Development of a new diagnosis test for simultanagnosia

Simultanagnosia is a neurological disorder caused by bilateral lesions to the occipitoparietal brain regions. The disorder causes an inability to attend to more than one object or one feature at once. The ambition of this project was to create an ecological diagnosis tool to investigate patterns of visual exploration in normal perceivers and patients with simultanagnosia while looking at everyday scenes. The scenes were manipulated by having a neutral or busy background, having 2 or 3 actors present in the scene, and by having the actors interacting with each other or not. We administrated homemade videos to 40 control participants (24 women, mean age: 21.4). The principal aim of the study was to create norms from which to investigate a patient with simultanagnosia. The participants were asked to simply look at the videos, so that they could describe what they saw at the end of each scene. Presentation order of the scenes was randomized. Participants' eye movements were recorded using an Eyelink 1000 eye-tracking device. The eye tracking analyses consisted of measuring the proportion of total fixation time to regions of interest within each scene. We defined these regions in accordance to the relevant elements of the scene (e.g., the position of the actors, and the area of interaction). The results showed that participants’ attention to the scene was moderated by the number of actors, and by their interactivity. However, there was no significant effect of the background manipulation. The results are discussed in terms of the creation of a new diagnosis test for patients with simultanagnosia.