The purpose of the study is to determine if a new device, called the Anxiety Meter, improves recognition and management of psychological arousal associated with anxiety in children with ASD.

Anxiety is a prevalent, persistent, and disabling co-morbidity of autism spectrum disorder (ASD). In addition to its profound negative impact on physical and mental health, anxiety interacts with the core deficits of ASD to exacerbate symptomatology and increase functional impairment. Anxiety treatments efficacious in non-ASD children (e.g., Cognitive-Behavioural Therapy (CBT)) often have reduced potency and limited applicability in the ASD population due to impairments in cognitive ability, communication, emotional awareness, and introspection. Despite the urgency to treat co-morbid anxiety in ASD, there is limited evidence supporting treatment programs in higher-functioning individuals, and no evidence for those who are lower-functioning. In light of the urgent need for treatment of co-morbid anxiety in ASD and the paucity of evidence in this area, the investigators propose a study to establish early evidence on a technology-supported treatment of anxiety in children with ASD. This approach aims to reduce ASD-related barriers to treatment (e.g., deficits in emotional awareness and introspection) by providing children with a visual, real time display of their arousal level.

The proposed treatment focuses on the physiological arousal associated with anxiety. In particular, the investigators propose to use a physiological indicator of anxiety that can objectively measure and promote awareness of physiological arousal. To this end, the investigators have developed the Anxiety Meter, a device that measures arousal-related increases in heart rate using non-invasive wearable sensors and translates these to a visual display of the child's arousal level on a tablet computer. The investigators research questions are:

1. Primary: Does the Anxiety Meter improve awareness and management of physiological arousal induced by anxiogenic stimuli in a controlled setting? Hypothesis: The Anxiety Meter will improve awareness and management of symptoms because it promotes awareness of arousal - a skill which is impaired in ASD.
2. Secondary: What demographic and cognitive and behavioural variables predict response to the Anxiety Meter? Hypothesis: Age, IQ, sex, and severity of anxiety symptoms at baseline will affect treatment response.

To investigate the above questions, the investigators propose a randomized controlled trial comparing the Anxiety Meter to a control condition in children with ASD. Both the treatment and control groups will be taught a relaxation technique (three training sessions) and will be asked to apply the technique in a controlled anxiety-inducing task (one testing session). During the testing session, participants will be seated in front of a computer screen and will complete five tasks:

1. Baseline (30 minutes): After completing the STAI, participants will watch an animated movie clip. This task has been used successfully as a "baseline activity" in our previous studies in the target population.
2. Anxiety condition 1 (3 minutes): In this task, participants will be given 3 minutes to prepare a 3-minute talk. They will be told that the talk will be delivered to an audience of 3 strangers.
3. Intervention (2 minutes): Both groups will use this time to reflect on their anxiety level and apply the relaxation technique if they feel anxious. The treatment group will receive a real-time display of physiological arousal on the Anxiety Meter, whereas the control group will not receive feedback from the device. Our previous studies indicate that five minutes is sufficient for the heart rate to return to baseline. Both groups will complete the STAI (attached) as a report of their anxiety levels before and after the task.
4. Anxiety condition 2 (3 minutes): Participants will deliver a 3-minute talk to an audience of 3 strangers.
5. Return-to-baseline (15 minutes): Participants will watch an animated movie clip.

Inclusion Criteria:

1. Children 8-18 years of age.
2. Primary diagnosis of autism spectrum disorder according to Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5).
3. Full-scale intelligence quotient (IQ) >50.
4. Must be able to complete tasks and the relaxation technique. A participant will be deemed able to do the public speaking task if he/she is able to complete Modules 3 or 4 of the Autism Diagnostic Observation Schedule (ADOS) protocol.
5. Must show physiological arousal in response to anxiety-inducing stimulus (minimum 2 beats/minute increase in heart rate).

Exclusion Criteria:

1. Started other treatments within four weeks at the time of the study.
2. Completed Cognitive Behavioural Therapy in the past.
3. Using beta-blockers.