Throughout development, children become increasingly more able to control their motor actions (Hamilton, Southgate, & Hill,
2016). This developing motor control represents planning, organizing, monitoring, and controlling complex motor coordination
which seem to have an intuitive connection with executive functioning (EF). Although the exact definition is widely discussed, most
researchers would agree on the notion that EF refers to a set of higher-order cognitive processes, such as inhibition, working memory,
and cognitive flexibility, which are instrumental in supporting action control and thought (e.g., Carlson, Faja, & Beck, 2016). The
conceptual overlap has been highlighted previously: by definition, purposive movement involves action control, and action control is
an essential part of EF (Koziol, Budding, & Chidekel, 2012). Another key developmental skill to consider when exploring the relationship
between motor performance and EF is verbal ability. Verbalizing thoughts supports action control, i.e., expression of
actions, reflection of performed actions, and planning of future actions (Kray, Eenshuistra, Kerstner, Weidema, & Hommel, 2006).
The idea that there is a relationship between motor performance and higher-order cognitive functions, such as EF and language,
stems also in part from theoretical perspectives. For example, in the embodied cognition perspective, cognition – and EF and language
as subdomains of cognition – are considered to occur in the context of the individual's bodily interaction with the physical and social
environment (Barsalou, 1999; Gibbs, 2005; Smith & Gasser, 2005). Being able to act upon their environment allows children to gain
knowledge about their surroundings, which leads to changes in various perception-action systems (Von Hofsten, 2009). These
changes bring about advances in cognition that in turn will affect how children examine and manipulate their environment (Campos
et al., 2000; Von Hofsten, 2007). This is not to say that the physical body is the only system involved in cognition or that one can
assume a global association between motor performance and cognition, but that specific motor actions could play a role in this process
(Oudgenoeg-Paz, Volman, & Leseman, 2016).
In addition, several authors have argued that thought, reasoning, and other forms of complex cognitive processes, such as EF,
depend on interiorization of actions (Ardila, 2012). Verbal ability may be viewed as an essential means in the interiorization of
actions. For instance, a central point in Vygotsky’s theory (1962) is that verbal ability represents a major instrument of internal
representation of the world and thinking. Similarly, Clark (2008) describes language as cognitive scaffolding, extending the embodied
mind and making it possible to generalize across situations and experiences. Verbal ability thus helps children to regulate their own
actions and thoughts.
The conceptual and theoretical link between the aforementioned developmental domains is supported by neuroimaging research
(Diamond, 2000; Pangelinan et al., 2011; Pulvermüller, 2005). Brain areas associated with EF, such as the dorsolateral prefrontal
cortex, and brain areas necessary for the planning and execution of movements, such as the cerebellum and basal ganglia, are coactivated
during the execution of specific motor and EF tasks (Diamond, 2000). For example, a study examining brain activity in 8- to
12-year old children during a motor task showed activation of a broad network of regions, including the dorsolateral prefrontal
cortex, inferior parietal lobule, and the cerebellum (Zwicker, Missiuna, Harris, & Boyd, 2011). Furthermore, areas of the brain
implicated in language functions (e.g., Broca’s area) are also activated during EF tasks (Gerton et al., 2004) and motor tasks (i.e.,
action planning, action observation, action understanding, and imitation; Nishitani, Schürmann, Amunts, & Hari, 2005). In addition,
the activation of motor areas has been observed during language tasks (e.g., Casado et al., 2018; Pulvermüller, 2005; Willems &
Hagoort, 2007).
Yet behavioural studies looking at direct connections between developmental domains have not yielded clear results. Studies
examining the relationship between motor performance and EF have revealed only modest associations between both domains,
including studies that do not find these associations (Hamilton et al., 2016; Van der Fels et al., 2015). In addition, although studies
reported that children with motor coordination difficulties, including children with a diagnosis of Developmental Coordination
Disorder (DCD), have clear EF difficulties (Leonard & Hill, 2015; Wilson, Ruddock, Smits-Engelsman, Polatajko, & Blank, 2013),
research has also shown that the commonly assumed link between motor coordination difficulties and executive dysfunction is not
always present (Molitor, Michel, & Schneider, 2015).
Similarly, while in recent years increasing empirical evidence is reported for a link between motor performance and language in
typically developing children during the first 3 years of life (e.g., He, Walle, & Campos, 2015; Libertus & Violi, 2016; Walle & Campos,
2014), the relationship seems to weaken or disappear as a function of age (Libertus & Hauf, 2017; Oudgenoeg-Paz et al., 2016). In
addition, developmental disorders such as Specific Language Impairment (SLI) have been related to motor coordination difficulties
and DCD to language impairments (see Hill, 2001 and Leonard & Hill, 2014 for reviews). Although the general finding in children
with developmental disorders is one of relatively high rates of co-occurrence between motor coordination difficulties and language
impairments, not all children with motor coordination difficulties have language impairments and vice versa.
With regard to the relationship between verbal ability and EF, a number of studies have shown that typically developing children’s
verbal ability is related with EF performance, and that children with SLI score poorly on EF tasks (e.g., Fuhs & Day, 2011;
Gooch, Thompson, Nash, Snowling, & Hulme, 2016; Kaushanskaya, Park, Gangopadhyay, Davidson, & Weismer, 2017; see Müller,
Jacques, Brocki & Zelazo, 2009 for a review). However, with regard to the EF of children with SLI, conflicting results are also present
with some researchers finding evidence of dysfunction in children with SLI and others reporting equivalent performance between
S. Houwen et al. Research in Developmental Disabilities 84 (2019) 3–15
4
children with SLI and typically developing children (Kapa & Plante, 2015).
