research article examining the relative contribution of...

Hindawi Publishing CorporationChild Development ResearchVolume 2013 Article ID 763808 12 pageshttpdxdoiorg1011552013763808

Research ArticleExamining the Relative Contribution of MemoryUpdating Attention Focus Switching and Sustained Attentionto Childrenrsquos Verbal Working Memory Span

Beula M Magimairaj and James W Montgomery

Communication Sciences and Disorders Grover Center W 218 Ohio University Athens OH 45701 USA

Correspondence should be addressed to Beula M Magimairaj magimairohioedu

Received 25 October 2012 Revised 22 January 2013 Accepted 1 February 2013

Academic Editor Cheryl Dissanayake

Copyright copy 2013 B M Magimairaj and J W MontgomeryThis is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Whereas considerable developmental memory research has examined the contributions of short-term memory processingefficiency retention duration and scope of attention to complex memory span little is known about the influence of controlledattention The present study investigated the relative influence of three understudied attention mechanisms on the verbal workingmemory span of school-age children memory updating attention focus switching and sustained attention Results of generallinear modeling revealed that after controlling for age only updating accuracy emerged as a significant predictor of verbal workingmemory span Memory updating speed (that subsumed attention focus switching speed) also contributed but was mediated by ageThe results extend the developmental memory literature by implicating the mechanism of memory updating and developmentalimprovement in speed of attention focus switching and updating as critical contributors to childrenrsquos verbal working memoryTheoretically the results provide substantively new information about the role of domain-general executive attention in childrenrsquosverbal working memory

1 Introduction

Working memory (WM) refers to a limited-capacity systemthat functions to encode store and retrieve informationbeing processed in any cognitive task [1ndash6]Workingmemoryis conventionally measured using complex memory spantasks that are characterized by maintenance of items duringprocessing [7 8] Developmental memory research indicatesthat childrenrsquos WM system comprises the components ofshort-term memory storage processing speed [9ndash11] and acentral executive [2 12ndash20] There are considerable develop-mental data focusing on the influence of storage and pro-cessing speed on childrenrsquos WM [10 13 21ndash24] However fewstudies have directly explored the contribution of attentionmechanisms on WM [25] The present study therefore wasdesigned to directly investigate the contribution of attentionto school-age childrenrsquos verbal WM

Working memory functionally defined as the ability tomanage information storage and retrieval during an ongoingcognitive task requires controlled attention toward bothstorage and processing [13 14 16 19 26ndash29] Individuals withbetter controlled attention are better able than those withpoorer attention to maintain more items while performing acognitive activity [19] Cowan and colleagues have proposedthat WM is defined functionally as the number of informa-tion unitschunks that can be held in the scope of attentionat any given point and attention control allows individuals torapidly bring items from outside the scope of attention backinto the scope of attention [16] Barrouillet and colleagues [1330] have proposed the time-based resource-sharing model(TBRS) in which individuals in a rapid serial fashion switchtheir attention between processing and storage If attentionis captured by processing then it is unavailable for refreshingstorage items

2 Child Development Research

Much of the research addressing the specific aspectsof attention of childrenrsquos WM system has been based onBaddeleyrsquos model of the central executive (ie attentionalsupervisor) which controls the flow of information in WM[2 20 25 31] Overall research suggests that there are severalcentral executive functions important to childrenrsquos WMsystem Researchers have also explored the role of attentionby assessing the effects of cognitive load on childrenrsquos complexmemory span [13 16 17 30 32 33] and dual task performance[34ndash36] While attention functions are associated with chil-drenrsquos WM continued research is required to better under-stand the influential nature of attention onWMperformanceespecially given the fact that attention is a multicomponentconstruct Because attention is a complex construct it isimportant to better understand which components maycontribute to WM performance and which do not Suchunderstanding has two important broad implications Theo-retically such knowledge will advance developmental modelsof WM by incorporating empirically derived componentsof attention There are also clinical implications There isincreasing evidence that executive functions (ie attentionalfunctions) in children may be improved with training [37ndash41] However in evaluating the efficacy and transfer effectsof any WM training it is important to understand whichmechanisms may underlie the transfer [42 43]

11 Role of Attention in Working Memory In current concep-tions of WM there is not only a capacity-limited attentionconstraint that determines the number of items that canbe held in WM but also attention control function(s)which appear to influence the way information is storedand retrieved While attention capacity has been consistentlyindexed as the number of units or ldquochunksrdquo of informationthat can be held in the scope of attention in the absenceof strategies such as rehearsal [16 17 44] attention controlhas been conceptualized in multiple ways for exampleallocation inhibition updating and switching [3 13 17 2021 23 26 29 30 45ndash49]

The present study focused on three attention controlmechanisms memory updating attention switching and sus-tained attention and their relation to childrenrsquos verbal WM(see below) The selection of these mechanisms was stronglymotivated by the embedded process model of Cowan andcolleagues [16 27] and the TBRS model of Barrouillet andcolleagues [13 30] Both models propose that WM per-formance involves selectively updating relevant informationbrought into the focus of attention while ignoring irrelevantinformation that is outside the focus of attention On thisview the focus of attention is analogous to ldquoWM storagerdquoAccording to Cowan the capacity of WM storage reflectswhat can be held in the focus of attention at any givenmoment The TBRS model argues that memory updating(ie updating WM storage) requires the rapid switching ofattention fromprocessing to refresh storage itemsThe notionof attention switching is analogous to Cowanrsquos conceptionof bringing items intoout of the focus of attention Finallysustained attention was included because its role in WMhas not been explored but would seem to be a theoretically

relevant contributor (see below) Results of the presentstudy will provide a better understanding of the relativecontribution of three understudied attention mechanisms onchildrenrsquos verbal WM performance

12 Memory Updating Several memory updating tasks suchas runningmemory span and n-back have been used to indexWM [25 50ndash56] This is because WM performance involvesselectively updating relevant information in the focus ofattention while ignoring irrelevant information Studying theassociation of updating functions in childrenrsquosWM howeverhas seen little empirical evaluation To our knowledge thestudy by St Clair-Thompson and Gathercole [25] is the onlystudy that has evaluated the role of updating along withshifting and inhibition in childrenrsquosWMperformance Lettermemory and keep-track tasks were used as updating mea-sures Results revealed that updating was closely associatedwith childrenrsquos WM performance

13 Attention Focus Switching Attention switching duringcomplex memory span tasks in children was first suggestedby Towse and colleagues [22ndash24] However the relationof attention switching to complex memory span has seenlittle direct empirical investigation Most studies examiningswitching in children have done so with reference to taskswitching and not attention focus switching [57] (In taskswitching participants are assessed for the ability to switchattention between two tasks while focus switching requiresaccurately and rapidly switching the focus of attention acrossdimensions of a given task)There is some evidence that focusswitching and task switching are distinct abilities [58] Thisis an important distinction for the present study because itis attention focus switching which is more relevant to WMperformance

Attention switching in childrenrsquos complex memory spandevelopment has been highlighted in the TBRS model Themodel is rooted in four main assumptions [13 33] First bothprocessing and storage draw on the same limited pool ofattention resources Second only one attention-demandingstep in a complex memory span task can occur at a givenmoment due to an inherent ldquobottleneckrdquo in the use ofcentralattention processes (ie if attention is captured by theprocessing it is unavailable for storage) Third immediatelyupon switching attention away from storage to processingthe stored items suffer activation decay and begin to fade untilrefreshed Fourth attention is shared via rapid continuousswitching between processing and storage As the propor-tion of time for which attention is allocated to processingincreases so does the time required to store the memoryitems increase An increase in storage time in turn leads toan increased probability of the memory traces decaying Inshort the TBRS model proposes that time-based attentioncontrol is a critical determinant of complex memory spanwith attention switching being a crucial mechanism [48]The literature also suggests that attention focus switchingimproves with age in children [59] However the switchingmechanism has neither been measured nor examined in

Child Development Research 3

relation to childrenrsquos complex memory span along with otherattention mechanisms

14 Sustained Attention Sustained attention for purposesof the present study represents the capacity to maintainattention over the course of a given task in the presenceof distracting stimuli It is conventionally measured usingcontinuous performance tasks that are a group of paradigmsthat reflect different but related aspects such as sustainedattention impulsivity and vigilance [60] Developmentalimprovement in sustained attention has been found to berelated to early learning skills IQ language and academicskills [61ndash65]

