This study evaluated the impact of a computerized visuospatial memory training intervention on the memory and behavioral skills of children with Down syndrome. Teaching assistants were trained to support the delivery of a computerized intervention program to individual children over a 10–16 week period in school. Twenty-one children aged 7–12 years with Down syndrome were randomly allocated to either an intervention or waiting list control group. Following training, performance on trained and non-trained visuospatial short-term memory tasks was significantly enhanced for children in the intervention group. This improvement was sustained four months later. These results suggest that computerized visuospatial memory training in a school setting is both feasible and effective for children with Down syndrome.
Down syndrome is one of the most common causes of intellectual disability, affecting 1 in 690 live births (Parker et al., 2010). It has been estimated that there were 83,400 children and adolescents with Down syndrome living in the United States in 2002 (Shin, Besser, Kucik, Lu, Siffel, & Correa, 2009). It is additionally associated with significant delays and difficulties in verbal short-term memory (STM) development (Jarrold, Baddeley, & Phillips, 1999), language (Miller, 1999), and speech (Roberts, Stoel-Gammon, & Barnes, 2008). Establishing effective interventions to reduce these cognitive difficulties is a priority in order to provide evidence-based education and therapy for individuals with Down syndrome.
Working memory (WM), the multicomponent cognitive system responsible for the temporary storage of information during complex mental activities, plays a key role in learning (e.g., Gathercole & Alloway, 2008), and deficits in WM are present in many cognitive and genetic neurodevelopmental disorders, including Down syndrome. The most enduring model of WM originally proposed by Baddeley and Hitch (Baddeley, 2000; Baddeley & Hitch, 1974) includes specialized systems for the storage and maintenance of verbal and visuospatial information: the phonological loop/verbal STM and the visuospatial sketchpad / visuospatial STM, respectively. It also includes a domain-general central executive system that is associated with attentional control and supervises the flow of information between the storage systems and long-term memory. Differential performance on tasks designed to assess the verbal and visuospatial storage components of WM provides evidence for a more severe deficit in verbal STM than visuospatial STM in Down syndrome (Jarrold, Purser, & Brock, 2006). This aspect of WM plays a vital role in language acquisition, particularly during new word learning (Baddeley, Gathercole, & Papagno, 1998) and the development of grammar (Wang & Bellugi, 1994). It also correlates with reading ability in typically developing individuals (Swanson & Jerman, 2007) and in those with Down syndrome (Fowler, Doherty, & Boynton, 1995). Although it is common for verbal STM deficits to be reported in children with Down syndrome, it is important to remember that any relative strength in nonverbal / visuospatial aspects of WM do not reflect spared functioning. Rather, the disparity between functioning in verbal and visuospatial domains occurs in comparison with the general level of mild–moderate intellectual disability that individuals present with, and individuals with Down syndrome do indeed have impairments in both verbal and nonverbal WM tasks relative to chronological age-matched individuals (Kay-Raining Bird & Chapman, 1994).
Interventions designed to target the memory difficulties associated with Down syndrome typically focus on improving verbal memory skills by training children to use techniques such as verbal rehearsal (e.g., Broadley & MacDonald, 1993; Comblain, 1994; Connors, Rosenquist, Arnett, Moore, & Hume, 2008). These methods have shown moderate success in boosting verbal STM, but often the improvements are not significant, are not sustained over time, and do not transfer to other cognitive skills. More recently, research with typically developing children has demonstrated that providing direct training on memory tasks improves performance on both trained and non-trained memory measures in both the verbal and visuospatial domains (e.g., Holmes, Gathercole, & Dunning, 2009; Jaeggi, Buschkuehl, Jonides, & Shah, 2011; Klingberg et al., 2005). Programs that appear to be most effective are those that are involve intense repeated practice, specifically on WM tasks that adapt to an individual's current ability level.
