#20. Executive functions influence most daily activities
Research is beginning to explore the development of executive functions in children with Down syndrome. These skills underpin many aspects of cognition and learning. Further research is needed to explore if early interventions targeting executive function can improve outcomes.
What research has shown
In recent years there has been a great deal of research into the development of executive functions in children and they are increasingly being explored in children and adults with Down syndrome. The three main components of executive function are considered to be working memory (holding and manipulating information in mind), inhibition (self-control - resisting temptations and resisting acting impulsively and selective attention - focusing on relevant input and ignoring distractions) and shifting (cognitive flexibility, being able to adapt to changing requirements of a task). These underpin higher order executive functions, reasoning, problem solving and planning.
"Executive functions make possible mentally playing with ideas; taking time to think before acting; meeting novel, unanticipated challenges; resisting temptations and staying focused ."[ 1 ]
Young children's performance on executive function tasks predict learning and academic outcomes. The development of executive functions is influenced by temperament, sleep and self-regulation (early control of behaviour). It can also be influenced by parenting behaviour and by training.[ 2 - 7 ]
Executive function is defined by some researchers as conscious control over thought and behaviour directed towards a goal and they have shown that from as young as 30 months of age language abilities - being able to label picture cues - influence performance on executive tasks.[ 8 , 9 ] Acquiring language has very significant effects on being able to think, remember, reason and control actions. Eminent thinkers such as Piaget, Vygotsky and Luria drew attention to the significance of language development for cognitive development. Vygotsky suggested that at the first stage of talking, children learn words in a social context and their words must be spoken aloud to others to have meaning for them - social speech. Children then move on to learn to speak to themselves, often during play when they can be heard thinking and controlling their own actions aloud - private speech. The last stage is the ability to use inner speech or silent speech to oneself when thinking, remembering, planning, reasoning, problem solving 'in mind'.
However, researchers suggest that the early foundations of executive functions can be seen in the first year of life as children begin to show control over their behaviour, explore, play, make choices, initiate new actions with toys, learn about cause and effect and solve problems like shape sorters or stacking toys. At this stage, motor skills matter for exploring and manipulating toys and objects. Children show they are controlling their behaviour before they are using language to think and when presumably visual, other sensory and emotional representations 'in mind' underpin recall and control of people, objects and actions.
It may be important to consider that some behaviours which clearly reflect learning and planning are actually controlled by the brain at a subconscious level. This applies to most daily motor activities (reaching, picking up objects, cups, walking, bending, stepping up steps or around objects) where practice leads to smoother and faster automatic control over time. Some motor activities (learning to play tennis, ski, drive a car, play a musical instrument, dance) may be taught by encouraging a child or adult to control movements with conscious instruction but over time practice leads to automatisation and control goes to a subconscious level.
In the recent literature on executive control in children and adults with Down syndrome the role of language and the difference between subconscious automatic control (also called implicit) or conscious real time control (also called explicit) has not been explored, though it has been in some memory studies. It is possible that it is easier for individuals with Down syndrome to develop implicit than explicit control given their delays and difficulties with expressive language. Many teenagers and adults with Down syndrome are described as often using self-talk or private speech when thinking and working out what to do in situations where others would be using inner or silent speech. This could indicate that many individuals with Down syndrome actually find inner speech difficult to use to think, deal with emotions and control their behaviour.
The research on executive functions in individuals with Down syndrome has used two approaches to collect information. The research looking explicitly at executive functions in younger children has used questionnaire measures completed by parents and teachers to describe examples in daily activities.[ 10 , 11 ] The research looking at executive function in older children, adolescents and adults has used a range of experimental tasks.[e.g. 12 , 13 ] The questionnaire studies indicate that children with Down syndrome tend to show specific difficulties in working memory and planning but not in shifting or emotional control when compared with mental age matched typically developing children. Parents, but not teachers, also report difficulties in inhibitory control. The older children/adult studies report conflicting findings. Some report specific difficulties in shifting, planning, inhibition, attention and working memory while others report no difficulties in planning, inhibition or working memory. These conflicting findings may reflect assessing children of different age ranges, using different comparison groups and using different measures.
Frequently, the matching of comparison groups has been based on non-verbal abilities and no language abilities are reported. It is likely that the language abilities of the groups being compared vary and this may be significant in understanding underlying reasons for differences. In addition, individuals with Down syndrome - even as young children - have not had the same play, learning or educational experiences as the comparison groups and they are unlikely to be as familiar with the kinds of tasks they are being asked to do as other children.
