Effectiveness and Retention of Teaching Memory Strategy Use to Children With Autism Spectrum Disorder

Abstract

Although low levels of memory strategy use have been found in children with autism spectrum disorders (ASDs), few studies have explored the effectiveness of interventions for improving strategy use with this population. In two studies, we examined the short- and longer term effectiveness of rehearsal strategy training. In Study 1, children with ASD made strong gains during a focused teaching session, but rehearsal strategy use was not well maintained after training. In Study 2, we increased training with multiple individualized sessions. Longer term maintenance of gains occurred, demonstrating the possibility of successfully teaching and generalizing of strategy use, findings that have important implications for classroom and intervention contexts with children with ASD.

Keywords

memory autism spectrum language and literacy

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in communication and social interaction, and restricted or repetitive behaviors and interests (American Psychiatric Association [APA], 2013). Children with ASD often demonstrate impairments in executive control and language (Hill, 2004; Lord & Luyster, 2009; Solomon et al., 2009) that may contribute to deficits in memory (Southwick et al., 2011) by limiting use of verbal mnemonic strategies (Smith, Gardiner, & Bowler, 2007). We conducted two studies to provide an evidence base on methods for teaching verbal memory strategies to children with ASD. Promoting memory strategy use has broad implications for learning and potential for positive and reliable effects on recall performance (e.g., Turley-Ames & Whitfield, 2003; Unsworth, 2016).

Although intact abilities have been reported in ASD for some areas, such as semantic memory, iconic memory, and free recall (e.g., McMorris, Brown, & Bebko, 2013; Poirier, Martin, Gaigg, & Bowler, 2011), other studies report impaired memory functioning in areas such as serial recall and episodic memory (e.g., Cheung, Chan, Sze, Leung, & To, 2010; Southwick et al., 2011; Wojcik, Moulin, & Souchay, 2013). Limited use of mnemonic strategies is regularly reported, including difficulties with basic strategies such as cumulative rehearsal (e.g., Bebko, Rhee, McMorris, & Ncube, 2015; Bebko & Ricciuti, 2000; Joseph, Steele, Meyer, & Tager-Flusberg, 2005). Smith et al. (2007) suggested that individuals with ASD tend to rely on rote memory abilities and use less elaborative rehearsal than typically developing (TD) individuals.

TD children begin to consistently use spontaneous rehearsal strategies, where items are rapidly repeated in sequence to facilitate recall, when they are about 7 or 8 years of age (e.g., Bebko, 1984; Bebko & McKinnon, 1990; Kron-Sperl, Schneider, & Hasselhorn, 2008); the effectiveness and the number of times these strategies are used increases with age (e.g., Bebko & McKinnon, 1990; Bebko & Ricciuti, 2000). Younger children typically fail to use memory strategies spontaneously and have difficulty transferring learned strategies to novel events; however, they can engage in rehearsal when explicitly instructed (Flavell, 1970; Gruenenfelder & Borkowski, 1975). Likewise, children with ASD are able to engage in rehearsal when prompted, but spontaneous use is less frequent when compared with same-age peers and little transfer has been observed (Bebko & Ricciuti, 2000; Smith et al., 2007). Strategy use is of critical importance as there is a significant relationship between strategy use, including verbal rehearsal and recall (e.g., Lehmann & Hasselhorn, 2007, 2010).

Several studies have demonstrated successful training of rehearsal strategy use in TD children (e.g., Rodríguez & Sadowki, 2000; St Clair-Thompson, Stevens, Hunt, & Bolder, 2010; Turley-Ames & Whitfield, 2003) and in populations with identified executive functioning deficits such as working memory impairments (e.g., Hulme & Mackenzie, 1992; Loomes, Rasmussen, Pei, Manji, & Andrew, 2008). Besides ASD, executive functioning deficits have been identified in many other disorders, such as attention-deficit/hyperactivity disorder (ADHD; Martinussen, Hayden, Hogg-Johnson, & Tannock, 2005), Down syndrome (Broadley, MacDonald, & Buckley, 1994), severe learning difficulties (Conti-Ramsden, Botting, & Faragher, 2001), and fetal alcohol spectrum disorder (FASD; Rasmussen, 2005). Although children with these disorders have the ability to rehearse, spontaneous strategy emergence is less systematic than its emergence in TD children (Archibald & Gathercole, 2007; Broadley & MacDonald, 1993; Gill, Klecan-Aker, Roberts, & Fredenburg, 2003; Hulme & Mackenzie, 1992). However, rehearsal training has been effective in increasing strategy use in children with FASD (Loomes et al., 2008) and children with learning difficulties (Hulme & Mackenzie, 1992). Rehearsal training has also improved strategy use in children with Down syndrome; however, gains tend to disappear gradually after training as the children apparently fail to internalize the rehearsal strategies and eventually stop using them altogether (Comblain, 1994). Overall, rehearsal training in populations with executive functioning difficulties appears to have a positive influence on strategy use.