There are no developmental studies examining the rela-tion of sustained attention and WM However it seems rea-sonable to assess this relation given that sustained attentionis important to other cognitive skills More important brainmechanisms responsible for attention including sustainedattention are also shared byWM [66]Wemight assume thattime-based storage across multiple processing trials requiresvigilance

Studies suggest the involvement of attention control inWM span performance [16 19 20 48 49] However thespecific nature of this control and which specific mechanismsmight subserve WM performance are not yet clear Thepresent study was designed to begin to address this issue

2 Purpose of Present Study and Hypotheses

The purpose of the study was to evaluate the relative contri-butions of memory updating attention focus switching andsustained attention in predicting the verbalWMperformanceof 7- to 11-year-old children We hypothesized that each ofthe three predictors would account for significant variancein childrenrsquos verbal WM performance after adjusting forage Sustained attention should predict WM because wehypothesized that children need sustained attention to pro-cess incoming stimuli which act as distractors while needingtomaintain items to be recalledUpdating and attention focusswitching should emerge as even more robust predictorsbecause it might be argued that the ability to rapidly switchattention from processing to refreshupdate storage itemsthat are outside the focus of attention is at the heart of WMperformance [13 25]

3 Method

31 Participants Sixty-one 7- to 11-year-old typically devel-oping children participated (119872Age = 95 years Range= 7ndash116 years) (This age range was selected because (a)there is evidence of developmental improvements in school-age childrenrsquos verbal WM [17 67] and (b) previous studiessuggest that school-age children demonstrate attention focusswitching skills [13 21 31 33 59 68]) All of the childrendemonstrated normal-range nonverbal IQ (gt85) normal-range hearing sensitivity and normalcorrected vision andpresented no history of any developmental disorders oracademic difficulties All children also passed standardized

language screening (The screening battery consisted ofDevelopmental questionnaire Test of Nonverbal Intelligence[69] Audiometric hearing screening [70] Concepts andDirections and Recalling Sentences subtests of the ClinicalEvaluation of Language Fundamentals-4 [71] Test for Recep-tion of Grammar-2 [72] Peabody Picture Vocabulary Test[73]) Children were seen individually across three to fourtesting sessions each lasting for about an hour with restbreaks

32 Experimental Tasks The three predictor constructs werememory updating attention focus switching and sustainedattention The outcome variable was verbal WM Two mea-sures of each construct were used to derive a robust index ofeach construct [51] Three different counterbalanced ordersof the experimental tasks were created About equal numbersof children completed each order All computerized taskswere created and delivered using E-Prime version 1 [74]Standard demonstration and practice trials were carried outfor all experimental tasks prior to the test trials A compositescore for each construct was created by converting raw scoresfrom individual tasks to 119911 scores and then combining them(Table 1)

321 Memory Updating and Attention Focus Switching Twotasks were developed based on the Garavan paradigm whichinvolved count updating and attention switching [49 75 76]an auditory task and a visual task (Because the memoryupdating and attention focus switching tasks were developedbased on the adult literature various versions of both taskswere piloted on 7- to 8-year-olds and 10- to 11-year-olds todetermine their suitability for children consistency and todetermine stimulus features trial length and ceiling andflooreffects) The Garavan paradigm is based on the proposal thatonly one item can be maintained in the focus of attentionat a time The Garavan proposal with its assumptions ofmemory updating and attention switching is in line with bothCowanrsquos model of WM and the TBRS model of Barrouilletand colleaguesMemory UpdatingAttention Focus Switching TasksStimuliThestimuli for the auditory task consisted of a 250Hztone (500ms) and a 4000Hz tone (500ms) The stimuli forthe visual task consisted of a small red square and a bigred square Each task consisted of a total of 30 test trialsEach trial sequence consisted of 7 to 11 tones or squares withsix trials at each sequence length The order of appearanceof stimuli followed a predetermined order within a trial Arandom sequence length was used across trials The entiretask consisted of six blocks of five trials each

Presentations were switch or nonswitch in nature Ina non-switch presentation the stimulus presented was thesame as the previous one (ie low-pitch tone followed by alow-pitch tone small square followed by a small square) Ina switch presentation the stimulus presented was differentfrom the previous one (ie low-pitch tone followed by a high-pitch tone and vice versa) Approximately one-third (108) ofthe total 270 presentations were switch presentations while


Table 1 Summary of all experimental tasks examined variables and variables used in the model

Task Examined variablesMemory updating-attention focusswitchingAuditory stimuli Overall accuracy (across all 30 trials)

Accuracymdashhigh-frequency trials low-frequency trialsAccuracymdashhigh tones low tonesMean switch cost accuracy (difference in accuracy between high and low frequency trials)Mean switch RT mean non-switch RTMean switch cost RT (difference in RT between switch and non-switch presentations)

Visual stimuli Overall accuracy (across all 30 trials)Accuracymdashhigh-frequency trials low-frequency trialsAccuracymdashbig squares small squaresMean switch cost accuracy (difference in accuracy between high and low frequency trials)Mean switch RT Mean non-switch RTMean switch cost RT (difference in RT between switch and non-switch presentations)

Variables used in the model Composite of 119911 scores of overall accuracy from the two tasksComposite of 119911 scores of mean switch RT from two tasksComposite of 119911 scores of switch cost accuracy from two tasksComposite of 119911 scores of switch cost RT from two tasks

Sustained attentionHit rate (child hits45-total possible hits)

Gordonmdashauditory stimuli False alarm rate (child false alarms495-total possible false alarms)1198891015840prime (difference between 119911 scores of hit and false alarm rates)

Hit rate (child hits45-total possible hits)Gordonmdashvisual stimuli False alarm rate (child false alarms495-total possible false alarms)

1198891015840prime (difference between 119911 scores of hit and false alarm rates)

Variable used in the model Composite 1198891015840prime from auditory and visual 1198891015840prime indicesVerbal working memoryListening span Total trials with accurate digit recall Sentence comprehension accuracy and processing timeCounting span Total trials with accurate count recallVariable used in the model Composite 119911 scores from recall scores on listening and counting span

the remaining two-thirds (162) were non-switch Across the30 trials 15 included high-frequency switches (where 50of the presentations within a trial were switch presentations)while the other half included low-frequency switches (where25 of the presentations within a trial were switch presenta-tions)Procedure Each child was asked to keep count of each typeof stimulus that was heardseen (high tone low tone orbig square small square) The child pressed the space barto deliver each stimulus Each task began with a fixationpoint on the screen for 150 300 or 600ms (random acrosstrials) followed by a stimulus item After the child overtlyupdated the count (eg ldquoone high two lowrdquo or ldquothree big foursmallrdquo) heshe pressed the space bar for the next stimulusThe child was instructed to be as fast and accurate as possiblein updating the counts and as fast as possible pressing the

space bar At the end of each trial the computer screen turnedgreen cueing the child to verbally report each count

Four dependent variables were derived [49 77 78]Variable 1 was count accuracy indexing memory updatingA score of 1 was given for every trial where both countswere recalled correctly a score of 5 was given if one ofthe two was correct and 0 if neither were correct Countaccuracy on high- and low-frequency switch trials was alsocomputed The second and third variables were RT basedRT was defined as the time taken to update each count (iethe time between the onset of one space bar press to thenext space bar press) Variable 2 was updating speed thatis speed of count updating on switch presentations Variable3 was switch cost RT the difference between the mean RTbetween switch and non-switch presentations (Switch costRT used in the study was based on all trials irrespective of


the frequency of switches Switch cost RT was also computedseparately for high-frequency and low-frequency switch trialsbut not used in the modeling because (a) there was nosignificant difference in the switch cost RT between high-versus low-frequency trials on the visual focus switching taskthat involved updating counts of squares (b) overall cost ofswitching attention was of primary interest and (c) switchcost RTs by frequency did not contribute new or uniquefindings to the existingmodel and its conclusions) Variable 4was switch cost accuracy the difference in accuracy betweenhigh-frequency and low-frequency switch trials

