Article for Category: ‘Mental Health’

Behavioral sensitivity to changing reinforcement contingencies in attention-deficit hyperactivity disorder

May 05th, 2016
  • Attention-deficit hyperactivity disorder;
  • response allocation;
  • reinforcement;
  • change


Altered sensitivity to positive reinforcement has been hypothesized to contribute to the symptoms of attention-deficit hyperactivity disorder (ADHD). In this study, we evaluated the ability of children with and without ADHD to adapt their behavior to changing reinforcer availability.


Of one hundred sixty-seven children, 97 diagnosed with ADHD completed a signal-detection task in which correct discriminations between two stimuli were associated with different frequencies of reinforcement. The response alternative associated with the higher rate of reinforcement switched twice during the task without warning. For a subset of participants, this was followed by trials for which no reinforcement was delivered, irrespective of performance.


Children in both groups developed an initial bias toward the more frequently reinforced response alternative. When the response alternative associated with the higher rate of reinforcement switched, the children’s response allocation (bias) followed suit, but this effect was significantly smaller for children with ADHD. When reinforcement was discontinued, only children in the control group modified their response pattern.


Children with ADHD adjust their behavioral responses to changing reinforcer availability less than typically developing children, when reinforcement is intermittent and the association between an action and its consequences is uncertain. This may explain the difficulty children with ADHD have adapting their behavior to new situations, with different reinforcement contingencies, in daily life.

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January 27th, 2012

Everyone experiences anxiety at some point in response to threatening or challenging situations. The anxious response can range from mild physiological symptoms such as rapid breathing and heart rate through to panic attacks. Anxiety becomes a problem when it is chronic and out of proportion to the threat or challenge.

Causes of anxiety

There are likely to be numerous factors involved in causing anxiety. It is also likely that most individuals will experience a different mix of causal factors, which may include genetic factors, unique life experiences, disruption of neurochemicals in the brain, personality, and individual behavioural and thinking styles.

In most cases it is useful to consider that anxiety results from one’s perception of a situation, rather than the situation per se. Imagine yourself in a room with Steve Irwin (the late, great Crocodile Hunter) and a brown snake. Your response may be an initial perception of extreme threat, followed by intense fear and physiological reactions such as increased automatic nervous system responses (e.g., heart rate, breathing, blood rushing from the extremities to the vital organs), followed by a behavioural response such as running from the room. That your physiological and emotional responses diminish once you are safely outside the room reinforces the idea in your mind that snakes are inherently dangerous creatures and that when one sees a snake one needs to run away. In contrast, Steve’s perception of the same situation would most likely have prompted excitement and a strong desire to touch and look more closely at a beautiful animal. His successful behavioural response reinforces his idea that snakes are animals requiring respect but that he is competent to deal with their threat. The same situation, but very different emotion and behaviour. This example shows that it is the perception of the situation that is most important, not the situation itself.

Perhaps a more correct way of putting is that it is the learning experiences one has had in certain situations that are most important. Steve Irwin was born with the inbuilt human trait to fear the unknown. Therefore the first time he saw a snake he would have experienced the same burst of fear as the typical person. However, because of his exposure to the animals and because he learned to handle them competently he also learned not to fear them. In contrast, many people fear snakes despite having never seen one “in the wild”. One could argue that their fear is a ‘failure of learning’ because they have not yet learned that snakes can be avoided or handled competently. Therefore, their default response is the inbuilt human flight mechanism.

Symptoms of Anxiety

Anxiety can be acute (as in the snake example above) or a pattern of chronic worrying. Physiological and behavioural symptoms include:

  • Sweating, elevated heart and breathing rate, shortness of breath, chest pain or discomfort, dizziness, trembling or shaking, sweating, chills or hot flushes, and nausea.
  • Sleep disturbance, irritability or anger outbursts, difficulty concentrating, hyper-vigilance, exaggerated startle responses, muscle tension, fatigue.
  • Fears or worries about general or specific events.
  • Recurrent and persistent thoughts or impulses.
  • Compulsive and repetitive behaviours.
  • Recurring and distressing thoughts/images about a traumatic event.
  • Active avoidance of situations seen as threatening.
  • Decrease in academic, social or occupational functioning.

