1. Executive functions in adults with developmental dyslexia
James H. Smith-Spark 1, Lucy A. Henry 2, David J. Messer 3, Elisa Edvardsdottir 1, and Adam P. Zięcik 1
1 London South Bank University, London, United Kingdom
2 City University, London, United Kingdom
3 Open University, Milton Keynes, United Kingdom
INTRODUCTION
Executive functions (EFs) are higher-order cognitive abilities. There is much evidence to indicate that EFs are impaired in children with dyslexia (for a review, see Booth et al., 2010).
However, the evidence is predominantly laboratory-based and does not tend to show how dyslexia-related EF problems impact on everyday life (although see Locascio, Mahone, Eason & Cutting, 2010).
Moreover, the study of EF in dyslexia has tended not to extend across a range of different EFs or be bound to a particular theoretical framework.
Despite the effects of dyslexia persisting into adulthood (e.g., McLoughlin, Fitzgibbon & Young, 1994), EFs in adults with dyslexia are less well-documented (although see Brosnan et al., 2002).
The two studies reported here sought to understand both typical everyday EFs and also performance on a comprehensive battery of EFs under laboratory conditions, reflecting the difference between Stanovich’s (2009) reflective and algorithmic levels of cognition.
The same participants took part in Studies 1 and 2. There were thirty adults with dyslexia and 30 adults without dyslexia, matched for age and short-form IQ and differing significantly on measures of reading and spelling.
STUDY 1: SELF-REPORT QUESTIONNAIRE STUDY
Investigating EFs under typical day-to-day conditions using a self-report questionnaire.
METHOD
Seventy-five item Behavior Rating Inventory of Executive Function (BRIEF-A; Roth, Isquith & Gioia, 2005) completed by participants.
Participants rate frequency of EF failure in the past month on a three-point scale (1 = Never, 2 = Sometimes, and 3 = Often).
The BRIEF-A comprises two indices, Metacognition and Behavioral Regulation.
The Metacognition Index was made up of five clinical scales: Initiate, Working Memory, Plan/Organize, Task Monitor, and Organization of Materials.
The Behavioral Regulation Index consisted of four clinical scales: Inhibit, Shift, Emotional Control, and Self-Monitor.
RESULTS
Adults with dyslexia indicated significantly more EF difficulties overall, Wilks’ Λ = .653, F(9, 51) = 3.02, p = .006, ηp2 = .347
Significantly more prone to problems on three of the nine BRIEF-A clinical scales
Working Memory, Plan/Organize, and Task Monitor; all p-values ≤ .004
DISCUSSION
Problems with EF reported to be more frequent by adults with dyslexia. These difficulties affected the Metacognition Index but not the Behavioral Regulation Index. Problems related to the ability to solve problems in an organized, planned, systematic way, using working memory but not the control and regulation of emotions.
STUDY 2: LABORATORY-BASED STUDY
Testing optimal EF performance under laboratory-based conditions.
Three EFs investigated (inhibition, updating, and set shifting), using the Miyake et al. (2000) unity-diversity framework (see also Friedman & Miyake, 2012).
METHOD
Inhibition was measured using a variant on the Go/No Go task (e.g., Luria, 1966), requiring a different response to be made when a less frequently occurring stimulus was presented.
Set shifting was tested using the Plus-Minus task (Jersild, 1927), requiring simple arithmetical operations from which a cost of switching between adding and subtracting three from a two-digit number can be calculated.
Updating was tested using two working memory span measures
The Operation Span task (Conway et al., 2005; Unsworth et al., 2005), requiring participants to solve arithmetic problems whilst also retaining a gradually increasing series of letters for later serial recall.
The Symmetry Span task (Conway et al., 2005; Unsworth et al., 2009), asking participants to decide whether patterns were symmetrical whilst remembering a series of cells highlighted in a 5x5 grid.
RESULTS
Adults with dyslexia were significantly worse than controls in all three EFs
being less accurate in inhibiting the pre-potent response on the inhibition task,
showing a shifting cost which was 2.5 times the magnitude of that of the controls,
and having worse performance on both updating measures.
DISCUSSION
Poorer performance found in the adults with dyslexia in all three EFs tested, across different task demands and different processing modalities.
GENERAL DISCUSSION
Dyslexia-related problems with EFs indicated at both the reflective and algorithmic levels (Stanovich, 2009) in the same sample of participants. The results highlight the need for an awareness of the cognitive challenges facing adults with dyslexia.
ACKNOWLEDGEMENTS
Some of the data reported here formed part of Elisa Edvardsdottir’s MSc Neuropsychology at Maastricht University. Additional data collection was funded by a seed-corn grant from the Centre for Research in Psychology at London South Bank University.