The Development of Selective Attention in Children With Attention Deficit Hyperactivity Disorder

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  • P1: VENDOR/GFU/GCZ P2: GDP/GEE/GCQ/FOM/LOV QC: GCQJournal of Abnormal Child Psychology PP114-299976 March 16, 2001 9:26 Style file version July 26, 1999

    Journal of Abnormal Child Psychology, Vol. 29, No. 3, 2001, pp. 229239

    The Development of Selective Attention in Children WithAttention Deficit Hyperactivity Disorder

    Darlene A. Brodeur1;2 and Miranda Pond1

    Received October 22, 1999; revision received May 3, 2000; accepted September 28, 2000

    The influence of age on a selective attention task was studied in a sample of children with and withoutAttention Deficit Hyperactivity Disorder (ADHD). The impact of methylphenidate (MPH) treatmenton selective attention was also investigated in the children with ADHD. Two age groups of childrenwith ADHD and two age groups of control children were tested using a timed computer task. The taskconsisted of identifying visual target stimuli under various distracter conditions. Distracters varied onthe basis of modality (i.e., visual, auditory, or both) and task relevance (i.e., meaningful or irrelevant).Reaction times and accuracy were measured. Children with ADHD were less efficient on the selectiveattention task than were children without ADHD, and older children were more efficient than youngerchildren in both groups. Children without ADHD were influenced more by the nature of distractersthan were children with ADHD. For children with ADHD, MPH improved performance overall.

    KEY WORDS: Selective attention; ADHD; development; methylphenidate.

    INTRODUCTION

    Attention Deficit Hyperactivity Disorder (ADHD)has become a common childhood diagnosis with preva-lence figures ranging from 3 to 7% of the population(Barkley, 1997). Over the years, researchers have attemp-ted to isolate specific attention deficits that may contributeto the overall behavioral pattern associated with ADHD.Selective attention is the process of selecting what is rel-evant to current behavior from our environment whileignoring that that is not (Halperin, 1991). The extent towhich an individual can ignore irrelevant information maybe dependent on a number of factors including age, state ofarousal, visual processing abilities, the nature of the stim-uli, and the presence of any attentional difficulties. Thepresent study was designed to examine the role of ageon selective attention abilities in children with and with-out ADHD, and the impact of drug treatment for childrenwith ADHD.

    1Department of Psychology, Acadia University, Wolfville, Nova Scotia,Canada.

    2Address all correspondence to Darlene A. Brodeur, Department ofPsychology, Acadia University, Wolfville, Nova Scotia, Canada BOP1X0; e-mail: darlene.brodeur@acadiau.ca.

    The Development of Selective Attention

    In examining the nature of selective attention in chil-dren with ADHD, it is necessary to understand how theseabilities develop in children without ADHD. Developmen-tal studies of selective attention have consistently shownthat children between the ages of 3 and 12 years improveconsiderably in their ability to attend selectively (e.g.,DeMarie-Dreblow & Miller, 1988; Enns & Akhtar, 1989;Lane & Pearson, 1982). These results have been consis-tent across various research methodologies, although thepattern of interference effects has not always been foundto be consistent. Although a comprehensive review is notcalled for here, reviews are available (Brodeur, Trick, &Enns, 1997; Plude, Enns, & Brodeur, 1994). To illustratethe approach adopted in the current paper, a developmen-tal study by Enns and Akhtar (1989) will be reviewed insome detail.

    Using the flanker task developed by Eriksen andEriksen (1974), Enns and Akhtar (1989) tested children(aged 47 years) and adults (20 years) on a task that iso-lated several sources of interference. Participants were re-quired to make a forced choice identification response tofour different targets. Two targets were assigned to oneresponse and the others to a second response. Distracter

    2290091-0627/01/0600-0229$19.50/0 C 2001 Plenum Publishing Corporation

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    230 Brodeur and Pond

    items consisted of the four target items as well as items thatwere never part of either response category. Using theseitems Enns and Akhtar were able to manipulate the rela-tionship between the target and the distracters such thatdistracters were either meaningful or irrelevant on anygiven trial with respect to the task of target identification.Meaningful distracters were distracters that appeared astargets on other trials (mapped to an alternate response).Irrelevant distracters only ever appeared as distracters anddid not map onto any response. It was assumed that be-cause meaningful distracters could trigger an inaccurateresponse, they would be more difficult to ignore than irrel-evant distracters. The results of Enns and Akhtars studysuggested, however, an overall improvement with age intask performance, and relatively minimal impact of dis-tracter type in a normative sample of children.

