While interacting with the external world, the brain can only represent very little of this world in working memory (WM). WM is therefore generally referred to as a limited-capacity system. This limitation is not a problem in daily life, however, because the external world typically remains available and can be accessed relatively easily. The current dominant theory of WM does not explain how the brain balances between internal storage and external sampling, as this theory exclusively relates to situations in which the remembered information is no longer physically present. The HOMEOSTASIS project is motivated by the idea that WM should be studied in interaction with the world that is still within view.
HOMEOSTASIS will develop a new theoretical model of WM based on an internal mental economy: we hypothesize that WM maintains a perceptual homeostasis by dynamically trading the costs of accurate internal storage against external sampling of the external visual world. Whereas current research on WM has a strong focus on its maximum capacity, this capacity may hardly be used as observers prefer to minimize internal storage due to the effortful nature of WM storage.We rigorously test the model’s theoretical basis using novel experimental paradigms in which WM is studied in interaction with the physically present environment. To decode the current content of WM, we adopt state-of-the-art electroencephalographic decoding techniques. Finally, we investigate patients with restricted deficits to specific components of the model and use machine learning techniques to discover biometric signatures in eye movements. This new model of WM will open a new window to diagnose WM disorders and for understanding how we interact with computer-manipulated virtual environments in an increasingly computer-dominated world.
The world that we consciously experience is an internal representation of the world, rather than the physical world itself. Through the different stages of perception, observers construct a model of the physical world by internalizing certain aspects of the visual information that is presented to our retina. Although research on visual perception has made great leaps forward in understanding which aspects of the visual world are selected by the brain for further processing, the HOMEOSTASIS project will fundamentally advance vision research: what determines which visual information is maintained in internal memory after it has been selected? This research program has various potential future applications:
First, the project will result in clear hypotheses about which properties of the environment determine the amount of information that will be internalized (e.g. reliability and familiarity). As the amount of internalized information is an index of the current memory load, this knowledge will be of great assistance in designing efficient (work) environments in which memory load is minimized.
Second, our clinical work will result in the development of a novel screening tool for specific dysfunctions in VWM by revealing the oculomotor features (biomarkers) that best reflect deficits in visual memory. Given the rise of easy-to-use and low-cost eye trackers, this approach is promising and feasible. In the near future, the cameras in mobile devices, such as tablets and smartphones, will be used to record eye movements, making such data widely available.
