Working Memory Updating in Individuals with Intellectual Disability

Working Memory Updating in Individuals with Intellectual Disability ORDER NOW FOR CUSTOMIZED AND ORIGINAL ESSAY PAPERS ON Working Memory Updating in Individuals with Intellectual Disability For this class content, you are required to read and the discussion with an emphasis on: Working Memory Updating in Individuals with Intellectual Disability Key definitions Key findings / “takeaways” What do the findings mean for students with an ID? What are potential implications for practice / educational programming? Postings must show evidence of reading the article with direct linkage to the article You will read your article in-depth in order to post a comprehensive response addressing the above points. Please use correct grammar. Article is attached. attachment_1 Journal of Intellectual Disability Research 337 doi: 10.1111/j.1365-2788.2010.01267.x volume 54 part 4 pp 337–345 april 2010 Difficulties in working memory updating in individuals with intellectual disability jir_1267 337..345 B. Carretti,1 C. Belacchi2 & C. Cornoldi1 1 Department of General Psychology, University of Padova, Italy 2 Institute of Psychology, University of Urbino, Italy Abstract Background Despite the critical role attributed to working memory ( WM) updating for executive functions and fluid intelligence, no research has yet been carried out on its specific role in the vital case of fluid intelligence weakness, represented by individuals with intellectual disability (ID). Furthermore, the relationship between updating and other WM functions has not been considered in depth. Method The current study examines these areas by proposing a battery of WM tasks (varying in degree of active attentional control requested) and one updating task to groups of ID individuals and typically developing children, matched for fluid intelligence performance. Results Comparison between the group of ID individuals and a group of children showed that, despite being matched on the Raven test, the updating measure significantly differentiated the groups as well as the WM complex span. Furthermore, updating proved to be the task with the greatest power in discriminating between groups. Conclusions Our results confirm the importance of the demand for active attentional control in explaining the role of WM in fluid intelligence perforCorrespondence: Dr. Barbara Carretti, Department of General Psychology, Via Venezia, 8, 35131 Padova, Italy (e-mail: [email protected]) mance, and in particular show that updating information in WM plays an important role in the distinction between typically developing children and ID individuals. Keywords working memory, updating, intellectual disability, fluid intelligence Introduction Executive functions (EF) are related to ability to control and flexibly adjust thoughts and actions in relation to activities to be carried out. However, EF are usually involved when tasks are not automated, but instead demanding in terms of attentional control. For example, EF are only moderately implicated in tasks measuring vocabulary knowledge, while they are strongly involved in fluid intelligence tasks. The concept of EF is also crucial for the definition of working memory ( WM) – in fact most WM models have postulated that the fundamental aspect of WM is connected with controlled attention, i.e. the flexible management of attentional resources (Kane & Engle 2002). Within EF, updating has received particular attention for its strict relationship with typical WM tasks (e.g. Miyake et al. 2000) and for its role in fluid intelligence performance (e.g. Friedman et al. 2006). Updating represents a particular case of WM elaboration as it refers to the ability to dynamically modify the © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd volume 54 part 4 april 2010 Journal of Intellectual Disability Research 338 B. Carretti et al. • Working memory updating in intellectual disability content of memory according to task requests (Morris & Jones 1990).Working Memory Updating in Individuals with Intellectual Disability By this definition, some information is entered in a temporary memory system during updating, while other information previously maintained is excluded. Maintenance, continuous exclusion of material and its substitution by new material based on a pre-defined criterion are needed in order to meet the task request (Kessler & Meiran 2006; Carretti et al. 2007). In contrast, in the classical complex memory spans, new information is simply added to the memory set without any operation of substitution. As regards the relationship between WM updating and other aspects of WM, Miyake et al. (2000) used the structural equation model to demonstrate that within EF the latent factor derived from different updating tasks significantly predicted performance in the operation span task; in contrast, the paths from inhibition and shifting were not significant. Recently, other authors studied the relationship between updating and complex span tasks. Results were sometimes inconsistent, and in some cases updating and WM were modestly correlated (0.20, see Kane et al. 2007), whereas in other cases the correlation was relatively high (0.55, Shamosh et al. 2008) or