    ADHD and Selective Attention

    The results of selective attention studies on childrenwith ADHD have been mixed. In her review of cogni-tive abilities in children with ADHD, Douglas (1988) listsseveral selective attention tasks on which children withADHD show deficits, and some on which they do not.For example, ADHD children have difficulty inhibiting re-sponses to irrelevant stimuli, and ignoring irrelevant stim-uli, but perform adequately on tasks requiring recall ofspatial locations, and on digit span tasks (Douglas, 1988).

    More recent examples of studies that have reported nodifferences between children with ADHD and typical chil-dren on selective attention tasks include Hooks, Milich,and Lorch (1994) using a speeded classification task, andDalebout, Nelson, Hletko, and Frentheway (1991) usinga selective auditory attention task.

    Recent studies that do report differences in selectiveattention include the investigation by Satterfield, Schell,Nicholas, Satterfield, and Freese (1990) of event-relatedpotentials (ERPs) in boys with and without ADHD, as-sessed while performing visual or auditory selection tasks.Higginbotham and Bartling (1993) also found differenceson a recall task under conditions of auditory and visual dis-traction, although these effects were tempered by the pres-ence of a difference between ADHD and control childrenin the baseline, no distracter condition. Carter, Kerner,Chaderjian, Northcutt, and Wolfe (1995a), however, haveprovided more rigorous evidence of selective attentiondeficits in children with ADHD, using a Stroop color-naming task.

    Differences in the results of studies examining se-lective attention in children with ADHD could easily beattributed to the diversity in methods used to assess the

    construct. Variability in methods is demonstrated by stud-ies that have reported mixed effects depending on the taskparameters employed within a single study. For exam-ple, Ceci and Tishman (1984) found that children withADHD performed worse on selective attention tasks thandid controls, only when task demands were high. The con-trol groups performance remained constant across taskswith high and low demands. Inconsistent deficits were alsoreported by Landau, Lorch, and Milich (1992) who stud-ied the attention of boys with and without ADHD, using atask that required them to watch a television program withand without distraction and subsequently answer ques-tions concerning the programs content. Children withADHD attended less to the television in the presence ofdistraction, but their recall of events was not significantlydifferent from that of the children without ADHD.

    Children with ADHD appear to demonstrate deficitsunder some selective attention conditions but not others.This leads to the following question: Under what condi-tions do children with ADHD demonstrate selective at-tention deficits? This is a difficult question because of themultifaceted nature of selective attention. We argue thatthe best way to approach this issue is through the system-atic investigation of various aspects of selective attentionin both typical and ADHD populations.

    Furthermore, the majority of studies combine chil-dren of various ages into one group. For example, Hookset al. (1994) combined children aged 712 years in onegroup. Shibagaki, Yamanaka, and Furuya (1993) andLandau et al. (1992) both used samples of children be-tween the ages of 6 and 12 combined into a single group.This practice is problematic, given that there is evidencefor developmental change in sustained attention in chil-dren with ADHD (Barkley, Karlsson, Polland, & Murphy,1985), and that selective attention is known to change sig-nificantly with age in normative populations (Plude et al.,1994). The current study attempts to address this issueby narrowing the age ranges in ADHD groups, and bylooking for age differences in ADHD samples.

    The Effects of Methylphenidate (MPH) on Attention

    Psychostimulant medication has become the mostcommonly utilized treatment for children with ADHD,and MPH has become the most commonly prescribedstimulant medication (Greenhill, 1992). Given its preva-lence, it becomes necessary to understand the impact ofthis medication on the various deficits associated withADHD.

    van der Meere, Gunning, and Stemerdink (1999)found no effect of MPH on a GO-NO GO task. A GO-NO

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    Selective Attention in Children With ADHD 231

    GO task is similar to the standard vigilance task in thatit requires participants to respond when presented withone stimulus type and inhibit responding when presentedwith another. Although not necessarily a selective atten-tion task, the version adopted by van der Meere et al.(1999) included the presentation of three stars with eachstimulus type. The position of the stimuli varied from trialto trial. As such, the task included two components of se-lective attention: (1) filtering (the stars) and (2) searchinga display for the relevant item. It is therefore interestingto note that MPH had no influence on the performance ofchildren with ADHD in this task, suggesting MPH maynot influence basic selective or sustained components ofattention or both. This is inconsistent with earlier reports(see Douglas, 1988). For the purposes of the present pa-per it is most relevant to determine whether or not MPHinfluences performance on selective attention tasks.

