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Concurrent validity of the German version of S.B. Eysenck’s impulsiveness questionnaire for children
Personality and Individual Differences 35 (2003) 51–58 www.elsevier.com/locate/paid
Concurrent validity of the German version of S.B. Eysenck’s impulsiveness questionnaire for children Christina Stadlera,*, Wilhelm Jankeb a
Klinik fu¨r Psychiatrie und Psychotherapie des Kindes- und Jugendalters, Klinikum der Johann-Goethe Universita¨t, 60528 Frankfurt am Main, Germany b Lehrstuhl fu¨r Biologische und Klinische Psychologie, Julius-Maximilians-Universita¨t, Wu¨rzburg, Germany Received 26 November 2001; received in revised form 24 April 2002; accepted 13 May 2002
Abstract This study examined whether the German adaptation (IVE) of the I6 Impulsiveness Questionnaire from Eysenck, Easting, and Pearson (1984) is a sufficiently valid instrument to assess impulsivity in school-aged children. Concurrent validity was investigated within a well established laboratory test developed in accordance with a task used by Newman Wallace, Schmitt, and Arnett (1997). Children aged 9–11 years were administered a go/nogo paradigm assessing the ability to inhibit ongoing behaviour (passive avoidance) in order to avoid punishment and nonreward. Results clearly indicate that children who score high on impulsiveness are more impulsive in the used laboratory task than non-impulsive children. # 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction Eysenck, Easting, and Pearson (1984) developed the I6 Impulsiveness Questionnaire for children that was designed to assess impulsiveness reflecting poor behavioural control and lack of ability to delay gratification, venturesomeness reflecting sensation-seeking and risk-taking behaviour as well as sociability and empathy reflecting sensitivity to feelings and reactions of others and susceptibility to social cues. The child and adolescent version of this self-report has gone through several revisions. The I6 — the most recent version (Eysenck et al., 1984) is a self-report inventory consisting of 23 yes–no items, which are face-valid measures of impulsiveness (e.g. ‘‘Do you often get into a jam because you do things without thinking?’’). The number of responses
* Corresponding author. Tel.: +69-6301-5995; fax: +69-6301-5843. E-mail address: [email protected] (C. Stadler). 0191-8869/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved. PII: S0191-8869(02)00139-3
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C. Stadler, W. Janke / Personality and Individual Differences 35 (2003) 51–58
indicative of impulsiveness are summed to provide a total score. The scale discriminates conductdisordered children from controls and is predictive of future conduct problems (Luengo, Carrillode-la-Pena, Otero, & Romero, 1994). It was originally constructed to assess British subjects, but was adapted for American English (e.g. White et al., 1994) and translated into Spanish (Silva, Martorell, & Clemente, 1987). This self-report questionnaire was also translated into German (Stadler, 2000). On the basis of factor analyses, using principal-components methods and using three factors, several changes in the final scoring key were considered necessary, so the final scales chosen comprised 16 items for each scale and, therefore a total of 48 items. The psychometric data of the German version, tested on 392 children aged 8–15, which is shorter than the English version, is as good or slightly better. Cronbach’s coefficient for the impulsiveness subscale was 0.80 in a sample of 190 boys and 0.77 in a sample of 202 girls; Cronbach for the venturesomeness scale was 0.81 for boys and 0.83 for girls (Stadler, 2000). The aim of this study was to examine the concurrent validity of this questionnaire. As impulsiveness has been conceptualised as a form of behavioural disinhibition resulting in a lack of behavioural control, we tested whether children scoring high on the impulsiveness subscale would show deficits in their ability to adjust ongoing behaviour in accordance with different changing environmental contingencies. The failure to withhold a response that will lead to punishment (deficit in passive avoidance learning) is a widely used behavioural operationalization of impulsivity (e.g. Gray, Owen, Davis, & Tsaltas, 1983). According to Gray impulsive subjects may be less likely to interrupt ongoing behaviour and redirect attention to punishment cues owing to their stronger approach system. The go/nogo paradigm is a laboratory analogue of a situation requiring inhibitory control that distinguishes stimuli that elicit impulsive behaviour (go-task stimuli to gain reward) from those that inhibit it (nogo stimuli to avoid punishment). Subjects engaged in a primary task (to press a key when a certain stimulus, e.g. a row of letters, is seen on a computer screen) are presented with an occasional nogo stimulus (a different character of the row of letters). Research using the go/nogo task has increased during the past decade. Gray et al. (1983) have proposed that impulsive subjects are insensitive to stimuli associated with punishment, may display an excessive sensitivity to stimuli associated with reward, and display a deficit in passive avoidance learning. Passive avoidance learning is the ability to withhold a response that would lead to punishment. Many studies have shown that impulsive individuals are deficient in passive avoidance learning; they are less responsive to cues for punishment and are much impaired in their ability to adjust ongoing behaviour in accordance with changing environmental contingencies (Newman, 1987; Newman & Kosson, 1986; Newman, Patterson, Howland, & Nicholas, 1990; Newman, Widom, & Nathan, 1985; Patterson, Kosson, & Newman, 1987). In general, impulsive individuals exhibit greater errors of commission (rate of non-inhibited behaviour) than non-impulsive subjects. As the go/nogo task is an operationalization of impulsivity as theorized by Gray et al. (1983) and research has supported this operationalization in various clinical and healthy control subjects, this paradigm is used to test the validity of the German version of the impulsiveness scale in children. In contrast to Newman et al. (1990) however, who state that passive avoidance learning is only obvious in latent contingencies we expect high-impulsive children to show poor passive avoidance learning even under clearly defined instrumental contingencies. The decisive criterion for impulsive behaviour therefore is the rate of non-inhibited behaviour (passive avoidance errors) in the laboratory task.