One such program that has a growing evidence base is Cogmed Working Memory Training (CWMT). In this program, individuals train intensively over several weeks on computerized adaptive WM tasks that are embedded within a game-style environment. Several studies have now shown positive training effects with children using this program. Klingberg et al. demonstrated significant improvements in both verbal and visuospatial STM, as well as in inhibitory control and nonverbal reasoning in children with ADHD following training (Klingberg et al., 2005; Klingberg, Forssberg, & Westerberg, 2002). These findings have been replicated and extended in children with ADHD and children with poor WM skills without ADHD, in both cases taking the majority of children from memory performance in the deficit range to that well within, and in many cases exceeding, age-appropriate levels across all aspects of WM (Holmes et al., 2009; Holmes, Gathercole, Place, Dunning, Hilton, & Elliott, 2010). These gains were sustained after a delay of six months for both groups. Most recently, CWMT was evaluated with a small group (N = 9) of children who were hard of hearing, aged 7–15, and had cochlear implants (CI) (Kronenberger, Pisoni, Hennings, Gehrlein, & Hazzard, 2011). Children with CI often have shorter WM spans than typically developing children of the same age, which may be linked to delays in speech and language functioning (Pisoni et al., 2008). Significant improvements in verbal, visuospatial, and sentence STM were reported for this group following training.
Based on the success of CWMT in boosting memory skills in a wide range of developmental groups, the aim of the current study was to investigate whether it could be used to reduce the memory difficulties associated with Down syndrome. Children with Down syndrome typically have mild to moderate intellectual disability and often have mental ages equivalent to much younger children (for example an eight year old will have an approximate mental age of a four year old). Therefore, any training program or intervention has to be tailored to the appropriate mental age. Because the majority of the previous studies with CWMT have been conducted with children aged seven years and older, we conducted a small pilot study to establish whether children of the same age with Down syndrome could cope with the demands of the standard form of the memory training program. Our pilot work with five children aged 7–10 years indicated that the majority of the tasks in CWMT were too difficult (e.g., backward digit recall task starting at a span of two items was impossible for nearly all of the children) and that the standard training session that should take approximately 30 minutes at baseline took 50 minutes, which was too challenging. On the basis of this data, it was decided that the preschool version of CWMT, Junior Cogmed Working Memory Training (JCWMT), which was developed for use with typically developing (TD) preschool children, would be a more appropriate intervention to trial. JCWMT includes only visuospatial memory training activities but has been shown to improve verbal as well as visuospatial memory skills at outcome in TD preschool children (Thorell et al., 2009).
It is hypothesized that training will result in improved performance on the trained tasks contained within JCWMT, as well as other non-trained WM tasks, and that these improvements will be dose dependent, such that improvements will be directly related to amount of time spent training on the activities (Jaeggi et al., 2011). WM is one of a collection of skills known as executive functions (EF), which enable us to cope with changing task demands and solve problems. Other EFs include inhibition, cognitive flexibility, and planning (see Pennington & Ozonoff, 1996, for a review). Very little is known about the development of other EFs in Down syndrome, but parent ratings of these behaviors as measured by the Behavior Rating Inventory of Executive Function (BRIEF-P, Gioia, Espy, & Isquith, 2003) suggest children with Down syndrome have elevated problems in the areas of WM, planning, inhibition, and shifting (Raitano et al., 2011). A further aim of this study is to assess whether benefits to WM following training might transfer to improvements in parent ratings of these behaviors in children with Down syndrome. The specific aims of this study were to (i) evaluate the feasibility of using JCWMT with children with Down syndrome, (ii) investigate whether training leads to improvements in non-trained tasks of both verbal and visuospatial STM and WM, and (iii) establish whether training leads to any changes in parent ratings of behavior.
