Assesing intettion and impulsivity in children during the Go/No Go task

7/27/2019 Assesing intettion and impulsivity in children during the Go/No Go task

1/20

British Journal of Developmental Psychology (2009). 27. 365-383 2009 The Brivsti Psychological Society

365

TheBritishPsychological

wv/w . bps|ournals.co.uk

Assessing inattention and impulsivity in childrenduring the G o/NoG o task

Serena Bezdjian, Laura A. Baker*, Dora Isabel Lozanoand Adrian Raine 'Department of Psychology, University of Southern California, Los Angeles,California, USA

Behavioural performance in the Go/NoGo task was compared with caregiver andteacher reports of inattention and hyperactivity-impulsivity in 1,151 children{N 5 5 7 boys; N ~ 594 girls) age 9-10 years old . Errors of commission (N oG oerrors) were significantly correlated with symptom counts of hyperactivity-impulsivity,while errors of omission (Go errors) were significantly correlated with symptomcounts for inattention in both caregiver and teacher reports. Cross-correlations were

also evident, however, such that errors of commission were related to inattentionsymptoms, and errors of omission were related to hyperactivity-impulsivity. Moreover,hyperactivity-impulsivity and inattention symptoms were highiy intercorrelated in bothcaregiver (r = .52) and teacher r ep orts (r = .70), wh ile er rors of comm ission andomission v^ere virtually u ncorre lated in the G o/ N oG o task (r = .06). The resultshighlight the difficulty in disentangling hyperactivity-impulsivity and inattention inquestionnaires, and suggest that these constructs may be more clearly distinguished inlaborato ry measures such as the G o/N oG o task.

The constructs of impulsivity and inattention are key features of self-regulatory abilityand arc an integral part of development in school-aged children (Kochanska, Murray,&Harlan, 2000; Ktipp, 1989). During school years children learn how to "focus theirattention on teacher-directed activities, interact appropriately with pee rs and authorityfigures, and follow spoken and unspoken rules in the cla,ssroom" (SpiraSc Fische!, 2005P- 7S5). Thus, they attain the building-blocks of academic success as they learnemergent literacy, math, and language skills (Spira & Fischel, 2005).

Not all children however, m aster these critical skills. For some children difficultieswith impulse control, attentional capacity, and hyperactivity hinder the ability to benefitfrom the lessons of grade school and academic experiences (Spira& Fischel, 2005).C'hildren who are deficient in these skills are at an elevated risk for a diverse range ofbehavioural, social, and academic problems in childhood and adolescence (Calkins,


2/20

366 Serena Bezdjian et al .

1994; Campbell, 1995). Furthermore, impulsive and inattentive behaviours are definingfeatures of several disorders associated with aggression (Plutchik & Van Praag, 1989,1995), conduct and attention deficit problems (August, Realmuto, MacDonald, Nugent,& Crosby, 1996), peer rejection (Hinshaw& Melnick, 1995;Whalcn, Henker,& Granger,1990) and problems in learning and achievement CHinshaw, 1992). The prevalence andpotential long-term consequences of impulsivity and inattention necessitate furtherexploration and clarification.

Past measures of inattention and hyperactivity-impulsivity have relied onquestionnaire, interview, and self-report methods. Self-report questionnaires havebeen by far the most commonly used techn ique for measuring impulsivity among youngadolescents and adults. Tlic number of questionnaires and/or surveys that have beendeveloped to measure impulsivity is extensive (see Barratt & Patton, 1985). Mostquestionnaires and structured interview measures have low or negligible correlationswith one another (Monahan & Steadman, 1994), and have low order and often,insignificant correlations with non-questionnaire measures (of inattention orimpulsivity) (Barratt& Patton, 1983). Furthermore, questionnaires might be unsuitablefor repeated use, which may also be a disadvantage (Moeller, Barratt, Dougherty,Schmitz, & Swann, 2001).

Most studies that have used children's self-reports have primarily relied on surveys andinterviews, the results of which could he lifected by social desirability, poor reading skills,and a general lack of comprehension, which are likely to occur in children (Lyonset al.,1995). Furthermore, it may be more difficult to delineate different, complex constructs(such as impulsivity and inattention) using questionnaire and interview measures.

For example, a psychiatric disorder where impulsivity is evident is attention deficit

b)'peractivity disorder (ADHD). According to the DSM-IV definition of the disorder,attention deficit and hyperactivity can occur together, or independently (Fvenden, 1999).The diagnostic criteria related to impulsivity in the definition are 'often blurts answersbefore questionshave been completed', 'often has difficultyin awaiting turns', and 'ofteninterrupts or intrudes on to others . However, other items defined as inattention such as'often has difficulty in sustaining attention in tasks or play activities', or 'often doesnot follow through on instructions or fails to finish schoolwork, chores, or duties inworkplace", or hyperactivity items such as 'often leaves seat in classroom or in othersituations in which remaining seated is expected' seem to be well related to a broaddefinition of impulsivity (Evenden, 1999). Thus, the general behaviour pattern maybechanicterizedby common factors or mechanisms in 'impulsivity', 'hypcractivit>^'. and'inattention', but may also occtir independently of one another (Evenden, 1999).Therefore, laboratory measures such as the Go/NoGo may provide successful,alternative methods of investigating complex constructs such as impulsivity (of lack ofinhibition) and inattention in children.