There have been other efforts to improve executive functions in individuals with ASD by using methods such as positive reinforcement and computerized training (Baltruschat et al., 2011a, 2011b; de Vries, Prins, Schmand, & Geurts, 2015). However, these efforts have been largely unsuccessful. Direct rehearsal training may be a more promising tool to improve strategy use, because children with ASD can use them effectively, when prompted (Bebko & Ricciuti, 2000; Smith et al., 2007). Because populations with executive functioning impairments have demonstrated a positive response to rehearsal training, it is likely that this type of training can also facilitate the spontaneous use of rehearsal in children with ASD.

For children with ASD, and those who have intellectual impairments with or without ASD, the implications of effective strategy use are far reaching. Everyday memory impairments potentially limit the ability to learn important information, recall names, and remember deadlines, appointments, and locations (Jones et al., 2011). Fleury et al. (2014) estimated that memory impairments have a large impact on academic performance in individuals with ASD. Improving memory performance by facilitating strategy use, therefore, has the ability to impact the lives of individuals with ASD in multiple domains, including academic and social skills. Language impairments leave many individuals with ASD without the means to communicate with others. Although augmentative and alternative communicative (AAC) devices can facilitate communication, they rely heavily on the learning and memory abilities of individuals with ASD (Mirenda, 2008). The difficulty of teaching the use of AAC devices to individuals with ASD has often resulted in devices being limited to the basics of requesting and rejecting (Still, Rehfeldt, Whelan, May, & Dymond, 2014). Mirenda (2008) suggested that these difficulties point to the necessity of new methods of instruction. Facilitating the remembering of associations between concepts and symbols can improve the ability to learn to use such devices to communicate more complex ideas. In fact, memory strategy use has been found to be related to the use of AAC devices (Oxley & Norris, 2000). On a broader level, facilitating effective strategy use can enable children with intellectual impairments to learn more effectively, and thereby increase their quality of life (Lifshitz, Shtein, Weiss, & Svisrsky, 2011; Lifshitz, Shtein, Weiss, & Vakil, 2011).

Despite the clear importance of strategy use, there is a paucity of studies on the effects of strategy training in ASD. Some researchers have demonstrated that if a strategy is used, then recall is equally strong for both clinical and nonclinical populations (e.g., Bebko, McMorris, Metcalfe, Ricciuti, & Goldstein, 2014; Bebko & Ricciuti, 2000), whereas limited strategy use leads to limited recall. The goal of the current studies is to provide evidence that training can be effective for increasing strategy use in ASD, with a goal of helping prevent the loss of learning opportunities that might result from reduced strategy use. We focus on a basic strategy—verbal rehearsal—but it is representative of a more general repertoire of strategies children use as they mature.

In Study 1, we evaluate the effectiveness of a highly structured training session in teaching the use of rehearsal strategies to participants with ASD. Because a number of studies have found broad impairments in maintaining and generalizing newly learned strategies (e.g., Solomon, Frank, Smith, Ly, & Carter, 2011), in Study 2, we focused on improving the maintenance and generalization of strategy training.

Study 1

Strategy use, maintenance of training over time, and transfer of a learned strategy to novel stimuli require the motivational and cognitive systems to work in tandem. Borkowski, Johnston, and Reid (1986) noted that the motivational belief systems of a person can inhibit or facilitate the use and transfer of strategies. They proposed that attribution of success and failure is bidirectionally associated with strategy use. For instance, individuals who attribute failure to controllable factors, such as effort, are likely to increase their effort when solving a future task and are unlikely to have lower expectations of future success. In contrast, individuals who attribute failure to external uncontrollable factors such as luck, or to stable internal characteristics such as ability, are likely to approach future tasks passively as these beliefs can undermine their efforts to control their performance. Kozminsky and Kozminsky (2002) found that children with learning disabilities who underwent an attribution training program developed positive attribution beliefs about the importance of effort and the appropriate application of strategies in determining performance. Other studies have reported success with combined strategy learning and attribution training on reading comprehension (Berkeley, Mastropieri, & Scruggs, 2011), spelling (Fulk, 1996), and mathematics (Fulk & Mastropieri, 1990). Among children with intellectual disabilities (IDs), Turner (1998) also showed that attributional beliefs and the belief in the importance of internal strategies were facilitative of recall and strategy use. Training on attributional beliefs and memory strategy use has not been investigated with children with ASD, and is the focus of Study 1. Two components were evaluated: (a) the immediate effectiveness of combined strategy and attribution training on strategy use and (b) the maintaining of the trained strategy 2 or 3 weeks later.