Overall, studies are inconclusive about the exact extent of the relationships between developmental domains, which might be due
to developmental differences within children, individual differences across children, and to different measures used to assess children’s
motor performance, EF, and verbal ability (Leonard & Hill, 2015; Libertus & Hauf, 2017). Furthermore, despite empirical
associations between motor performance, EF, and verbal ability in different bivariate combinations, no study has yet explored how
these three domains interact. This research is the first to examine these three areas of child development concurrently in early
childhood in order to shed light on the constellations of motor performance, EF, and verbal ability in young children.
Mainly variable-oriented and correlational methods have been used when examining the relationship between the aforementioned
developmental domains, which have been based on the assumption of linearity of relationships. Such an approach potentially
oversimplifies the complex interplay between developmental domains in young children. The possibility that subgroups of individuals
may show profiles with different interrelations between motor performance, EF, and/or verbal ability has rarely been taken
into account. A person-centered approach, such as latent profile analysis (LPA), can describe the patterning of multiple variables
within individuals to capture essential features of functioning that may be lost when simple linear associations are analysed (Bergman
& Magnusson, 1997; Collins & Lanza, 2010). Using a person-centered approach for examining the relationship between motor
performance, EF, and verbal ability may be vital at all stages of child development, but even more so during the preschool-age period
because this developmental period is characterized by both a rapid growth as well as considerable intra- and interindividual
variability in motor performance, EF, and verbal ability (Howard, Okely, & Ellis, 2015; Piek, Hands, & Licari, 2012).
An important issue to consider when examining EF in preschool children is the structure of EF. For primary school children,
adolescents, and adults there is conclusive evidence concerning three distinguishable, yet interrelated, constructs of EF; that is:
working memory, inhibition, and cognitive flexibility (Huizinga, Dolan, & van der Molen, 2006; Miyake, Emerson, & Friedman,
2000). Yet, in preschool aged children the evidence regarding the structure of EF is less conclusive. Factor analysis studies with 3-year
olds consistently show a unitary EF factor model (Wiebe, Espy, & Charak, 2008; Willoughby, Wirth, & Blair, 2012). Both one- and
two-factor models have been found within samples of 4- and 5-year old preschoolers, with the majority of two-factor models revealing
an inhibition and working memory component (e.g., Lee, Bull, & Ho, 2013; Monette, Bigras, & Lafrenière, 2015). It is
important to note however, that in many of these two-factor models working memory and inhibition were significantly correlated
(with correlations>.80; Monette et al., 2015). Additionally, it is argued that cognitive flexibility is only emerging from the primary
school age and thus not yet distinguishable in preschool aged children (e.g., Garon, Bryson, & Smith, 2008). In sum, empirical
evidence seems to support an initial unitary structure of EF, and as a function of age a differentiation of components occurs.
Related to the structure of EF, is the operationalization and measurement of EF, specifically performance-based measures versus
parent ratings of EF (Leonard & Hill, 2015; Toplak, West, & Stanovich, 2013). There is mounting evidence that performance-based
measures and parent ratings of EF do not assess the same construct (Toplak et al., 2013). While performance-based EF measures
typically assess specific, individual executive functions under highly structured and standardized conditions, rating scales of EF were
developed to tap into complex, real-world manifestations of executive functions (Toplak et al., 2013). It has been suggested that the
type of EF measurement may affect the relationship found between motor performance and EF (Houwen, van der Veer, Visser, &
Cantell, 2017; Ten Eycke & Dewey, 2016). Addressing this issue is particularly relevant in early childhood, where assessment of EF by
performance-based measures is a challenge, as validated tests are relatively few, norms are uncertain, and variables as limited
attention span, motivation, and confidence in the testing situation might influence the results (Nilsen, Huyder, McAuley, &
Liebermann, 2016).
Therefore, the first aim of the current study was to identify distinct constellations of motor skills, EF, and verbal ability in
preschool aged children. For EF both multiple performance-based measures and a parent rating measure were used. Based on the
reviewed evidence and our young sample, we expected a one-factor model for EF including inhibition and working memory tasks. As
performance-based EF measures and parent ratings of EF have been found to provide complementary but distinctive information, we
assumed a model with a unitary EF variable based on performance-based tasks and a unitary EF variable involving the parent rating.
We have chosen to focus on receptive vocabulary as a measure of verbal ability, as receptive vocabulary develops rapidly in early
childhood and builds the foundation for language acquisition and literacy (Powell & Diamond, 2012). Furthermore, it has been
suggested that receptive vocabulary tests provide the purest measure of language ability (Milligan, Astington, & Dack, 2007). Given
the exploratory and innovative nature of our study, it was impossible to have a comprehensive view on the number of possible
profiles. We did, however expect to delineate profiles that not only differ in quantity, but exhibit qualitatively distinct patterns of
motor, EF, and verbal ability skills. The second aim was to explore how individual and contextual variables were related to profile
membership.