The Go/NoGo task, which demotistrates reasonable test-retest reliability (Kindlon,Mezzacappa,& Earls, 1995), requires participants to respond to the p resence of a targetstimulus (e.g.a single digit or le tter) amidsta stream of similar stimuli(e.g.other digits orletters). In the most common version of the Go/NoGo task, participants have to make amotor response (button press) to one stimulus category(G


3/20

Childhood inattention and impulsivity 36 7

Numerous studies that explore the disinhibitory nature of ADHD have utilizedlaboratory measures such as the Go/NoGo task (Nigg, 2001). The symptom domains ofboth impulsivity (which include difficulties in inhibitory control and response) andinattention (which include difficulties in sustaining and focusing attention) areexemplified ina Go/NoGo paradigm, Forexample, because errors of commission (Ni)Croerrors) are responses that occur when no response is required, they are assumed toreflect impulsivit'. Errors of omission ( the absence ofrespon.se to a target) are assumedto reflect symptoms of inattention (Barkley,1991; Halperin, Wolf, (ireenblatt, & Young,1991).Furthermore, deficient inhibitor^' control is considered to be the core cognitivesymptom of attention deficit disorders in children (Barklcy, 1997; Brandisetal.., 1998;Nigg, 2001). Research confirms that disinhibited children respond too quickly and toooften when they are required to wait and watch for events as is often seen in impulsiveerrors (errors of commission) (Corkum& Siegel, 1993). Research has also shown thatmales commit more impulsive errors (NoGo errors) than females during continuouspertbrmance-type tasks (Newcornel al, 2001).

Laboratory based measures have considerable utility for investigating symptoms ofimpulsivity and inattention because they are not as suscep tible to informant biases as arequestionnaire measures, and may thus provide a less contaminated assessment ofimpulsivity. inattention, and occasionally hyperactivity symptoms (LaneSi Cherek,2000). Laboratory' procedures also provide precision and control over manipulating thevariables related to the desired behaviour. Furthermore, they provide an operationaliza-tion under which the behaviour can be clearly specified (Lane & Cherek, 2000).Relevant laboratory tasks include continuous performance tasks (CPT) and variations,such as the Go/NoGo task. Moreover, studies of children with ADHD foutid that an

increased num ber of commission errors(i.e. false alarms) were made when compared tocontrol children (Nigg, 2001).Tilt aim of the present study ^vas to assess impulsivity and inattention in children

during a Go/NoGo task and compare the behavioural performance measures of theCio/NoGo task to symptom count ratings of hyperactivity-impulsivity and inattentionobtained from the childrens caregivers and teachers. The primary goal was todemonstrate that a laboratory task such as the Go/NoGo maybe useful in assessing anddelineating complex constructs including hyperactivity-impulsivity and inattention inchildren. Understanding the relationship between Go/NoGo performance measures andquestionnaire measures of hyperactivity-impulsivity and inattention may help shed light

on the nature of these two important constructs in children.

M e t h o dParticipantsThe participants were recruited from the Los Angeles community, and consisted of 9and 10-year-old twins (totalA'= 1, 219children) and their primary caregivers. Twinswere recruited from both private and public school districts, as well as advertisementsin local newspapers and public buildings. Children's ethnicity w^as determined by theethnicity of their two biological parents, as reported by the primary caregiver. Theethnic composition ofthetw^ins was as follows:37.5% Hispanic;26.6% Caucasian; 14.3%


4/20

368 Sereno Bezdjian et al.

socioeconomically. Moreover, the chdren partidpatitig in the study were fluenspeakers, as demonstrated hy a standardized test of English prociency adminthrough their sehools.

Families identified as having twins were sent letters describing the study in edetail. Each letter contained an enclosed prcaddressed/prepaid envciopcontained a form for interested families to provide contact information and rthe twin studystaff. Basic demographic information was also requested. Interefamilies were contacted and the study was explained to them in detail. The fwho agreed to participate were scheduled fora ftill day's labonuory visit at IISC,duringwhich assessments were made of the twins and their primary caregivers. Thparticipated in an extensive interview process, cognitive and neuropsychotesting (including IQ testing and the Go/NoCio task), and psychophysioassessment. , . '

The caregivers were also asked to participate in an extensive interview procincluded questions about parental antisocial behaviour, substance use, as wdetailed information about the twins' bebaviours (at home and at school). With permission, the twins' teachers were also contacted via mail to fill out questioabout the twins' bebaviours at school. Participating families were offeredsummaries of study results.

Procedure .--' -^ . , ,I^rticipants were brought to the laboratory at USC hy an adult caregiver (usuabiological m oth er) for a full day s visit (approx ima tely 7 -8 hours) . Tbc sessio

divided itito tw o 3 -4 h ou r sessions (before and after a 45 tninute lunc h break). Otwas interviewed about their behaviou r and tested on the neurocogn itive tasks, whotber participated in the psychopbysiological testing. After lunch, the twins switch. The order of which twin participated in interview/neurocognitive vpsychophysiological testing was randomly determined before tbe families arrivedlab.Botb twins were administered tbe tasks for either the interview/neurocognitpsychophysiological session in the same order. Caregivers were administered selfquestionnaires and interviewed about their habits and bebaviour, their marriage, as their twins' behaviour with one another and their peers while at home and in The families were compensated for their visit t(i the lab.

Examiners consisted of full- or part-time staff members with a B.A., as well agraduate students and upper-class undergraduates. All examiners were rigotrained (approximately 3-4 weeks) on the psychophysiological and neuropsychotesting procedures and in tbe administration of tbe behavioural interviews. Trincluded inter-examiner reliability checks, videotaped monitoring to ensure adherence to standardized testing protocols, and supervised training sessions aspects of testing. A more detailed description of the study sample, designprocedures can be found in Baker, Barton, Lozano, Raine, and Fowler (2006) andJacobson, Raine, Lozano, and Bezdjian (2007).

M e a s u re s ! - , j ;'"i-: i . i '


5/20

Childhood inattenonand impulsivity 369

The CK)/NOGO was administered during the psychophysiology session, while thequestionnaires were administered during caregiver interviewsand surveys mailed toteachers.