Method

Participants

Participants in this study were 20 children with ASD and 20 children without ASD between 6 and 16 years of age. The ASD sample were drawn from classrooms designated for children with ASD, who had been diagnosed by registered health care professionals based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; APA, 1994) or Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; APA, 2000) criteria. A review by Fombonne (2003) estimated that 70% of individuals with ASD present with some form of ID, defined as those with IQ scores falling below the 70th percentile (American Association on Intellectual and Developmental Disabilities, 2010). Because the goal of the present study was to evaluate the effectiveness of teaching strategies with children with ASD generally, it was important to include a representative range of children with ASD, that is, not only those with average or higher intellectual functioning (often termed, “high functioning”) but also those with a coexisting ID. Although testing this broader range of participants is highly desirable, it is also important to try to evaluate the relative influences of ASD without ID and ASD + ID on memory strategy acquisition in the participants. To tease apart the influence of ASD and ID on memory strategy acquisition in children with ASD, it was necessary to include a non-ASD comparison group that included a similar range of intellectual functioning: both individuals with average intellectual functioning and those with an ID but no ASD diagnosis. The comparison group was also included to enable the results of the study to be situated within the existing non-ASD literature.

The ASD sample was 20 moderate- to high-functioning children, VIQ (verbal intelligence quotient) ≥ 40, and whose VMA (verbal mental age) was above 4 years so that the verbal instructions would be understood. There were an equal number of children with and without identified ID, that is, IQ ≤ 70 (see Table 1). The comparison group was 20 children without ASD, 10 with mild to moderate ID (VIQ = 40-70, VMA > 4 years), and 10 TD children (VIQ > 70). The rationale for this combined comparison group was that any differences in performance between groups could be more specifically attributed to ASD than any associated cognitive impairments. The ID of the children within the non-ASD group had no known organic etiologies, similar to those in the ASD group with cognitive impairments. The TD children were nonclinical children assumed to be in the average range of intellectual functioning (VIQ ± 100) and served as matches for the higher functioning participants with ASD.

Table 1.

Descriptors of Participants in Study 1, With Rehearsal Use and Ordered Recall Performance When Unprompted in Part 1.

Participant group	Chronological age	Estimated mental age
ASD sample (N = 20; 20 M, 0 F) VIQ < 70 = 10; VIQ > 70 = 10
Mean in years	10.30	7.49
Range	6.21-16.58	3.13-11.25
Non-ASD sample (N = 20; 7 M, 13 F) VIQ < 70 = 10; VIQ > 70 = 10
Mean in years	10.69	7.52
Range	5.80-14.00	3.94-10.33
Ordered recall performance by rehearsal use	Strategy usen (% of sample)	Proportion correctM (SD)
ASD sample
Rehearsers	6 (30%)	0.78 (0.25)
Non-rehearsers	14 (70%)	0.43 (0.24)
Non-ASD sample
Rehearsers	13 (65%)	0.81 (0.18)
Non-rehearsers	7 (35%)	0.45 (0.18)

Note. ASD = autism spectrum disorder; VIQ = verbal intelligence quotient; M = male; F = female.

The combined comparison group was matched to the group with ASD on chronological age (CA) and VMA (see Table 1). Matching was done using VMA scores (vs. nonverbal or combined verbal and nonverbal) for several reasons. Most IQ test results are heavily affected by verbal skills (e.g., Lennen, Lamb, Dunagan, & Hall, 2010) and those with ASD tend to have lower verbal scores than nonverbal, likely due to the delay of language acquisition that is a common feature in ASD, and often the first recognized symptom (Lord & Luyster, 2009). Matching on nonverbal skills would be matching based on the strongest skills of the participants with ASD, which is more likely to overestimate their true IQ, disadvantaging them in comparisons with non-ASD participants, where verbal and nonverbal IQ are more likely to be similar. Therefore, matching participants based on VMA was important in this study, as matching is based on the skill area that is likely to contribute more to overall intellectual ability. The second reason for the use of VMA when matching the groups is the relationship between language abilities and rehearsal use. In previous studies, language proficiency was found to be a strong predictor of memory strategy use, and accounted for the relationship between metamemory and strategy use as well (Bebko et al., 2014; Bebko et al., 2015). Matching groups on VMA, therefore, allows us to control for the impact of language proficiency on memory strategy use in this study.

Overall, groups were well matched on most variables except for sex, due to the preponderance of males with ASD. However, literature spanning the last five decades (e.g., Bebko, 1979; Flavell, Beach, & Chinsky, 1966) has shown no significant differences in strategy emergence by sex.

Materials

Intellectual screening

Intellectual scores for each participant were obtained from school or clinic reports, and were derived from the Stanford–Binet Intelligence Scales–4 or the Wechsler Intelligence Scale for Children–III or Wechsler Intelligence Scale for Children–IV.

Procedure: Part 1—Ordered recall trials

Stimuli consisted of 6 × 8 cm colored photographs of common objects mounted on 8 × 10 cm white Bristol cards. After pilot testing to identify the simplest and most easily identifiable pictures, the following 12 were used in the study: apple, ball, chair, chips, coat, crayons, cup, hands, knee, scissors, shoes, and spoon. Two identical sets of stimulus cards were used, one set as stimuli, the other set as response cards. A blank Bristol board (20 × 70 cm) was used to cover the response cards during stimulus displays. All sessions were video recorded for later review.