322 Sustained Attention Childrenrsquos ability to sustain atten-tion was assessed using two continuous performance subtestsof the Gordon Diagnostic System a commercially availabletest [79] Continuous performance tests measure sustainedattention using stimulus repetition and task duration as keytask design features [80]Sustained Attention Tasks

Stimuli Stimuli consisted of a random series of numbersbetween 1 and 9 presented from the Gordon box Each digitwas presented for 400ms with a silence of 600ms separatingeach digit

Procedure In the auditory task the child listened to a malespeaker saying a series of numbers and pressed a button eachtime heshe heard the number sequence ldquo1 9rdquo In the visualtask the child saw a series of digits on the screen and pressedthe button each time heshe saw the sequence ldquo1 9rdquo Thechild was not provided any feedback during the task Theprimary dependent variable was 1198891015840 prime (ie the differencebetween 119911 scores of hit rate and false alarm rate) [81 82] 1198631015840prime indexes the ability to distinguish target stimuli fromnontarget stimuli

323 Verbal Working Memory Span Complex memory spantasks are the most commonly used measures to index WMcapacity Verbal WM span was assessed using conventionallistening span and counting span tasks

Listening Span Task The listening span task was a revisedversion of the span task used by Magimairaj et al [83]Children were presented sets of sentences (auditorily) andasked to comprehend the meaning of each sentence andremember a digit presented immediately after the last wordof each sentence [21]

Stimuli The task consisted of syntactically simple 8-wordsubject-verb-object (SVO) structures for which 6- to 12-year-old children show very good comprehension (93 orhigher eg [84ndash86]) All of the words in the sentenceswere high-familiarity words [87 88] The task consisted ofa total of 40 sentences ranging from two-sentence sets tosix-sentence sets (order of presentation by set size 4 3 62 5) (List length was not incremental from two- to six-sentence sets to avoid childrenrsquos expectancies that the taskwould get incrementally harder which could likely influence

their motivation [51]) The sentences were read at a normalrate sim 44 syllablessecond [89] and with normal prosodicvariation by a male speaker

There were two trials at each set size Half of the sentencesrequired a ldquoYesrdquo response and half required a ldquoNordquo responseFor the ldquoNordquo sentences the sentence was false because ofa semantic violation (eg The cat saw the house that washopping) Immediately following each YesNo response amonosyllabic number between one and ninewas heardwhichwas to be remembered for later recall No sentence-finalnumber was repeated within a set

Procedure The child sat in front of the computer monitorresting hisher elbow on a soft pad and was instructed toplace hisher middle finger tips of hisher dominant handon the ldquo+rdquo that appeared in the middle of the screen Thechild was told that heshe would hear a man saying somegroups of sentences and heshe would need to do two things(1) respond to the truth value of each sentence (ie whetherthe sentence reflected an event that could occur in real life)by touching the word ldquoyesrdquo or ldquonordquo on the touch screen asquickly as possible after the sentence ended and (2) at theend of the set (cued by the screen turning green) recall asmany of the sentence-final numbers in the set as possible inserial order As soon as the child responded to the sentence anumber was presented Immediately following the numberthe experimenter presented the next sentence (Presentingeach sentence immediately after the digit was intended toprevent the child from rehearsing the numbers betweensentence trials While stimulus presentations in this studywere based on Conway et al [51] recent studies in thememory literature suggest that better time control of theprocessing episode is obtained by fixing the total processingtime allowed (see [13 14])) The primary dependent variablewas total trials for which the child correctly recalled thesentence-final numbers Sentence comprehension accuracyand processing timewere also examined Processing timewascalculated as the difference between sentence offset andwhenthe child made hisher response Any response occurringbefore sentence offset was scored a false alarm

Counting Span TaskA computerized adaptation of the count-ing recall subtest from the Working Memory Test Battery forChildren [90] was the second WM task Children were askedto count arrays of dots presented on a computer screen onearray at a time After a set of arrays was counted the childrecalled the total count from each array in serial order whichdetermined the counting span of the child Because there wasa verbal component to this task we considered it a verbalWMtask

Stimuli Stimuli consisted of arrays of dots with each arrayranging between four and sevenThe dots (85 px in diameter)were red and appeared on a white background Before eacharray was presented a fixation point ldquo+rdquo appeared on thescreen for 100ms Arrays ranged from one to six arrays Ateach array length there were six trials The selection of arraylength had a predetermined order (4 3 6 2 5)


Procedure The child sat in front of the computer screen andwas instructed to point to and count each dot aloud oneach array while at the same time keeping the total countof each previous array in memory for later recall The childwas instructed to count aloud to ensure heshe was countingeach dot thereby allocating attention to the ldquoprocessingrdquocomponent of the task After the child counted the dots onall successive arrays the screen turned green and the childrecalled the total from each array The task was discontinuedif the child incorrectly recalled the totals on four trials at anygiven array length

For each trial recalled accurately and in the correct orderthe child was allotted a score of 1 The maximum possiblescore was 36 (credit was given for array length 1 though itwas not administered unless there was a failure at length2) Occasionally if a child made an error in counting therespective count reported was regarded as the number to berecalled

4 Data Preparation

On the updating and attention focus switching tasks therewere missing data for one child due to inability to completethe task For accuracy of less than 50 on count updating oneither high- or low-frequency switch trials three childrenrsquosdata were excluded from analyses The remaining childrenrsquosRT data for switch and nonswitch presentations (on auditoryand visual tasks) for high- versus low-frequency trials wereseparated This procedure yielded four separate RT data setseach for high- versus low-frequency trials Each RT dataset was trimmed in two phases based on the approach byFriedman and Miyake [91] First arbitrary lower and uppercut-off criteria were established by visual inspection Thecriteria turned out to be the same across RT data sets (ie500ms 10 s) All RTs below 500ms and above 10 s wereremoved to prevent extreme RTs from influencing the meanBased on observational notes during testing these extremeRTs occurred due to rare interruptions In the second phasemeans and standard deviations were computed for eachchildrsquos RT data set obtained after the first trimming phaseOutlier RTs plusmn3 SD from the mean were removed Usingthis cut-off range (plusmn3 SD) during data trimming ensuredthat useful data points representing the childrenrsquos switching-updating timeswere not lost as validated by considerable pilotdata In each phase less than 2 of the RTs were removedfrom each data set (It is to be noted that the updating andattention focus switching tasks were not designed to take intoaccount accuracy on each presentation or individual updaterather count accuracy reported at the end of the trial wasthe outcome Therefore no RTs were designated as incorrectresponses All responses were considered valid since nochildren performing at or below chance were included inthe analyses Of interest was overall response time on switchversus non-switch presentations)

5 Results

51 Preliminary Analyses (Diagnostic measures such as his-togram of errors studentized residuals and Cookrsquos distance

were used to examine for cases that might fall far fromthe regression equation There were no outliersinfluentialcasesThis indicated that the assumptions for the model weresatisfied and the conclusions obtained from the model couldbe endorsed Collinearity statistics (tolerance and varianceinflation factor) indicated that there was no multicollinear-ity)

511 Descriptive Statistics Final descriptive statistics for eachexperimental task as well as unitary outcomes indexingpredictor and outcome constructs are summarized in Table 2Item reliability on all tasks was found to be good On updat-ing and attention focus switching there was a significantdifference between accuracy on low- versus high-frequencyswitch trials with poorer accuracy on high-frequency switchtrials for the auditory task (119872LF = 1267 119878119863 = 177 119872HF= 1096 119878119863 = 276) t(59) = 775 119901 lt 01 and visual task(119872LF = 13 119878119863 = 159 119872HF = 1185 119878119863 = 232) t(60) =510 119901 lt 01 For the auditory task mean switch RT (119872119890119886119899 =337229ms 119878119863 = 90818) was significantly longer thanmeannon-switch RT (119872119890119886119899 = 261473ms 119878119863 = 68836) t(59) =1420 and 119901 lt 01 Likewise for the visual task mean switchRT (119872119890119886119899 = 322951ms 119878119863 = 85224) was significantlylonger thanmean non-switch RT (119872119890119886119899 = 248213ms 119878119863 =65455) t(60) = 1390 119901 lt 01 There was no significantdifference in count accuracy for the two different stimuli (iehigh versus low tones or big versus small squares) within eachswitching task (119901 gt 05)