extremely strong (0.96, Schmiedek et al. 2009), to such an extent that updating and complex span performance is suggested to be impossible to distinguish. The relationship between WM and intelligence has been documented in an extensive number of studies. For example Engle et al. (1999) demonstrated that a latent variable derived from the complex span tasks predicts general fluid intelligence performance (measured by Raven’s and Cattell’s tests), whereas the latent variable derived from the simple span tasks does not. Furthermore, Engle et al. (1999) found that in removing the variance common to the WM latent variable and the shortterm memory latent variable, the relationship between WM and fluid intelligence was still significant. In addition, Kane et al. (2004) demonstrated that this relation was independent of the type of material used (verbal or visuospatial). They provided evidence that the increase in attentional resources needed to carry out typical WM span tasks results in the disappearance of domain specific differences, because all the WM measures are loaded on a single general common factor. In con- trast with this view, Ackerman et al. (2005) showed that WM and fluid intelligence are not isomorphic constructs. In addition, Ackerman et al. (2005) did not confirm the complete a-modal nature of the relationship between WM and fluid intelligence, finding that the correlations between tasks with overlapping content for WM and fluid intelligence were higher than those for non-overlapping tasks. For the particular case of WM updating, it has been suggested that this predicts fluid intelligence performance to the same extent as other WM measures (Schmiedek et al. 2009). Nevertheless, in recent years interest in a specific role of updating in fluid intelligence performance has been particularly intense. For example, addressing the distinction between three fundamental EF components (inhibition, updating and shifting), Friedman et al. (2006) investigated the differential contribution of these components to intelligence performance. From their results, it was clear that the process of updating represents the component with highest correlation with fluid and crystallized intelligence. In addition, these latter results were extended by a large twin study in which Friedman et al. (2008) showed updating to represent the most critical and biologically rooted component of EF (for conflicting results see Colom et al. 2008). Working Memory Updating in Individuals with Intellectual Disability Moreover, Friedman et al. (2008) demonstrated that IQ performance is more strongly related to updating than the other two EF (i.e. inhibition and shifting), because of the common genetic substrate. In addition, studying subjects aged 18–80 years, Chen & Li (2007) found updating to be the critical mediator between age and fluid intelligence. Recently, Belacchi et al. (2010) administered a battery of tests to children of different ages and found that performance in a variant of the relevance-based updating proposed by Palladino et al. (2001) was the best predictor of fluid intelligence. They also showed the rate of growth in fluid intelligence and in the relevance-based updating task from 4 to 11 years old to be comparable. Updating, WM and fluid intelligence in ID Research to date has explored the structural and functional characteristics of WM in individuals with ID, but has not examined the specific case of updating. In particular, in the case of adults with © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd volume 54 part 4 april 2010 Journal of Intellectual Disability Research 339 B. Carretti et al. • Working memory updating in intellectual disability ID, Numminen et al. (2000) reported that WM performance in ID adults has two components, one ‘phonological’, the other described by Numminen and co-authors as ‘general’; furthermore, Numminen and colleagues demonstrated that only this latter component predicted fluid intelligence performance, as measured using Raven’s Coloured Matrices. In a subsequent study, Numminen et al. (2002) found no differences between ID and typically developing (TD) groups matched for fluid intelligence in forward and backward digit span, whereas differences were evident in the Corsi block task and in a non-word span, the TD group outperforming the ID group. Consistently with this finding, Numminen et al. (2001) found poorer performance by the ID group in the Tower of Hanoi (TOH) task when their scores of rule violations and number of trials needed to complete the task were compared with scores of the fluid intelligence-matched group of children. In addition, Numminen et al. (2001) examined the role of the three components of Baddeley’s WM model to explain TOH performance of ID individuals. Their findings demonstrated that the visuospatial and complex WM tasks (i.e. demanding in terms of attentional control) were significantly related to the TOH performance of persons with ID, whereas phonological WM tasks were not. As a whole, these findings suggest that – similarly to the case for children (e.g. Lanfranchi et al. 2004) – WM performance of adults with ID differs from that of TD individuals especially when WM tasks are demanding in terms of attentional control. This