The general procedure for this task was a standard ordered recall procedure adapted from previous studies (e.g., Bebko, 1984; Bebko, Bell, Metcalfe-Haggert, & McKinnon, 1998; Bebko & Ricciuti, 2000; Flavell, 1970; Flavell et al., 1966). Participants were tested individually in a quiet room. They were asked first to label the stimulus cards to ensure that the pictures depicted on the cards were familiar to them. At the beginning of each trial, the stimuli were placed face down in a row on a table in front of the child with the covered response cards nearby. Beginning at the child’s left, each card was exposed for 3 s and then was turned down prior to exposure of the next card. After all the cards were individually exposed and turned down, there was a 15-s unfilled waiting period. Following this delay, the 12 response cards were uncovered, and participants were asked to recall by placing the correct response card on the table below each face down stimulus card. When the child indicated she or he was finished, the stimulus cards were then turned over to compare with the response cards and the child was reinforced for effort on the task, regardless of the accuracy.

Each session began with several practice trials that used a different set of cards. Practice cards used solid colors as stimuli, instead of pictures. Children were instructed to remember the color sequences so that they could recall them in the same locations presented. The child needed to recall successfully at least two stimuli on a minimum of two practice trials to proceed. Following the practice, there were six data trials consisting of two groups of three, four, and five picture arrays, presented in ascending order within each group. Varying lengths of arrays were included to avoid frustration and ceiling effects. Stimulus arrays were randomly constructed with the constraints that no picture occurred more than once per array and an adjacent pair of pictures could not recur in consecutive arrays. Each picture occurred an approximately equal number of times across arrays.

Ordered recall scores were the number of items recalled in the correct spatial positions. Children were not penalized for the order in which they recalled items; only the final positional order was recorded. The sum of all the scores across individual trials was calculated. This score represents an index of the child’s memory performance (maximum score = 24).

As in other studies examining rehearsal directly (e.g., Bebko, 1984; Bebko et al., 1998; Bebko et al., 2014; Flavell et al., 1966), during display and delay phases of the trials, the child’s behavior was carefully monitored, and any observations of overt cumulative rehearsal were recorded. Overt signs included verbal cumulative rehearsal (e.g., “apple, ball, shoes . . . apple, ball, shoes”), recognizable lip movements, and rhythmic body movements (e.g., finger pointing, rhythmic head movements, eye movements). Children were identified as “rehearsers” if these rehearsal behaviors were observed on a minimum of two trials. Due to the possibility of covert rehearsal, participants were also asked how they remembered the sequences. A child could also be classified as a rehearser if she or he reported having cumulatively rehearsed (e.g., “I said the words over and over in my head”). If rehearsal was neither observed nor reported, the child was considered to be a “non-rehearser” (for further detail, see, for example, Bebko et al., 2014; Bebko & Ricciuti, 2000; Flavell et al., 1966).

Procedure: Part 2—Strategy training

Materials used for training included those used in Part 1 as well as new pictures for generalization training purposes. The training session began with a brief explanation to the child of what a strategy is, what rehearsal is, and when rehearsal could be used. The steps of a cumulative rehearsal strategy were then modeled for the child. When the child appeared to understand, the child was prompted to rehearse with the examiner. Rehearsal progressed from one picture, up to as high as five pictures repeated in sequence, depending on the child’s success. Beginning with a single picture, the card was turned over, and the child was encouraged to keep repeating the name of the picture while it was turned down. Next, the child was shown the set of response cards and was asked to match the correct response to the original card. The same procedure was used with two, three, four, or five pictures progressively, with the examiner directly rehearsing with the child in a cumulative manner as needed throughout the training process (e.g., “the third one is spoon; now it’s: ball, cup spoon, ball, cup, spoon”). The examiner did not proceed to the next, larger, array of stimuli until the child rehearsed and was successful on the previous level. Importantly, the point of the training was not to reach the maximum of five pictures with each child, but rather to stay within the capabilities of each child and focus on learning to use a strategy to the best of his or her ability. Therefore, if a child became frustrated at a certain array size, that was the limit for training.

Attributional element

After each trial, the children were asked why they thought they did so well/not so well. Two attribution cards were then shown. One picture was of a smiling face and was labeled “I Rehearsed,” and the other picture was of a sad face and was labeled “I Did Not Rehearse.” The children were asked to point to the picture that corresponded with what they had done (i.e., rehearsed/not rehearsed). Emphasis was placed on the fact that the children did well because of their use of rehearsal. The attribution component was used solely as a training manipulation, and not as a specific outcome variable, so no attribution data were collected.

Generalization training

The examiner explained that the rehearsal strategy could be used at home, in a store, or at school. The examiner provided an example of when people go grocery shopping and need to remember their grocery list. The steps of cumulative rehearsal were reviewed and pictures of grocery items were introduced. The “shopping list” increased from one to five picture cards, depending on the child, with continual encouragement to use rehearsal until prompting could be gradually lessened. Additional stimuli were used for generalization training, including number cards and pictures of “Dora the Explorer” cartoon characters. The intent was to generalize the use of the strategy across different sets of stimulus cards.

