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Behaviour Research and Therapy 44 (2006) 1017–1028 www.elsevier.com/locate/brat
a,
b
a
a a
Department of Psychology, Ghent University, Henri Dunantlaan 2, B-9000 Ghent, Belgium b
R.G.C. Zeeuws-Vlaanderen, Emergis Centre for Mental Health, Wielingenlaan 2, NL-4535 PA Terneuzen, The Netherlands
Received 29 November 2004; received in revised form 14 July 2005; accepted 8 August 2005
Abstract
The cognitive behavioural model of depression holds that negative cognitions related to the self have etiological importance for the maintenance and relapse of depression. This has been confirmed by research using questionnaires.
Recent research using the Implicit Association Test, however, showed positive implicit self-esteem in formerly depressed participants, even after negative mood induction [Gemar, Segal, Sagrati, & Kennedy (2001). Mood-induced changes on the implicit association test in recovered depressed patients.
Journal of Abnormal Psychology , 110 , 282–289]. These results are not in line with cognitive theory of depression. Since this could be an artifact of the specific procedure that was used, we investigated implicit self-esteem of currently depressed participants and healthy controls using three different paradigms:
The Implicit Association Test, the Name Letter Preference Task, and the Extrinsic Affective Simon Task. The results of the three experiments are unequivocally indicative of positive implicit self-esteem in currently depressed patients. However, it remains an intriguing question what exactly these indirect measures assess.
r 2005 Elsevier Ltd. All rights reserved.
Keywords: Depression; Self-esteem; Implicit; Cognitive behavioural model
Introduction
Many researchers from different theoretical orientations such as Freud (1961) , Maslow (1954) , and more recently Baumeister and Leary (1995) consider the desire to view the self positively and the human need for esteem as an important universal aspect of well being. This general idea is supported by different kinds of research, showing that people tend to make self-serving attributions ( Zuckerman, 1979 ), use self-enhancing and self-presentational strategies ( Jones, 1991 ) and make self-serving assessments of ability ( Dunning,
Meyerowitz, & Holzberg, 1989 ).
In cognitive theories of depression, however, the self-concept is considered to be biased in a negative way
(e.g., Beck, Rush, Shaw, & Emery, 1979 ; Clark, Beck, & Alford, 1999 ). In comparison with the idea of inaccurately positive illusions and esteem-enhancing biases in healthy people, depressed people would have
Corresponding author. Tel.: +0032 9 264 64 47; fax: +0032 9 264 64 89.
E-mail address: Rudi.DeRaedt@UGent.be (R. De Raedt).
0005-7967/$ - see front matter r 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.brat.2005.08.003

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R. De Raedt et al. / Behaviour Research and Therapy 44 (2006) 1017–1028 1018 inaccurately negative self-cognitions. Reviewing the literature on this topic, Haaga, Dyck, and Ernst (1991) concluded that the thinking of depressed patients is more negatively biased as compared to absolute standards of objective reality and that increased negative thinking about the self is a central feature of depression.
Indeed, cognitive distortions such as enhanced negative thinking and increased accessibility to negative information have been reported frequently as a core cognitive style observed during depression ( Williams,
Watts, MacLeod, & Mathews, 1997 ). Within the cognitive research tradition, the existence of negative selfrelated dysfunctional schemata is emphasised to explain maintenance and vulnerability for future episodes of depression ( Williams, 1997 ). Using questionnaires, it has already been thoroughly demonstrated that depressive people think negatively and report lower self-esteem than nondepressed controls (see: Ingram,
Miranda, & Segal, 1998 , for a review). However, this research uses explicit self-report measures and is therefore susceptible to bias and one could even doubt whether meaningful results concerning the underlying self-schemata can be achieved in this way. First, self-reporting may be influenced by demand characteristics, social desirability, and self-presentation. Second, within cognitive models of depression it is assumed that the crucial schemata are not always consciously accessible and thus cannot be reported ( Beck et al., 1979 ; Young,
1994 ). They are considered primary cognitive processes that are automatically activated but which escape reflection and logical reasoning ( Clark et al., 1999 ). For this reason, a distinction is drawn between the underlying schema processes that are not accessible and the products of such processes that are accessible within the conscious mind as opinions, inferences and interpretations ( Ingram & Wisnicki, 1991 ).
Recently, new paradigms have been developed that could provide a satisfactory means of evaluating the underlying schema-processes related to self-esteem. These paradigms measure so-called ‘‘implicit self-esteem’’ which can be defined as an automatic evaluation of the self ( Greenwald & Banaji, 1995 ). Since a basic feature of the concept of implicit self-esteem is its automatic nature, it must be measured indirectly and by means of a procedure that is relatively free of influence of self-representational processes ( Bosson, Swann, & Pennebaker,
2000 ). Recent research suggests that automatic and controlled self-evaluations stem from different sources and should be seen as different constructs ( Rudman, 2004 ).