The Go/NoGo task , . .i iThe Go/N


6/20

370 Serena Bezdjian et al.

Symptom measures of hyperactivity-impulslvity and inattention

Caregiver interviews: Diagr}ostic Interview Schedulefor Chi/dren versiot) IV (DiSC-IV) (Shaffer,Fisher,

Lucas, & Comer. 2000)

The Diagnostic Interview Schedule for Children is a highly structured interviewdesigned to assess psychiatric disorders (adapted fromthe DSM-IV) and symptoms inchildren and adolescents aged 6-17 yeai^. The DISCis designed tor administrationbywell-trained lay interviewers for epidemiological research. TheDISC-IV (parent version)was administered to the caregivers during their interview assessmentof each twin'sbehaviour. The caregivers were asked to report on their tw ins' symptoms of impuisivity,hyperactivity, and inattentionat home within the past year.

Teacher surveys

With parental permission, the twins' teachers were also contactedvia mail to fill out

comprehensive questionnaires aboutthe twins' behaviours at school. These includedthe 18 items listed as criteria forADHD in the DSM-III-R, placed into a checklist format(DuPaul et al. , 1990). The items were ratedon a -i-point Ukert scale (neveror rarely,sometimes, often, and very often). The teachers returned completed surveys in prepaidself-addressed envelopes, and were sent small gifts as com pensation for theirtime. Sincethe teacher report items were taken directly from DSM criteria, which included bothhyperactivity/impulsivity and inattention symptoms in versionsIHR and IV, comparablescales for these groups of symptoms could be obtained from caregiverand teacherreports. Table 1 presents the 21 items com prising the DISC-IVADHD symptoms rated bythe parents, along with the corresponding itemsin the teacher questionnaire.

Comparisons among the laboratory and questionnaire m easures were made to assessthe constructs of inattention and impulsivity derived from both teacher and caregiverreports. The Go/NoGo should serveas a valuable tool in measuring inattentionandimpulsivity in children since it is not susceptible to informant biases, and thus maygenerate a less contaminated assessment of these constructs (Marks, Himelstein,Newcorn, & Halperin, 1999).

Data analyses

Several preliminary analyses were conductedon the Go/NoGo data in order to ensurereliable and valid estimatesof the response parameters derived from this task. We firstexamined contiguous trials indicating verylow RTs preceded by a missing response.Corrections to some trials were made if children had late responses or very low RTsonthe Htb triai (RT < 0.12 seconds), combined with no response on the previous(n 1th) trial (V?,,_i= no). On such trials,it was assumed that the ciiild respondedonthe n 1th trial, but the response time exceeded the allotted1-second interval for thetrial, thus carr>'ing over to the next trial. The subsequent trial was then considered to bemissing. Thus, RT_ i was modified to be I + RT,, and R _ i yes (would equala yesresponse). For the remaining trials with a very low RT (


7/20

Childhaod inattention and impulsivity 371

Ta b le I . Items from ADHD interview (caregiver) and questionnaire (teacher)

Inattention Hyperactivity (H)/impulsivity (I)

Caregiver

Had trouble finishing homeworkOften lost things in the past yearForgot what they were supposed to doCouldn't keep mind on one thingTrouble keeping mind on taskOften disliked doing things that require

mental effortOften tried to avoid doing things that require

mental effortOften made a lot of mistakesWas disorganized in the past year

Started activities without finishing them

Often didn't listen when people were speakingTeacher

Does not follow through on instructions orfails to finish

Avoids tasks that require mental effortIs forgetful in daily activitiesHas difficulty organizing tasksFails to give close attention to detailIs easily distracted

Does not seem to be listening when spokento directly

Has difficulty sustaining attention

Loses things necessary for tasks

Often climbed on things and ran around (H)Often talked a lot more than other children (H)Made much more noise while playing (H)Fidgety/restless in past year (H)Been on the go more than usual (H)Left seat (in class, movies, etc.) (H)

Often butted in on what others were doing (I)

Often had trouble waiting for turns (I)Often interrupted others (I)

Blurted out answers before hearing wholequestion (I)

Fidgets with hands and feet (H)

Is on the go driven by a m oto r (H)Talks excessively (H)Has difficulty playing quietly (H)Runs about or climbs on things (H)Left seat (as in school, movies, et c) (H)

Interrupts or intrudes (I)

Blurts out answers before questions arecompleted (I)

Has difficulty waiting for turn (I)

additional cases of children w ho reftised to partic ipate in the task. Thus, valid Go/NoGodata were available for 1,151 children.

RTs and RT variability lor trials with Go responses, as well as the number of errors

during both Go and NoGo trials were calculated. The total number of errors during bothGo conditions was calculated by summing the number of misses (omission errors)committed during both the Go and NoGo conditions (P and R, respectively). Theaverage reaction times were computed for each of tbe Go conditions by summing thetotal number ofhits (correct responses) divided by the total num ber of times the letterappears on the screen (128). Intra-subject reaction time variability was tabulated bycomputing the standard deviations for the Go response reaction times across trials (128in each condition) (Letli-Steenscn. Elbaz.& Douglas, 2000).A greater number of NoGoerrors and sh orter reaction times are typically considered to be indicators of impulsiveresponding (Baker, 1995; Halpcrinetal, 1991).

(Correlational analyses were employed to examine the relationship between ADHDsymptoms (hyperactivity/impulsivity and inattention) with the Go/NoGo task. In


8/20

372 Sereno ezdjian et al.

for each of the two conditions in the Go/NoGo task, as well as for the average acrossconditions for each of the four performance measures.