Testing

Immediately following the rehearsal/generalization training session, the child was tested using a set of novel pictures. The original procedure was used on this ordered recall task to examine their spontaneous use of the strategy. As a result, no encouragement or prompting to rehearse was provided as in the training sessions. The child was tested using one set of three, then four, then five pictures, using the same timing for stimuli and response method. Overt signs of rehearsal were recorded during the delay and the children were again asked the neutral question of how they had remembered so many items.

Procedure: Part 3—Follow-up

Maintenance of training was examined during a brief follow-up session 2 to 3 weeks following the training session. The procedure and stimulus cards from Part 1 were used again to study maintenance and a new set of stimulus cards were used to study generalization. Participants were tested using one set of trials of three, four, and five pictures and, following a 15-s delay, the response cards were used to match to the stimulus cards. The child was not prompted or reminded in any way to use the rehearsal strategy that was taught weeks ago. Any reports or overt signs of rehearsal were recorded.

Results

Part 1: Ordered recall task

To obtain reliability on the identification of spontaneous strategy users, a second researcher who was familiar with the project but not directly involved independently rated half of the participants. Ninety-eight percent agreement was obtained.

From the ASD group, six of the 20 participants (30%) were classified as spontaneous rehearsers (see Table 1). For the non-ASD group, 13 of the 20 participants (65%) were classified as rehearsers. With more than twice as many rehearsers in the non-ASD group, the difference was significant, χ² = 4.91, p < .03.

Recall performance

The number of pictures recalled in the correct order by group was compared in a 2 (rehearser, non-rehearser) × 2 (ASD, non-ASD) ANOVA. Rehearsers across groups (M = 0.80) recalled significantly more items than non-rehearsers (M = .43), F(1, 39) = 23.54, p < .01 (see Table 1). Neither the main effect for group nor the interaction was significant, both F(1, 39) < 1.0, both p > .65, indicating that the rehearsal advantage was equally effective regardless of group.

Parts 2 and 3: Rehearsal training and follow-up

Mindful of the challenges of training children with ID in strategy use (e.g., Comblain, 1994; Laws, MacDonald, Buckley, & Broadley, 1995), strategy training outcomes were examined separately for subgroups of the ASD and non-ASD samples, corresponding to those with VIQs greater or less than 70. Consistent with the first hypothesis, the strategy training for all participants was initially successful and all participants were able to learn to rehearse along with the examiner. However, the majority who were not spontaneous strategy users before training did not continue to use the strategy. Furthermore, when tested at follow-up, all three clinical subgroups (ASD with VIQ greater or less than 70, and non-ASD with VIQ less than 70) had returned to their pretraining levels of spontaneous strategy use, with only two participants showing a maintenance effect. Note that for the non-ASD with VIQ > 70 subgroup, all the children had been spontaneously rehearsing in Parts 1 and 2, so follow-up was not warranted to avoid boredom and frustration.

Brief Discussion

The results of Part 1 of the present study reinforce previous findings that children with ASD do not show spontaneous strategy use at a similar level to TD children (Bebko & Ricciuti, 2000). When rehearsal is used, it is equally beneficial for ordered recall among those who use it in both groups, as indicated in Table 2. In addition, rehearsal use varied in the subgroups defined by higher and lower IQ for both samples, as indicated in the Figure 1, Part 1 graphs. The higher IQ groups engaged in more strategy use than the lower, but consistently more of the children in the non-ASD subgroups used rehearsal than did the corresponding matched ASD subgroups, regardless of IQ.

Table 2.

Participants in Study 2, With Rehearsal Use and Ordered Recall Performance When Unprompted in Part 1.

Participant group	Chronological age	Estimated mental age
ASD sample (N = 20; 16 M, 4 F) VIQ < 70 = 10; VIQ > 70 = 10
Mean in years	10.19	8.42
Range	7.08-13.08	4.54-15.83
Non-ASD sample (N = 20; 9 M; 11 F) VIQ < 70 = 10; VIQ > 70 = 10
Mean in years	10.08	7.93
Range	7.00-14.42	3.92-14.42
Ordered recall performance by rehearsal use	Strategy usen (% of sample)	Proportion correctM (SD)
ASD sample
Rehearsers	7 (35%)	0.87 (0.15)
Non-rehearsers	13 (65%)	0.67 (0.28)
Non-ASD sample
Rehearsers	11 (55%)	0.90 (0.73)
Non-rehearsers	9 (45%)	0.52 (0.21)

Note. ASD = autism spectrum disorder; VIQ = verbal intelligence quotient; M = male; F = female.

Figure 1.

Study 1—Percent rehearser classification across sessions.

The goal of Study 1 was to determine the effectiveness of training strategy use in this population. All three clinical samples learned to use rehearsal when it was systematically taught to them with ongoing prompting and support as needed. However, when the support was removed, strategy use decreased to near pretraining levels. Although posttraining maintenance of strategy use was poor, the results suggest that generalization is a possibility. Just as many children were found to be using rehearsal strategies when faced with novel stimuli as when faced with the familiar “old” stimuli on which they had been trained. Enhancing maintenance and generalization of training are explored further in Study 2.

