Barkley (1997) developed a model that predicted the deficit in behavioural inhibition that typifies Attention Deficit Hyperactivity Disorder (ADHD) reduces effective use of the four executive abilities that underly self-control and goal-directed behaviour. This deficit thereby indirectly disrupts the control of goal-directed motor behaviour by its influence on these executive functions. As a consequence, the actions of individuals with ADHD are controlled more by the immediate context and its consequences than long-terms consequences compared to people without ADHD. The behaviour of people without ADHD is controlled moreso by internally represented information, such as self-talk, self-monitoring, hindsight, forthought and self-motivation. These skills help people to reach long-term goals.
Barkley (1997) proposed that there are four main executive functions that contribute to behavioural inhibition. Behavioural inhibition is the ability to stop a response that is not serving the individual (e.g., lashing out, speaking out of turn, buying something impuslively, making an impulsive decion, doing something else rather than the original task they were supposed to be doing). These four executive functions are outlined below:
1. WORKING MEMORY
Working memory is the ability to hold events of information in mind and then acting on or processing that information. It also involves the imitation of complex behavioural sequences that allow us to learn complex tasks. It is responsible for hindsight and forethought, anticipation of "what might happen next" and our in-built sense of time. It is also involved in how we organise our behaviour over time to achieve goals.
2. SELF-REGULATION OF EMOTION, MOTIVATION AND AROUSAL
We require our frontal lobe to help us control and manage our emotions appropriately. It also allows us to take the perspective of others in social situations to then adapt our behaviour to the situation. We require executive functioning to help motivate us to do the things we need to do, even when they are boring. This executive function also helps us gain enough arousal and momentum to complete tasks to move towards a bigger goal.
3. INTERNALISATION OF SPEECH
Have you ever had a conversation with yourself in the car? Given yourself a pep talk on the ay to work to help you get through a long, tough day? We do this a lot during the day but it is kept in our brain. We are constantly "talking to ourselves" to regulate our actions. People with ADHD have less ability to use internal speech to regulate behaviour and emotions. This ability helps us to follow rules as we remind ourselves quietly of what we should be doing. Self-talk helps us to reflect and solve problems. It also helps us make connections to new rules that help to make us grow and learn. Self-talk is also important for moral reasoning.
4. RECONSTITUTION
Reconstitution involves the analysis and synthesis of behaviour. It helps us creatively engage in goal-directed behaviour to learn as we go. It involves the ability to predict what behaviours might lead to what outcomes. It also involves the syntax of behaviours.
“The poor sustained attention that apparently characterises those with ADHD probably represents an impairment in goal- or task- directed persistence arising from poor inhibition and the toll it takes on self-regulation. And the distractibility ascribed to those with ADHD most likely arises from poor interference control that allows other external and internal events to disrupt the executive functions that provide for self-control and task persistence. The net effect is an individual who cannot persist in effort toward tasks that provide little immediate reward and who flits from one uncompleted activity to another as disrupting events occur. The inattention in ADHD can not be seen as not so much a primary symptom as a secondary one; it is a consequence of the impairment that poor behavioural inhibition and interference control create in the self-regulation or executive control of behaviour."
The impairment of these executive functions can vary in terms of how much they are affected. Their net effect is one of a difficulty with day-to-day functioning that can be difficult for the individual with ADHD to manage or overcome without the appropriate support and intervention.
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