Further analyses of the relationship between ADHD and Go/NoGo performanceexamined changes in behavioural performance within the Go/NoGo task for the threeADHD subtypes (inattention only (ADHD-IA), hyperactive only (ADHD-Hi), andcombined (ADHD-C)l compared to noti-ADHD controls. The ADHD subtype diagnoseswere determ ined by paren t ratings from the DISC-IV. .,

The ADHD groups included 507 male and 576 female normal comparisons; 39 maleand 20 female inattention only ; 28 male and 15 female 'hyperactive only; and 20 maleand 14 female 'com bined' subtypes. In both the ADHD-HI and ADHD-L\ subtypes, malesoutnum bered the females by nearly a 2:1 ratio, while the ADHI>C group had a male tofemale ratio of 1.43:1. Conversely, the non-ADHD control group consisted of morefemales than males with a male to female ratio of1:1.40. According to caregiver reports,48 children from our sample were currently diagnosed with ADHD or some form ofattention deficit disorder, and 18 cliildren were currently on medication for theirsymptoms.

Results

Factor analyses on the ADHD sym ptoms confirmed a two-factor solution for the ADHDitems in both teacher surveys using the ADHD checklist and in caregiver interviewsusing the DlSC-IV interview. This result falls in line with previous literature on the factorstructure of ADHD symptoms (Hudziaket al. , 1998; Marsh & Williams, 2004). ITie two

emerging factors were ( 1 )a

hyperactivity/impulsivity factor and (2) an inattention factor(analyses available upon request). Thus, composite mean scores for hyperactivity/im-puisivity and inattention were created separately for caregiver and teacher reports ofADHD and used in all subsequent analyses.

The Pearson correlations for the caregiver and teacher reports of hyperactivity/impulsivity and inattention are provided in Table 2. The relationship betweenhyperactivity/impulsivity and inattention was significantly and strongly correlatedwithin each rater (r ^ .52 ,p < .01 for caregiver reports and r =.70.p < .01 forteacherreports). In addition, mean symptoms scores for hyperactivity/impulsivity andinattention were also significantly correlated across raters. Hyperactivit>/impulsivity

and inattention were moderately and significantly correlated between caregiver and

Ta b l e 2 . Correlations among caregiver and teacher reports of Inattention and hyperactivity/impulsivity

Caregiver Teacher

Inattention Hyperactivity/impulsivity Inattention Hyperactivity/impulsivity

CaregiverInattention - .S3f" .48** .35**

Hyperactivity/impulsivity - .35** .44**Teacher

I i ' " ' 70**


9/20

Childhood inattention and imputsivity 373

teacher reports (r = .44;p < .01 for hyperactivity/impulsivity and r .48; p < .01 forinattention respectively).

Go/NoGo task

De scriptive statistics for the G o and N oGo e rrors, as well as RT and RT variability for tbeP-Go and R-Go con dition s are pre se nte d in Table 3- Co nsisten t w ith pre viou s literature(Newcorn et al., 2001) there w ere sex differences for the NoG o errors and Go reactiontimes for bo tb conditions |i ( l . 149) = 14.07,p < .001 (R-NoGo); /(I, 149) = 11.33,/ ; < .001(P-NoGo) ; / (l , 1 4 9 ) - - 10 .3 6 , p < .001 P-Go RT ; / ( I , 1 4 9 ) - -11 .56 , /^ < .01(R-Go RT)] With males committing significantly more NoGo errors and displayingsignificantly faster reaction times. No sex differences were found for the Go errors toreither P-Cio or R-Go [i(l, 149)= 1.77, p= .08 (P-Go); i( l, 1 4 9 ) - 1-30, p-^ .08(R-Go)l, or for RT variability eith er for the P-Go o r R-Go RT variability [i (l , 149) = 1.2,p ^ .21 ; i( 1 , 149) - 0.S6.p = .58). Go errors were slightly skewed (see Table 3), thussquare root transformations were computed on these data. After transformation, tbeske w nes s for the Go errors decre ase d in th e com bin ed s am ple from 1.99 to 0.48 (for P-Go)and 1.70 to 0.44 (for R-Go). The square root transformed Go errors were used insubsequent analyses.

Tab le 3 . Descriptive statistics for the Go/NoGo task (N = 1,151)

ErrorsP-Go

MalesFemales

R-GoMalesFemales

R-NoGo

Males tFemales

P-NoGo

MalesFemales

Reaction timesP-Go

MalesFemales

R-GoMalesFemales

Reaction time variabilityP-Go RT variability

Males

FemalesR-Go RT variabilityMales

Mean

8.257.32

10.669.85

15.18"10.32

17.04'13.12

0.48"0.53

0.47'0.53

0.14

0.14

0.16

SD

9.408.43

10.97

ia49

6.13

5 ^

5.73

5.98

0.08

0.07

0.080.08

0.03

0.03

0.04

Skev^ness

1.912.05

1.551.80

0.030.61

- 0 . 1 90.32

0.230.26

0.220.17

0.84

0.50

0.74

Kurtosis

4.525.75

2.355.75

- 0 . 6 2- 0 . 1 5

- 0 . 5 7- 0 . 5 6

0.35- 0 . 0 6

0.13- 0 . 1 4

i.670.50

1.90


10/20


11/20

Childhood inattentior) an d impulsivity 375

Ta b le 4 . Correlations between Go/NoGo performance and caregiver and teacher reports ofinattention and hyperactivity/impulsivity factors

Go errors (sqrt)NoGo e r r o r sGo RTsGo RT variability

Garegiver reports

inattention

. 2 2 * *

.1 2 * *

.02

. 1 8 * *

Hyperactivity/impulsivity

. 1 2 * *

.0 6 *

.0 2

. 1 3 * *

Inattention

. 2 1 * *

. 2 0 * *

- . 0 1

.25=**

Teacher reports

Hyperactivity/impulsivity

. 1 7 * *

. 14**

- . 0 2

. 1 6 * *

*Significant at p < .05 level. ^Significant at p < .01 level.

reports of ADHD symptoms. This could be due to the multidimensional factor ofimpulsivity, in that a fast response does not necessarily reflect impulsivity.A participantmay respt)nd quickly, btit may not make errors that are indicative of inattention orimpulsivity.