The currently available experimental paradigms to evaluate implicit self-esteem are mainly based on the assumption that people assign value to objects that are associated with the self, and that attitudes can be activated automatically upon confrontation with attitude-objects. One of the earliest methods to evaluate implicit self-esteem that has been widely used is the Name Letter Preference Task (NLPT). This task is based on the assumption that the initials of one’s own name are closely associated with the self and that an assessment of how well people like their initials relative to other letters reflects their implicit attitudes toward the self ( Nuttin, 1985 ). Because people are not necessarily aware of the logic behind the task, their attitudes towards their own initials can be interpreted as an implicit index of self-esteem (see Greenwald & Banaji,
1995 ). In a recent study, Koole, Dijksterhuis, and van Knippenberg (2001) found that the positive bias for name letters became smaller when participants were asked to respond in a deliberative way. Moreover, Koole et al. could demonstrate that implicit self-evaluations corresponded with explicit self-evaluations only when participants made the explicit ratings very quickly or when under cognitive load. These findings support the idea that implicit self-esteem as measured by the NLPT is driven by automatic self-evaluations.
A second measure that has gained an enormous amount of interest during the last few years is the Implicit
Association Test (IAT) ( Greenwald & Farnham, 2000 ; Greenwald, McGhee, & Schwartz, 1998 ). During a prototypical self-esteem IAT, participants are asked to categorize words that appear in the middle of a computer screen as referring to ‘‘me’’ (e.g., own name) ‘‘not-me’’ (e.g., other name), ‘‘negative’’ (e.g., evil) or
‘‘positive’’ (e.g., happy) by pressing one of two keys. During one block of trials, the same key is pressed for
‘‘me’’ and ‘‘negative’’ words and the other key for ‘‘not-me’’ and ‘‘positive’’ words. The reaction times (RTs) during this block are compared to those of another block of trials during which the same key is used for ‘‘me’’ and ‘‘positive’’ words and the other key for ‘‘not-me’’ and ‘‘negative’’ words. Previous research demonstrated that healthy people categorize words significantly faster when the same response is required for self and positive words as compared to the task during which self and negative words require the same response, which is indicative of a positive implicit self-esteem (e.g.
Greenwald & Farnham, 2000 ).
Recently, De Houwer (2003) developed the Extrinsic Affective Simon Task (EAST), a modified version of the IAT based on a comparison of performance on trials within a single task rather than on a comparison of performance on two different tasks. During the first phase of a self-esteem EAST, positive and negative white

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R. De Raedt et al. / Behaviour Research and Therapy 44 (2006) 1017–1028 1019 words appear in the middle of a computer screen and participants have to use one key for the positive words and the other key for negative words. In this way, the keys become extrinsically associated with a negative or a positive valence. During the second phase, coloured words are displayed that are either self-relevant or selfirrelevant. All these words can either be blue or green. The subject is asked to react only on the basis of the colour of the word (e.g. blue ¼ press left, green ¼ press right). After these two preparatory phases, both white and coloured words are displayed in random order. Albeit irrelevant for the execution of the task, it has been found in an experiment with undergraduate students that the meaning of the coloured words does have an influence on reaction speed and accuracy ( De Houwer, 2003 ). On trials where the coloured word was selfrelevant, performance was superior when the correct response was assigned to the positive key. The reverse was true on trials where the coloured words were self-irrelevant.
Although (implicit) self-esteem is thought to play a crucial role in depression, at this moment, research that evaluates implicit self-esteem in depressed individuals is extremely limited. The only study we are aware of was conducted by Gemar, Segal, Sagrati, and Kennedy (2001) . They used the self-esteem IAT to examine mood related changes in implicit and explicit self-esteem in formerly depressed people and never depressed controls.
After negative mood induction, the formerly depressed group showed both a larger drop in implicit and explicit self-esteem relative to controls, but the two measures (explicit and implicit) were not associated.
However, a closer inspection of the data reveals that both the formerly depressed group and the never depressed controls showed a positive implicit self-esteem, before as well as after mood induction. Moreover, the pre–post mood induction difference scores observed by Gemar and colleagues were, in fact, due to higher implicit self-esteem in the formerly depressed participants before mood induction: the magnitude of the remaining positive bias score after mood induction was apparently not different between the formerly depressed population and the controls. Interestingly, the authors mention that the implicit self-esteem scores shown by the formerly depressed after mood induction was not significantly different from that found in a group of currently depressed patients.