Following ethical approval, informed written consent from one caregiver was obtained for all participating children and agreement to participate was also obtained from each child's head teacher, class teacher, and Special Educational Needs Coordinator (SENCo). Children were randomly allocated to either an intervention group or waiting list control group, and caregivers, schools, and school staff who were supporting the implementation of the training program were informed of group allocation (i.e., were not blind to the condition children were in). Arrangements were made to install the training software on the school computers and to train SENCos / teaching assistants (TAs) how to use the program and support the children through the training. The CWMT tasks were initially trialed (using the CWMT demonstration mode) to all participants by the same researcher in school with the SENCo/TA present to ensure that all children and staff understood the nature of the training program and what was expected of them. Children in both the intervention and waiting list control groups completed a set of pre-assessments (t1). Children in the intervention group began training within three weeks of these assessments. Training lasted approximately 10–12 weeks. During this time, children in the waiting list control group continued with their normal education. Within two weeks of completing the training the intervention group completed a set of postassessments (t2), which they completed again at follow up (t3) four months after training had ceased. After approximately 16 weeks of no intervention from t1, the waiting list controls completed a set of postassessments (t2) to allow for comparison of intervention versus no intervention. These assessment scores also served as baseline measures for the waiting list control group, who then commenced training. They were assessed again (t3) within two weeks of completing training.
Twenty-five children with Down syndrome were recruited. They were aged between 7 and 12 at the start of the study (M = 9∶6, SD = 1∶11) and had a mental age (MA) of between four and seven years (M = 5.5, SD = 1.01), as assessed by the Kaufman Brief Intelligence Test (KBITII; Kaufman & Kaufman, 2004). Children were recruited from the South of England across five counties, Sussex, Surrey, Hampshire, Middlesex, and Hertfordshire. All of the children were able to operate a computer mouse effectively and had normal or corrected-to-normal vision and normal or corrected-to-normal hearing. One child from the 25 was considered not suitable for JCWMT as he was unable to remember a sequence of two items (the start sequence level of JCWMT). He was excluded from the study. The remaining 24 children were randomly allocated to one of two groups: intervention or waiting list control. One child did not complete the training program due to staff illness, one child did not complete the program due to preexisting behavioral difficulties (noncompliance with school tasks in general), and one school had technical difficulties that prevented them from delivering the program. Data was therefore analyzed for 21 children, and Figure 1 displays additional information about the recruitment process and timeframe for delivery of the intervention and assessments.
There were six males in the intervention group and five males in the waiting list control group. Ten children in the intervention group and eight children in the waiting list control group attended a mainstream school. A series of Multiple Analysis of Variance (MANOVA) analyses confirmed that the two groups of children did not significantly differ at baseline with regards to chronological age or measured mental age (see Table 1).
Pre- and Postassessments
All children completed a set of assessments at t1, t2, and t3. The assessments lasted approximately 45 minutes and were identical across testing sessions. The Kaufman Brief Intelligence test (K-BITII; Kaufman & Kaufman, 2004) was used to measure verbal and nonverbal IQ at baseline. It provides both standardized scores and age equivalents. WM was assessed at each time point using the Automated Working Memory Assessment (AWMA; Alloway, 2007). The AWMA is a computerized test battery that assesses four different aspects of WM and has been standardized for use with typically developing children aged four and above. Four subtests were administered, one for each aspect of WM; a test of verbal STM (word recall), verbal WM (counting recall), visuospatial STM (dot matrix), and visuospatial WM (odd one out). The word recall task required the children listen to and recall a series of single words in the correct order (no visual support). The counting recall task required the children to count shapes presented on a computer screen and then recall the number of shapes they had counted when the shapes had disappeared from the screen. The dot matrix task required the child to remember a sequence of dots presented in a matrix on the computer screen and tap them out in the correct order on a blank matrix on the screen at recall. The odd one out task involved the presentation of three objects on screen in a horizontal line (left, middle, or right). Two of the shapes were identical and one was different. The child was required to select the shape that was different and then recall the location of that object (left, middle, or right) by pointing to the correct locations on screen when the three objects disappeared. All of the memory tasks started at a span level of one (one item of information to remember) and moved to the next span level, increasing by one storage item per span when the child got four correct answers (administration would discontinue if the child got three trials incorrect at a particular span level).