ANCWAs were used to com pare mean Go/NoGo performance for the three ADHDgroups (hyperactive only, inattentive only, and comhined) and normal controls, andrevealed some group differences for each ofthe four performance measures. Moreover,these group differences appeared to vary across sex forGo errors, based on a significantSexXADIiDGroup interaction (F=4.21, df = ^, p < .01"). Given this significantinteraction [although theSex X ADHDGroup interactions were not significant for NoGoerrors (F=1.13, df ^ i, /? = .34), Go reaction times (/ ^=1 .5 5 , df = ^. 1,139,

p

.20), or (io reaction time variabilityCF = 1.92, f = 5, p = .12)], we decidedto graphically display the data for all four-performance measures separately by sex(see Figure la and lb).

As shown, our results indicate that there were no significant ADHD groupdifferences for any of the Go/NoGo behavioural performance measures in boys.However, males did seem to respond faster than females and had significantly shorterreaction times overall (see Table 3)- The ADHD combined type females made themost Go errors, had significantly longer reaction times and displayed more variabilityin their response times and thus appeared to be the most inattentive compared tocontrol or other ADHD females. Overall, there appeared to be sex differences in

patterns of response for ADHD groups in the Go/NoGo task, with somew hat differentpatterns or the ADHD subtypes. In addition, Bonferronipost hoc analyses of groupdifferences within each sex revealed significant mean level differences between theADHD-C group and controls for Go errors. Go reaction times (marginal significance),and Go RT variability in females (p < .05) (see Figure lb). Furthermore,post hocanalyses also revealed significant mean level differences between ADHD-C and ADHD-IA for Go errors in females ip < .05). There were no mean level group differencesfor any of the Go/NoGo behavioural performance measures in boys.

Some studies have found ass(x:iations between IQ and performance on vigilanceor CPTs (Pascualvaca et al., 1997), therefore differences in IQ were also investigated

in this study to ensure that deficits associated with inattention or impulsivity cannotbe more parsimoniously explained by group differences in intelligence. Mean IQs for

b l d f IQ d i T bl 5 Addi i l ANOVA


12/20

376 Sereno Bezdjian et al.

(a) Males

1.50000 -

to

I 1.00000C DIIO g 0.50000

S 0,00000 -

-0,50000 -

Go errors (sqrt)

NoGo errors

Go_RTs

G o RT

variability

(b)

Controls Inattention Hyperactive Com binedonly only type

Females

1,50000 -

o(S

no

'NoG

CDc

Me

c

rom

VQ .

1,00000 -

0,50000 -

0,00000 -

-0.50000 -

Go errors (sqrt)NoGo errorsGo_RTsG o RTvariability

I r

Controls Inattention Hyperactive Com binedonly only type

Figure I . (a) Note: Illustrates ADHD group performance for each Go/NoGo behavioural measure(standardized) in males, (b) Note: Illustrates AD H D group performance for each G o/N oG o behaviouralmeasure (standardized) in females.

counts with verbal and performance IQ indieated a signifieant inverse relationship inthe entire sample. Specifically, symptotn counts for ADHD-IA were inversely correlatedwith verbal and performance IQ (r .I4,p< .01 ; r -.16, p < .01. respectively).Ihe symptom counts for ADHD-HI were also inversely correlated with verbal andperformance IQ (r = - . 1 0 , ^ < .01 ; r = - I2,p < .01 , respectively).


13/20

Childhood inattention and impu/siVity 377

Ta b l e S. Description of the sample and ADHD groups

A D H D - I A A D H D - H I A D H D - C C o n tr ol s(N - 59) (N - 43) (N - 34) (N = 1,083)

Gender (M:F)Inattention symptoms*Hyperactive/impulsivity symptoms'Verbal IQPerformance IQ

1.95:1

4.29

1.73

97.63

97.64

1.86:1

2.284.13101.95

97.21

1.43:1

4.50

4.03

100.12

95.85

1:1.40

1.17

0.94101.80100.91

' Sym ptom coun ts are based on caregiver rep orts on the D ISC-IV (based on DSM -IV criter ia).

Go reaction times were also significantly correlated with performance IQ only(r = -.10, p < .01). Moreover, Go reaction time variability was also correlated with

both performance (r = -.27,p < .01), and verbal IQ (r - -.2 3, / < .01).

DiscussionPrevious studies examining the constructs of inattention and hyperactivity-impulsivityhave been to some extent hindered by inadequate assessment methods, which relyprimarily on questionnaire ratings by parents and teachers. This study aimed to gain abetter grasp of hyperactivity-impulsivity and inattention in children through the use of alaboratory task, the Go/NoGo.

Performance in the Go/NoCio task (Go erro rs, NoGo errors. Go reaction times, andvariability of Go reaction times) was compared to ADHD symptom ratings ofhyperactivity-impulsivity and inattention. Consistent with previous literature, therewas a strong inverse relationship between the number of NoCio errors and the Goreaction times (r ^ -.70;p < .01), both of which are posited to indicate impulsiveresponding (Halperinetal., 1991). There was a relatively small relationship, however,between Go and NoGo errors, or between Go errors and Go reaction times, suggestinggreater independence between disinhibition (impulsive responding) and inattentionwitliin this task.

Exploratory factor analyses suggested a two-fiactor solution for the ADHD symptoms

(hyperactivity/impulsivity and inatten tion) n these school age children as rated by boththeir caregivers and teachers. Research has generally supported this twtxlimensionalsymptom structure for ADHD (Htidziakel al.. 1998; Marsh & Williams, 2004). Thus,mean scores for the hyperactivity/impulsivity and inattention sym ptoms were tabulated.Caregiver and teacher ratings of inattention were significantly and moderatelycorrelated, as were caregiver and teacher ratings of hyperactivity-impulsivity. Thecorrelations between multiple raters in the present study are stronger than what hasbeen previously reported in the literature on child behaviour ratings (Achenbach,McConaughy, & Howell, 1987).