These results suggest that implicit self-esteem remains positively biased in depressed participants, which is not in line with the existence of negative self-schema processes as postulated by the cognitive theory of depression. However, since these findings might be an artifact of the specific procedure that was used, the question remains whether or not implicit self-esteem remains positive in depressed patients. Therefore, we tested implicit self-esteem using a different version of the self-esteem IAT and two other implicit measures. In our IAT version, we used labels that are more specific for the cognitive model of depression. In two subsequent studies, we used the NLPT and the EAST as measures of implicit self-esteem. Moreover, a matched nondepressed control group was used to investigate if the magnitude of implicit self-esteem differs between depressed and nondepressed participants.
Study 1: method
Participants
The healthy control sample consisted of 15 staff members (11 women and 4 men) of a general hospital. They were screened for the absence of any depressive disorder using a structured clinical interview for DSM-IV axis
1 disorders (Mini International Neuropsychiatric Interview, Dutch translation by Overbeek, Schruers, &
Griez, 1999 ). They were between 21 and 59 years old ( M ¼ 42
:
6, SD ¼ 12.1), had Beck Depression Inventory
(BDI) scores between 0 and 11 ( M ¼ 2
:
7, SD ¼ 2.7) and their Hamilton Rating Scale for Depression (HRSD) score ranged between 0 and 3 ( M ¼ 0
:
7, SD ¼ 0.9).
The clinical sample consisted of 15 inpatients (11 women and 4 men). They were all referred to the psychiatry department of a general hospital specialized (specialized reference centre for depression) because of depressive symptoms. Patients were included when they met diagnostic criteria for major depressive disorder, according to a clinical interview for DSM-IV axis 1 disorders. They ranged in age from 30 to 62 years
( M ¼ 45
:
3, SD ¼ 8.5). Their score on the BDI ranged between 30 and 49 ( M ¼ 37
:
5, SD ¼ 4.9) and their
HRSD score ranged between 18 and 31 ( M ¼ 22
:
9, SD ¼ 4.4).
Controls and depressed patients did not differ significantly in age, F o
1.

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Materials
Measure of depressive symptoms
A Dutch translation of the BDI by Bouman, Luteijn, Albersnagel, and van der Ploeg (1985) was used to assess depressive symptoms. The questionnaire consists of 21 items designed to measure presence and severity of depressive symptomatology. Each item consists of four expressions in terms of increasing intensity followed by a score number (0-1-2-3), with total scores ranging from 0 to 63.
The HRSD (Dutch translation of the semi-structured interview of Williams, 1988 ) was administered before the start of the study. This measure of severity of depressive symptoms covers a wide range of affective, behavioural, and somatic symptoms. The interview consists of 17 items that have to be rated by a clinician on
5-point and 3-point scales (0-1-2-3-4 and 0-1-2), with total scores ranging from 0 to 52.
Both instruments are commonly regarded as good measures of depression and are extensively used in research and clinical practice, also in the Dutch versions ( Albersnagel, Emmelkamp, & Van Den Hoofdakker,
1989 ).
Implicit self-esteem measure
During the IAT, words related to ‘‘self’’ or ‘‘not-self’’ appeared one by one in random order on a computer screen, as well as words related to ‘‘worth’’ and ‘‘worthlessness’’. The self-words were self-related words (i.e.
first name, surname, hometown and month of birth of the participant). The not-self words were the words used for the previous participant, insofar as they were different. If not, the not-self items were based on the participant before the previous one. The words related to worth were the Dutch words for the adjectives
‘‘capable’’ (bekwaam), ‘‘competent’’ (competent) and ‘‘good’’ (goed), the words related to worthlessness were the Dutch words for the adjectives ‘‘inferior’’ (minderwaardig), ‘‘failed’’ (mislukt) and ‘‘bad’’ (slecht). Due to a programming overlook, the control population received an IAT version with a slightly different set of words
(‘‘capable’’ (bekwaam), ‘‘competent’’ (competent), ‘‘loved’’ (geliefd), ‘‘successful (succesvol), ‘‘powerfull’’
(krachtig), ‘‘worth’’ (waardevol), ‘‘inferior’’ (minderwaardig), ‘‘failed’’ (mislukt), ‘‘worthless’’ (waardeloos),
‘‘weak’’ (zwak), ‘‘loser’’ (verliezer) and ‘‘stupid’’(dom).