Study 2

The findings of Study 1 confirmed previous research that long-term maintenance and generalization of strategy training are challenges among groups with developmental disabilities. The children with ASD successfully learned the rehearsal strategy, but were largely unsuccessful in using it without prompting beginning immediately following the training session. In Study 2, we investigated whether there was a critical level of additional training needed to maximize the likelihood of retention of training gains over time.

Method

Participants

Parallel to Study 1, the ASD sample was composed of 20 moderate- to high-functioning children (VIQ ≥ 40, VMA > 4 years) with a previous diagnosis of an ASD made by a registered health care professional (psychologist, pediatrician) based on the DSM-IV or DSM-IV-TR criteria. Half had a VIQ below 70 (i.e., in the range of ID) and half were above 70. The blended non-ASD comparison group was composed of 20 children without an ASD. Half were identified with ID (VIQ 40-70) and half were not (VIQ > 70.) All participants had a VMA > 4 years. As in Study 1, the blended comparison group was used to enable comparison with children with ASD who had varying cognitive abilities, rather than only those considered “high functioning.” The non-ASD sample was matched to the ASD group on CA and VMA (see Table 2). The primary focus was on each child’s progress through repeated testing, so ultimately each participant acted as his or her own control. Similar to Study 1, intellectual scores for participants were obtained from school or clinic reports.

Design

The overall design of Study 2 was similar to the first study except that the training portion was extended. Training sessions continued until the child was using the strategy spontaneously when tested without any aid or prompting from the examiner. In addition to recall and strategy use, another key dependent variable recorded was the number of sessions required.

Procedure: Part 1—Ordered recall trials

Materials and procedures for the familiarization and recall trials were those used in Study 1.

Procedure: Part 2—Multiple strategy training sessions

The materials used for the training sessions were drawn from those used in Part 1, plus new sets of pictures for generalization training purposes. The procedure followed that of Study 1 for the first session. The key difference in the current study was that the participants were given multiple sessions until they were spontaneously rehearsing; that is, they rehearsed on their own without prompts from the examiner in the test at the end of the training session. There were up to five training sessions, with each session held on a different day. Training terminated in less than five sessions if the child met the above criterion of rehearsing without prompting. If not, training was terminated after five sessions to avoid frustration or boredom for the participant, because the procedure did not appear to be enhancing performance. Each session lasted 30 to 60 min. Each training trial was followed by an attributional element identical to that of Study 1, where children were encouraged to attribute their success or lower recall to the use/absence of cumulative rehearsal. Each session was followed by a generalization training portion identical to that of Study 1.

Testing

Immediately following each rehearsal/generalization training session, the child was tested using novel pictures. Testing involved the same procedure used in Part 1 above, and in the previous studies, including recording any overt signs of rehearsal and asking participants how they remembered the stimuli. If there was no overt evidence or report of rehearsal at this point, another training session was provided 2 to 3 days later. However, if the participant demonstrated evidence of, or reported, rehearsal during testing without any aid from the examiner, the rehearsal/generalization training was assumed to have been completed.

Procedure: Part 3—Follow-up

The effects of training were examined during a brief follow-up session that took place 2 to 3 weeks after the last training session. The same procedure and stimulus cards were used as in Part 1 to study maintenance; entirely new stimulus cards were also used to study generalization to new stimuli.

Results

As in Study 1, there was a higher proportion of rehearsers in the non-ASD group (55%, 11 of 20) compared with the ASD group (35%, seven of 20), although the difference did not achieve statistical significance (χ² = 1.62, p > 0.05).

Recall performance

Recall was examined using a 2 (rehearser, non-rehearser) × 2 (ASD, non-ASD) ANOVA for ordered recall scores. Rehearsers again recalled significantly more items than non-rehearsers on the ordered recall task, F(1, 39) = 14.78, p < 0.01 (see Table 2). There was no significant main effect for group, F(1, 39) = 0.744, p = .39, and the interaction was also nonsignificant (p > .54), indicating that children who rehearsed recalled more than non-rehearsers, regardless of group. These data are largely consistent with the results presented in Study 1.

Parts 2 and 3: Rehearsal training and follow-up

The number of training sessions required for participants to begin rehearsing independently was a main dependent variable. Given the likely difference in training difficulty for participants with and without ID, we examined strategy training outcomes separately for subgroups of the samples, corresponding to those with VIQs greater or less than 70. The participant groups with ID (VIQ < 70), required double the total number of training sessions to reach the spontaneous rehearsal criterion than the children without cognitive impairment (see rightmost “Total no. of sessions” column in Table 3). Most of the children without cognitive impairment, particularly in the non-ASD group, required only one or two training sessions.

Table 3.

Number of Individuals Who Required Each Number of Training Sessions by Group in Study 2.

	Number of training sessions required
	1	2	3	4	5	Total no. of sessions
ASD sample (n = 20)
VIQ < 70	1	2	6	0	1	28
VIQ > 70	7	2	1	0	0	14
Non-ASD sample (n = 20)
VIQ < 70	1	4	3	1	1	27
VIQ > 70	9	1	0	0	0	11

Note. ASD = autism spectrum disorder; VIQ = verbal intelligence quotient.

