The limits of working memory: Consequences for school learning. Outline

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1 Unité de psychologie différentielle et développementale FPSE Stéphane Baron (8-9) Les quatre Âges de La Vie The limits of working memory: Consequences for school learning Anik de Ribaupierre University of Geneva Genève 6 7 décembre Outline Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained Conclusion Genève 6 7 décembre

2 Working memory: Definitions Various definitions: neopiagetians, Baddeley s model, Engle, Cowan Consensus: WM is a «system» with very limited resources for temporarily maintaining and processing information for use in other cognitive tasks. Very limited, Miller (956): magical number 7. Temporary: different from long term memory Maintenance and processing of information: controlled processing, attentional system; different from short term memory Genève 6 7 décembre Miller, 956 My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals Genève 6 7 décembre

3 Working memory: Definitions Various definitions: neopiagetians, Baddeley s model, Engle, Cowan Consensus: WM is a «system» with very limited resources for temporarily maintaining and processing information for use in other cognitive tasks. Very limited, Miller (956): magical number 7. cf also «stone age brain» Temporary: different from long term memory Maintenance and processing of information: controlled processing, attentional system; different from short term memory Genève 6 7 décembre 5 Klingberg, 9 «Stone age brain» and large increase in the flow of information Genève 6 7 décembre 6

4 Working memory: Definitions Various definitions: neopiagetians, Baddeley s model, Engle, Cowan Consensus: WM is a «system» with very limited resources for temporarily maintaining and processing information for use in other cognitive tasks. Very limited, Miller (956): magical number 7. cf also «stone age brain» Temporary: different from long term memory Maintenance and processing of information: controlled processing, attentional system; different from short term memory Genève 6 7 décembre 7 Working memory (WM) versus Short-term Memory (STM) WM is not so much memory per se, but rather attention Most WM tasks require some transformation and/or processing => prevent chunking, and allow better assessment of attentional capacity WM entails: memory, processing, updating, possibly multi-tasking Close relation to executive functions, too. Genève 6 7 décembre 8

5 Why is it important to measure WM? Involved in many different everyday tasks: Multiply two numbers, e.g. 5 * (with no pen): Store the numbers in WM Apply multiplication rules to calculate successive products which also have to be stored in WM, update content of WM 5*7 is easy, but 655*79 almost impossible if no pencil, because storage of intermediate information exceeds the limited capacity of WM. Follow directions such as: Go straight ahead for blocks, and turn left for block = easy Go straight ahead for blocks, block to the left, right for blocks, left, and then blocks right A code of digits is easy to remember, but a digit code is difficult Capacity of WM most often described in terms of units, or chunks of information Genève 6 7 décembre 9 Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre

6 Informational unit versus chunk List of 6 letters to memorize CBASBUMBIAVTNATO => Probably 7-8 letters are remembered Same letters in the inverse order OTANTVAIBMUBSABC => Probably more than 7-8 letters if one finds a way to organize them Same letters, same order, grouped OTAN TVA IBM UBS ABC => Probably all letters are remembered Once a chunk is established, difficult to break down. Cf telephone numbers, e.g.: 79 9 (standard) in 7 99 Genève 6 7 décembre Examples of WM tasks Strings of digits :forward, backward, complement to Reading span => usually tasks which require to maintain task-relevant information in an active state, while ignoring other aspects (distracting information) Often require to respond to some question, or some manipulation Recall information that increases in set size Genève 6 7 décembre

7 Developmental aspects of WM Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre Pascual-Leone s model: a dynamic interplay between several mechanisms Knowledge base (Long termmemory) (adapted from Pascual-Leone & Baillargeon, 99) H * = Field of activation Field of centration Field of mental attention Controlled attention Genève 6 7 décembre

8 Zoom on the field of mental attention (adapted from Pascual-Leone, 98) The content of the field of mental attention is dynamically constituted by a sequence of controlled activations (M mechanism) and inhibitions (I mechanism) E Overall activation of a number of informational units. Executive schemes help «deciding» which units should be effortfully activated (by M) and which should be desactivated (activation and inhibition) I i Some schemes are desactivated (inhibited) M A small number of schemes are effortfully inhibited and activated I i More schemes are inhibited Sequence of activation/inhibition may continue (depends on the complexity of the task) Activation by stimulus Activation (controlled) by M Inhibition Genève 6 7 décembre 5 Age Developmental change in the size of the field of mental attention E I M I Age Note changes: in size (increase of M and I with age) in color (inhibition becomes more efficient with age) Age Increase with Age in: the number of units which can be effortfully activated the informational complexity of each unit the efficiency with which irrelevant or less relevant items can be desactivated/ inhibited the complexity and efficiency of executive schemes Genève 6 7 décembre 6