The words were displayed in the centre of the screen in white ARIAL font 12 letters. The background colour of the computer screen was black. The Dutch names for the labels ‘‘me’’, ‘‘not-me’’, ‘‘worth’’ and
‘‘worthlessness’’ were displayed in black ARIAL font 24 capital letters (in a white bar 1.3 cm high) in the left and right corner of the screen. Participants responded using the Q and M keys on an AZERTY keyboard for left and right responses respectively. Participants were seated at a distance of approximately 50 cm from a 15 00 computer screen. The experiment was programmed in Inquisit Millisecond Software and was run on an IBM compatible PC.
Procedure
Participants took part individually. During informed consent, they were told that the experiment would be about the relationship between cognitive functioning and depression. Participants willing to volunteer in the experiment began with the HRSD and the BDI. Afterwards, the participants were informed about the IAT procedure and were given written instructions on the computer screen.
Participants were asked to categorize words by pressing one of two keys. The types of words that were assigned to the left or right key would vary from block to block. Before each block, participants would be informed on the computer screen about the key assignments. During the different blocks of trials, the categories assigned to the left and right key would be displayed in the top left and right corner of the screen, respectively. Participants were asked to respond as quickly but also as accurately as possible. Finally, they were told that the task would take about 10 min.
The experiment consisted of seven blocks. It started with one block of 24 practice trials with only ‘‘worth’’ and ‘‘worthlessness’’ adjectives and a second block of 24 practice trials during which only ‘‘self’’ and ‘‘not-self’’ words had to be categorized. Thereafter, a first data collection block of 48 trials was presented during which adjectives and self-items were randomly mixed in one list. After this block, participants started a second data collection block of 48 trials that was the same as the first data collection block except that the items were

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R. De Raedt et al. / Behaviour Research and Therapy 44 (2006) 1017–1028 1021 presented in different order. After these two data collection blocks, the right and left response keys used for the self and non-self words were swapped. Again, a practice block of 24 trials with self and not-self items was presented with this new key assignment. This practice block was followed by two data collection blocks of 48 trials using a mixed list of adjectives and me-items under this new key assignment. Whether participants started by pressing left or right for self-items was counterbalanced across participants but the response keys used for the worth/worthless categories were constant for each participant during the whole experiment. Each word was presented on the screen until a response was given. The response stimulus interval was 400 ms. If a response was incorrect, the word was immediately replaced by a red X that remained for 400 ms (the participants were informed about this procedure beforehand) and the next trial started 400 ms after the red X disappeared.
Results
Only RTs on data collection trials with correct responses were analysed (blocks 3, 4, 6, 7), discarding RTs of the first trial of each block. RTs below 300 ms and above 3000 ms were recoded to 300 and 3000 ms, respectively (see Greenwald et al., 1998 ). To reduce the skew associated with response latencies, RTs were logtransformed.
Thereafter, mean log-transformed RTs were calculated separately for both tasks: (a) the task during which one response was required for the self-items and adjectives referring to worth and the other response for notself-items and worthlessness adjectives and (b) the task during which one response was assigned to self-items and adjectives referring to worthlessness and the other response to not-self-items and worth adjectives.
A 2 (task: worth/self versus worthlessness/self) 2 (group: depressed versus control) mixed ANOVA on the mean log-transformed RTs as dependent variables yielded a highly significant effect for task, with faster RTs on the worth/self task as compared to the worthlessness/self task, F ð 1
;
28 Þ ¼ 108
:
56, p o
:
001, and a main effect for group with overall slower reactions for the depressed group, F ð 1
;
28 Þ ¼ 12
:
42, p ¼
:
001, but no interaction effect ( F o
1). For the depressed group, a paired t -test yielded a highly significant effect, t ð 14 Þ ¼ 7
:
72, p o
:
001, with faster RTs on the worth/self task compared to the worthlessness/self task. A similar effect was observed for the healthy control group, t ð 14 Þ ¼ 7
:
00, p o
:
001, also with faster RTs on the worth/self task versus the worthlessness/self task. Untransformed RTs are outlined in Table 1 .
Study 2: method
Participants
The control group consisted of 16 healthy persons (13 women and 3 men) (for the screening and selection procedure, see Experiment 1) ranging in age between 22 and 53 years ( M ¼ 37
:
2, SD ¼ 11.6). They had BDI scores between 0 and 9 (( M ¼ 2
:
9, SD ¼ 2.5) and HRSD scores between 0 and 7 ( M ¼ 1
:
2, SD ¼ 2.6).