In contrast to the negligible relationship between impulsive responding andinattention in the Go/NoGo task, mean scores for hyperactivity-impulsivity andInattention symptoms created from caregiver and teacher reports in the DISC-IV were

f l d l l d h ( bl ) h d


14/20

378 Sereno Bezdjian et ai

highlighting tbe difficulty of delineating and separating these constructs inquestionnaire measures. Tbe lack of independence of these constructs in behaviouralrating scales miglit make their effects difficult to distinguish in external validity studies.Furtbermore, it might also be the case that parents who have children with behaviourproblems migbt be biased, and tend to rate tbeir children more highly on a variety ofbehaviour scales.

On the contrary, the correlations between tbe Go errors (purported to measureinattention) and NoGo errors (purported to measure disinhibition/impulsivity) werer .06 for the first condition and r .05 for the second condition, and r .08 whenthe conditions were combined, indicate that a laboratory task such as the Go/NoGomigbt serve as a better alternative in assessing these complex bebaviours com pared tosurvey reports. Funbermore, the fact that Go and NoGo errors were relativelyindependent suggests tbat the Go/NoGo task maybe a more effective and less bias wayof separating tbese two related processes, perhaps even better than questionnairemeasures of these constnicts.

In addition, 3-6-month test-retest analyses conducted on the Go/NoGo taskindicated that the performance measures within the task were quite stable over time.This is consistent with previous research on the Go/NoGo, wliich found tbe task to beboth reliable and stable over time (Kindlonet al., 1995). Correlations for the Go/NoGoperformance measures ranged fromr .50, p < .01 (for the Go errors) to r =^ .86,p < .01 (for tbe Go reaction times).

In comparisons of Go/NoGo performance and ADHD symptoms, NoGo errorswere correlated with botb hyperactive-impulsive and inattentive symptt)ms frombotb caregiver and teacber ratings. There were significant correlations between tbeGo errors and the Inattentive and hyperactive-impulsive symptoms (in both caregiverand teacher reports as well). Thus, perhaps the constructs of inattentioti andimpulsivity are closely intertwined, especially in survey measures. For example,Loeber, Green, Lahey. and Stouthamer-Loeber (1989) has identified discrepanciesbetween parent and teacher ratings, suggesting that certain elements of a disordermay be situationally specific and difficult for infbrmants who do not observe tbe childin tbat situation or setting to clearly identify. Furthermore, tbe significant inter-correlations among tbe Go/NoGo performance measures and the ADHD symptomsmay be due to the fact tbat impuisivity is not unidimensional, but ntther may reflectseveral different facets.

Tasks that tap into neurocognitive domains such as impulsivity (lack of inhibition),and attention have been useful in distinguishing children with ADHD from controls.Thus we peribrmed additional analyses on the Cio/NoGo task, which integrates thedomains of inhibition and attention. We examined the bebavioural performance ofthe cbildren during the Go/NoGo task. Our results indicated tbat: (1) the ADHDcombined type females make tbe most Go errors, have significantly longer reactiontimes and display more variability' in their response times and thus appear to be themost inattentive compared to control or other ADHD females: (2) there were nosignificant ADHD group differences for any of the Go/NoGo behavioural performancemeasures in boys; (3) for Go Reaction Times, combined type ADHD females areslowest across the board compared to otber females; and (4) there were nosignificant group differences for NoGo errors in either males or females. However,


15/20

Ch ildhood inattention and impulsivity379

differences in patterns of responding for ADHD groups in the (o/NoCo task, withsomew hat different patterns for the ADHD subtypes. Combined-type girls are bothslow and make more Go errors, suggesting they have the greatest problems attendingto the task. These girls are not, however, more impulsive than otherADHD or controlgirls accordijig to their NoGo errors.

The ADHD groups did not seem to be characterized in their Go/NoGo performanceas might be predicted (i.e. more frequetit NoGo errors for those with H/I, and more Goerrors for those with lA). Instead a common factor among the subtype groups may beattention (or deficit in attention) since it is also a crucial component of the ADHD-Cgroup. In addition, several studies have suggested that children witb ADHD-C andchildren with ADHD-IA display similar impairments (laheyet a l . , 1998; Willcutt,Pennington, Chhabildas, Friedman, & Alexander, 1999). Our results fall in line withprevious literature. Chhabildas, Pennington. and Willcutt (2001) demonstrated thatsymptoms of inattention were associated with neuropsychological or neurocognitiveimpairment. However, our results did demonstrate that the ADHD-C groupwas significantly different from the ADHD-IA group in females for their Go errors(a purported measure of attention). We did not see atiy significant group differencesamong any of the groups for any of the performance measures in m ales. One reason tbrthis might be due to the difficult nature in assessing children's behaviour throughreports or interviews. Another reason might be due to the tact thai the numbersof participants in the ADHD groups are quite small, and this in turn could limit thepower to detect any significant group differences for the different Go/NoGoperformance measures.

Since the symptom ratings for the two ADHD dimensions are highly correlated inour sample, it is possible that both inattention and hyperactivity/impulsivity areassociated with similar underlying deficits. Thus, because the two dimensions are sohighly correlated, one symptom dimension could be associated with underlyingneuropsychological impairments while the other dimension may simply be indexingsymptoms that are highly correlated with the deficits associated with the firstdimension (Chhabildas e t a l . ,2001). As demonstrated by the significant correlationbetw een the tw o ADHD dimensions, caregivers miglit find it difficult to decipher the'hyperactive-im pulsive' questions from the inattention" questions. Some question-naire items purported to measure inattention might be mistaken for impulsivity(or impulsive actions) depending on the rater (in this case, caregivers and teachers)

For example, items such as, 'often does not follow through on instructions andfails to complete work" also might fall within the broader definition of impulsivity(Evenden, 1999). Since the inattention symptoms correlate highly with thehyperactive/ impulsive symptoms, several of the hyperactive/impulsive symptomsmay also describe behaviours that arguably reflect deficits in attention (Nigg, 1999,2(X)1). Perbaps deficits can be more severe for the ADHD-C type because they haveelevated levels on both dimensions, so one would expect them to exhibit deficits inall three-performance measures (or exliibits deficits in inhibition, attention, andprocessing speed).