conclusion forms the basis of our present study, the main objective being to investigate not only the WM but also the updating performance of individuals characterised by a weakness in fluid intelligence. To this aim, a group of adults with ID was presented with a battery of WM tasks, varying in demand for active attentional control, and an updating task. The distinction between WM tasks according to their level of attentional control was introduced following the theoretical proposal by Cornoldi & Vecchi (2003). In their WM model, Cornoldi & Vecchi (2003) argued that it is possible to distinguish WM tasks by reference to two dimensions, i.e. domain (horizontal continuum) and degree of attentional control (vertical continuum), and stated that, within the WM tasks themselves, the degree of controlled activity can vary along a continuum. In fact, they considered each memory task to require a certain level of control activities (vertical continuum), the degree of involvement depending on the task demands. Working Memory Updating in Individuals with Intellectual Disability They proposed a distinction between more passive processes (simple recall of previously acquired information), and various degrees of active processing (manipulation of information to produce an output different from the original inputs). In less active tasks, denoted by Cornoldi and Vecchi as passive memory tasks or simple span tasks (i.e. forward digit span, see also Engle et al. 1999), the degree of controlled processes is very low, as participants only have to reproduce the item just presented. To do this, rote rehearsal of items is usually sufficient. Along the vertical continuum, the backward word span comes next, as it is assumed to require slightly more control, the subject having to perform a simple operation on the material (i.e. reverse the word order). Examples of tasks at a high level of active processing are those requiring active processing and temporary maintenance of information, such as the WM span following the procedure of Daneman & Carpenter (1980) and EF tasks such as the updating tasks. Assuming the distinction between WM tasks on the basis of the dimension of active control, Lanfranchi et al. (2004) explored the role of control processes in verbal and visuospatial WM performance of individuals with Down syndrome (DS). For verbal WM, as expected from the literature ( Jarrold et al. 2000), the DS group showed poorer performance regardless of the involvement of control. In contrast, in the case of visuospatial WM, the results demonstrated that individuals with DS are poorer in highly controlled visuospatial WM whereas they can be as good as TD children with the same mental age in low-control visuospatial WM tasks. Lanfranchi et al. (2004) concluded that a core deficit of mentally retarded individuals could reside in a controlled WM deficit. Convergent findings on the importance of WM control for understanding variations in fluid intelligence performance were reported by Lanfranchi et al. (2009) investigating the case of individuals with Fragile X syndrome. In the latter study, Lanfranchi and colleagues compared groups of individuals with and without Fragile X syndrome in two batteries of four © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd volume 54 part 4 april 2010 Journal of Intellectual Disability Research 340 B. Carretti et al. • Working memory updating in intellectual disability verbal and four visuospatial WM tasks requiring different levels of control. Children with Fragile X syndrome showed performance equal to controls in WM tasks requiring low and medium-low control but significant impairment where greater control was required. Their results show that participants with Fragile X syndrome present a WM deficit only when the task demands high control, supporting the hypothesis that control can be a critical variable distinguishing WM functions and explaining intellectual differences. Overview of the study A review of the literature showed that exploration of WM performance of individuals with ID might reveal an interesting functional distinction in comparison to TD individuals, even when level of general intelligence is controlled for. This is particularly the case when considering WM tasks demanding in terms of attentional control, such as complex spans and updating tasks. Working Memory Updating in Individuals with Intellectual Disability The main objective of the current study was therefore to investigate this latter point by presenting a verbal WM battery in which the demand of attentional control was manipulated, together with an updating task that represented unequivocally a high level of WM control. According to the Cornoldi & Vecchi (2003) model, we predicted that the dimension distinguishing the two groups would be related to the request for attentional control. Thus performance on tasks requiring few attentional resources (e.g. simple span) would not differ in the two groups. In contrast, differences would emerge where an active manipulation of the information is requested. Differences would be particularly evident in tasks requiring high attentional control, as is the case not only in complex span tasks but also in the updating task. In this study, updating was measured