The clinical sample consisted of 16 inpatients (13 women and 3 men) who were referred to the psychiatry department of a general hospital (specialized reference centre for depression) with depressive symptoms. All
Table 1
Mean untransformed IAT reaction time and standard deviations for the worth/self task and the worthlessness/self task as function of group in experiment 1
Task
Control
Worth/self Worthlessness/self
Depressed
Worth/self Worthlessness/self
M
857
SD
178
M
1216
SD
320
M
1170
SD
327
M
1656
SD
387

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R. De Raedt et al. / Behaviour Research and Therapy 44 (2006) 1017–1028 1022 patients met diagnostic criteria for major depressive disorders (for screening/selection, see Experiment 1).
Their age ranged from 26 to 63 years ( M ¼ 40
:
2, SD ¼ 10.5). Their score on the BDI ranged between 22 and
46 ( M ¼ 34
:
6, SD ¼ 7.3) and their HRSD score ranged between 18 and 38 ( M ¼ 25
:
5, SD ¼ 5.9).
Age was not significantly different between the depressed and the nondepressed, F o
1
Materials
Measure of depressive symptoms
See Experiment 1.
Implicit self-esteem measure
During a computer-administered version of the NLPT, the 26 letters of the alphabet were presented one by one in random order on a computer screen. They were displayed in the centre of the screen in grey letters of
7 mm high and 5 mm wide. The background colour of the computer screen was black. People were seated at a distance of approximately 50 cm from the 15 00 computer screen. Each letter was presented once with the text
‘‘how much do you like this letter’’ printed underneath. Under this text, a 9-point Likert scale was presented with at the left ‘‘not at all beautiful’’ and at the right ‘‘very beautiful’’. Participants responded by pressing the correspondent digit on the AZERTY keyboard. The experiment was programmed in Turbo Pascal 5.0
software and was run on an IBM compatible PC.
Procedure
Participants completed the experiment one by one. During informed consent, the participants were told that the experiment would be about the relationship between cognitive functioning and depression. Thereafter, participants willing to volunteer in the experiment underwent the HRSD and completed the BDI. Before the onset of the task, participants received information about the NLPT and were additionally given written instructions on the computer screen. It was explained that the task was about the esthetical evaluation of elementary stimuli, namely the letters of the alphabet. Moreover, it was stated that it might be rather unusual to assess how much one likes letters but that earlier research demonstrated certain relevance for the understanding of human emotions (see Koole et al., 2001 , for similar instructions). People were asked to rate how beautiful they found each letter of the alphabet by pressing the corresponding digit, from one (not at all beautiful) to nine (very beautiful). It was stated that it was very important to assign a value as an intuitive reaction.
Results
In preparing the data, we followed the guidelines of Koole et al. (2001) . For each participant, all 26 ratings were first Z -transformed based on the mean and the standard deviation of all ratings of that participant. In this way, the data were corrected for inter-individual differences in rating tendencies. Based on these Z transformed scores, a global baseline evaluation for each group (depressed and controls) was calculated for each letter. This was the mean evaluation for each letter of the alphabet based on the evaluations of the participants that did not have that letter in their name. For every participant, this baseline rating of the initials of their name was subtracted from the Z -transformed baseline rating for that letter. The name letter effect corresponded to the mean of the difference score for both initials.
Independent samples t -test failed to show a significantly different name letter effect for the depressive and the control group ( t o
1). Moreover, one-sample t -tests showed that the mean Z -transformed difference score was significantly different from zero for the depressive group, t ð 16 Þ ¼ 4
:
93, p o
:
001, M ¼ 0
:
47, SD ¼ 0.38, as well as for the control group, t ð 16 Þ ¼ 3
:
71
; p ¼
:
002, M ¼ 0
:
62, SD ¼ 0.66. This indicates that all the participants, depressives and controls, rated the initials of their name more positively compared to the participants who did not have those letters in their names.

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Study 3: method
Participants
Thirteen control participants (9 women and 4 men) volunteered to take part (for the selection and screening procedure, see Experiment 1). They were between 26 and 68 years old ( M ¼ 39
:
6, SD ¼ 14.5), their BDI scores ranged between 0 and 5 ( M ¼ 2
:
3, SD ¼ 1.8), and their HRSD scores between 0 and 3 ( M ¼ 0
:
7, SD ¼ 1.2).
Thirteen inpatients (9 women and 4 men) referred to the psychiatry department of a general hospital
(specialized reference centre for depression) with depressive symptoms participated in the experiment. They were all diagnosed with major depressive disorder (see Experiment 1 for the selection/screening criteria) ranging in age from 18 to 63 years ( M ¼ 38
:
2, SD ¼ 12.7). Their score on the BDI ranged between 16 and 46
( M ¼ 32
:
6, SD ¼ 9.9) and their HRSD score ranged between 20 and 38 ( M ¼ 26
:
4, SD ¼ 5.3).