512 Correlation Analyses Correlation analyses revealedthat childrenrsquos performance on all of the attention measures(sustained attention memory updating and attention focusswitching) and verbal WM span tasks improved with age(119901 lt 01) Partial correlations (controlling for age) betweenall experimental measures were also significant (see Table 3)

52 Primary Adjusted Analyses General linear modeling(GLM) was used for model estimation with verbal WMspan score as the dependent variable The predictor variablesrepresenting updating (count accuracy) updating speed onswitch (indexing both switching speed and updating speed)attention focus switching (switch cost accuracy and switchcost RT) sustained attention (overall1198891015840 prime) and age as thecovariate were all entered into the model (Speech rate whichwas relevant particularly to the updating and attention focusswitching task was also measured for use as a covariate for allthe children However it was observed that speech rate wasnot a useful covariate as it was already associated with ageThat is evenwithout speech rate in themodel the relationshipof the predictors to verbal WM span in the presence of ageremained unchanged Speech rate was thus disregarded fromany further analyses and discussion) Univariate analysis ofvariance revealed that all the predictors including age jointlyexplained 57 of the variance in verbal WM span score F(652) = 1169 1198772 = 57 119901 lt 01 (Table 4)

Analysis of individual parameter estimates revealed thatin the presence of age and all the predictors only updatingaccuracy contributed significantly to unique variance in


Table 2 Descriptive statistics for all experimental tasks (119873 = 61)

Measure M SD Range Reliabilitylowast

Memory updating and attention focus switchingUpdating A (Overall acc) 2361 (79) 430 16ndash30 83Switch cost accuracymdashA 170 170 minus100ndash800Updating V (Overall acc) 2489 (83) 357 18ndash30 84Switch cost accuracymdashV 115 175 minus250ndash650Updating accuracy 042 181 minus450ndash292Switch cost accuracy minus018 159 minus252ndash412A

Mean switch RT 337229 90818 156089ndash535518 97Mean non-switch RT 261473 68836 129822ndash475665 98Mean switch cost RT 75756 41317 minus686ndash178291

VMean switch RT 322951 85224 147302ndash526223 98Mean non switch RT 248213 65455 140259ndash422909 98Mean switch cost RT 74738 41992 minus9742ndash169239

Updating speed on switch minus028 191 minus406ndash451Switch cost RT minus014 171 minus321ndash339Sustained attentionGordonmdashA (hits) 3654 (81) 618 15ndash45 851198891015840prime (119911 score) minus009 100 minus372ndash140

GordonmdashV (hits) 4131 (92) 416 19ndash45 851198891015840prime (119911 score) minus007 100 minus555ndash88

Overall 1198891015840prime minus016 171 minus758ndash227Verbal working memory (WM) spanListening span (recall accuracy) 2595 (65) 670 11ndash40 85Counting span (recall accuracy) 2307 (64) 450 11ndash32 87Verbal WM span 000 171 minus380ndash480A auditory stimuli V visual stimuli RT reaction time lowastCronbachrsquos alpha coefficient of reliability Outcomes in bold font represent unitary measures obtainedby combining 119911-scores from the two separate tasks used for each construct

Table 3 Bivariate and partial correlations between composite 119911 scores of all experimental outcomes and age (119873 = 61)

Variables (1) (2) (3) (4) (5) (6) (7)(1) Age 1 463lowastlowast minus310lowast minus651lowastlowast minus468lowastlowast 380lowast 528lowastlowast

(2) Updating accuracy 1 minus651lowastlowast minus727lowastlowast minus666lowastlowast 452lowastlowast 697lowastlowast

(3) Switch cost accuracy minus603lowastlowast 1 508lowastlowast 420lowast minus430lowast minus465lowastlowast

(4) Updating speed on switch minus632lowastlowast 424lowast 1 694lowastlowast minus611lowastlowast minus677lowastlowast

(5) Switch cost RT minus574lowastlowast 327lowast 581lowastlowast 1 minus441lowastlowast minus485lowastlowast

(6) Sustained attention (1198891015840prime) 337lowast minus355lowast minus518lowastlowast minus322lowast 1 469lowastlowast

(7) Verbal working memory span 601lowastlowast minus373lowast minus517lowastlowast minus317lowast 342lowast 1lowastlowastCorrelation is significant at 120572 = 01 (2 tailed) lowastCorrelation is significant at 120572 = 05 (2 tailed) Values below the diagonal represent partial correlations aftercontrolling for age

verbal WM 119861 = 469 F(1 52) = 976 119901 lt 01 For everyone unstandardized unit increase in the accuracy of updatingthe increase in childrenrsquos verbalWM span score was 469 (seeTable 4) When age was removed from the model updatingspeed also emerged as a significant predictor (119901 lt 05) alongwith memory updating accuracy

6 Discussion

Controlled attention has been emphasized in the WM lit-erature [2 4 15 20 92] but its role has not been clearlyspecified [31 93]There appear to be two reasons for this lackof specificity First attention is a multimechanism construct


Table 4 General linear model table of primary adjusted analyses predicting verbal working memory span performance using the predictorvariables updating accuracy updating speed on switch switch cost accuracy switch cost RT and1198891015840prime (sustained attention) in the presenceof age

Variables in the model 11986195 confidence interval

119865 119901Lower bound Upper bound

Age 019 minus008 046 194 170Updating accuracy 469 168 770 976 003Updating speed on switch minus225 minus543 092 203 160Switch cost accuracy 025 minus234 285 038 845Switch cost RT 129 minus134 392 964 3311198631015840prime 097 minus141 334 668 417119865(6 52) = 11691198772 = 57 119901 lt 01 When age was removed from themodel updating speed on switch also emerged as a significant predictor along with accuracyof updating 119865(5 53) = 1341 1198772 = 56 119901 lt 05

Determining which mechanism(s) are relevant to specificcognitive activities requires careful theoretical and empiricalexamination Second deployment of specific mechanismsdepends on the nature of the cognitive task [20 31 93] Weexamined three attention mechanisms (memory updatingattention focus switching and sustained attention) and theirrelation to childrenrsquos verbal WM performance We selectedthese mechanisms because of their theoretical relevance

61 Influence ofMemoryUpdating andAttention Focus Switch-ing on Verbal WM Span First performance patterns similarto those reported in the previous literature were obtained inthe present study regarding memory updating and attentionfocus switching [25 59] Even the youngest children (7-yearsold) were able to perform memory updating and attentionswitching but they were slower doing so than their oldercounterparts as evidenced by the significant correlationbetween age and updating speed

With respect to explaining verbal WM span the resultsclearly showed that accuracy of memory updating but notspeed of memory updating is a critical determinant ofchildrenrsquos WM span That memory updating accuracy wasa significant contributor to the childrenrsquos WM performanceresonates well with the recent adult literature Recall thatthe adult literature also argues that the ability to accuratelyupdate memory with the correct item brought into the focusof attention plays an important role in WM performance [1317 26 49 94ndash96] Also recall that more recent formulationsof WM emphasize that retrieval of contents in WM involvesswitching attention from items that are already in the focusof attention to those that are currently activated but needretrieving so they might be brought back into the focus ofattention [13 26 94 95 97 98]

That childrenrsquos accuracy of memory updating and notspeed of updating is a robust predictor of verbal WM per-formance is consistent with findings reported in the literature[49] Similar to theUnsworth andEngle [49] study secondaryanalyses in the present study showed that controlling for agethere was a linear relationship between speed of updating (onboth non-switch and switch presentations) and accuracy ofmemory updating (119903 = minus427 119901 lt 001 and 119903 = minus632119901 lt 001 resp) That is children who were more accurate to

update were also faster to update A speed-accuracy tradeoffthus was not responsible for reducing the impact of updatingspeed on childrenrsquos verbal WM performance

Like adults [49] the children demonstrated switch costsan index of attention focus switching The childrenrsquos meanswitch RTs were longer than their mean non-switch RTsThisfinding suggests that retrieving an item already in the focusof attention is less attention demanding than retrieving anitem outside the current focus of attention In conventionalWM span tasks such as those used in the present studythe processing activity and the items to be recalled areinterleaved with each other During processing executiveattention resources are invoked and in order to refresh itemsto be recalled there is a need to switch attention from theprocessing activity to storage in order to refresh those itemsThat is during processing the items to be recalled lie justoutside the focus of attention and hence they need to bebrought back into the focus of attention to be refreshed forrecall