C. Stadler, W. Janke / Personality and Individual Differences 35 (2003) 51–58
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2. Methods 2.1. Subjects Subjects were 65 children aged 9–11 years (M=9.65; SD=0.54) from various primary schools, 3rd and 4th grade. Eight children had to be excluded because of existing developmental reading or expressive writing disorders. A total of 40 boys and 25 girls participated in this study to which their parents had to give written consent. 2.2. Procedure Children first completed the Impulsiveness Questionnaire IVE. According to their test scores, subjects were subsequently divided into high-impulsive and low-impulsive children identified by split at the median for impulsiveness. For the go/nogo task subjects were tested separately, being seated at a table in front of a computer monitor. Presentation of stimuli and recording of responses were controlled by a TurboPascal-based programme. All subjects were examined by one female investigator. Pre-treatment (first block): during the pre-treatment with 75 trials, each trial was initiated by a 1000 ms signal (‘‘Ready’’), followed by a string of four letters presented for 2000 ms. Subjects were instructed to press the space key as soon as possible when a string was seen on the screen (go-condition), but they were not supposed to press the space key when there was a Q within the string (nogo-condition). Only the letters N, P, R, S, T, V, W, X, Z were used. After each trial, subjects received a feedback display telling them they had responded right or wrong: ‘‘You have won! You winpoints’’ (x is equal to 1, 2 or 3 points depending upon the speed of their response) or ‘‘Lost! You lose 5 points!’’ The Q was programmed to appear randomly in 50% of the trials. According to Newman, Wallace, Schmitt, and Arnett (1997), this procedure would establish the Q as a cue for punishment during the pre-treatment, because subjects are systematically trained to detect the Q so that they might avoid punishment by inhibiting responses when the Q was present. Test trials (second block): following the pre-treatment, instructions for the next phase were presented followed by 110 trials. During test trials, the stimulus display contained four letters (or three letters and one number) arranged in a way that each character appeared in one corner of an imaginary rectangle. Subjects were instructed as following ‘‘Press the space key as soon as possible if the symbols are all letters (go-condition) but if one of the symbols is a number do not press the key (nogo-condition)’’. In addition, the instructions indicated that subjects would win 1, 2 or 3 points for correct responses depending upon the speed of their response and that they would lose five points if they respond incorrectly (i.e. when a number was present). In the test trials the go-condition is represented by a character of four letters, the nogo-condition by a character of three letters and one number. Timing of the trials was the same as in the pre-treatment. Randomization procedures were used to approximate 50 nogo trials and 50 gotrials. In 50% of the trials there was the letter Q in the presented character. Test trials differed immensely from pre-treatment trials in that the Q had no special relationship to task requirements during this phase of the experimental task.
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The rate of non-inhibited behaviour—mistakes when subjects press a certain button when they should not do it (passive avoidance errors or errors of commission)—will be the decisive indicator for impulsiveness. The concurrent validity of the IVE would be supported if children scoring high or low on the impulsiveness subscale differ in the rate of errors of commission in this behavioural test. By subtracting a subject’s mean response time on Q-absent trials from their mean response time to Q-present trials in the second block (test trials) in accordance to Newman et al. (1997) it should be possible to assess the degree to which the Q elicited behavioural inhibition. In this regard the dependant measure is the extent to which cues for punishment (Q) interrupt (i.e. slow) responding on the ‘‘go’’ trials. So as a further aspect of concurrent validity high-impulsive children should show less behavioural inhibition in Q-present trials in the second block. 2.3. Statistical analysis The question whether high-impulsive children and low-impulsive children differ in passive avoidance learning was examined using two-way ANOVAS with the between-subject factors group (high-impulsive and low-impulsive) and sex. The classification into high- and low- impulsive children is based on median split. The median of the impulsiveness score was MD=7.0. As in 12 children the impulsiveness score was 7 we identified 28 high-impulsive (M=11.00, SD=2.16, impulsiveness score > Median) and 37 low-impulsive children (M=4.51; SD=2.35; impulsiveness score 4 Median). For each scale of the IVE Cronbach was computed as measure of internal consistency. In addition, we tested whether there are significant differences in self-rated impulsiveness, venturesomeness and empathy in boys and girls using t-tests for independent samples.
3. Results and discussion 3.1. Internal consistency and gender effects Table 1 gives mean scores and standard deviations for the three subscales. Internal consistency coefficients are also listed in Table 1. Impulsiveness and venturesomeness have reasonable reliabilities, whereas empathy has rather poor reliability. Table 1 Descriptive statistics of IVE Scale
Impulsiveness Venturesomeness Empathy a n.s., not significant * P< 0.10.