The depressed patients did not differ significantly in age compared to the controls, F o
1.
Materials
Measure of depressive symptoms
See Experiment 1.
Implicit self-esteem measure
During the EAST, white and coloured words were presented randomly in the middle of the computer screen. The white words were the Dutch words for the negative adjectives ‘‘false’’ (vals), ‘‘hostile’’ (vijandig),
‘‘mean’’ (gemeen), ‘‘boring’’ (vervelend) and ‘‘hateful’’ (hatelijk), the positive adjectives were the Dutch words for ‘‘cheerful’’ (blij), ‘‘friendly’’ (vriendelijk), ‘‘good’’ (goed), ‘‘happy’’ (gelukkig) and ‘‘nice’’ (prettig). The coloured words were related to the self or words unrelated to the self. The self-word was the first name of the subject, the self-unrelated word was the first name of the previous participant, insofar this name differed from their own name. Otherwise, the first name of another participant was chosen. Other coloured words were
‘‘flowers’’ (bloemen), and ‘‘slime (slijm)’’ and the letter string ‘‘XXXXX’’. These other stimuli were included to replicate exactly the experiment described by De Houwer (2003) , but were not analysed since they were not relevant for the purpose of this experiment. All coloured words were presented in a blue or green colour. The blue colour was created by setting the red, blue, and green values in the Turbo Pascal program at 0, 38, and 46, respectively. The green colour was created by setting red on 0, blue on 46, and green on 38. In this way, the colours were quite similar and the participants had to focus their attention on the relevant colour feature in order to make correct responses. The words were displayed on a black background. Letters were
7 mm high and 5 mm wide. The Q and M keys of an AZERTY keyboard were used for left and right responses, respectively. The participants were seated at a distance of approximately 50 cm from a 15 00 computer screen. The experiment was programmed in Turbo Pascal 5.0 software and implemented on an IBM compatible PC.
Procedure
Participants were tested one by one. They were told that the experiment would investigate the relation between cognitive functioning and depression. Participants who volunteered to participate after informed consent underwent the HDRS interview and completed the BDI. After that, the participants were informed about the EAST procedure and were given instructions on the computer screen. They were asked to classify words by pressing a positive key or a negative key, depending on the meaning or the colour of the word. If the word was white, the meaning of the word was the response relevant feature (negative key Q for negative adjectives and positive key M for positive adjectives), if the word was coloured, they were asked to press the positive or the negative key based on the colour of the word. Participants were asked to respond as quickly but also as accurately as possible and were informed about the different blocks that would appear during the experiment. Finally, they were told that the task would take about 15 min. Instructions about which keys were assigned to which stimulus were given on the computer screen before each block. Half of the participants were

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R. De Raedt et al. / Behaviour Research and Therapy 44 (2006) 1017–1028 1024 asked to push the positive key if the word was printed in a green colour and the negative key if the colour of the word was blue. The other participants received instructions for reversed colour-response assignments.
The experiment started with a practice block of 20 trials with only white words and a practice block of 20 trials with only coloured words. Thereafter, six experimental blocks of 30 trials were presented, during which each of the five coloured words was presented four times, twice in each colour, and each of the 10 white words was presented once. In all blocks, stimuli were presented in random order, with the restriction that the same word could not be presented on two or more consecutive trials and that the required response could not be the same on four or more consecutive trials. Each trial consisted of the same sequence of events: A white fixation cross for 500 ms, followed by the word until the correct response was given. The inter-trial interval was
1500 ms. If an incorrect response was made, a red cross appeared under the word and both word and a cross remained on the screen until a correct response was made (the participants were informed about this procedure beforehand).
Results
Only RTs of correct responses on coloured me and not-me data collection trials were analysed. In line with De Houwer (2003) , RTs below 300 ms and above 3000 ms were recoded to 300 and 3000 ms, respectively. RTs were log-transformed to reduce the skew associated with response latencies but untransformed RTs can be found in Table 2 . Thereafter, mean log-transformed RTs were calculated separately for (a) trials on which a self-item was presented and an extrinsically positive response was required
(i.e., the response assigned to the key that was also required for positive white words), (b) trials on which a self-item was presented and an extrinsically negative response was required (i.e., the response assigned to the key that was also required for negative white words), (c) trials on which a not-self item was presented and an extrinsically positive response was required, and (d) trials on which a not-self item was presented and an extrinsically negative response was required. We created two bias-scores: one for the ‘‘self’’ category by subtracting self-positive (a) from self-negative (b), and one for the ‘‘not-self’’ category by subtracting not-selfpositive (c) from not-self-negative (d). A positive bias score refers thus to positive esteem for self or not-self, respectively.