Accuracy of updating also suffered as the demand forfrequent attention switches increased suggesting that morefrequent switching of attention is disruptive to childrenrsquosmemory updating processThis is in linewith studies suggest-ing that increasing the pace of the processing component orcontrolling processing time onWM tasks (eg [13]) disruptsthe switching process making children more vulnerable toerrors (ie children may switch to the incorrect element)and preventing more retrievals Increasing such disruptionstherefore places a burden on the attention switching processand thus leads to poorer WM performance

Shared variance could be one of the factors that causedspeed of updating to be nonsignificant in the presence of theother predictors Faster updating speedwas closely associatedwith greater updating accuracy (indirectly reducing theretention interval during which decay was possible) whichwas in turn related to verbal WM span Finally without agein the model both updating accuracy and updating speedcontributed unique variance to WM in the presence of allother predictors These findings suggest that there are age-related improvements in updating speed that contribute tobetter verbal WM performance

Switch cost variables were included in the model torepresent the attention switching construct over and above


updating accuracy and updating speed Switch cost accuracyrepresented the difference in accuracy between high- andlow-frequency switch trials Switch cost RT reflected thedifference in response time between switch versus nonswitchpresentations Neither switch cost variable contributed anyunique variance to verbal WM span in the presence of theother predictors Switch cost RTmay have failed to contributeunique variance because of its shared variance with updatingspeed

That the switch cost variables did not contribute uniquevariance to verbal WM performance has important impli-cations for current models of developmental WM Whileaccuracy of memory updating is closely associated withverbal WM performance attention switching per se is notThese findings first suggest that attention focus switchingis in and of itself an incomplete contributor to verbal WMperformance Rather it is what the WM system does rightafter the switch which is more important namely updatememory with a proper count Age-related improvements inmemory updating speed subsumed both speed of switchingto an item outside the focus of attention and the ability toupdate memory following a switch Therefore with regard toswitching it is primarily the age-related improvement in thespeed of switching andmemory updatingwhich contribute todevelopmental verbal WM performance These findings aretimely given the emphasis on attention switching in severalWM models [13 14 26 49 58 99] in that relative to theswitching mechanism the memory updating mechanism is amore robust predictor of childrenrsquos verbal WM performanceThe role of attention switching is primarily mediated by thejoint age-related improvement in speed of switching andspeed of memory updating

62 Influence of Sustained Attention on Verbal WM SpanWe hypothesized that sustained attention should be requiredover the course of each processing and retrieval episodeacross multiple trials of the WM tasks Results of the GLMshowed that contrary to our hypothesis sustained attentionfailed to contribute any unique variance to verbal WM spaneven though it was linearly related to span Item recall thusappears to predominantly require a refreshing mechanism toreactivate items in memory Thus attention refreshingitemupdating seems to be more functionally equivalent to atten-tion focus switching [13] than sustained attention

To further examine the weak relation of sustained atten-tion to verbal WM span partial correlations between sus-tained attention and each of the two measures of WM werecomputed Controlling for age sustained attention (compos-ite score) correlated significantly with counting span (119903 =462119901 lt 001) but not with listening span (119903 = 111119901 gt 05)The differential correlation pattern may reflect the nature ofthe unique processing demands of each task The countingspan task may have instantiated sustained attention given therapid and continuous nature of its processing activity Recallthat the children were presented in rapid succession differentseries of dots on the computer screen with the requirementof having only to count (and remember) the number ofdots on each screen The pace of the task was rather quick

with each new screen of dots being presented immediatelyafter the child finished counting The continuous and fluidnature of each trial may have invited significant vigilanceBy contrast it might be argued that the listening span taskwas performed in a less continuous ldquofluidrdquo fashion Thechildren heard sets of sentences and judged the truth valueof each one Making a correct response entailed multipleand different processes including comprehending the inputsentence making a semantic-pragmatic evaluation of its real-world meaning and performing a motor response The taskstructure and performance demands may have elicited agreater use of attention mechanisms other than sustainedattention for example switching inhibition

The interpretation that the nature of the processingepisode may influence the attention control processes usedis consistent with recent arguments put forth in the WMliterature [100] For instance Towse and Cowan [100] haveargued that complex memory span tasks are multifacetedand that attention control functions could be involved indifferent ways in different WM tasks For example readingspan involves more inhibitory mechanisms while operationspan with word recall invokes greater controlled attentionsince the processing and storage elements are distinct [100]The relation of WM span to cognition is thus complex[101] and therefore the use of multiple tasks and latentvariable analyses to assess WM is recommended [51] Theabove finding is also important because it speaks to theissue of WM training in children Recent studies report thatexecutive functions can be improved with training [37ndash41]Better understanding attention mechanisms of WM allowsfor better understanding of (a) aspects that may or may notimprove with training and (b) what aspects may transfer toother cognitive skills based on the nature of the tasks usedduring training and while evaluating transfer effects [43]

7 Conclusion

Thepurpose of the studywas to investigate the relative contri-butions of memory updating attention focus switching andsustained attention to childrenrsquos verbal WM performanceMemory updating accuracy emerged as the single uniquepredictor of verbal WM span Memory updating speed(that included attention focus switching speed) also wasa contributor but was mediated by age However neitherattention focus switching as indexed by switch cost nor sus-tained attention played a significant role in explaining verbalWM performance in the presence of the other predictorsOverall results support the view that children employ activeattention mechanisms to facilitate WM performance (eg[102]) Understanding the relative contribution of attentionmechanisms allows for convergence of theoretical models ofWM better understanding of the predictive value of WMto higher-order cognition and explaining improvements ordeficits in childrenrsquos WM

Acknowledgments

The authors are grateful to all the parents and children whoparticipated in the study This study was made possible by


a Graduate Student Scholarship from the American Speech-Language and Hearing Foundation The authors also wish tothank Naveen Nagaraj for assistance with programming

References

[1] R C Atkinson and R M Shiffrin ldquoThe control of short-termmemoryrdquo Scientific American vol 225 no 2 pp 82ndash90 1971

[2] A Baddeley ldquoWorking memory and language an overviewrdquoJournal of Communication Disorders vol 36 no 3 pp 189ndash2082003

[3] N Cowan Attention and Memory An Integrated FrameworkOxford University Press New York NY USA 1995

[4] R Engle M Kane and S Tuholski ldquoIndividual differencesin working memory capacity and what they tell us aboutcontrolled attention general fluid intelligence and functions ofthe prefrontal cortexrdquo in Models of Working Memory Mecha-nisms of Active Maintenance and Executive Control A Miyakeand P Shah Eds pp 102ndash134 Cambridge University PressCambridge UK 1999

[5] MA Just andPACarpenter ldquoA capacity theory of comprehen-sion individual differences in working memoryrdquo PsychologicalReview vol 99 no 1 pp 122ndash149 1992

[6] G Miller E Gallanter and K Pribram Plans and the Structureof Behavior Holt New York NY USA 1960

[7] R Case DMKurland and J Goldberg ldquoOperational efficiencyand the growth of short-term memory spanrdquo Journal of Exper-imental Child Psychology vol 33 no 3 pp 386ndash404 1982

[8] M Daneman and P Carpenter ldquoIndividual differences inworking memory and readingrdquo Journal of Verbal Learning andVerbal Behavior vol 19 pp 450ndash466 1980

[9] D M Bayliss C Jarrold D M Gunn and A D Baddeley ldquoThecomplexities of complex span explaining individual differencesin working memory in children and adultsrdquo Journal of Experi-mental Psychology vol 132 no 1 pp 71ndash92 2003

[10] D M Bayliss C Jarrold D M Gunn A D Baddeley andE Leigh ldquoMapping the developmental constraints on workingmemory span performancerdquo Developmental Psychology vol 41no 4 pp 579ndash597 2005

[11] R Case Intellectual Development Birth to Adulthood AcademicPress New York NY USA 1985

[12] P Barrouillet and V Camos ldquoDevelopmental increase in work-ingmemory span resource sharing or temporal decayrdquo Journalof Memory and Language vol 45 no 1 pp 1ndash20 2001