Parents completed the Behavior Rating of Executive Function—Preschool Version (BRIEF-P, Gioia et al., 2003) at t1, t2, and t3; this is a standardized measure of behaviors related to executive function for children of preschool age. Parents rate their child's typical behavior against a set of statements describing different behaviors on a three point scale: 1 = Never, 2 = Sometimes, 3 = Never. This measure enables standardized scores to be calculated for the following subscales: inhibition, shift, emotional control, working memory, and planning/organize. Inhibition measures the ability to inhibit responses and avoid engaging in impulsive behavior (e.g., “acts sillier or wilder than others in groups”). Shift measures the child's ability to move freely from situations or tasks (e.g., “becomes upset with new situations”). Emotional control measures the ability to regulate emotions appropriate to the situation (e.g., “overacts to small problems”). WM measures the ability to hold information in mind and stick with an activity (e.g., “makes silly mistakes on things he or she can do”). Planning/organize measures the ability to anticipate future events or consequences (e.g., “when instructed to clean up, put things away in a disorganized random way”).
The WM training program, JCWMT, consists of seven different computerized visuospatial memory training tasks. Each task involves the temporary storage (and sometimes manipulation) of visuospatial sequences, e.g., bumper cars that move around the screen and light up one at a time that have to be subsequently recalled in serial order by the participant who clicks with the computer mouse on the cars on screen. Four of the seven tasks involved only the storage of visual information (pool, hotel, rollercoaster, twister) two involved both manipulating and storing visual information (Ferris wheel, bumper cars), and one incorporated the storage of auditory information alongside visual information (wheel of animals). In each training session participants completed three of the seven training activities. Every five days one of the training tasks was replaced with a new task to maintain the child's interest. Each training task took approximately 6–10 minutes to complete, meaning each completed session lasted for approximately 25 minutes. There were several motivational features in the program, which included frequent positive verbal feedback, the accumulation of stars after every correct trial, and after every completed session the child received an item for their virtual fish tank, e.g., a fish, a boat, or some seaweed. Every participant completed 25 training sessions, totaling 75 tasks. Children were encouraged to complete all three training activities for a session on the same day, but they were allowed to carry over their performance to the next day (data was saved ready for when the child logged on next). Training was carried out with support from each child's TA or SENCO at school in a quiet room to minimize distractions. The TA was required to provide continuous feedback and support during the training. On average, training took place three times a week and was completed within 10–12 weeks (including Christmas or Easter vacation time). The research team maintained contact with the schools throughout the training period via weekly telephone calls and were able to monitor training performance via the Cogmed Training Web to ensure fidelity of the intervention. The Cogmed Training Web enabled the research team to remotely review each child's usage and progress on the program. External rewards were given to each child by their TA after every five training sessions or approximately every two weeks. These external rewards varied by child and school but included activities such as extra play time, stationery items, or access to a particular toy or game.
There were no significant (p < .05) differences in STM/WM or behavior ratings at baseline between groups, see Table 1. The approaching significant difference in shift scores (p = .06) should be noted, as this is relevant for later discussion.
Improvements on Trained Tasks
Performance on the trained tasks, the total number of tasks trained, and the total amount of time spent training for both groups are shown in Table 2.
Overall, children completed 92% of the program, which took an average of 8.62 hours over a period of 13 weeks (including vacation time). The Cogmed Index of Improvement (CII), which is calculated by the software automatically, provides a measure of overall improvement on the trained tasks. It is the difference between the mean span score of the first three training sessions and the highest span achieved at any point in the training period. The CII is reported for both groups in Table 2 and shows that on average they improved by 14 points. The mean start span score and highest span score during training is reported by group of children for each of the seven training tasks individually in Table 3. There was a similar pattern of improvement across all the seven tasks, with children on average having a span of three items at the start of training and finishing with a span of four.