Anxiety Disorders

When symptoms reach a level of frequency and intensity that interferes with daily functioning (i.e., it creates impairment in job, school or interpersonal functioning) the patient may be diagnosed with an anxiety disorder, or which there are several, including:

  • Panic Attacks
  • Agoraphobia
  • Specific Phobias
  • Social Phobia
  • Obsessive-Compulsive Disorder
  • Posttraumatic Stress Disorder
  • Acute Stress Disorder
  • Generalized Anxiety Disorder


Evidence-based treatment tends to differ between the different anxiety disorders. However, all good clinicians will use a combination of some of the following:

  • Education about the nature of anxiety; particularly about management of the fight or flight response and the circular role of the physiological symptoms such as shortness of breath.
  • Relaxation methods.
  • Structured problem-solving.
  • Gradual exposure to disturbing situations or things.
  • Cognitive therapy designed to help the patient understand that anxiety is a normal part of the human condition and to help them develop resilience that allows them to tolerate emotional distress when it arises.
  • Lifestyle change (e.g., reducing reliance on sleep medication and alcohol, and increasing relaxing activity).
  • Cognitive therapy which involves helping the patient identify unhelpful beliefs and thought patterns and replace them with more positive and helpful ways of thinking. The behavioural component of CBT involves assisting the patient to change behavioural responses, such as restlessness, avoidance, or engaging in compulsions.
  • Medication.


A psychotherapist or a GP who specialises in mental health is usually necessary to diagnose and treat anxiety disorders. Still, there are many things that the patient can do to help themselves.

  • Anxiety produces a response in the brain that leads to secretion of the neurochemical adrenaline. Adrenaline causes the fight or flight response (the body getting ready to run from a stressor or fight it by increasing heart rate and pumping blood from the extremities to the vital organs, increasing breathing, and so on). While the fight or flight response was very adaptive thousands of years ago, in our current society stressful events are often recurring and chronic (e.g., the work situation you can’t get away from).
  • One way we can reduce secretion of adrenaline is to reduce other activities and substances that produce the same neurochemical. These include risky activities and drinking caffeine. Anxious patients should therefore reduce their caffeine intake and try to engage in relaxing recreational pursuits (e.g., do yoga or go for a brisk walk rather than doing a series of sprints or rock climbing).
  • Some people may worry about putting on weight as a result of reducing their exercise level. This may in fact not be the case due to a second neurochemical called cortisol. While adrenaline is the acute (short-term) stress hormone, cortisol is the chronic stress hormone that is produced after prolonged anxiety or ongoing exposure to a challenging event (think rats in a trap). As a survival mechanism, cortisol slows down metabolic rate and it can also create a sugar craving (the quickest way to avoid expiration being to ingest sugar). Continuing to engage in strenuous exercise may therefore be counter-productive. The patient may be better off eating more (but healthier food) and exercising more gently.
  • Be wary of ‘avoidance’ behaviour. Avoiding an anxiety provoking situation is often very successful in the short-term. In the long-term, it tends to reinforce the anxiety. Take social anxiety as an example. A patient who typically was anxious in social situations in which he had to meet new people attended a wedding of his wife’s friend. The gentlemen of the party were to play golf the day before the ceremony; something the patient was quite anxious about. As his wife drove him to the course he became increasingly anxious. He sat in the carpark for a while before deciding not to play golf. His anxiety immediately disappeared (i.e., it was successful in the short-term). However, he missed out on an opportunity to gather evidence that he could cope in such a situation (i.e., it did not help the anxiety in the long-term). Luckily, the patient’s wife remembered his therapy lessons and told him that if he avoided golf he had to talk to five new people at dinner that night, a feat he accomplished with her help. This second feat at least did something to help with his social phobia.
  • The lesson for all anxious patients should be: (1) don’t avoid things if you can help it, and, (2) if you really can’t do something, bargain with yourself and come up with an alternative activity that is not as anxiety provoking but that at least does something for the therapeutic goals.
  • Make lifestyle changes:

Take part in a pleasant activity every day.

Increase gentle exercise.

Reduce caffeine and alcohol intake.

Improve time-management skills.

Rather than pressuring yourself to finish jobs, set a time limit on your work and try to be satisfied with doing a good job within that period.



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