[13] P Barrouillet N Gavens E Vergauwe V Gaillard and VCamos ldquoWorking memory span development a time-basedresource-sharing model accountrdquo Developmental Psychologyvol 45 no 2 pp 477ndash490 2009

[14] P Barrouillet S Portrat andVCamos ldquoOn the law relating pro-cessing to storage in working memoryrdquo Psychological Reviewvol 118 no 2 pp 175ndash192 2011

[15] A R A Conway and R W Engle ldquoIndividual differences inworkingmemory capacity more evidence for a general capacitytheoryrdquoMemory vol 4 no 6 pp 577ndash590 1996

[16] N Cowan E M Elliott S J Saults et al ldquoOn the capacity ofattention its estimation and its role in working memory andcognitive aptitudesrdquo Cognitive Psychology vol 51 no 1 pp 42ndash100 2005

[17] N Cowan C C Morey A M Aubuchon C E Zwilling andA L Gilchrist ldquoSeven-year-olds allocate attention like adults

unless working memory is overloadedrdquo Developmental Sciencevol 13 no 1 pp 120ndash133 2010

[18] N Gavens and P Barrouillet ldquoDelays of retention processingefficiency and attentional resources in working memory spandevelopmentrdquo Journal of Memory and Language vol 51 no 4pp 644ndash657 2004

[19] M J Kane A R A Conway M K Bleckley and R W EngleldquoA controlled-attention view of working-memory capacityrdquoJournal of Experimental Psychology vol 130 no 2 pp 169ndash1832001

[20] A Baddeley ldquoExploring the central executiverdquo Quarterly Jour-nal of Experimental Psychology A vol 49 no 1 pp 5ndash28 1996

[21] B Magimairaj and J Montgomery ldquoChildrenrsquos verbal workingmemory relative importance of storage general processingspeed and domain-general controlled attentionrdquo Acta Psycho-logica vol 140 pp 196ndash207 2012

[22] J N Towse and G J Hitch ldquoIs there a relationship betweentask demand and storage space in tests of working memorycapacityrdquoThe Quarterly Journal of Experimental Psychology Avol 48 no 1 pp 108ndash124 1995

[23] J N Towse G J Hitch and U Hutton ldquoA re-evaluation ofworking memory capacity in childrenrdquo Journal of Memory andLanguage vol 39 no 2 pp 195ndash217 1998

[24] J N Towse G J Hitch and U Hutton ldquoOn the nature of therelationship between processing activity and item retention inchildrenrdquo Journal of Experimental Child Psychology vol 82 no2 pp 156ndash184 2002

[25] H L St Clair-Thompson and S E Gathercole ldquoExecutive func-tions and achievements in school shifting updating inhibitionand working memoryrdquo The Quarterly Journal of ExperimentalPsychology vol 59 no 4 pp 745ndash759 2006

[26] P Barrouillet and V Camos ldquoWorking memory and executivecontrol a time-based resource-sharing accountrdquo PsychologicaBelgica vol 50 no 3-4 pp 353ndash382 2010

[27] N Cowan ldquoAn embedded-process model of working memoryrdquoin Models of Working Memory Mechanisms of Active Mainte-nance and Executive Control A Miyake and P Shah Eds pp62ndash101 Cambridge University Press Cambridge UK 1999

[28] R W Engle J Cantor and J J Carullo ldquoIndividual differencesin workingmemory and comprehension a test of four hypothe-sesrdquo Journal of Experimental Psychology vol 18 no 5 pp 972ndash992 1992

[29] M L Turner andRW Engle ldquoIs workingmemory capacity taskdependentrdquo Journal ofMemory and Language vol 28 no 2 pp127ndash154 1989

[30] P Barrouillet S Bernardin and V Camos ldquoTime constraintsand resource sharing in adultsrsquo workingmemory spansrdquo Journalof Experimental Psychology vol 133 no 1 pp 83ndash100 2004

[31] C Zoelch K Seitz and R Schumann-Hengsteler ldquoFromrag(bag)s to riches measuring the developing central exec-utiverdquo in Young Childrenrsquos Cognitive Development Inter-Relationships among Executive Functioning Working MemoryVerbal Ability andTheory of Mind W Schneider R Schumann-Hengsteler and B Sodian Eds pp 39ndash70 Lawrence ErlbaumAssociates Mahwah NJ USA 2005

[32] N Cowan L D Nugent E M Elliott I Ponomarev and J SSaults ldquoThe role of attention in the development of short-termmemory age differences in the verbal span of apprehensionrdquoChild Development vol 70 no 5 pp 1082ndash1097 1999

[33] S Portrat V Camos and P Barrouillet ldquoWorking memoryin children a time-constrained functioning similar to adultsrdquo


Journal of Experimental Child Psychology vol 102 no 3 pp368ndash374 2009

[34] H Irwin-Chase and B Burns ldquoDevelopmental changes inchildrenrsquos abilities to share and allocate attention in a dual taskrdquoJournal of Experimental Child Psychology vol 77 no 1 pp 61ndash85 2000

[35] C Karatekin ldquoDevelopment of attentional allocation in the dualtask paradigmrdquo International Journal of Psychophysiology vol52 no 1 pp 7ndash21 2004

[36] C Karatekin J W Couperus and D J Marcus ldquoAttentionallocation in the dual-task paradigm as measured throughbehavioral and psychophysiological responsesrdquo Psychophysiol-ogy vol 41 no 2 pp 175ndash185 2004

[37] A Diamond ldquoActivities and programs that improve childrenrsquosexecutive functionsrdquoCurrentDirections in Psychological Sciencevol 21 no 5 pp 335ndash341 2012

[38] K Ebert J Rentmeester-Disher andK Kohnert ldquoNonlinguisticcognitive treatment for bilingual children with primary lan-guage impairmentrdquo Clinical Linguistics and Phonetics vol 26pp 485ndash501 2012

[39] T Klingberg E Fernell P J Olesen et al ldquoComputerizedtraining of working memory in children with ADHDmdasha ran-domized controlled trialrdquo Journal of the American Academy ofChild andAdolescent Psychiatry vol 44 no 2 pp 177ndash186 2005

[40] H St Clair-Thompson R Stevens A Hunt and E BolderldquoImproving childrenrsquos working memory and classroom perfor-mancerdquo Educational Psychology vol 30 no 2 pp 203ndash219 2010

[41] L B Thorell S Lindqvist S B Nutley G Bohlin and TKlingberg ldquoTraining and transfer effects of executive functionsin preschool childrenrdquo Developmental Science vol 12 no 1 pp106ndash113 2009

[42] Z Shipstead T S Redick and R W Engle ldquoDoes workingmemory training generalizerdquo Psychologica Belgica vol 50 no3-4 pp 245ndash276 2010

[43] Z Shipstead T Redick and R Engle ldquoIs working memorytraining effectiverdquo Psychological Bulletin vol 138 pp 628ndash6542012

[44] N Cowan J Rouder C Blume and J Saults ldquoModels of verbalworking memory capacity what does it take to make themworkrdquo Psychological Review vol 119 no 3 pp 480ndash499 2012

[45] E Awh E K Vogel and S H Oh ldquoInteractions betweenattention andworkingmemoryrdquoNeuroscience vol 139 no 1 pp201ndash208 2006

[46] A R A Conway and R W Engle ldquoWorking memory andretrieval a resource-dependent inhibition modelrdquo Journal ofExperimental Psychology vol 123 no 4 pp 354ndash373 1994

[47] L Hasher C Lustig and R Zacks ldquoInhibitory mechanisms andthe control of attentionrdquo in Variation in Working Memory AConway C Jarrold M Kane A Miyake and J Towse Eds pp227ndash249 Oxford University Press New York NY USA 2007

[48] R Lepine S Bernardin and P Barrouillet ldquoAttention switchingand working memory spansrdquo European Journal of CognitivePsychology vol 17 no 3 pp 329ndash345 2005

[49] N Unsworth and RW Engle ldquoSpeed and accuracy of accessinginformation in working memory an individual differencesinvestigation of focus switchingrdquo Journal of Experimental Psy-chology vol 34 no 3 pp 616ndash630 2008