Girls (N=25)
Boys (N=40)
Mean
SD
Mean
SD
6.36 8.12 11.24
4.01 3.33 2.48
7.90 9.75 10.45
3.84 3.19 2.81
t-Tests
Cronbach (N=65)
n.s.a * n.s.
0.80 0.82 0.65
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3.2. Group and sex differences in passive avoidance learning To assess passive avoidance learning we calculated the number of commission errors in the nogo-trials (non-inhibited trials). As shown in Table 2 there is a significant group effect in the first [F(3,61)=5.18, P<0.05] and second block [F(3,61)=5.97, P <0.05]. Children scoring high on the IVE impulsiveness subscale are more impulsive in the laboratory task assessing the ability to inhibit goal-directed behaviour. Although the factor sex did not reach significance [F(3,61)=3.66, P<0.10] for the pre-treatment boys showed a tendency to make more errors of commission than girls. In the second block there was neither a significant sex effect nor a significant two-way interaction. As can be seen in Table 2 2 2-ANOVAS of non-inhibited trials in the go/nogo task by group (high and low-impulsive in IVE ) and age Boys
Girls
Imp 20
Imp+20
P
Imp 17
Imp+8
Group
Sex
Groupsex
Non-inhibited trials first block
Mean SD
2.25 2.57
3.80 2.57
1.41 1.42
2.25 1.83
**
*
n.s.
Non-inhibited trials second block
Mean SD
6.50 4.29
10.60 4.81
8.59 5.09
9.25 3.99
*
n.s.
n.s.
Non-inhibited trials: passive avoidance errors (=errors of commission). n.s.: Not significant. Imp-: impulsiveness score 4Median; Imp+: impulsiveness score > Median. * P< 0.10. ** P< 0.05.
Table 3 2 2-ANOVAS of response times scores in the go/nogo task by group (high and low-impulsive in IVE) and age Boys Imp 20
Girls
P
Imp+20
Imp 17
Imp+8
Group
RT first block (ms)
Mean SD
613 295
660 199
752 144
730 176
n.s.
RT second block (ms) (Q-absent trials)
Mean SD
952 333
738 163
900 261
905 189
RT second block (ms) (Q-present trials)
Mean SD
1008 357
803 173
944 236
RT difference
Mean SD
56 81
65 80
44 89
Sex
Groupsex
*
n.s.
**
n.s.
n.s.
982 247
*
n.s.
*
78 88
n.s.
n.s.
n.s.
RT: reaction times; n.s.: not significant. Imp : impulsiveness score 4Median; Imp+: impulsiveness score > Median. * P< 0.10. ** P< 0.05.
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Table 3 the ANOVA for response times in pre-treatment reached significance for the factor sex suggesting that boys responded faster than girls [F(3,61)=3.86, P<0.10]. In accordance to Newman et al. (1997), the degree to which the Q elicited behavioural inhibition in the second block was calculated by subtracting a subject’s mean response time on Qabsent trials from their mean response time to Q-present trials (Table 3). Low-impulsive children responded 51 ms slower on Q-present than on Q-absent trials and also high-impulsive children responded slower on Q-present than on Q-absent trials (68 ms). Girls responded 55 ms slower on Q-present than on Q-absent trials and also boys were slower on Q-present trials with a difference of 60 ms. The ANOVA for response times for Q-present trials revealed a trend towards a group sex interaction suggesting that impulsive boys showed a tendency to respond faster than nonimpulsive boys [F(3,61)=2.96, P<0.10] under this trial condition. The ANOVA for the defined behavioural inhibition measure (RT-difference score) however revealed no significant effect for group [F(3, 61)=0.65, P>0.10], sex [F(3, 61)=0.01, P>0.10] or a significant two-way interaction [F(3, 61)=0.32, P>0.10] indicating that there was no significant difference between high-impulsive and low-impulsive children in slowing down in presence of punishment cues. The assumption that high-impulsiveness is related to the degree to which the stimulus Q elicited behavioural inhibition could not be confirmed.