using the relevance-based updating task, proposed by Palladino et al. (2001), in which participants had to listen to a list of words (objects or animals) and then remember the three smallest items, assuming relevance to be defined by item size. Palladino et al. (2001) demonstrated that the relevance-based updating task was more successful than the task used by Morris & Jones (1990) (where subjects have simply to recall the last items of a list of unknown length) in capturing individual differences in reading comprehension, revealing in particular the difficulty encountered by poor comprehenders in controlling irrelevant items (see also Carretti et al. 2005). Palladino and colleagues speculated on this result, suggesting that the relevance-based updating task required an active processing of information typical of cognitive everyday tasks, such as reading comprehension, where updating is required. Subsequent studies lent further support to the usefulness of the relevance-based updating task, demonstrating a strong relation with problem solving (Passolunghi & Pazzaglia 2004, 2005) and fluid intelligence (Belacchi et al. 2010). Consistently with previous studies, the ID group was compared with a group of TD children matched on Raven’s Coloured Matrices performance. ID individuals were considered independently of their organic aetiology but with reference to a clinical diagnosis of poor level of fluid intelligence supported by problems in everyday life associated with their condition of intellectual weakness. Analysis of this population enabled us to test the hypothesis that, even for individuals with an intellectual weakness matched with controls with the Raven test, the discriminative power of controlled WM (measured with complex span task and updating task) is maintained. Method Participants A total of 28 adults (15 men, 13 women) with unknown aetiology of ID, diagnosis given by expert clinicians, participated. Table 1 shows the mean chronological age and the mean mental age estimated using performance on the Raven’s Coloured Matrices. ID individuals had a mean mental age of 6 years and 2 months (the range of estimated IQ varied between 40 and 75). In the group, we included only participants without severe neurological signs or acute psychiatric disorders or dementia. Persons with ID were matched with a group of 28 children (15 men, 13 women) using the estimated mental age obtained in the Raven’s Coloured Matrices. Working Memory Updating in Individuals with Intellectual Disability © 2010 The Authors. Journal Compilation © 2010 Blackwell Publishing Ltd volume 54 part 4 april 2010 Journal of Intellectual Disability Research 341 B. Carretti et al. • Working memory updating in intellectual disability Table 1 Group characteristics ID group Chronological age (in years) Mental age (in years) Raven total TD group M SD M SD 38;4 6;2 17.36 12;3 1;6 4.46 6;5 6;6 17.50 1;3 1;4 4.28 ID, intellectual disability; TD, typically developing. Materials WM updating word span This task was an adaptation of the relevance-based updating task proposed by Palladino et al. (2001) (see Belacchi et al. 2010). The task used words with high values of concreteness and familiarity (Barca et al. 2002) and referred to objects easily comparable for size. For each level of WM load (from 1 to 5), two trials composed of two lists were presented to the participant who had to remember an increasing number of items (from 1 to 5) according to the criterion ‘recall the smallest object/s within each list’ and in the order of presentation. In particular, the number of words in the list was twice (first trial) and two and a half times (second trial) the number of words to be recalled. An example of first type level-2 trial (i.e. two items to be recalled) might be: pillow, ladder, pen, tree. In this case the correct response is pillow and pen. WM battery The battery consisted of four verbal WM tests, already used in previous studies (Belacchi et al. 2010), all comprising the same type of material as that used for the WM updating span. The graduation in controlled attention requested by the task was carried out according to Lanfranchi et al. (2004). In the forward word span (low control), lists of 2–7 words were presented to the participant who had to repeat the list immediately and in the order of presentation. In the backward word span (medium-low control), again lists of 2–6 words were presented, but the participant was asked to repeat each list in reverse order immediately after presentation. In the selective word span (medium-high control), for each level of memory load (from 2 to 5), two trials composed of two lists were presented to the participant who had to recall the first word of each list after presentation of the entire series. Thus at level 2, in the first trial, the participant was presented with two 2-word lists, in the second trial, with two 4-word lists, at level 3, with three 2-word lists and then three 4-word lists and so on. For example, the second trial was as follows: (1) school, evening, fish, arrow; and (2) ground, mother, leaf, wood. The child thus had to remember the words school and ground. Finally, in the d … Get a 10 % discount on an order above $ 100 Use the following coupon code : NURSING10