[50] N Morris and D Jones ldquoMemory updating in workingmemory the role of the central executiverdquo British Journal ofPsychology vol 81 pp 111ndash121 1990

[51] A R A Conway M J Kane M F Bunting D Z HambrickO Wilhelm and R W Engle ldquoWorking memory span tasks amethodological review and userrsquos guiderdquo Psychonomic Bulletinand Review vol 12 no 5 pp 769ndash786 2005

[52] W K Kirchner ldquoAge differences in short-term retention ofrapidly changing informationrdquo Journal of Experimental Psychol-ogy vol 55 no 4 pp 352ndash358 1958

[53] J F Mackworth ldquoPaced memorizing in a continuous taskrdquoJournal of Experimental Psychology vol 58 no 3 pp 206ndash2111959

[54] I Pollack L B Johnson and P R Knaff ldquoRunning memoryspanrdquo Journal of Experimental Psychology vol 57 no 3 pp 137ndash146 1959

[55] N C Waugh ldquoSerial position and the memory-spanrdquo TheAmerican Journal of Psychology vol 73 pp 68ndash79 1960

[56] F Schmiedek A Hildebrandt M Lovden O Wilhelm and ULindenberger ldquoComplex span versus updating tasks of workingmemory the gap is not that deeprdquo Journal of ExperimentalPsychology vol 35 no 4 pp 1089ndash1096 2009

[57] N J Cepeda A F Kramer and J C Gonzalez de SatherldquoChanges in executive control across the life span examinationof task-switching performancerdquoDevelopmental Psychology vol37 no 5 pp 715ndash730 2001

[58] P Verhaeghen andW JHoyer ldquoAging focus switching and taskswitching in a continuous calculation task evidence toward anewworkingmemory control processrdquoAging Neuropsychologyand Cognition vol 14 no 1 pp 22ndash39 2007

[59] D A Pearson and D M Lane ldquoAuditory attention switching adevelopmental studyrdquo Journal of Experimental Child Psychologyvol 51 no 2 pp 320ndash334 1991

[60] J Egeland and I Kovalik-Gran ldquoMeasuring several aspects ofattention in one test the factor structure of connersrsquos continuousperformance testrdquo Journal of Attention Disorders vol 13 no 4pp 339ndash346 2010

[61] R A Hanson and J W Montgomery ldquoEffects of general pro-cessing capacity and sustained selective attention on temporalprocessing performance of children with specific languageimpairmentrdquo Applied Psycholinguistics vol 23 no 1 pp 75ndash932002

[62] L B Jones M K Rothbart and M I Posner ldquoDevelopmentof executive attention in preschool childrenrdquo DevelopmentalScience vol 6 no 5 pp 498ndash504 2003

[63] T Manly V Anderson I Nimmo-Smith A Turner P Watsonand I H Robertson ldquoThe differential assessment of childrenrsquosattentionTheTest of Everyday Attention for Children (TEA-Ch)normative sample and ADHD performancerdquo Journal of ChildPsychology and Psychiatry and Allied Disciplines vol 42 no 8pp 1065ndash1081 2001

[64] M Noterdaeme H Amorosa K Mildenberger S Sitter andF Minow ldquoEvaluation of attention problems in children withautism and children with a specific language disorderrdquo Euro-pean Child and Adolescent Psychiatry vol 10 no 1 pp 58ndash662001

[65] T J Spaulding E Plante and R Vance ldquoSustained selectiveattention skills of preschool children with specific languageimpairment evidence for separate attentional capacitiesrdquo Jour-nal of Speech Language and Hearing Research vol 51 no 1 pp16ndash34 2008

[66] J Jonides S C Lacey and D E Nee ldquoProcesses of workingmemory inmind and brainrdquoCurrent Directions in PsychologicalScience vol 14 no 1 pp 2ndash5 2005


[67] S E Gathercole ldquoCognitive approaches to the development ofshort-term memoryrdquo Trends in Cognitive Sciences vol 3 no 11pp 410ndash419 1999

[68] R Morris ldquoRelationships and distinctions among the conceptsof attention memory and executive function a developmentalperspectiverdquo in Attention Memory and Executive FunctionG Lyon and N Krasnegor Eds pp 11ndash16 Paul H BrookesBaltimore Md USA 1996

[69] L Brown R Sherbenou and S Johnsen Test of NonverbalIntelligence-3 Pro-ed Austin Tex USA 1997

[70] American Speech-Language-Hearing Association Guidelinesfor Audiologic Screening [Guidelines] 1997 httpwwwashaorgpolicy

[71] E Semel E Wiig and W Secord Clinical Evaluation ofLanguage Fundamentals-4 The Psychological Corporation SanAntonio Tex USA 2003

[72] D Bishop Test for Reception of Grammar-2 The PsychologicalCorporation London UK 2003

[73] L Dunn and L Dunn Peabody Picture Vocabulary Test 3American Guidance Service Circle Pines Minn USA 1997

[74] W Schneider A Eschmann and A Zuccolotto E-Prime UserrsquosGuide Psychology Software Tools Pittsburgh Pa USA 2002

[75] HGaravan ldquoSerial attentionwithinworkingmemoryrdquoMemoryand Cognition vol 26 no 2 pp 263ndash276 1998

[76] H Garavan T J Ross S J Li and E A Stein ldquoA parametricmanipulation of central executive functioningrdquoCerebral Cortexvol 10 no 6 pp 585ndash592 2000

[77] M C Davidson D Amso L C Anderson and A DiamondldquoDevelopment of cognitive control and executive functionsfrom 4 to 13 years evidence from manipulations of memoryinhibition and task switchingrdquo Neuropsychologia vol 44 no11 pp 2037ndash2078 2006

[78] M Huizinga and M W van der Molen ldquoTask switching andshifting between stopping and going developmental changein between-trial control adjustmentsrdquo Journal of ExperimentalChild Psychology vol 108 no 3 pp 484ndash503 2011

[79] M Gordon FMcClure andG AylwardTheGordonDiagnosticSystem Instructional Manual and Interpretive Guide GordonSystems New York NY USA 3rd edition 1996

[80] C Riccio C Reynolds and P Lowe Clinical Applicationsof Continuous Performance Tests Measuring Attention andImpulsive Responding in Children John Wiley amp Sons NewYork NY USA 2001

[81] D M Green and J A Swets Signal Detection Theory andPsychophysics John Wiley amp Sons New York NY USA 1966

[82] R E Pastore and C J Scheirer ldquoSignal detection theoryconsiderations for general applicationrdquo Psychological Bulletinvol 81 no 12 pp 945ndash958 1974

[83] B Magimairaj J Montgomery S Marinellie and J McCarthyldquoRelation of threemechanisms of workingmemory to childrenrsquoscomplex span performancerdquo International Journal of BehavioralDevelopment vol 33 no 5 pp 460ndash469 2009

[84] J R Booth B MacWhinney and Y Harasaki ldquoDevelopmentaldifferences in visual and auditory processing of complex sen-tencesrdquo Child Development vol 71 no 4 pp 981ndash1003 2000

[85] F Dick B Wulfeck M Krupa-Kwiatkowski and E Bates ldquoThedevelopment of complex sentence interpretation in typicallydeveloping children compared with children with specificlanguage impairments or early unilateral focal lesionsrdquo Devel-opmental Science vol 7 no 3 pp 360ndash377 2004

[86] BMacWhinney ldquoBasic syntactic processesrdquo inLanguageAcqui-sition S Kuczaj Ed vol 1 of Syntax and Semantics pp 73ndash122Erlbaum Hillsdale NJ USA 1982

[87] M J Cortese andMM Khanna ldquoAge of acquisition ratings for3000 monosyllabic wordsrdquo Behavior Research Methods vol 40no 3 pp 791ndash794 2008

[88] AMoe C Hopkins and R RushTheVocabulary of First-GradeChildren Thomas Springfield Ill USA

[89] S E Weismer and L J Hesketh ldquoThe influence of prosodic andgestural cues onnovelword acquisition by childrenwith specificlanguage impairmentrdquo Journal of Speech and Hearing Researchvol 36 no 5 pp 1013ndash1025 1993

[90] S Pickering and S GathercoleWorkingMemory Test Battery forChildren The Psychological Corporation London UK 2001