4. General discussion The purpose of this investigation was to assess the validity of the German version of Eysenck’s Impulsiveness Questionnaire for children (IVE). According to Gray et al. (1983), high impulsivity is characterized by poor passive avoidance learning. Given the assumption that the IVE is a valid instrument to assess impulsiveness in children, the ability to inhibit ongoing behaviour (passive avoidance) in order to avoid punishment and nonreward should be related to self-reported impulsiveness. In fact, the results of both blocks of the go/nogo task were fairly consistent in demonstrating poor passive avoidance learning in children scoring high on self-reported impulsiveness confirming the validity of this questionnaire. Impulsive children made more passive avoidance errors in the pre-treatment of the task and during test trials. Although this finding was not found in Newman et al.’s university sample (Newman et al., 1997), it is typical of other results obtained with impulsive participants. (i.e. Iaboni, Douglas, & Baker, 1995; Newman & Kosson, 1986; Scerbo et al., 1990) clearly indicating that passive avoidance learning in high-impulsive adults and children is deficient even under explicit instrumental contingencies involving an approach-avoidance conflict. The rate of successfully inhibited trials was greater during pre-treatment than during test trials. This might be a result of the higher amount of trials in the second block than in the first block. But in addition it should be also discussed whether the setting of the passive avoidance task was more difficult during test trials (second block) than during pre-treatment. Consequently the greater numbers of non-inhibited trials would be related to a cumulative effect of different punishment cues in the second block. Contrary to expectation, low-impulsive children are not characterized by a greater degree to which the Q—learned as cue for punishment in the first block—elicited behavioural inhibition in
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the second block. As can be concluded from the calculated response time means, both low- and high-impulsive children are slower in Q-present than in Q-absent trials reflecting a similar tendency for all subjects under this task condition. Although we found a statistical trend for impulsive boys in responding faster in Q-present trials than non-impulsive boys we did not find a significant difference between high- and low-impulsive participants in the RT-difference score: low-impulsive children did not slow down more than high-impulsive children in presence of punishment cues. It should be mentioned that also Newman et al. (1997) were not able to differentiate high- and low-impulsive groups by this behavioural measure. Only high-anxious subjects displayed significantly greater behavioural inhibition than low-anxious subjects in response to the Q, supporting the proposal that this task constitutes a relative specific measure of behavioural inhibition functioning in response to punishment cues in high-anxious subjects, but that it does not reflect the core deficit of behavioural impulsiveness. In the current study, impulsive participants display inhibitory deficits that do not appear associated with sensitivity to punishment cues. Whereas the degree to which the Q elicited behavioural inhibition was not sensitive to differentiate between high- and low-impulsive children, the passive avoidance deficits in children scoring high on the impulsiveness score appear to be associated to goal-directed behaviour. It could be concluded that deficits in passive avoidance learning do not always reflect insensitivity to punishment cues (i.e. a weak behavioural inhibition system). Rather they often reflect impulsivity, a trait that Gray and others regard as independent of anxiety and associated with the strength of behavioural approach and reward sensitivity (e.g. Gray, 1991; Gray et al., 1983). The disruptive effect of immediate incentives on the behaviour of impulsive individuals has been frequently noted (e.g. Shapiro, Quay, Hogan, & Schwartz, 1988) and the importance of the strength of approach behaviour in response to cues of reward in explaining disinhibited behaviour is further highlighted in a couple of recently published studies (Avila & Parcet, 2001; Segarra, Molto, & Torrubia, 2000). In this regard the results of the current study also confirm the importance of different pathways of disinhibited behaviour, discussed for example by Newman and Wallace (1993) Finally with regard to the aim of this study, results of pre-treatment and test trials were fairly consistent in demonstrating more passive avoidance errors in high-impulsive children than in lowimpulsive children confirming the validity of our German version of Eysenck’s Impulsiveness Questionnaire for children. References Avila, C., & Parcet, M. A. (2001). Personality and inhibitory deficits in stop-signal task: the mediating role of Gray’s anxiety and impulsivity. Personality and Individual Differences, 31, 975–986. Eysenck, S. B., Easting, G., & Pearson, P. R. (1984). Age norms for impulsiveness, venturesomeness and empathy in children. Personality and Individual Differences, 5, 315–321. Gray, J. A., Owen, S., Davis, N., & Tsaltas, E. (1983). Psychological and physiological relations between anxiety and impulsivity. In M. Zuckerman (Ed.), Biological bases of sensation seeking, impulsivity and anxiety (pp. 198–228). Hillsdale: Lawrance Erlbaum Associates. Gray, J. A. (1991). Neural systems, emotion and personality. In J. Madden IV (Ed.), Neurobiology of learning, emotion and affect. New York: Raven Press. Iaboni, F., Douglas, V. I., & Baker, A. G. (1995). Effects of reward and response cost on inhibition in ADHD children. Journal of Abnormal Child Psychology, 104, 232–240. Luengo, M. A., Carrillo-de-la-Pena, M. T., Otero, J. M., & Romero, E. (1994). A short-term longitudinal study of impulsivity and antisocial behaviour. Journal of Personality and Social Psychology, 66, 542–548.