9 Development of WM In brief: Working memory capacity increases with age because: More elements (units, chunks) can be activated simultaneously Distracting information is more efficiently dampened or suppressed (increase of inhibition) Children know better which elements should be activated/ suppressed (increase in knowledge and in executive functions) Genève 6 7 décembre 7 Some examples of developmental change in WM capacity NeoPiagetian models postulate of a stage wise development increase of one unit every two years 5 Case: data from three studies Counting, Crammond Visual, Crammond Predicted, Case Cucui,Case Age Genève 6 7 décembre 8

10 Longitudinal study WM (A. de Ribaupierre et al., ) Genève 6 7 décembre 9 Life-span Study (A. de Ribaupierre et al., ) Age differences: Standardized units, relative to young adults (with means) Working Memory Processing Speed Interference (intr + stcoul) <7 > Genève 6 7 décembre

11 Study : Inhibition study (de Ribaupierre et al., ) Age differences: Standardized units, relative to young adults (means) 8 9 Y <7 >7 Working Memory Processing Speed Interf Genève 6 7 décembre WM and cognition Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre

12 WM and cognition Many studies have observed a strong relation between WM and cognition, across the lifespan: general cognition, executive functions, etc (cf Engle) As concerns development: Strong relationship Developmentalists, in particular neopiagetians have attempted to establish more precise relationships than correlations For instance, Balance task (scientific reasoning), or other, similar tasks: A relation of implication has been hypothesized: A given level is not achieved if the participant does not present a minimal level n of WM capacity. Does not mean that all participants with the n level will solve the problem, but means that all those with level inferior to n should fail or adopt a simpler behavior. Genève 6 7 décembre The Balance Task (Piaget, 955; de Ribaupierre, 975; Thomas, Pons, & de Ribaupierre et al., 996; see also Siegler, Case) Items A: Would the balance be level if unblocked? Items B: Place a given weight, e.g.. P, once P has been placed at D, so that the balance will be level Score: 6 ordered levels (dimensions oftransformation); analysis of the task P, D versus P, D5 complexity Genève 6 7 décembre

13 Balance task P, D versus P, D5 Item Type Minimal cognitive level for correct solution P, D5 / P, D5 Weight P, D8 / P, D6 Distance P, D / P, D6 Conflict- Weight P5, D / P, D5 Conflict - distance P, D5 / P, D Conflict balance? («qualitative» response) or 6 P8, D / P6, D Conflict balance 6 Genève 6 7 décembre 5 Item P, D5 / P, D5 Balance task P, D8 / P, D6 P, D / P, D6 P5, D / P, D5 P, D5 / P, D P8, D / P6, D Cog. Level Example of behavior Focus on one variable, dissociate arms; P, D5 will go down, and P, D5 remains horizontal Focus on one variable (weight or distance): P, D5 goes down because more weight Takes two variables into account, but no coordination: P, D5 should go down because farther, but P5, D because more weight Qualitative compensation: Balance, because P8, D has more weights and P6, D has more distance 5 Differences: P8, D (left) goes down because fewer weights right, and only fewer hole left 6 Quantitative coordination (easy trials): Balance, because P (left) is twice as heavy, and D (right)is twice as far Min. att. level 5 Genève 6 7 décembre 6

14 Implicative hypothesis (adapted from A. de Ribaupierre, 975, 5, and from Thomas et al., 996) st administration, N = 5 nd administration, N = Balance CSVI >5 5 6 Del =.8, p <. Balance CSVI >5 5 Del =.6, p <. Balance CSVI 5 6 => The hypothesis of implication is statistically validated, particularly for the st year > Del =.9, p <.5 rd administration, N = 98 Genève 6 7 décembre 7 Training in the cognitive task is only successful if the WM level is sufficient. e.g., Case, 985 Control of variables (OP + S) Implicative hypothesis and training Balance task: training of an additive strategy applicable to relatively easy items. Corresponds to OP + S Condition Dimensional % passing Posttest level Treatment OP + S 7 Measured STSS Condition Cucui BDS Mean age OP + Control OP + S OP + Pretest (%) Genève 6 7 décembre 8 N Posttest (%) Treatment Control

