h y s i o l o g i c a l c h a n g e t h a t s u g g e s t s
f a c i l it a t io n o f s ti m u l u s i n t a k e ( B o h l i n & K j e l b e r g , 1 9 7 9 ). F u r t h e r m o r e , t h e s e
i n d i v i d u a l s a l s o e x h i b i te d a H R a c c e l e r a t i o n i n r e s p o n s e t o t h e th r e a t w o r d s ,
w h i c h , i n a c c o r d w i t h m o d e l s t h a t l i n k i n c r e a s e d a d r e n e r g i c a c t i v i t y w i t h
e n h a n c e d m e m o r y , m i g h t ha v e i m p r o v e d s ti m u lu s r e te n ti o n ( M c G a u g h ,
1 9 9 2 ). T h e a d a p t i v e v a l u e o f th i s m e c h a n i s m p r e s u m a b l y e n t a i l s th e s e l e c t iv e
r e c a l l o f s a l i e n t e m o t i o n a l e v e n t s , s u c h a s a t h r e a t e n i n g e n c o u n t e r . I n G A D ,
d e f e n s i v e c o g n i t i v e o p e r a t i o n s o c c u r a t m u l t i p l e s t a g e s o f i n f o r m a t i o n p r o -
c e s s in g : T h e r e i s a p r e -a t t e n ti v e b i a s t o w a r d d e t e c t i o n o f th r e a t e n i n g s t im u l i
a n d e x c e s s i v e r u m i n a t i o n o f s t o r ed t h r e a t i n f o rm a t i o n . T h is c o m b i n a t i o n m a ya c c o u n t f o r t he c o n v e r g e n t f in d i n g s o f a n i m p l i c it m e m o r y b i a s in G A D ( se e
B ecker e t a l . , 1999 ; Wi l l i ams e t a l . , 1997 , fo r r ev i ews ) , a s we l l a s pos i t i ve
f in d i n g s o f a n e x p l i c it m e m o r y b i a s i n G A D u n d e r c e r t a in c o n d i ti o n s .
I t h a s a l s o b e e n s u g g e s t e d t h a t t h e p r o c e s s i n g o f e m o t i o n a l s t i m u l i is p r i-
m a r i l y m o d e r a t e d b y p r e - i n t e n t i o n a l , a u t o m a t i c m e c h a n i s m s ( L i b k u m a n ,
N i c h o l s - W h i t e h e a d , G r i f f i th , & T h o m a s , 1 9 9 9 ). S t i m u l u s o r i e n t i n g , w i t h
a c c o m p a n y i n g H R d e c e l e r a ti o n , o c c u r s a t t h is e a r l y s t a g e o f i n f o r m a t i o n pr o -
c e s s i n g . T h i s r e s p o n s e i s in d i c a t i v e o f e n h a n c e d a t t e n t io n t o e x t e r n a l s t i m u l i ,
w h i c h m a y i n tu r n e l i c it g r e a t e r in t a k e o f p e r i p h e r a l c u e s , a n o t i o n t h a t i s c o n -
s i s t e n t w i t h t h e h y p e r v i g i l a n c e a n d c h a r a c t e r i s t i c s c a n n i n g o f t h e e n v i r o n -
m e n t f o r th r e a t c u e s t h a t i s a s s o c ia t e d w i t h a n x i e t y ( M a t h e w s , 1 9 9 0) . V i e w e d
a s s u c h , t h e e n h a n c e d r e t e n t i o n o f t h r e a t i n f o r m a t i o n in a n x i e t y is e s s e n t i a l l y
a n e n c o d i n g , r a t h e r t h a n r e h e a r s a l o r e l a b o r a t i o n , p h e n o m e n o n ( L i b k u m a n e t
a l .) . The H R acce l e ra t i on i n response t o th rea t words , obse rved i n G A D sub j ec ts
i n Th aye r e t a l . ( in p res s ) , l i ke ly r e f lec t s a de fens ive r e sponse , r a t he r t han cogn i -
t ive e l abo ra t i on , t ha t fu r t he r improv es r e t en t i on v i a e m ot iona l a rousa l .
I n s u m , a l t h o u g h t h e d a t a o n e x p l i c i t r e c a l l b ia s e s i n a n x i e t y r e m a i n " d i f f i-
c u l t to c h a r a c t e r i s e " ( W i l li a m s e t a l ., 1 9 9 7, p . 2 8 6 ) , i t s e e m s p r e m a t u r e a t th i s
j u n c t u r e t o d i s m i s s o u t o f h a n d s u c h a b i a s . R a t h e r , s u c h t e n d e n c i e s c a n b eo b s e r v e d i n c e r t a i n s i tu a t i o n s ( e .g . , e x t e n d e d s t i m u l u s e x p o s u r e t i m e s ) a n d i n
i n d i v i d u a l s w i t h p a r t i c u l a r d i s t i n g u i s h i n g f e a t u r e s ( e . g . , l e f t - h e m i s p h e r e
d o m i n a n c e ) . T h e p a r a m e t e r s o f t h e s e t e n d e n c i e s s h o u l d b e p u r s u e d f u r t h e r
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75 4 FRIED MA N ET A L.
through employment of var ious types and combinat ions of l earning and
m emo ry tasks rather than with f ixed procedures that may yie ld cons is tency
across s tudies but occ lude a com prehens ive depic t ion of G A D . I t a l so may b e
rash to chal lenge broadly influential cognitive models of memory in anxiety(e .g . , Beck , Em ery, & Greenberg, 198 5; Bow er , 1981 ; W ill iams e t a l . ; c f .
Be cke r et al. , 1999, p. 16 2) based on a narrowly defined m emory methodology.
Ad dit ional ly , the concurrent assessment of phys io log ical data wi th spec i f ic
theoretical l inks to information processing, such as phasic cardiac responding
(e.g. , Thayer et al. , 2000) or HR variability (Friedman & Thayer, 1998; Lyon-
fie lds et al . , 1995; Thayer et al . , 1996) may a l low fo r the precise mapping of
somatic activity to cognitive phenomena. This approach is l ikely to be more
fruit fu l t ha n inc lus ion o f nonsp ec i f ic , g lobal measures of ph ys io logical
arousal , a dated paradigm that has been cons istently refuted in psy cho ph ysio-
logical research (Lacey, 1967; Venables, 1984; Wolf, 1995). Ultimately,
methodological diversity coupled with an appreciation of the psychophysio-
log ic a l c om p le x i t ie s o f G AD wi l l h e lp advan ce c ogn i t ive m o d e l s th at c an
account for a wide range of information processing phenomena in this and
other anxiety disorders.
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RECEIVED: January 3, 2000
ACCEPTED: May 1,2000