The Development of Executive Function in Autism

Table 1

Definition of key constructs and examples of tasks used to test these skills in preschool and primary school-age children.

Construct	Component	Definition	Description of an example task
	Working memory	The ability to hold information “on-line” and manipulate it. Working memory is differentiated according to whether the information is verbal or spatial in nature.	Verbal working memory can be tested using the Digit Span task from the Wechsler Intelligence Scales [44] in which participants are asked to repeat number sets, which progressively increase in complexity, back to the experimenter either in the same (forwards) or reverse (backwards) order. Spatial working memory can be tested using a Spatial Span or Corsi Blocks task [45] in which the child is shown a block board containing 9 cubes in fixed positions. The experimenter taps the wooden blocks (1–9) in a sequence and child is asked to repeat the sequence in the same (forwards) or reverse order (backwards). Backward span for both tasks requires manipulating the to-be-remembered elements and thus targets working memory.
	Inhibitory control	The capacity to hold a rule in mind, responding according to this rule, and resist a prepotent response.	In Luria’s hand-game [46, 47], a test of motor inhibition, the child first imitates the experimenter’s hand movements (make a fist or point a finger). Next, the child must execute the opposite action (i.e., when the experimenter makes a fist, the child points finger, and vice versa). Success on this task demands that the child both hold in mind an arbitrary rule and inhibit the prepotent tendency to copy the experimenter’s gesture.
Executive function	Set-shifting	The ability to shift flexibly one’s attentional focus.	Card-sorting tasks require children to switch cognitive set in response to verbal feedback. The child is shown a set of cards and must sort the cards according to one dimension (e.g., shape). The rule then changes and the child must shift to sort according to new dimension (e.g., colour). In some tasks (e.g., in the Dimensional Change Card Sort task [48]), children are explicitly told the rule change, while in others (e.g., in the teddy bear set-shifting task [26]), the rule change is implicit. Children who can switch flexibly between cognitive sets make fewer “post-switch” errors.
	Planning	The ability to formulate a plan (including selecting appropriate goals and sub-goals) and executive this plan effectively.	In the Tower of London task [26, 49], children are shown a peg-board containing three vertical pegs of increasing size and three beads (red, white, black) arranged in a particular configuration (“start state”). Children are then given a picture showing the beads in a different configuration (“goal state”) and instructed to move the beads from the start state to the goal state within the minimum number of moves possible while observing various rules. Success on this task requires children to plan ahead and to generate and maintain a series of moves.
	Theory of mind	The ability to infer the mental states (e.g., beliefs, desires) of others in order to make predictions about their behavior.	In the now-classic false-belief paradigm [50, 51], children watch one character (Sally) place an object (e.g., a ball) in one location (a basket) and leave the room. While the main character is absent, another character (Ann) surreptitiously moves the object from one location to another. Children are then asked to predict the main character’s behavior (“Where will Sally look for her marble?”). Successful performance on such a task involves children predicting an action based on an attributed false belief.
Social competence	Joint attention	Requires the triadic coordination or sharing of attention with another person around an object or event.	Semi-structured observational schedules like the Early Social Communication Scales [52] are designed to elicit joint attention behaviours, including children’s ability to (a) respond to the experimenter’s eye gaze or gestures (e.g., pointing) to share a common point of reference and (b) initiate joint attention using eye contact and gestures to direct the experimenter’s attention to the point of interest.
Adaptive behavior		Those skills necessary for individuals to live independently and to function well in real-life personal and social settings.	The Vineland Adaptive Behavior Scales—Second Edition (Vineland-II) [53] is one standardized parent-report measure designed to assess a variety of typical developmental milestones with respect to social and communicative competence and real-life daily living skills.