These mean log-transformed bias scores were analysed using a 2 (identity: self versus not-self) 2 (group: clinical versus control) mixed ANOVA. A significant main effect was observed for identity, with higher biasscores for self as compared to not-self, F ð 1
;
24 Þ ¼ 6
:
66, p ¼ and ‘‘group’’ reached significance, F ð 1
;
24 Þ ¼ 6
:
17, p ¼
:
02.
:
02. Moreover, the interaction between ‘‘identity’’
To test our hypotheses in more detail, this interaction effect was further analysed by two independent t tests. The bias score for self was higher for depressed patients as compared to the control sample, t ð 24 Þ ¼ 2
:
26, p ¼
:
03, which means that depressed patients showed higher implicit self-esteem. For the not-self bias score, no significant difference between the clinical and the control sample emerged, t ¼ 1
:
13.
Table 2
Mean untransformed EAST reaction time and standard deviations in ms on target stimulus trials as function of group, extrinsic response valence and stimulus category in experiment 3
Target stimulus Extrinsic response valence
Control
Pos Neg
Depressed
Pos Neg
Self
Not-self
M
838
882
SD
222
240
M
809
853
SD
177
198
M
956
1017
SD
273
355
M
1101
916
SD
341
230

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Moreover, for the depressed participants, responses to coloured self-items were made faster when an extrinsically positive response was required as compared to when an extrinsically negative response was required, as reflected by a significant one sample t -test on the self bias score, t ð 12 Þ ¼ 2
:
24, p ¼
:
045.
Furthermore, these participants tended to respond faster when an extrinsically negative response was required for not-self items, as compared to when an extrinsically positive response was required, but this effect was only marginally significant, t ð 12 Þ ¼ 2
:
04, p ¼ significantly from zero ( t’ s o
1).
:
065. The bias scores of the control participants did not differ
General discussion
We investigated implicit self-esteem in currently depressed patients and nondepressed controls. When the
IAT was used to measure implicit self-esteem (Experiment 1), RTs were shorter when the same response was required for the self-words and adjectives referring to worth than when the same response was required for the self-words and worthlessness words. Depressed patients and nondepressed controls matched for age and gender showed the same pattern. In the NLPT (Experiment 2), depressed participants rated the initials of their name more positive as compared to participants who did not have these letters in their names, just as the matched nondepressed controls did. An EAST measure of implicit self-esteem (Experiment 3) also provided evidence of positive self-esteem, even when such evidence was not found in healthy controls. For depressed patients, responses to coloured self-items were faster when an extrinsically positive response was required as compared to when an extrinsically negative response was required. The results of the three experiments are unequivocally indicative of a positively biased implicit self-esteem in currently depressed patients, similar (IAT and NLPT) or higher (EAST) than in nondepressed people.
The fact that we found a positive bias in nondepressed people is in line with a large literature demonstrating a positive bias in implicit self-esteem in healthy people over many different western countries ( Greenwald et al., 2002 ) and our findings of a lack of difference between depressed and nondepressed people are in line with the data of Gemar et al. (2001) , who found apparently no differences in implicit self-esteem between formerly depressed participants after mood induction and controls before mood induction (although they do not mention it in their paper). Since these authors mention that their currently depressed group did not differ from the formerly depressed after mood induction, this would mean that the controls and the currently depressed patients did also not differ substantially in implicit self-esteem.
