TY  - JOUR
T1  - Salivary alpha-amylase and cortisol in infancy and toddlerhood: Direct and indirect relations with executive functioning and academic ability in childhood
JF  - Psychoneuroendocrinology
Y1  - 2012
A1  - Berry, Daniel
A1  - Clancy Blair
A1  - Michael T. Willoughby
A1  - Granger, Douglas A.
KW  - Academic achievement
KW  - Early childhood
KW  - executive function
KW  - Salivary alpha-amylase
KW  - Salivary cortisol
AB  - <p>Using data from a predominantly low-income, population-based prospective longitudinal sample of 1292 children followed from birth, indicators of children&#39;s autonomic (salivary alpha-amylase; sAA) and hypothalamic&ndash;pituitary&ndash;adrenal (HPA) axis (salivary cortisol) activity at 7, 15, and 24 months of age were found to predict executive functioning at 36-months and academic achievement in pre-kindergarten. The findings suggested that the respective cortisol and sAA effects on executive functioning and academic achievement were interactive. Optimal developmental outcomes were associated with asymmetrical cortisol/sAA profiles. Higher cortisol levels were predictive of lower executive functioning and academic abilities, but only for those with concurrently moderate to high levels of sAA. In contrast, higher sAA concentrations were predictive of better executive functioning and academic abilities, but only for those with concurrently moderate to low levels of cortisol. These relations were statistically identical across infancy and toddlerhood. The conditional effects of cortisol and sAA on pre-kindergarten academic achievement were mediated fully by links between these early physiological indicators and executive functioning.</p>
VL  - 37
UR  - http://linkinghub.elsevier.com/retrieve/pii/S0306453012000881
IS  - 10
JO  - Psychoneuroendocrinology
ER  - 

TY  - JOUR
T1  - Contributions of modern measurement theory to measuring executive function in early childhood: An empirical demonstration
JF  - Journal of Experimental Child Psychology
Y1  - 2011
A1  - Michael T. Willoughby
A1  - Wirth, R.J.
A1  - Clancy Blair
KW  - Early childhood
KW  - executive function
KW  - Item response theory
KW  - Measurement
KW  - preschool
KW  - Psychometrics
AB  - <p>This study demonstrates the merits of evaluating a newly developed battery of executive function tasks, designed for use in early childhood, from the perspective of item response theory (IRT). The battery was included in the 48-month assessment of the Family Life Project, a prospective longitudinal study of 1292 children oversampled from low-income and African American families. IRT models were applied to a select set of tasks to demonstrate empirically (a) a principled method for item evaluation, including the utility of item characteristic curves; (b) how to explicitly test whether the measurement properties of executive function tasks are invariant across mutually exclusive subgroups of youths; (c) how the precision of measurement of a given task can vary according to underlying child ability; and (d) the utility of using IRT-based versus percentage correct scores. Results are discussed with respect to the importance of developing psychometrically sound and scalable instruments that facilitate the measurement of interindividual differences in intraindividual change of executive function across the early childhood period.</p>
VL  - 108
UR  - http://linkinghub.elsevier.com/retrieve/pii/S0022096510000676
IS  - 3
JO  - Journal of Experimental Child Psychology
ER  - 

TY  - JOUR
T1  - Test-retest reliability of a new executive function battery for use in early childhood
JF  - Child Neuropsychology
Y1  - 2011
A1  - Michael T. Willoughby
A1  - Clancy Blair
KW  - Early childhood
KW  - executive function
KW  - Latent variables
KW  - preschool
KW  - Retest reliability
AB  - <p>This study reported test-retest reliability for a newly developed executive function battery designed for use in early childhood. A total of 140 predominantly low-income children (<em>M</em>&thinsp;=&thinsp;48.1 months; 51% male; 43% African American) completed up to six tasks on two occasions an average of 18 (<em>Mdn</em>&thinsp;=&thinsp;16) days apart. Pearson correlations between individual task scores indicated moderate retest reliability (mean <em>r</em>&thinsp; =&thinsp;.60; range&thinsp;=&thinsp;.52&minus;.66) similar to that observed in other retest studies of executive function in preschool, school-aged, and adult samples. In contrast, confirmatory factor analyses of performance on the task battery across time indicated high retest reliability (<img alt="" src="http://www.tandfonline.com/na101/home/literatum/publisher/tandf/journals/entities/03D5.gif" />&thinsp; =&thinsp;.95) that was identical to that observed in a recent study that used an identical method involving a sample of older adults. The short-term test-retest reliability of executive function in early childhood is comparable to that observed in childhood and adult samples. The retest reliability of children&#39;s performance on batteries of executive function tasks is appreciably stronger than the retest reliability of their performance on individual tasks. Studies that focus on inter- and intraindividual differences in executive function would be better served by using scores that are derived from task batteries than those derived from individual tasks.</p>
VL  - 17
UR  - http://www.tandfonline.com/doi/abs/10.1080/09297049.2011.554390
IS  - 6
JO  - Child Neuropsychology
ER  -