Exploring and Expanding Multisensory Scotoma Research

Spatial perception forms the cornerstone of how we interact with our environment. However, for those affected by scotomas—blind spots in the visual field mainly caused by age-related macular degeneration, but also arising from other retinal or neurological diseases—these interactions are disoriented. My research investigates how visual and auditory spatial perception is affected by scotomas and how understanding these disorientations can facilitate the development of new early detection strategies and assistive technologies. Particularly, I have worked on the multisensory consequences of scotomas, their effect on decision-making behavior and spatial perception in ecologically relevant environments. To address these questions, I conducted a series of experiments on distinct but interconnected aspects of the mentioned perceptual mechanisms. In chapter 2, I investigated the decision-making behavior of visual occlusion under different visual conditions. While the main focus of this thesis is on scotoma, occlusions represent a related phenomenon, as both conditions partially block the available visual information and influence how the visual system processes the scene. With the mouse, they navigated the cursor towards one of the 3 targets with one partially occluded, one fully occluded and one non-occluded paths. While doing so their trajectories and target choices were recorded. Using the same mechanics, I have developed 5 different designs with different difficulty levels by changing the occlusion size and target sizes. The results suggested systematic avoidance behavior in designs where motor precision is required due to increased occlusion size and decreased target size. This work revealed how vision loss might affect decision-making and motor behavior strategies in daily life. To convert the insights from the chapter 2 into a practical application, in chapter 3 I developed a game design named as V-Spy Scotoma that aims at early detection of central scotomas. V-Spy Scotoma collects behavioral data such as target choice, trajectory, and speed from an engaging touchscreen game. It uses the choice from 3 targets, one of which is placed on the other side of an occluded path due to scotomas. It aims to investigate how participants interact with targets that are either freely accessible or located behind the occlusion caused by the scotoma, requiring interaction with the occluded area. The results showed that the clinical participants showed different behaviors compared to the control participants by avoiding using the center of the screen more. This proves that V-Spy Scotoma can differentiate central scotomas on a group level using trajectory data and has a potential utility as a supportive pre-clinic assessment tool. Building on the previous, in chapter 4 I developed a mixed immersive reality-based experiment paradigm to simulate central vision loss in healthy participants. This experiment serves as a bridge between the state of chapter 3, and future studies where simulations can enable faster and larger-scale investigations. By validating the system with a previously tested design, chapter 4 aims to establish the foundation for extending the scope of spatial and multisensory perception research. With gaze-contingent scotoma simulation, and a real-time auditory and visual localization task, in this chapter, I experimented to see whether the long-term cross-modal adaptation of the clinical population can be recreated with a short-term temporary exposure. The experiment was composed of assessment of auditory and visual spatial perception followed by wearing a VR set where the experiment group will have a simulation of scotoma. Then there is an adaptation and we do the same task again. The results suggest that even a short-term exposure can result in behavioral and perceptual changes in the spatial perception, only in the auditory spatial perception, providing proof of the cross-model plasticity of the sensory system.