Towards the use of visual masking within virtual environments to induce changes in affective cognition

This thesis concerns the use of virtual environments for psychotherapy. It makes use of virtual environment properties that go beyond real-world simulation. The core technique used is based on research found within perception science, an effect known as backwards visual masking. Here, a rapidly displayed target image is rendered explicitly imperceptible via the subsequent display of a masking image. The aim of this thesis was to investigate the potential of visual masking within virtual environments to induce changes in affective cognition. Of particular importance would be changes in a positive direction as this could form the foundation of a psychotherapeutic tool to treat affect disorders and other conditions with an affective component. The initial pair of experiments looked at whether visual masking was possible within virtual environments, whether any measurable behavioural influence could be found and whether there was any evidence that affective cognitions could be influenced. It was found that the technique worked and could influence both behaviour and affective cognition. Following this, two experiments looked further at parameter manipulation of visual masking within virtual environments with the aim of better specifying the parameter values. Results indicated that the form of visual masking used worked better in a virtual environment when the target and mask were both highly textured and that affective effects were modulated by the number of exposures of the target. The final pair of experiments attempted to induce an affect contagion effect and an affect cognition-modification effect. An affect cognition-modification effect was found whereas an affect contagion effect was not. Overall, the results show that using visual masking techniques within virtual environments to induce affect cognition changes has merit. The thesis lays the foundation for further work and supports the use of this technique as basis of an intervention tool