The number of spontaneous rehearsers increased notably and the gains were mostly maintained after the multiple training sessions (Figure 2, Part 2). Specifically, there were eight spontaneous rehearsers in the subgroup with ASD and VIQ < 70 in Part 2 test trials (an increase of seven participants from Part 1), nine in the subgroup with ASD and VIQ > 70 group (vs. six in Part 1), all 10 non-ASD with VIQ > 70 children, and eight spontaneous rehearsers from the non-ASD with VIQ < 70 subgroup (vs. three in Part 1). Five of the 40 participants across the samples did not show signs of spontaneous rehearsal following the training sessions, with four of them from the groups with ID (VIQ < 70). Allowing for enough training sessions for autonomy in rehearsal appeared to have a positive and lasting effect. However, the most important finding of the study is that, in contrast with the results from a single training session in Study 1, long-term gains in strategy use were demonstrated during follow-up 2 to 3 weeks after training for nearly all participants (Figure 2, Part 3). In addition, identical gains were also seen when using the novel stimuli, indicating successful generalization of skills to new stimuli. Only two participants with ID, one with ASD and one without, failed to maintain the gains.

Figure 2.

Study 2—Percent rehearser classification across sessions.

A final question examined was whether the taught strategies were helping the participants as much as the rehearsal of the original spontaneous rehearsers in Part 1 of this study, and particularly for the children with ASD. The answer was positive: Participants classified as rehearsers from the ASD groups improved their ordered recall performance somewhat from 87% of the total possible items recalled in Part 1 (seven rehearsers) to 96% in Part 3 (now with 16 rehearsers); non-rehearsers’ ordered recall remained about the same, 67% in Part 1 (13 non-rehearsers) and 64% in Part 3 (4 non-rehearsers). The levels of performance among the non-ASD sample were comparable pre- and post-training. Specifically, rehearsers from the non-ASD group recalled 90% of items in Part 1 (11 rehearsers) and 86% in Part 3 (17 rehearsers). The non-rehearsers’ scores were similarly unchanged, from 52% in Part 1 (nine non-rehearsers) to 50% in Part 3 (three non-rehearsers).

Overall, these findings indicate that allowing children with developmental disabilities the opportunity to learn until a demonstrated criterion of spontaneous and autonomous strategy use is met is very effective in the maintenance and generalization of memory strategies training, and that the positive impact carries over to recall performance.

General Discussion

Despite findings of varied memory skills (Cheung et al., 2010; Southwick et al., 2011; Wojcik et al., 2013) and deficits in strategy use (e.g., Bebko & Ricciuti, 2000; Joseph et al., 2005), few studies have explored interventions to improve memory and strategy use in individuals with ASD. Studies that do exist have been somewhat equivocal in their effectiveness. The two studies presented in this article examined the issue of training of a strategy in depth, and included generalization and follow-up phases to determine the extent to which gains were maintained for several weeks and transferred to other stimuli.

Training Strategy Use in ASD

To optimize the likelihood of success, one-on-one individualized strategy training including behavioral reinforcement was accompanied by an attribution training component in each study. Children were not only trained and reinforced for using rehearsal strategies, they were also taught to link their performance explicitly to their own use of rehearsal. The results of these two studies were positive and provide unequivocal evidence that children with ASD, and with a wide range of intellectual skills, can learn to use memory strategies to the benefit of their performance. In Study 2, their newly learned strategy use was maintained, leading to clear potential long-term benefits for learning in school and in daily living, particularly if these methods were used to teach a wider variety of skills.

These findings help to contextualize previous memory training efforts in ASD. Baltruschat and colleagues (2011a, 2011b) explored the facilitatory effects of positive reinforcement on working memory performance in children with ASD. However, strategy use was not directly measured or reported in the study, and the increase in recall performance may have been due to increases in motivation when reinforcers were present. Longer lasting effects may be expected if the focus was on the teaching of strategies that are useful in a variety of situations, and not only when a reinforcer is present. Smith et al. (2007) measured the effect of multiple rehearsal training sessions, but training did not appear to include an attribution training component. Their group with ASD remained significantly impaired in recall, relative to controls. de Vries et al. (2015) examined the effectiveness of computerized training to improve executive functions (including working memory) in children with ASD, but concluded that their procedures appeared not suitable for children with ASD.