Non-Trained Memory Tasks
Mean scores for the non-trained AWMA measures at all three assessment times are presented in Table 4. All analyses reported are for raw scores because the Automated Working Memory Assessment (AWMA) does not provide standardized scores lower than 60 and the majority of the children in this sample scored below this cutoff. Children in the intervention group showed significant improvements pre- to post-training (t1 to t2) for both visuospatial memory tasks: visuospatial STM (p = .04, d = 0.59) and visuospatial WM (p = .03, d = 0.83). These gains were sustained at four-month follow up (see Figure 2). There were no significant improvements for verbal STM or WM (again, see Table 4).
There were no significant improvements for the waiting list control group between t1 and t2 without training (all ps > .05); however, there was a significant decrease in verbal WM (p = .03, d = 0.34). A 2 × 2 Analysis of Variance (ANOVA) (with time of test and group entered) established a significant group by time interaction for visuospatial STM at t2, F(1, 19) = 6.29, p = .02, Iη2 p = .25, indicative of significantly greater gains in visuospatial STM for the intervention group who underwent training than the waiting list control group who did not receive the intervention at this stage (see Figure 2).
Improvements in visuospatial STM following training for the intervention group were replicated by the waiting list controls when they completed training between t2 and t3 (p = .01, d = 0.70), but there were no significant gains in visuospatial WM or verbal WM. There was also a significant increase in verbal STM scores for this group following training (p = .04, d = 0.67), but in the absence of a control group it is not possible to rule out practice effects.
Executive Function (EF)
Parent ratings on the Behavior Rating of Executive Function—Preschool Version (BRIEF-P, Gioia et al., 2003) are provided in Table 4. These scores were standardized using the norms given for TD of children aged 4 years to 5 years 11 months (the average MA in this sample was 5 years 5 months). All mean scores for both groups for all of the BRIEF-P subscales were lower at t2 than at t1. Children in the intervention group showed significant improvements pre- to post-training (t1 to t2) for both shift; (p = < .001, d = 1.22) and WM (p = .04, d = 0.46). These gains were sustained at four month follow up. There were no significant improvements for the waiting list control group between t1 and t2 in inhibition, shift, emotional control, and planning/organize (all ps > .05); however, there was a significant improvement in WM for this group (p = .03, d = 0.31). There were no significant group by time interactions for the five subscales of the BRIEF-P, as shown by a series of 2 × 2 ANOVAs (with time of test and group entered, all ps >.05, refer to Table 4 for values). Significant improvements in shift or WM following training for the intervention group were not replicated by the waiting list controls after they had completed training, and there were no significant improvements on the other three BRIEF-P subscales.
Overall, gains on the non-trained WM tasks following CWMT were not significantly related to the number of training tasks completed, chronological or mental age, or IQ (all ps > .05), but the relationship between gains in non-trained visuospatial STM and the number of tasks completed (r = .36, p = .06, N = 21, one tailed) approached significance. Data was collapsed across both groups to explore whether gains on the trained measures were related to age and verbal and performance IQ (see Table 5). Table 5 shows that improvement on the trained tasks (as measured by CII) was significantly related to baseline verbal IQ (r = .52, p < .05, N = 21) and the number of tasks completed (r = .49, p < .05, N = 21).
This is the first study to date to test whether computerized WM training is feasible and effective with children with Down syndrome. The main findings were that children were able to complete computerized memory training at school and that it was effective in boosting performance on both trained and non-trained visuospatial STM tasks. Improvements in non-trained memory skills were sustained four months after training had ceased. These findings suggest that a relatively short but intensive training regime can lead to sustained improvements in memory skills for children with Down syndrome, which is consistent with data from other developmental groups (e.g., Holmes et al., 2009; Kronenberger et al., 2011).
