An Investigation of Complementary Autonomic Measurements as an Approach to Improve Single-switch Access for Children with Profound Physical Disabilities

The combination of single-switch access and scanning is arguably one of the most versatile solutions in restoring communication and environmental control for children with profound physical disabilities. Erroneous switch behaviours due to failures in decoding functional intent heighten the risk of declining use and technology abandonment, especially if those errors restrict participation. Complementary information about the user's internalized monitoring of single-switch scanning and reactions to switch output could lead to strategies for managing error instances as opposed to merely, and perhaps futilely, preventing them. This thesis investigates the possibility of using measurements of a switch user's autonomic nervous activity during single-switch scanning as complementary information. The thesis comprises three studies. The first study explains a process involving learning and mastery behaviours, whereby repeated exposure to isolated error instances can diminish the confidence of a proficient switch user and instill apprehension towards switch use. The findings of this study strongly motivate the need for augmenting single-switch access with complementary information to manage error instances. The second study demonstrates, at an ensemble level, the existence of autonomic responses (cardiac deceleration and increased phasic electrodermal activity) to correct, accidental and missed switch activations by three paediatric single-switch users. The third study analyzes a representation of the cardiac activity measurement (line length time series derived from the empirical mode decomposition of the inter-beat interval time series) that can independently track the state of single-switch scanning on an individual switch event basis, without any prior knowledge of the location of scanning events and dwell time. These findings encourage further study of autonomic measures as complementary information channels to enhance single-switch access.Ph.D