Correlations among the Go/NoGo performance measures, the ADHD subtype

symptom counts, and IQ (verbal and performance) indicated a significant inverserelationship between Go errors and verbal and performance IQ. Thus, the greater the

b f G ( d f i i ) h l h b l d


16/20

380 Sereno Bezdjian et al .

further suggest the importance of attention in these measures. As demonstrated hy theoverall results of this study, the Go/NoGo task appears to be quite a valuable tool indetecting deficits in both attention as well as inhibition, perhaps better thanquestionnaires or structured interviews that might incorporate certain intrinsic biases.Consistent with literature, no differences were found across the ADHD groups and

controls on either verbal or performance IQ (Rubia, Smith,& Taylor, 2007).As demonstrated by the overall results of this study, the Go/NoGo task appears to be

a valuable tool in detecting deficits in both attention as well as inhibition, perhaps betterthan questionnaires or structured interviews that migJit incorporate certain intrinsicbiases.

The results of the present study were also interesting because unlike previousstudies (e.g. Carrillo de ia Penaetal, 1993; White etal., 1994), our findings indicated asignificant relationship between laboratory measures of impulsivity and inattention andquestionnaire measures of these same constnicts. Our findings are consistent with amore recent study conducted by Avilaet al. (2(K)4), and suggest that tasks such as theGo/NoGo task miglit be more sensitive than parent or teacher ratings in capturingimpulsivity and inattention and related disorders.

Study limitationsThe fact that these analyses were based on data obtained in a general population couldbe considered hoth a strength and possible limitation. The use of school-based samplesand the requirement that families be willing to come to the laboratory for a fullassessment battery may have led to an under sampling of the most severely affected

impulsive and inattentive children. Moreover, the fact that 18 ofthe 48 children whohad received a diagnosis ofADHD or some form of attention deficit disorder were onmedication for their symptoms during the NoGo task might also help explain the lack ofstrong group differences found in this study.

The narrow age range of 9 and 10-year-olds could also be considered both a strengthand limitation. However, tai^eting pre-adolescent children may be beneficial whenstudying correlates or precursors to antisocial behaviour such as impulsivity. Anotherlimitation might have to do with the feet that the Cio/NoGo task is not primarily thoughtof as a task of assessing attention, however, errors of omission may provide a goodmarker of inattention. Furthermore, another limitation is the fact that we only used

parent-reports of the children s ADHD symptoms to conduct our subgroup analyses.This may have contributed to the lack of strong findings. Lastly, a major limitation to

the study is the fact that there is no 'gold standard' for measuring impulsivity. Sinceimpulsivity is perceived to be a multidimensional construct, it is quite difficult tocompare various methods of measurement. However, laboratory measures such as theGo/No(io might be an optimal and less biased way to isolate and m easure this importantconstruct.

AcknowledgementsThe au tho rs wish to thank th e USC twin proje ct staff for assistanc eLn data collection and scoring,and the twins and their families for their participation in this research. Tiiis study was supported


17/20

Chitdhaod inattention and impulsivity 381

References

Aclicnbach. T M., McConaughy, S. H., & Howell. C, T (1987), Child/adolescent emotional problems: Implications of cross-inibrniant correlations for situationPsychological Bultetin, lOI,213-232.

AvUa. C. Cuenca, I., Felix. V, Parcet. M. A,, & Miranda, A. (2004), Measuring impulaged boys and examining its relationship with ADHD and ODD ratings.yowniaofAbnommtChild Psychology,2, 295-304.

August, G., Realmiito, G. M., MacDonatd, A. W.. Nugent, S. M.. & Crosby, R, (1996)ADHD ami comorbid disorders among elementar)' school children screened behavior,/oMmc//of Ahuortnal Psychology , 24,571-596.

Baker, L. A., Barton, M., Lozano, D, I,, Raine, A.,& Fowler, J. H. (2006). The Southern CalifTwin Register at the University of Southern California: n.Twin Research and HumanGenetics.9(6). 933-994.

Baker, 1., A., Jacobson, K, C, Raine, A., Lozano, D, L, & Bezdjian, S. (2007)environmental bases of antisocial behavior in children: i, A multi-informan

Joumat of Ahnormat Psychology, 116(2),219-235.Baker, D. B., Taylor, C. J., & Leyva, C, (1995). Continuous performance tests: AmoiM tics. Joumat of Clinical Psychology,5 / , 548-551.

Barkley, R. A. (1991), The ecological validity of laboratory and analogue assessmsymptoms. Joumett of Abnormat ChitdPsycholog;}',19, 149-178,

Barkley. R. A. (1997). Behavioral inhibition, sustained attention, and executiConstructing a uniiying tlieory of ADHD.Psychological Bulletin, 121,65-94.

Barra, E. S., & Patton, J. H. (1983). Impulsivity: Cognitive, behavioral, and psyccorrelates. In M. Zuckerman (Ed.),Biotogical bases of sensation seeking, imputsivity aruxieiy ipp. 77-IMl).Hillsdale, NJ: F.ribaum,

Brandeis, D., va Leeuwen, T. H., Rubia, K., Vitacco, D., Steger. J., Pascual-Marquet al.(1998),Neurtielectric mapping reveals precursor of stop failures in children wdeficits.Behat>ioural Brtiiti Research, 94,111-125,

Calkins, S, D, (199-). Origins and outc om es of individual differences in em otion regFox (Ed.), The development of emotion regulation: Biological and behavioral ( pp. 53-72).Monographs of Society for Research I Child Development, 59,US: University oChicago Press.