Although these findings are surprising from the perspective of cognitive theories of depression, they do fit with certain existing findings in the literature. For instance, it has already been shown that the self-schemata of depressed people do not lack positive content. Former research found indications for self-schemata with mixed positive and negative content in depressed individuals ( Dozois & Dobson, 2001 ; Greenberg & Alloy, 1989 ), but the way in which positive content is activated, processed and organized might differentiate depressed from nondepressed people ( Dozois & Dobson, 2001 ). Since low self-esteem is a robust finding using questionnaires, this would imply that implicit tasks measure a construct that is different from self-report measures. This brings us to the following question: What exactly do these indirect measures assess? One possibility is that they evaluate the self through the automatic activation of latent positive self-related schemata. It is indeed a striking finding that implicit self-esteem measures do often not correlate well with explicit measures (e.g.,
Bosson et al., 2000 ; Greenwald & Banaji, 1995 ) and both types of self-esteem measures seem to predict different variables. As compared to measures of explicit self-esteem, implicit self-esteem measures were more accurate in predicting spontaneous and affective behaviour, such as nonverbal signs of anxiety and negative mood in reaction to ego-threatening feedback ( Hetts & Pelham, 2001 ). Hetts and Pelham suggested that this independence would be related to different learning processes for both forms of self-esteem. Explicit selfevaluations would rely on conscious strategic processes, while implicit self-evaluations would have been learned by automatic processes such a classical evaluative conditioning and implicit learning ( Berry & Dienes,
1993 ). This is in line with the idea that self-schemata develop during childhood as a result of emotional experiences that become represented in mental codes, and automatic self-evaluations based on early selfevaluations are generally positive ( Paulhus, 1993 ). Repeated activation may render these early positive selfevaluations an integral part of the ‘‘automatic’’ self, consisting of well practiced and at the end, mostly chronically activated positive self-evaluations ( Paulhus, 1993 ). Later in life, people might experience situations

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Greenwald and Banaji (1995) have also argued that automated implicit attitudes stem from past and largely forgotten experiences whereas explicit attitudes might reflect recent and more accessible events. This idea has already been confirmed by recent research of Rudman and
Heppen (in Rudman, 2004 ), who observed that people raised primarily by their mothers preferred women to men when measured implicitly, whereas explicit attitudes towards gender were not related to early parenting.
The fact that early experiences are biased towards self-esteem enhancing mechanisms is underpinned by developmental trends. Young children’s self-evaluations are characterized by a preference for positive feedback ( Swann & Schroeder, 1995 ), such as preferential orienting to voices that sound accepting ( Fernald,
1993 ), which might be favourable in an evolutionary perspective.
Since it is compelling to conclude that the implicit measures would tap remaining underlying early positive schemata in depressed patients, it would be interesting to assess different populations of depressed patients with different co-morbid disorders. As suggested by Young (1994) , patients with co-morbid borderline personality disorder might be the ones with deeply rooted negative self-schemata developed during childhood, while in depressed patients without these features the self would be less affected.
From another perspective, Roberts and Monroe (1994) also highlight that the nature of vulnerable self-esteem is considerably more complex than the simple dichotomies (i.e., high versus low self-esteem) and that other dimensions of self-esteem, such as stability of self-esteem, might be more causally related to depression. Research already indicated that higher implicit than explicit self-esteem was associated with unstable explicit self-esteem whereas higher explicit as compared to implicit self-esteem was related to stable explicit self-esteem (Smith, 2000, in Bosson et al., 2000 ). Moreover, since recent theory and research suggests that unstable self-esteem might be more causally related to vulnerability to depression as compared trait level of self-esteem ( Roberts, Kassel, & Gotlib, 1995 ; Roberts & Monroe, 1992, 1994 ), measuring implicit self-esteem in combination with measures of self-esteem stability might be another challenge for further research.
It can be considered as a drawback of the studies that we did not include an explicit standard measure of self-esteem. In future research it would be useful to directly compare implicit and explicit self-esteem in the same sample.
Although the adjectives (exemplars) used in the IAT study were not exactly the same for the depressed subjects and the controls, research has revealed (e.g.
De Houwer, 2001 ) that IAT effects reflect mainly attitudes toward the target concepts (that were the same for both populations in our experiment) rather that attitudes toward the individual exemplars of those concepts. This suggests that the procedural lapse by which the exemplars were different for both groups in our study did not compromise our results.
Another important consideration is the possibility that we found no differences in implicit self-esteem between depressed and nondepressed people due to a lack of statistical power. The sample sizes of our groups were indeed small but based on cognitive theory we would expect very large differences between depressed and nondepressed groups. Moreover, in the EAST study (with the smallest sample size) implicit self-esteem was even significantly higher in the depressed group compared to the controls. The findings of a significant positive self-esteem in depressed patients despite the small sample size are also indicative for the robustness of the results. Moreover, although implicit measures might also reflect aspects that are more method-based than process-based ( Bosson et al., 2000 ) the fact that we found these surprising results in three studies based on different methodologies and designs suggests that these results reflect a certain concept that is not fully affected by current depression.
Therefore our results and results of future similar research based on implicit measures of self-esteem might challenge the traditional widespread practice to evaluate only the conscious product of underlying processes regarding self-esteem. In future research, it will be important to use different methodologies to evaluate selfesteem, and we need prospective studies comparing depressed patients in remission with controls to explore if the observed positive implicit self-esteem is state or trait dependent. Since the causal link between self-esteem and depression is currently a basic feature of the cognitive behavioural model of depression, it might be important to further illuminate different aspects of self-esteem.

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