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Newman, J. P. (1987). Reaction to punishment in extraverts and psychopaths: implications for the impulsive behaviour in disinhibited individuals. Journal of Research and Personality, 21, 464–480. Newman, J. P., & Kosson, D. S. (1986). Passive avoidance learning in psychopathic and nonpsychopathic offenders. Journal of Abnormal Psychology, 95, 252–256. Newman, J. P., Patterson, C. M., Howland, E. W., & Nichols, S. L. (1990). Passive avoidance in psychopaths: the effects of reward. Personality and Individual Differences, 11, 1101–1114. Newman, J. P., & Wallace, J. F. (1993). Diverse pathways to defiant self-regulation: implications for disinhibitory psychopathology in children. Clinical Psychology Review, 13, 699–720. Newman, J. P., Wallace, J. F., Schmitt, W. A., & Arnett, P. A. (1997). Behavioural inhibition system functioning in anxious, impulsive and psychopathic individuals. Personality and Individual Differences, 23, 583–592. Newman, J. P., Widom, C. S., & Nathan, S. (1985). Passive avoidance in syndromes of disinhibition.: psychopathy and extraversion. Journal of Personality and Social Psychology, 48, 1316–1327. Patterson, C. M., Kosson, D. S., & Newman, J. P. (1987). Reaction to punishment, reflectivity, and passive avoidance learning in extraverts. Journal of Personality and Social Psychology, 52, 565–575. Scerbo, A., Raine, A., O’Brien, M., Chan, C. J., Rhee, C., & Smiley, N. (1990). Reward dominance and passive avoidance learning in adolescent psychopaths. Journal of American Child Psychology, 33, 1174–1184. Segarra, P., Molto, J., & Torrubia, R. (2000). Passive avoidance learning in extraverted females. Personality and Individual Differences, 29, 239–254. Shapiro, S. K., Quay, H. C., Hogan, A. E., & Schwartz, K. P. (1988). Response perseveration and delayed responding in undersocialized aggressive conduct disorder. Journal of Abnormal Psychology, 97, 371–373. Silva, F., Martorell, M. C., & Clemente, A. (1987). I.6. (junior) Questionnaire: Spanish version. Psychological Assessment: An International Journal, 3, 55–78. Stadler, C. (2000). Impulsives Verhalten bei Kindern: Entwicklung von Methoden und experimentelle Ansa¨tze zur Validierung im Feld und im Labor. Marburg: Tectum Verlag. White, J. L., Moffitt, T. E., Daspi, A., Bartusch, D. J., Needles, D. J., & Stouthamer-Loeber, M. (1994). Measuring impulsivity and examining its relationship to delinquency. Journal of Abnormal Psychology, 103, 192–205.
Concurrent validity of the German version of S.B. Eysenck’s impulsiveness questionnaire for children Christina Stadlera,*, Wilhelm Jankeb a
Klinik fu¨r Psychiatrie und Psychotherapie des Kindes- und Jugendalters, Klinikum der Johann-Goethe Universita¨t, 60528 Frankfurt am Main, Germany b Lehrstuhl fu¨r Biologische und Klinische Psychologie, Julius-Maximilians-Universita¨t, Wu¨rzburg, Germany Received 26 November 2001; received in revised form 24 April 2002; accepted 13 May 2002
Abstract This study examined whether the German adaptation (IVE) of the I6 Impulsiveness Questionnaire from Eysenck, Easting, and Pearson (1984) is a sufficiently valid instrument to assess impulsivity in school-aged children. Concurrent validity was investigated within a well established laboratory test developed in accordance with a task used by Newman Wallace, Schmitt, and Arnett (1997). Children aged 9–11 years were administered a go/nogo paradigm assessing the ability to inhibit ongoing behaviour (passive avoidance) in order to avoid punishment and nonreward. Results clearly indicate that children who score high on impulsiveness are more impulsive in the used laboratory task than non-impulsive children. # 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction Eysenck, Easting, and Pearson (1984) developed the I6 Impulsiveness Questionnaire for children that was designed to assess impulsiveness reflecting poor behavioural control and lack of ability to delay gratification, venturesomeness reflecting sensation-seeking and risk-taking behaviour as well as sociability and empathy reflecting sensitivity to feelings and reactions of others and susceptibility to social cues. The child and adolescent version of this self-report has gone through several revisions. The I6 — the most recent version (Eysenck et al., 1984) is a self-report inventory consisting of 23 yes–no items, which are face-valid measures of impulsiveness (e.g. ‘‘Do you often get into a jam because you do things without thinking?’’). The number of responses
* Corresponding author. Tel.: +69-6301-5995; fax: +69-6301-5843. E-mail address: [email protected] (C. Stadler). 0191-8869/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved. PII: S0191-8869(02)00139-3
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C. Stadler, W. Janke / Personality and Individual Differences 35 (2003) 51–58
indicative of impulsiveness are summed to provide a total score. The scale discriminates conductdisordered children from controls and is predictive of future conduct problems (Luengo, Carrillode-la-Pena, Otero, & Romero, 1994). It was originally constructed to assess British subjects, but was adapted for American English (e.g. White et al., 1994) and translated into Spanish (Silva, Martorell, & Clemente, 1987). This self-report questionnaire was also translated into German (Stadler, 2000). On the basis of factor analyses, using principal-components methods and using three factors, several changes in the final scoring key were considered necessary, so the final scales chosen comprised 16 items for each scale and, therefore a total of 48 items. The psychometric data of the German version, tested on 392 children aged 8–15, which is shorter than the English version, is as good or slightly better. Cronbach’s coefficient for the impulsiveness subscale was 0.80 in a sample of 190 boys and 0.77 in a sample of 202 girls; Cronbach for the venturesomeness scale was 0.81 for boys and 0.83 for girls (Stadler, 2000). The aim of this study was to examine the concurrent validity of this questionnaire. As impulsiveness has been