[91] N P Friedman and A Miyake ldquoThe relations among inhibitionand interference control functions a latent variable analysisrdquoJournal of Experimental Psychology vol 133 no 1 pp 101ndash1352004

[92] RW Engle J E Laughlin SW Tuholski and A R A ConwayldquoWorking memory short-term memory and general fluidintelligence a latent-variable approachrdquo Journal of ExperimentalPsychology vol 128 no 3 pp 309ndash331 1999

[93] J Towse and C Houston-Price ldquoReflections of the concept ofthe central executiverdquo in Working Memory in Perspective JAndrade Ed pp 240ndash260 Psychology Press New York NYUSA 2001

[94] N Cowan ldquoEvolving conceptions of memory storage selectiveattention and their mutual constraints within the humaninformation processing systemrdquo Psychological Bulletin vol 104no 2 pp 163ndash191 1988

[95] B McElree ldquoWorking memory and focal attentionrdquo Journal ofExperimental Psychology vol 27 no 3 pp 817ndash835 2001

[96] N Unsworth and R W Engle ldquoOn the division of short-termand working memory an examination of simple and complexspan and their relation to higher order abilitiesrdquo PsychologicalBulletin vol 133 no 6 pp 1038ndash1066 2007

[97] K Oberauer ldquoAccess to information in working memoryexploring the focus of attentionrdquo Journal of ExperimentalPsychology vol 28 no 3 pp 411ndash421 2002

[98] K Oberauer ldquoSelective attention to elements in working mem-oryrdquo Experimental Psychology vol 50 no 4 pp 257ndash269 2003

[99] P Verhaeghen and C Basak ldquoAgeing and switching of the focusof attention in working memory results from a modified N-Back taskrdquoTheQuarterly Journal of Experimental Psychology Avol 58 no 1 pp 134ndash154 2005

[100] J Towse andN Cowan ldquoWorkingmemory and its relevance forcognitive developmentrdquo in Young Childrenrsquos Cognitive Develop-ment Inter-Relationships among Executive FunctioningWorkingMemory Verbal Ability and Theory of Mind W Schneider RSchumann-Hengsteler and B Sodian Eds pp 9ndash38 LawrenceErlbaum Associates Mahwah NJ USA 2005

[101] J May ldquoSpecifying the central executive may require complex-ityrdquo inWorking Memory in Perspective J Andrade Ed pp 261ndash277 Psychology Press New York NY USA 2001

[102] V Gaillard P Barrouillet C Jarrold and V Camos ldquoDevelop-mental differences in working memory where do they comefromrdquo Journal of Experimental Child Psychology vol 110 no3 pp 469ndash479 2011

Submit your manuscripts athttpwwwhindawicom

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Much of the research addressing the specific aspectsof attention of childrenrsquos WM system has been based onBaddeleyrsquos model of the central executive (ie attentionalsupervisor) which controls the flow of information in WM[2 20 25 31] Overall research suggests that there are severalcentral executive functions important to childrenrsquos WMsystem Researchers have also explored the role of attentionby assessing the effects of cognitive load on childrenrsquos complexmemory span [13 16 17 30 32 33] and dual task performance[34ndash36] While attention functions are associated with chil-drenrsquos WM continued research is required to better under-stand the influential nature of attention onWMperformanceespecially given the fact that attention is a multicomponentconstruct Because attention is a complex construct it isimportant to better understand which components maycontribute to WM performance and which do not Suchunderstanding has two important broad implications Theo-retically such knowledge will advance developmental modelsof WM by incorporating empirically derived componentsof attention There are also clinical implications There isincreasing evidence that executive functions (ie attentionalfunctions) in children may be improved with training [37ndash41] However in evaluating the efficacy and transfer effectsof any WM training it is important to understand whichmechanisms may underlie the transfer [42 43]

11 Role of Attention in Working Memory In current concep-tions of WM there is not only a capacity-limited attentionconstraint that determines the number of items that canbe held in WM but also attention control function(s)which appear to influence the way information is storedand retrieved While attention capacity has been consistentlyindexed as the number of units or ldquochunksrdquo of informationthat can be held in the scope of attention in the absenceof strategies such as rehearsal [16 17 44] attention controlhas been conceptualized in multiple ways for exampleallocation inhibition updating and switching [3 13 17 2021 23 26 29 30 45ndash49]

The present study focused on three attention controlmechanisms memory updating attention switching and sus-tained attention and their relation to childrenrsquos verbal WM(see below) The selection of these mechanisms was stronglymotivated by the embedded process model of Cowan andcolleagues [16 27] and the TBRS model of Barrouillet andcolleagues [13 30] Both models propose that WM per-formance involves selectively updating relevant informationbrought into the focus of attention while ignoring irrelevantinformation that is outside the focus of attention On thisview the focus of attention is analogous to ldquoWM storagerdquoAccording to Cowan the capacity of WM storage reflectswhat can be held in the focus of attention at any givenmoment The TBRS model argues that memory updating(ie updating WM storage) requires the rapid switching ofattention fromprocessing to refresh storage itemsThe notionof attention switching is analogous to Cowanrsquos conceptionof bringing items intoout of the focus of attention Finallysustained attention was included because its role in WMhas not been explored but would seem to be a theoretically

relevant contributor (see below) Results of the presentstudy will provide a better understanding of the relativecontribution of three understudied attention mechanisms onchildrenrsquos verbal WM performance

12 Memory Updating Several memory updating tasks suchas runningmemory span and n-back have been used to indexWM [25 50ndash56] This is because WM performance involvesselectively updating relevant information in the focus ofattention while ignoring irrelevant information Studying theassociation of updating functions in childrenrsquosWM howeverhas seen little empirical evaluation To our knowledge thestudy by St Clair-Thompson and Gathercole [25] is the onlystudy that has evaluated the role of updating along withshifting and inhibition in childrenrsquosWMperformance Lettermemory and keep-track tasks were used as updating mea-sures Results revealed that updating was closely associatedwith childrenrsquos WM performance

13 Attention Focus Switching Attention switching duringcomplex memory span tasks in children was first suggestedby Towse and colleagues [22ndash24] However the relationof attention switching to complex memory span has seenlittle direct empirical investigation Most studies examiningswitching in children have done so with reference to taskswitching and not attention focus switching [57] (In taskswitching participants are assessed for the ability to switchattention between two tasks while focus switching requiresaccurately and rapidly switching the focus of attention acrossdimensions of a given task)There is some evidence that focusswitching and task switching are distinct abilities [58] Thisis an important distinction for the present study because itis attention focus switching which is more relevant to WMperformance

Attention switching in childrenrsquos complex memory spandevelopment has been highlighted in the TBRS model Themodel is rooted in four main assumptions [13 33] First bothprocessing and storage draw on the same limited pool ofattention resources Second only one attention-demandingstep in a complex memory span task can occur at a givenmoment due to an inherent ldquobottleneckrdquo in the use ofcentralattention processes (ie if attention is captured by theprocessing it is unavailable for storage) Third immediatelyupon switching attention away from storage to processingthe stored items suffer activation decay and begin to fade untilrefreshed Fourth attention is shared via rapid continuousswitching between processing and storage As the propor-tion of time for which attention is allocated to processingincreases so does the time required to store the memoryitems increase An increase in storage time in turn leads toan increased probability of the memory traces decaying Inshort the TBRS model proposes that time-based attentioncontrol is a critical determinant of complex memory spanwith attention switching being a crucial mechanism [48]The literature also suggests that attention focus switchingimproves with age in children [59] However the switchingmechanism has neither been measured nor examined in








3 Method




































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7 Conclusion


Acknowledgments




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Volume 2014


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3 Method




































4 Data Preparation


5 Results

























6 Discussion























7 Conclusion


Acknowledgments




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Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal



































4 Data Preparation


5 Results

























6 Discussion























7 Conclusion


Acknowledgments




References



















































































































Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal























6 Discussion























7 Conclusion


Acknowledgments




References



















































































































Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal


























7 Conclusion


Acknowledgments




References



















































































































Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal







References



















































































































Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal





















































































Psychiatry Journal



















Volume 2014


AddictionJournal of




Geography Journal





research article examining the relative contribution of...

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