Campbell, S, B. (1995). Behavior problems in preschool children: A review of rJournal of Child Psychology and Psychiatry, 36,113-149.

Carrillo de ta Pena, M. T., Oter o,J. M,, & Romero, E, (1993). Comparison among variousof assessment of impulsiveness.Perceptual and Motor Skills,77, 567-575 .

Chhalbildas, N., Pennington. B, F, & Willcut, E. G. (2001), A comparineuropsychological profiles of the DSM-IV subtypes of ADHD,foumal of Abnormal ChilPsychology, 29,529-540.

Corkum, P V, & Siegel, L, S. (1993). Is the continuous performance task a valuawith cblldren with attention-deficit hyperactivity disorder?/wma/of Child Psychology andPsychiatry, 34,1217-1239.

DuPaul, G. J., Power, T. J,, Anastopoulos, A, D,, Reid, R., McGoey, K, E,,& Ikeda, M, J, (1990)Teacher ratings of attention-deficit/liyperactivity disorder symptoms: hacnormative data, and psychom etric prop erties.Psychological Assessment, 9,436-444.

Epstein, J. N., Erkanli, A,. Conners, C. K., Klaric, J., Costello, J. E., & Angold, A. (

between continuous performance test performance measures and ADHD behaof Abnormal Child Psychology, 31,543-554.

E d J L (1999) V i ti f i l i itP h h l 146348 361


18/20

382 Sereno Bezdjian et at.

Ha lpe rin,J. iM..Wolf, L. E., Pascualvaca, D. M., New co m , J. H., & Hca!cy,J. M. (1988). Diassessment of attention and impulsivity in children.Joumai of the American Academy ofChild and Adolescent Psychiatry, 27, 326-329.

Halperin, J. M.,Wolf, L. E., Gre enbla tt, E. R., & Young, G- ( 1 9 9 0 Subtype analysis of comerrors on the continuous performance test in children.Developmental Neuropsychoiogy, 7,

207-217.Hinshaw, S. P (1992). Externalizing behavior problems and academic underachiechildhood and adolescence: Causal relationships and underlying mechanisms.PsychologicalBulletin. Ill, 127-155.

Hinshaw, S. P, & Melnick, S. M. (1995). Peer rela tionsh ips in boys with attentihyperactivity disorder with and without comorbid aggression.Development andPsychopathology, 7, 627-647.

Hudziak,J.J., Heath, A. C, Madden, PF.,Reich, W , Bucholz, K. K., Slutske, W ,etal (1998). Latentclass and factor analysis ofDSM-IV ADHD:A twin study of female ado lescents . yoMma/q/"iAmerican Academy of Child and Adolescent Psychiatry. 37.848-857.

Kindlon, D.J.,M ezzacappa, E., & Earls,E (1995). Psycho me tdc p ropertie s of impulsivity m easTem poral stability, validity, and factor s truc ture .Journal of Child Psychology and Psychiatry.3 6 , 6 4 5 - 6 6 1 .

Kochanska, G., Murray, K. T.,& Harlan, E.T. (2000) . Effortful contro l in early childhood: C ontinand change, antecedents, and implications for social development.DevelopmentalPsychology, 36, 220-232.

Kopp,C. B. (1989). Regulation of distress and negative emotions: A developmenDevelopmental Psychology, 25,343-354.

Lahey, B. B., Pelhani, W. E., Stein, M. A., Loney,j . ,Trapani, C, Nugent, K.,et al. (1998). Validity ofDSM-IV attention-deficit/hypen ictivity disorder for young ch ildren. yoMrttfl/of the AmericanAcadefny of Child and Adolescent Psychiatry, 37,695-702.

Lane, S. D., & Cherek, D. R. (2000). Biological and behavioral investigation of aggimpulsivit'. In D. H. Eishbein (Ed.),The science, treatment, and prevention of antisocialbehaiHors: Application to the criminal Justice s}'stem(pp. 5-1 to 5-21). Kingston, NJ: CivicResearch Institute, Inc.

Leth-Steensen, C , Elhaz, Z. K., & Douglas, V. L (2000). Mean respon se time s, variabiliin the responding of ADHD children: A response time distributional approaActaPsychologica. 104. 167-190.

Loeber, R., Green, S. M., Lahey, B. B., & Stouthamer-Locbcr, M. (1989). Optimal infchildhood disruptive behaviors.Development and Psychopathology, I,317-337.

Lyons, M. J., True, W. R.. Eisen, S. A., & Goldberg, J. (1995 ). Differential heritabUity ojuvenile antisocial traits.Archives ofGenerat Psychiatry. 52,906-915.

Marks, D. J., Himerlstein, J., Ne wco m , J. H., & Halperin, J. M. (1999). Identificationsubtypes using laboratory-based measures: A cluster analysis./owrw/of Abnontial ChildPsycholog)'. 27 . 167-175.

Marsh,P. J., & Williams, L. M. (2004). An investigation of individual typologies of attenhyperactivity disorder using cluster analysis of DSM-V criteria.Persona lity and IndividualDifferences, 36, 1187-1195.

MocUer, F. G., Barnitt, E. S., Dougherty, D. M., Schmitz, J. M., & Swann, A. C. (2001)aspects of impulsivity.Anerican Journal of Psychiatry. 158, 1783-1793.

Monahan, J., & Steadman, H- J. (1994).Violence mid mental disorder: Developments in riskassessment. Chicago, IL: The University of Chicago Press.

Ne wc om , J. H., Halperin, J. M., Jensen, P S.,Abikoff, H. B., Arnold, E., & Cantwell, D. P (2001Symptom profiles in children with ADHD: Effects of comorbidity andgender. Journal of theAmerican Academy of Child and Adolescent Psychiatry 40137-146


19/20


20/20

Documents

Assesing intettion and impulsivity in children during the Go/No Go task