Most of the work on executive function in children with Down syndrome has come from Debbie Fidler's research group in Colorado. They argue that the foundations of executive function and cognitive development start with reaching, exploring and moving and they have shown that children with Down syndrome have difficulties with motor planning and problem solving.[ 14 ] Motor delays mean that children cannot explore and find out the properties of objects and the way things work and they recommend helping children to experience objects, explore and play to compensate for their motor delays. One longitudinal study indicates that mastery motivation measured at age 3 years predicts executive function of adults with Down syndrome when 23 years of age - supporting the view that it is important to address the skills underpinning executive function early.[ 15 ]
Research should also be considering how important vocabulary development is in labelling objects and drawing children's attention to concepts such as size, colour, texture and weight with words. In addition grammatical development and its role in allowing children to understand and express more complex ideas and to manipulate ideas in mind needs to be considered.
Training studies are needed to explore what is possible and what the underlying challenges may be for children and adults with Down syndrome on executive function tasks. In addition to allowing them to learn and practise until they reach their best performance, the effect of teaching them to self-direct using spoken language when planning or problem solving should also be explored. Diamond mentions Cogmed training in her review of effective training strategies[ 2 ] and the first study of Cogmed training for children with Down syndrome reported a benefit for visuo-spatial short term memory and an improvement on working memory and shift in everyday function.[ 16 ] Importantly this small study showed that this type of computerised training was possible with 7-12 year olds with Down syndrome but it needs to be replicated with a larger group of children and the benefits of training gains for daily executive function and learning explored over time.
How this is helping
Parents and teachers are aware of verbal short-term memory difficulties and that visual support for learning is important.
Future research is needed to:
- trace the development of all aspects of executive function over time and how they interact in children with Down syndrome
- explore the role that motor delays play in the early development of cognition and executive functions
- examine the links between the development of language and executive functions
- develop and evaluate training activities designed to improve the components of executive function
- Diamond, A. (2013) Executive functions. Annual Review of Psychology , 64, 135-168.
- Diamond, A. (2012) Activities and programs that improve children's executive functions. Current Directions in Psychology , 21, 335-341.
- Diamond, A. (2014) Want to optimise executive functions and academic outcomes? Simple, just nourish the human spirit. Minnesota Symposium on Child Psychology , 37, 205-232.
- Rueda, M.R. & Rothbart, M.K. (2009) The influence of temperament on the development of coping: the role of maturation and experience. In E.A. Skinner & M.J. Zimmer-Gembeck (Eds.) Coping and the development of regulation. New Directions for Child and Adolescent Development , 124 pp 19-31.
- Bernier, A. Carlson, S.M., Deschenes, M. & Matte-Gagne. (2012) Social factors in the development of early executive functioning: a closer look at the caregiving environment. Developmental Science . 15, 12-24.
- Bernier, A., Beauchamp, M.H., Bouvette-Turcot, A., Carlson, S. & Carrier, J. (2013) Sleep and cognition in preschool years: specific links to executive functioning. Child Development , 84, 1542-1553.
- Becker, D.R. Miao, A., Duncan, R. & McClelland, M.M. (2014) Behavioural self-regulation and executive function both predict visuomotor skills and early academic achievement. Early Childhood Quarterly , 29, 411-424.
- Miller, S.E. & Marcovitch, S. (2011) Toddlers benefit from labelling on an executive function search task. Journal of Experimental Psychology 108, 580-502.
- Miller, S.E. & Marcovitch, S. (2015) Examining executive function in the second year of life: coherence, stability and relations to joint attention and language. Developmental Psychology , 51, 101-114.
- Lee, N.R., Fidler, D. J., Blakely-Smith, A. Daunhauer, L., Robinson, C. & Hepburn, S. L. (2011) Caregiver report of executive functioning in a population- based sample of young children with Down syndrome. American Journal on Intellectual and Developmental Disabilities , 116, 209-304.
- Duanhauer, L.A., Fidler, D.J., Hahn, L., Will, E., Lee, N.R. & Hepburn, S. (2014) Profiles of everyday functioning in young children with Down syndrome. American Journal on Intellectual and Developmental Disabilities . 119, 303-318.
- Costanzo, F., Varuzza, C., Menghini, D., Addona, F., Gianesini, T. & Vicari, S. (2013) Executive functions in intellectual disabilities: a comparison between Williams syndrome and Down syndrome. Research in Developmental Disabilities , 34, 1770-1780.
- Borella, E., Carretti, B. & Lanfranchi, S. (2013) Inhibitory mechanisms in Down syndrome; Is there a specific or general deficit? Research in Developmental Disabilities , 34, 65-71.
- Will, E., Fidler, D & Daunhauer, L.A. (2014) Executive function and planning in early development in Down syndrome. International Review of Research in Developmental Disabilities , 47, 77-98.
- Hauser-Cram, P., Woodman, A.C. & Heyman, M. (2014) Early mastery motivation as a predictor of executive function in young adults with developmental disabilities. American Journal on Intellectual and Developmental Disabilities , 119, 536-551.
- Bennett, S.J., Holmes, J. & Buckley, S.J. (2013) Computerized memory training leads to sustained improvement in visuospatial short-term memory skills in children with Down syndrome. American Journal on Intellectual and Developmental Disabilities , 118, 179-192.