conceptualised as a form of behavioural disinhibition resulting in a lack of behavioural control, we tested whether children scoring high on the impulsiveness subscale would show deficits in their ability to adjust ongoing behaviour in accordance with different changing environmental contingencies. The failure to withhold a response that will lead to punishment (deficit in passive avoidance learning) is a widely used behavioural operationalization of impulsivity (e.g. Gray, Owen, Davis, & Tsaltas, 1983). According to Gray impulsive subjects may be less likely to interrupt ongoing behaviour and redirect attention to punishment cues owing to their stronger approach system. The go/nogo paradigm is a laboratory analogue of a situation requiring inhibitory control that distinguishes stimuli that elicit impulsive behaviour (go-task stimuli to gain reward) from those that inhibit it (nogo stimuli to avoid punishment). Subjects engaged in a primary task (to press a key when a certain stimulus, e.g. a row of letters, is seen on a computer screen) are presented with an occasional nogo stimulus (a different character of the row of letters). Research using the go/nogo task has increased during the past decade. Gray et al. (1983) have proposed that impulsive subjects are insensitive to stimuli associated with punishment, may display an excessive sensitivity to stimuli associated with reward, and display a deficit in passive avoidance learning. Passive avoidance learning is the ability to withhold a response that would lead to punishment. Many studies have shown that impulsive individuals are deficient in passive avoidance learning; they are less responsive to cues for punishment and are much impaired in their ability to adjust ongoing behaviour in accordance with changing environmental contingencies (Newman, 1987; Newman & Kosson, 1986; Newman, Patterson, Howland, & Nicholas, 1990; Newman, Widom, & Nathan, 1985; Patterson, Kosson, & Newman, 1987). In general, impulsive individuals exhibit greater errors of commission (rate of non-inhibited behaviour) than non-impulsive subjects. As the go/nogo task is an operationalization of impulsivity as theorized by Gray et al. (1983) and research has supported this operationalization in various clinical and healthy control subjects, this paradigm is used to test the validity of the German version of the impulsiveness scale in children. In contrast to Newman et al. (1990) however, who state that passive avoidance learning is only obvious in latent contingencies we expect high-impulsive children to show poor passive avoidance learning even under clearly defined instrumental contingencies. The decisive criterion for impulsive behaviour therefore is the rate of non-inhibited behaviour (passive avoidance errors) in the laboratory task.
C. Stadler, W. Janke / Personality and Individual Differences 35 (2003) 51–58
53
2. Methods 2.1. Subjects Subjects were 65 children aged 9–11 years (M=9.65; SD=0.54) from various primary schools, 3rd and 4th grade. Eight children had to be excluded because of existing developmental reading or expressive writing disorders. A total of 40 boys and 25 girls participated in this study to which their parents had to give written consent. 2.2. Procedure Children first completed the Impulsiveness Questionnaire IVE. According to their test scores, subjects were subsequently divided into high-impulsive and low-impulsive children identified by split at the median for impulsiveness. For the go/nogo task subjects were tested separately, being seated at a table in front of a computer monitor. Presentation of stimuli and recording of responses were controlled by a TurboPascal-based programme. All subjects were examined by one female investigator. Pre-treatment (first block): during the pre-treatment with 75 trials, each trial was initiated by a 1000 ms signal (‘‘Ready’’), followed by a string of four letters presented for 2000 ms. Subjects were instructed to press the space key as soon as possible when a string was seen on the screen (go-condition), but they were not supposed to press the space key when there was a Q within the string (nogo-condition). Only the letters N, P, R, S, T, V, W, X, Z were used. After each trial, subjects received a feedback display telling them they had responded right or wrong: ‘‘You have won! You winpoints’’ (x is equal to 1, 2 or 3 points depending upon the speed of their response) or ‘‘Lost! You lose 5 points!’’ The Q was programmed to appear randomly in 50% of the trials. According to Newman, Wallace, Schmitt, and Arnett (1997), this procedure would establish the Q as a cue for punishment during the pre-treatment, because subjects are systematically trained to detect the Q so that they might avoid punishment by inhibiting responses when the Q was present. Test trials (second block): following the pre-treatment, instructions for the next phase were presented followed by 110 trials. During test trials, the stimulus display contained four letters (or three letters and one number) arranged in a way that each character appeared in one corner of an imaginary rectangle. Subjects were instructed as following ‘‘Press the space key as soon as possible if the symbols are all letters (go-condition) but if one of the symbols is a number do not press the key (nogo-condition)’’. In addition, the instructions indicated that subjects would win 1, 2 or 3 points for correct responses depending upon the speed of their response and that they would lose five points if they respond incorrectly (i.e. when a number was present). In the test trials the go-condition is represented by a character of four letters, the nogo-condition by a character of three letters and one number. Timing of the trials was the same as in the pre-treatment. Randomization procedures were used to approximate 50 nogo trials and 50 gotrials. In 50% of the trials there was the letter Q in the presented character. Test trials differed immensely from pre-treatment trials in that the Q had no special relationship to task requirements during this phase of the experimental task.