15 Case (985) / Bidimensional quantification (Liquids, OP + S) Posttest Measured STSS Condition Cucui BDS Mean age N Posttest (%) Treatment Control Genève 6 7 décembre 9 WM and learning Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre

16 WM and reading across the lifespan (from Siegel, 99) Bons lecteurs Mauvais lecteurs Nombre moyen de mots corrects dans une tâche de mémoire de travail ans -9 ans -9 ans -9 ans -9 ans Age Number of recalled words: Readers with difficulty < readers without difficulty Augmentation du nombre de mots rappelés jusqu à ans Chiappe, P., Hasher, L., Siegel, L.S () Genève 6 7 décembre Gathercole & Alloway, 8 Learning difficulties and working memory Figs... &.. Verbal STM and WM scores of 6-7 year-old children grouped according to attainment level in English or in Maths Fig..5. WM scores of year-old children identified as in special educational need in different areas Fig... WM scores of - year-olds grouped according to attainment levels Fig..6. Proportion of children with reading difficulties, obtaining low (<86) and very low (<8) standard scores on measures of cognitive ability: Visuo-spatial STM Working memory Performance IQ Verbal IQ Language Verbal STM Phon. awareness Genève 6 7 décembre

17 Learning difficulties and working memory Swanson, 8 Several longitudinal studies, as well as meta-analyses : Battery of tests over a -year period, in grades,, and : Our preliminary longitudinal work supports the notion that growth in WM is an important predictor or children s problem solving beyond the contribution of reading, calculation skills and individual differences in phonological processing, inhibition, and processing speed. Focus on 7 year old children with Reading Difficulties (RD). Comparison of children with RD only, RD and arithmetic difficulties (MD), low verbal IQ, and skilled readers: WM growth for skilled readers differed significantly from subgroups of children with RD [ ] No significant differences in growth curves among subgroups of children with RD. Genève 6 7 décembre WM in the brain Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre

18 WM and Brain in adults Owen et al., 5, Figure. Meta-analytic activation maps for all n-back studies Owen et al, 5: Meta-analysis of n-back studies, including 668 foci : Six cortical regions consistently activated across all studies:. bilateral and medial posterior parietal cortex, including precuneus and inferior parietal lobules (approximate BA7,);. bilateral premotor cortex (BA6,8);. dorsal cingulate/medial premotor cortex, including supplementary motor area (SMA; BA,6);. bilateral rostral prefrontal cortex or frontal pole (BA); 5. bilateral dorsolateral prefrontal cortex (BA9,6); 6. bilateral mid-ventrolateral prefrontal cortex or frontal operculum (BA5,7). Additionally, there was a focus of activation in medial cerebellum. Genève 6 7 décembre 5 WM and Brain in children versus adults Crone & Ridderinkopf, from Jolles et al, Developmental Science, - year-olds and young adults. Words to remember, Forward (maintenance) versus Backward (maintenance and manipulation) More activation at higher loads in young adults, and more difference between maintenance and manipulation Functional changes within Dorso-Lateral PreFrontal Cortex and VentroLateral PFC; age group differences most pronounced in right DLPFC. Other authors have also observed not only quantitative but also qualitative differences, particularly when comparing 8- year-olds with adults Genève 6 7 décembre 6

19 WM and developmental changes in brain Crone & Ridderinkopf, Figure, adapted from Johnson, DLPFC: dorsolateral prefrontal cortex VLPFC: ventrolateral prefrontal cortex SUPPAR: superior parietal cortex Maturational account : performance increases because of the maturation of additional brain areas, such as DLPFC and SUPPAR. Interactive specialization: refinement of connectivity between brain regions (VLPFC, DLPFC and SUPPAR). Skill learning account: children may first perform a WM task based on reliance on a lower-level system (such as VLPFC) but, when older, they rely on different systems (such as DLPFC and SUPPAR). Genève 6 7 décembre 7 Training and WM Definitions of working memory (WM) How to measure WM Developmental aspects of WM Relations between WM and other aspects of cognition (example of the Balance task) Relations betweeen WM and learning (reading, math, etc.) WM in the brain: in adults in children Can WM be trained? Conclusion Genève 6 7 décembre 8