In the current study a purely visuospatial memory training program designed for use with typically developing preschool children was used with children with Down syndrome aged 7–12 years. Significant improvements were observed in a non-trained visuospatial STM task pre- to post-training for an intervention group. Importantly, these gains were significantly greater than for a waiting list control group who did not receive the intervention over the same period and were sustained at a four month follow-up. Comparable gains in visuospatial STM were additionally observed for the waiting list control group immediately after they had completed the same training program, which provides a partial replication of the training effect. Overall, there was an increase of one span item following training for both groups, both two to three. The highest trained span score was greatest for the wheel of animals task. This particular task involves the presentation of both visual (the animal pictures are lit up on the screen) and auditory information (the sound of the animal is made) and suggests that having information to be remembered presented in dual modalities may help boost the recall of that information. Performance was most likely higher on the trained activities than the non-trained tasks due to increased familiarity with the tasks and the game environment in which they were presented, which was more engaging and rewarding than the standardized outcome measures.
The highly selective improvement in visuospatial STM observed following training in this study was contrary to expectation, as previous studies have shown that using a domain-specific memory training program leads to domain-general improvements in WM in typically developing children (e.g., Thorell et al., 2009). It is possible that the underlying verbal STM deficits so commonly seen in children with Down syndrome are associated with a more pervasive difficulty in verbal skills, which is not easily trainable. That is, the poor performance of individuals with Down syndrome on verbal STM tasks might be a consequence of difficulties processing verbal information more generally, which limits both the impact of memory training and transfer of positive effects across domains in this particular population group. An alternative explanation might be that the benefits of training for this group are limited by their significant levels of cognitive delay (children in this study had an average IQ of below 70). That said, there were some small improvements in verbal memory STM immediately after training for the waiting list control group and at four month follow up for the intervention group (40% of the intervention group and 55% of the waiting control group made at least a two-point improvement in raw scores on the word recall test between t1 and t3). This improvement could reflect a developmental improvement or possibly a practice effect (children had completed the verbal STM task three times by this point), but there is also the possibility that it reflects an emerging transfer of improvements to the verbal domain. This effect is something that certainly warrants further investigation in studies that include follow-up assessments with appropriate control groups.
Training also had a significant impact on parent ratings of behavior for some of the children. There was a trend for behavior rating scores to indicate less areas of difficulty for all children at t2, which was immediately after training for the intervention group and following a no intervention period for the waiting list control group. What is interesting is that this reduction was greater for the intervention group than the waiting list control group on all five behaviors measures at t2: inhibition, shift, emotional control, WM, and planning/organize. Of particular interest was the highly significant reduction in difficulty with shifting behaviors for children in the intervention group, which was not apparent in the waiting list control group even after intervention. The children in the intervention group did have greater difficulties with shift at baseline (as evidenced by the higher standard scores), suggesting that CWMT may particularly benefit children with Down syndrome who are experiencing particular difficulties in these areas. Finding that some children with Down syndrome have less difficulty spontaneously shifting their attention between tasks and parts of tasks following training suggests that this particular executive function may be malleable in this population group and should therefore be a target for future interventions. It is acknowledged that the BRIEF-P measure is a subjective measure (particularly in the case of this study where group allocation was not blind) and is furthermore currently only standardized for use for typically developing children up to 5 years, 11 months, and therefore the standardized scores presented here should be interpreted with a level of caution. That withstanding, analysis on the BRIEF-P raw scores (not reported here) resulted in the same findings as documented above.
To investigate whether individual differences in age and IQ were associated with gains following training, correlational analyses were conducted. The main finding was that the number of training sessions completed was significantly related to the progress made on both the trained and was approaching significance on the non-trained visuospatial tasks. This suggests the effects are dose dependent and therefore that had the children had continued working on the program, their memory scores may have increased further. No other variables were associated with gains on the non-trained visuospatial task, suggesting that age and IQ are not boundaries to positive training effects on non-trained tasks. However, baseline verbal IQ was significantly related to the amount of progress on the trained tasks (r = .52, p < .05), indicating the children who scored higher on the verbal IQ measure were likely to make more progress on the training activities. Although it is not possible to explore in detail due to the sample size, it was an observation that children who engaged with CWMT on a regular basis (at least three times a week) tended to make more success on the trained tasks in comparison to the children who trained less frequently.