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The rate of non-inhibited behaviour—mistakes when subjects press a certain button when they should not do it (passive avoidance errors or errors of commission)—will be the decisive indicator for impulsiveness. The concurrent validity of the IVE would be supported if children scoring high or low on the impulsiveness subscale differ in the rate of errors of commission in this behavioural test. By subtracting a subject’s mean response time on Q-absent trials from their mean response time to Q-present trials in the second block (test trials) in accordance to Newman et al. (1997) it should be possible to assess the degree to which the Q elicited behavioural inhibition. In this regard the dependant measure is the extent to which cues for punishment (Q) interrupt (i.e. slow) responding on the ‘‘go’’ trials. So as a further aspect of concurrent validity high-impulsive children should show less behavioural inhibition in Q-present trials in the second block. 2.3. Statistical analysis The question whether high-impulsive children and low-impulsive children differ in passive avoidance learning was examined using two-way ANOVAS with the between-subject factors group (high-impulsive and low-impulsive) and sex. The classification into high- and low- impulsive children is based on median split. The median of the impulsiveness score was MD=7.0. As in 12 children the impulsiveness score was 7 we identified 28 high-impulsive (M=11.00, SD=2.16, impulsiveness score > Median) and 37 low-impulsive children (M=4.51; SD=2.35; impulsiveness score 4 Median). For each scale of the IVE Cronbach was computed as measure of internal consistency. In addition, we tested whether there are significant differences in self-rated impulsiveness, venturesomeness and empathy in boys and girls using t-tests for independent samples.
3. Results and discussion 3.1. Internal consistency and gender effects Table 1 gives mean scores and standard deviations for the three subscales. Internal consistency coefficients are also listed in Table 1. Impulsiveness and venturesomeness have reasonable reliabilities, whereas empathy has rather poor reliability. Table 1 Descriptive statistics of IVE Scale
Impulsiveness Venturesomeness Empathy a n.s., not significant * P< 0.10.
Girls (N=25)
Boys (N=40)
Mean
SD
Mean
SD
6.36 8.12 11.24
4.01 3.33 2.48
7.90 9.75 10.45
3.84 3.19 2.81
t-Tests
Cronbach (N=65)
n.s.a * n.s.
0.80 0.82 0.65
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3.2. Group and sex differences in passive avoidance learning To assess passive avoidance learning we calculated the number of commission errors in the nogo-trials (non-inhibited trials). As shown in Table 2 there is a significant group effect in the first [F(3,61)=5.18, P<0.05] and second block [F(3,61)=5.97, P <0.05]. Children scoring high on the IVE impulsiveness subscale are more impulsive in the laboratory task assessing the ability to inhibit goal-directed behaviour. Although the factor sex did not reach significance [F(3,61)=3.66, P<0.10] for the pre-treatment boys showed a tendency to make more errors of commission than girls. In the second block there was neither a significant sex effect nor a significant two-way interaction. As can be seen in Table 2 2 2-ANOVAS of non-inhibited trials in the go/nogo task by group (high and low-impulsive in IVE ) and age Boys
Girls
Imp 20
Imp+20
P
Imp 17
Imp+8
Group
Sex
Groupsex
Non-inhibited trials first block
Mean SD
2.25 2.57
3.80 2.57
1.41 1.42
2.25 1.83
**
*
n.s.
Non-inhibited trials second block
Mean SD
6.50 4.29
10.60 4.81
8.59 5.09
9.25 3.99
*
n.s.
n.s.
Non-inhibited trials: passive avoidance errors (=errors of commission). n.s.: Not significant. Imp-: impulsiveness score 4Median; Imp+: impulsiveness score > Median. * P< 0.10. ** P< 0.05.
Table 3 2 2-ANOVAS of response times scores in the go/nogo task by group (high and low-impulsive in IVE) and age Boys Imp 20
Girls
P
Imp+20
Imp 17
Imp+8
Group
RT first block (ms)
Mean SD
613 295
660 199
752 144
730 176
n.s.
RT second block (ms) (Q-absent trials)
Mean SD
952 333
738 163
900 261
905 189
RT second block (ms) (Q-present trials)
Mean SD
1008 357
803 173
944 236
RT difference
Mean SD
56 81
65 80
44 89
Sex
Groupsex
*
n.s.
**
n.s.
n.s.
982 247
*
n.s.
*
78 88
n.s.
n.s.
n.s.
RT: reaction times; n.s.: not significant. Imp : impulsiveness score 4Median; Imp+: impulsiveness score > Median. * P< 0.10. ** P< 0.05.
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Table 3 the ANOVA for response times in pre-treatment reached significance for the factor sex suggesting that boys responded faster than girls [F(3,61)=3.86, P<0.10]. In accordance to Newman et al. (1997), the degree to which the Q elicited behavioural inhibition in the second block was calculated by subtracting a subject’s mean response time on Qabsent trials from their mean response time to Q-present trials (Table 3). Low-impulsive children responded 51 ms slower on Q-present than on Q-absent trials and also high-impulsive children responded slower on Q-present than on Q-absent trials (68 ms). Girls responded 55 ms slower on Q-present than on Q-absent trials and also boys were slower on Q-present trials with a difference of 60 ms. The ANOVA for response times for Q-present trials revealed a trend towards a group sex interaction suggesting that impulsive boys showed a tendency to respond faster than nonimpulsive boys [F(3,61)=2.96, P<0.10] under this trial condition. The ANOVA for the defined behavioural inhibition measure (RT-difference score) however revealed no significant effect for group [F(3, 61)=0.65, P>0.10], sex [F(3, 61)=0.01, P>0.10] or a significant two-way interaction [F(3, 61)=0.32, P>0.10] indicating that there was no significant difference between high-impulsive and low-impulsive children in slowing down in presence of punishment cues. The assumption that high-impulsiveness is related to the degree to which the stimulus Q elicited behavioural inhibition could not be confirmed.