    Present Study

    The present study was designed to examine threemain questions: (1) Do the selective attention abilities ofchildren with ADHD change with age? (2) How does thenature of the distracting stimulus affect the selective at-tention performance of children with ADHD? (3) DoesMPH influence the performance of children with ADHDon selective attention tasks? Studies have suggested thatthe nature of interference in selective attention is contin-gent upon the task parameters (Ceci & Tishman, 1984). Toexplore the role of various forms of distracters we adoptedthe approach used by Enns and Akhtar (1989) to presentvisual and auditory distracters that varied in the degree oftask relevance to both children with ADHD and typicalchildren.

    The decision to use visual and auditory distracterswas motivated by the lack of an ADHD effect in a studyby Dalebout et al. (1991) that used an auditory task, andthe presence of an ADHD effect on several visual tasks(e.g., Carter et al. 1995a). Also, a study conducted byBedi, Halperin, and Sharma (1994) that included variousachievement measures as well as measures of auditory andvisual focused attention, suggested that distractibility wasmodality-specific and that performance on visual and au-ditory tests was unrelated. Thus, a deficit in one modalitydid not mean a deficit would also be present in the othermodality.

    The task relevance variable was included to assess thebelief that a primary deficit of children with ADHD is inthe ability to inhibit responses (e.g., Malone & Swanson,1993). It was expected that task meaningful distracterswould cause more interference than would irrelevant dis-tracters because they required inhibiting a response.

    To avoid collapsing across a wide age range, in thecurrent study we also included two age groups so thatdevelopmental comparisons could be made. Because de-velopmental work using similar tasks with normative pop-ulations suggests that significant changes occur between4 and 12 years of age (Enns & Akhtar, 1989), age groupswere formed to represent the lower and upper end of thatage range.

    Because most children with ADHD are treated withpsychostimulant medication, it seemed relevant to inves-tigate the impact of such treatment on the selective atten-tion task used in the current study. Children with ADHDwere tested both on- and off-MPH. There seems to belittle evidence that selective attention is influenced byMPH in the same way that more global behaviors are(e.g., van der Meere et al., 1999). The current design alsoallowed for an investigation of the relationship betweendevelopment and MPH treatment on a selective atten-tion task. Although age and MPH have been examinedtogether with regard to their impact on social behaviors(Whalen et al. 1987), the impact on selective attention isunknown.

    METHOD

    Participants

    Fifty-six children (primarily Caucasian) completed avisual attention task. Two groups of children participatedin the study; an ADHD group and a control group thatwas matched with the ADHD group on age, socioeco-nomic status (SES), and male:female ratio. All childrenin the ADHD and control groups were attending school atgrade levels consistent with their age. Family SES was de-termined for each child, using the 1981 socioeconomic in-dex for occupations in Canada (Blishen, Carroll, & Moore,1987).

    The ADHD group consisted of 24 children under-going treatment for ADHD. Participants were recruitedthrough a newsletter advertisement in the Attention DeficitAssociation of Nova Scotia Newsletter. Because the re-cruitment strategy used was community based, records ofassessment were not available to researchers. To ensuresome consistency in our definition of ADHD, we requiredthat all participants have a formal diagnosis of ADHDmade by a registered psychologist. In Nova Scotia, a for-mal diagnosis is defined as a diagnosis based on the crite-ria of the DSM IV (American Psychological Association,1994). Therefore, although all children with ADHD werediagnosed using the same criteria, they were not necessar-ily given the same battery of diagnostic assessments, norwere scores on assessments available.

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    232 Brodeur and Pond

    Twelve (10 males) of the children in the ADHD groupwere in the younger age group. This group had an averageage...

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