This pilot study did not include a blind or placebo condition. Although such a study would indeed provide a more stringent test of CMWT for children with Down syndrome, such a study would be too time consuming, expensive, and risky in the absence of the important evidence provided by this first study, which does indicate that the intervention is likely to be valuable. A further limitation of this study is that both feasibility and behavior ratings (e.g., BRIEF-P) were judged subjectively by caregivers who were aware of their child's allocation to either the intervention or waiting control group in this study. It is therefore acknowledged that the parent ratings of executive function can be difficult to interpret due to the likelihood of expectancy effects. Using objective measures of feasibility and behavior, such as rating scales completed by people blind to the intervention, may have helped determine the benefits of the intervention more accurately, and this is something that should be included in further studies with this population.
This study provides important evidence for the feasibility of using WM training in schools with children with Down syndrome. Unlike previous research studies such as Thorell et al.'s (2009), where the researchers delivered the intervention under tightly controlled experimental conditions, the method of delivery in this study replicated how it would more realistically be conducted in schools: School staff were trained on the administration and supervision of training, with a member of the research team monitoring progress remotely using performance data stored on a secure server. In addition to the potential differences in how each member of school staff implemented training, there were breaks in the delivery of the intervention due to either Christmas or Easter holidays and there were differences in the school placement of children recruited (three children in different special needs schools took part in this study, alongside 18 children from 16 mainstream schools that had a mix of special needs units and full inclusion classrooms). Despite these differences, the majority of children made gains on non-trained visuospatial tasks. Observations made by school staff indicated that there were behavioral changes even in those who did not improve on the standardized outcome measures. These included increased cooperation at school and during assessment, less frustration when getting things wrong, and the ability to concentrate for longer periods of time during class. Together, this demonstrates that memory training has the potential to be an effective intervention for use with children with Down syndrome in a variety of school settings.
Conclusions and Future Directions
This study has demonstrated that visuospatial WM training can be delivered in a school setting for children with Down syndrome and that it leads to sustained improvements in non-trained tasks assessing visuospatial STM. These gains did not transfer to verbal STM or WM skills. Improvements on the training tasks were associated with the amount of time spent training and baseline verbal skills, but gains on non-trained outcome measures were related (approaching significance) to the number of training tasks completed only. Although this study was conducted with a small sample, leading to reduced power, the significant gains for visuospatial memory are impressive (d = 0.59; 0.83) and the effect sizes suggest that, despite the small sample, we can be reasonably confident in our group differences. Training was additionally associated with a significant reduction in problem behaviors that are associated with executive function difficulties for some of the children, particularly behaviors relating to shifting attention. Future research should investigate this preliminary finding further by measuring executive functions objectively at outcome. Although this study failed to demonstrate a transfer from training on visuospatial tasks to the verbal domain, the computerized method of training used here shows great potential and paves the way for future evaluations of memory training with older children and adolescents with Down syndrome, who may benefit from programs that include verbal as well as nonverbal training activities.
Stephanie Bennett, University of Portsmouth, Portsmouth, PO1 2HY, Down Syndrome Education International, Cumbria, LA6 2DY; Joni Holmes, MRC Cognition & Brain Sciences Unit, Cambridge, CB2 7EF; Sue Buckley, Down Syndrome Education International, Cumbria, LA6 2DY
Editor-in-Charge: Tony Simon
This research was supported by a project grant from the Baily Thomas Charitable Trust and by Down Syndrome Education International. We would like to thank the children, teaching staff and families who participated in the study. We would also like to thank Pearson for giving us access to the training program for this evaluation.