4. General discussion The purpose of this investigation was to assess the validity of the German version of Eysenck’s Impulsiveness Questionnaire for children (IVE). According to Gray et al. (1983), high impulsivity is characterized by poor passive avoidance learning. Given the assumption that the IVE is a valid instrument to assess impulsiveness in children, the ability to inhibit ongoing behaviour (passive avoidance) in order to avoid punishment and nonreward should be related to self-reported impulsiveness. In fact, the results of both blocks of the go/nogo task were fairly consistent in demonstrating poor passive avoidance learning in children scoring high on self-reported impulsiveness confirming the validity of this questionnaire. Impulsive children made more passive avoidance errors in the pre-treatment of the task and during test trials. Although this finding was not found in Newman et al.’s university sample (Newman et al., 1997), it is typical of other results obtained with impulsive participants. (i.e. Iaboni, Douglas, & Baker, 1995; Newman & Kosson, 1986; Scerbo et al., 1990) clearly indicating that passive avoidance learning in high-impulsive adults and children is deficient even under explicit instrumental contingencies involving an approach-avoidance conflict. The rate of successfully inhibited trials was greater during pre-treatment than during test trials. This might be a result of the higher amount of trials in the second block than in the first block. But in addition it should be also discussed whether the setting of the passive avoidance task was more difficult during test trials (second block) than during pre-treatment. Consequently the greater numbers of non-inhibited trials would be related to a cumulative effect of different punishment cues in the second block. Contrary to expectation, low-impulsive children are not characterized by a greater degree to which the Q—learned as cue for punishment in the first block—elicited behavioural inhibition in
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the second block. As can be concluded from the calculated response time means, both low- and high-impulsive children are slower in Q-present than in Q-absent trials reflecting a similar tendency for all subjects under this task condition. Although we found a statistical trend for impulsive boys in responding faster in Q-present trials than non-impulsive boys we did not find a significant difference between high- and low-impulsive participants in the RT-difference score: low-impulsive children did not slow down more than high-impulsive children in presence of punishment cues. It should be mentioned that also Newman et al. (1997) were not able to differentiate high- and low-impulsive groups by this behavioural measure. Only high-anxious subjects displayed significantly greater behavioural inhibition than low-anxious subjects in response to the Q, supporting the proposal that this task constitutes a relative specific measure of behavioural inhibition functioning in response to punishment cues in high-anxious subjects, but that it does not reflect the core deficit of behavioural impulsiveness. In the current study, impulsive participants display inhibitory deficits that do not appear associated with sensitivity to punishment cues. Whereas the degree to which the Q elicited behavioural inhibition was not sensitive to differentiate between high- and low-impulsive children, the passive avoidance deficits in children scoring high on the impulsiveness score appear to be associated to goal-directed behaviour. It could be concluded that deficits in passive avoidance learning do not always reflect insensitivity to punishment cues (i.e. a weak behavioural inhibition system). Rather they often reflect impulsivity, a trait that Gray and others regard as independent of anxiety and associated with the strength of behavioural approach and reward sensitivity (e.g. Gray, 1991; Gray et al., 1983). The disruptive effect of immediate incentives on the behaviour of impulsive individuals has been frequently noted (e.g. Shapiro, Quay, Hogan, & Schwartz, 1988) and the importance of the strength of approach behaviour in response to cues of reward in explaining disinhibited behaviour is further highlighted in a couple of recently published studies (Avila & Parcet, 2001; Segarra, Molto, & Torrubia, 2000). In this regard the results of the current study also confirm the importance of different pathways of disinhibited behaviour, discussed for example by Newman and Wallace (1993) Finally with regard to the aim of this study, results of pre-treatment and test trials were fairly consistent in demonstrating more passive avoidance errors in high-impulsive children than in lowimpulsive children confirming the validity of our German version of Eysenck’s Impulsiveness Questionnaire for children. References Avila, C., & Parcet, M. A. (2001). Personality and inhibitory deficits in stop-signal task: the mediating role of Gray’s anxiety and impulsivity. Personality and Individual Differences, 31, 975–986. Eysenck, S. B., Easting, G., & Pearson, P. R. (1984). Age norms for impulsiveness, venturesomeness and empathy in children. Personality and Individual Differences, 5, 315–321. Gray, J. A., Owen, S., Davis, N., & Tsaltas, E. (1983). Psychological and physiological relations between anxiety and impulsivity. In M. Zuckerman (Ed.), Biological bases of sensation seeking, impulsivity and anxiety (pp. 198–228). Hillsdale: Lawrance Erlbaum Associates. Gray, J. A. (1991). Neural systems, emotion and personality. In J. Madden IV (Ed.), Neurobiology of learning, emotion and affect. New York: Raven Press. Iaboni, F., Douglas, V. I., & Baker, A. G. (1995). Effects of reward and response cost on inhibition in ADHD children. Journal of Abnormal Child Psychology, 104, 232–240. Luengo, M. A., Carrillo-de-la-Pena, M. T., Otero, J. M., & Romero, E. (1994). A short-term longitudinal study of impulsivity and antisocial behaviour. Journal of Personality and Social Psychology, 66, 542–548.
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