20 Can WM capacity be extended through learning? Most studies demonstrate improvement in performance in WM tasks, in particular in children, and/or in special populations, but rarely more than % improvement, despite long training Very few studies observe transfer or generalisation effects to other tasks (other WM tasks, fluid intelligence, etc.). Exceptions: Klingberg, in ADHD children, Jaeggi et al. in young adults). Cf Shipstead, Redick, & Engle, : Concluding Remarks An ostensible strength of WM training is that it provides a focused, theoretically motivated method through which broad cognitive change may be stimulated (Klingberg, ; Sternberg, 8). However, contrary to the reports provided at the beginning of this article (and contrary to the claims of commercial providers), the present literature provides insufficient evidence of its efficacy. Our primary concerns regard the need for researchers to (a)include multiple measures of abilities of interest, (b)consistently measure near transfer with valid WM capacity tasks that differ from the method of training, (c)eliminate the use of no-contact control groups, and (d)ensure that when subjective measures of change are used, raters are blind to condition assignment. Until these controls are consistently applied, the meaningfulness of training effects cannot be evaluated. Genève 6 7 décembre 9 An example of a training program Genève 6 7 décembre

21 Can WM capacity be extended through learning? Most studies demonstrate improvement in performance in WM tasks, in particular in children, and/or in special populations, but rarely more than % improvement, despite long training Very few studies observe transfer or generalisation effects to other tasks (other WM tasks, fluid intelligence, etc.). Exceptions: Klingberg, in ADHD children, Jaeggi et al. in young adults). Cf Shipstead, Redick, & Engle, : Concluding Remarks An ostensible strength of WM training is that it provides a focused, theoretically motivated method through which broad cognitive change may be stimulated (Klingberg, ; Sternberg, 8). However, contrary to the reports provided at the beginning of this article (and contrary to the claims of commercial providers), the present literature provides insufficient evidence of its efficacy. Our primary concerns regard the need for researchers to (a)include multiple measures of abilities of interest, (b)consistently measure near transfer with valid WM capacity tasks that differ from the method of training, (c)eliminate the use of no-contact control groups, and (d)ensure that when subjective measures of change are used, raters are blind to condition assignment. Until these controls are consistently applied, the meaningfulness of training effects cannot be evaluated. Genève 6 7 décembre WM capacity limits and learning in the classroom Is it necessary to wait that capacity limits increase before teaching a given content? How to overcome WM limitations (young children, poor WM capacity, etc.)? Simplify Decompose information in more, less complex steps By learning, pack information in chunks Genève 6 7 décembre

22 Principles of a WM intervention (Alloway & Gathercole, 8). Recognize WM failures incomplete recall, failure to follow instructions, place-keeping errors, task abandonment. Monitor the child Lookout for warning signs of WM overload (see above), ask the child. Evaluate the WM demands of learning activities Excessive length, unfamiliar and not meaningful content, demanding mental processing activity. Reduce WM loads First identify what the desired learning outcome is, and modify (e.g., shortening), reduce the amount of material, increase meaningfulness of material, simplify mental processing (e.g., simplify grammatical structure), restructure complex tasks 5. Be prepared to repeat 6. Encourage use of memory aids 7. Develop the child s use of strategies for supporting memory 8. Request help, Rehearsal, Note-taking, Using long-term memory, Place-keeping and organizational strategies Genève 6 7 décembre WM capacity limits and learning in the classroom Is it necessary to wait that capacity limits increase before teaching a given content? How to overcome WM limitations (young children, poor WM capacity, etc.)? Simplify Decompose information in more, less complex steps By learning, pack information in chunks Genève 6 7 décembre

23 Conclusion Take home message: Severe constraints in WM capacity, part of which is biological Slow increase in WMC during entire childhood Interest of neuroscience/ neuroimaging approaches: general, for research. Premature to apply in the classroom For applied purposes, it suffices to know that there are biological limits, only part of which can be circumvented by learning Ways to get around WM limits: help packing more information in each chunk; simplify instructions and procedures; provide external supports Genève 6 7 décembre 5 Unité de psychologie différentielle et développementale FPSE Stéphane Baron (8-9) Les quatre Âges de La Vie Thank you for your attention Genève 6 7 décembre 6