Consistent with previous research, at the outset of the present studies, children without ASD were more likely to be spontaneous rehearsal strategy users than children in the ASD group. It is possible that this discrepancy may be a result of delays in other prerequisite cognitive domains. For example, individuals with ASD show consistent impairments in language domains (e.g., Lord & Luyster, 2009), and level of language proficiency is one of the strongest predictors of the use of rehearsal strategies both in ASD and non-ASD children (Bebko et al., 2015). Individuals with ASD also have clear impairments in executive functions (Ozonoff & Jensen, 1999), which include skills such as organizing, planning, sustaining attention, and using strategies when solving problems. The training procedures used in the present studies essentially function as an externalization of the executive processes required in the use of a strategy; specifically, one must select the strategy, continue to use it, and monitor its effectiveness. By personalizing and repeating strategy training in an individualized manner, children were assisted in internalizing the training provided to them and becoming aware of the benefits of strategy use. Once internalized, the generalization training may have supported the extension of these executive skills, thus increasing the likelihood of strategy maintenance and generalization to new situations. Once the children used rehearsal spontaneously, their recall performance was comparable with that of peers without ASD, indicating that the skills brought to bear were equally efficient. Of broader importance, the findings indicate that the strategy training package used in the present study, across multiple sessions, can be highly beneficial in teaching new strategies to those with ASD, which, in turn, has the potential for long-term benefits to their quality of life.

Implications

Improving memory functions in children with ASD has many important implications. Memory impairments can affect day-to-day functioning, such as limiting the ability to remember appointments, responsibilities at work, and other everyday demands that are essential for independence. Jones and colleagues (2011) reported that parents of the teens in their study expressed concern that their child would not be able to cope independently in adulthood after leaving behind the structured environment of school to which they had grown accustomed.

Memory impairments may also affect functioning in other domains. For example, Ullman and Pullman (2015) suggested that memory plays an important role in compensating for language and social impairments. Individuals with ASD may memorize scripts for common social situations or memorize social rules and conventions to facilitate their success. In addition, effective memory strategy use has been linked with learning assistive communication systems (Oxley & Norris, 2000). Improving memory strategy abilities, therefore, has the potential to enable individuals with ASD to better compensate for impairments in other domains.

The results of Study 2 have particular implications for training and pedagogical practices. Practical ways to encourage maintenance of taught strategies in the “real world” would be to inform both parents and teachers of the training routine so that they may be able to provide additional practice by using the same procedures with the children at home and at school, and hopefully achieve the point of these skills becoming automatic. Specifically, our findings of robust gains after only three to five training sessions suggests that repeated training sessions are highly beneficial, but may not need to be extensive. Finally, it is important to not underestimate the importance of the attribution component of the training. Although its contribution in the present project cannot be quantified, because it was a part of the training package, emphasis on both the “why” (i.e., attribution) as well as the “how” (i.e., rehearsal training) aspects of the process of learning a strategy, and less emphasis on the content to be remembered, likely played a role in the improved maintenance and generalization of gains. This kind of training can be generalized to other academic domains (e.g., early literacy, numeracy) and daily living activities to the benefit of individuals with ASD.

Strengths, Limitations, and Future Directions

A notable strength of this study was the inclusion of representative samples of individuals with ASD, ranging from moderate ID to “high-functioning,” which enhances the generalizability of the data and of the procedures used. Even the most affected of our participants were able to benefit from training in strategy use. The findings are encouraging in that they provide an evidence-based method of teaching effective strategies. However, the apparent loss of gains, albeit by a small number of participants, warrants continued research.

Limitations of this study include ceiling performance for the TD subgroup in the non-ASD sample. Because these participants achieved the highest levels of performance in the initial training sessions, they were not trained further in Study 1 (a form of attrition), although they did continue with the training in Study 2. Although their rapid and maximal success was an ideal outcome, it limited our ability to evaluate further learning had there been greater difficulty, such as longer sequences to be remembered or longer delays before recall. However, greater difficulty may well have increased the challenge excessively for participants in the other groups, which may have reduced their success or increased frustration. In addition, the generalization effect examined here was simply to new materials versus more distal generalization to dissimilar learning situations, which would be helpful to evaluate. Finally, it would also be beneficial to examine the use of other memory strategies, such as association, elaboration, and organization. With the success of the present study, there is reason to assume that other memory strategies might also be trained to be used spontaneously by children with ASD, if similar, individualized procedures are followed.

Footnotes

Acknowledgements

The authors thank the staff at the Toronto (North York) School Board in Canada for their help with recruiting participants as well as the children and families who participated in the study.

Authors’ Note

Thomas Rhee is now at Holland Bloorview Kids Rehabilitation Hospital. Hadas Dahary is now at McGill University.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Author Biographies

James M. Bebko, PhD, C.Psych, is a psychologist and professor at York University in Toronto, Canada. His current research interests include the reciprocal relation between cognitive and language development in children with autism spectrum disorders and other developmental challenges, as well as the coordinating of inter-sensory information by children and adolescents.

Thomas Rhee, PhD, C.Psych, is a psychologist with the Child Development Program at Holland Bloorview Kids Rehabilitation Hospital. His primary area of research interest involves the cognitive abilities and memory skills in children with Autism Spectrum Disorder as well as Intellectual Disability.

Busisiwe L. Ncube is a PhD candidate in the Clinical-Developmental Psychology program at York University. Her research interests include the cognitive abilities and quality of life of children with Autism Spectrum Disorder and Intellectual Disability.

Hadas Dahary is a MA candidate in the School/Applied Child Psychology program at McGill University. Her current research interests include examining the influence of soundtracks on emotion recognition in children with Autism Spectrum Disorder.

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