Evidence for the world as an external memory: A trade-off between internal and external visual memory storage

We use visual working memory (VWM) to maintain the visual features of objects in our world. Although the capacity of VWM is limited, it is unlikely that this limit will pose a problem in daily life, as visual information can be supplemented with input from our external visual world by using eye movements. In the current study, we influenced the trade-off between eye movements and VWM utilization by introducing a cost to a saccade. Higher costs were created by adding a delay in stimulus availability to a copying task. We show that increased saccade cost results in less saccades towards the model and an increased dwell time on the model. These results suggest a shift from making eye movements towards taxing internal VWM. Our findings reveal that the trade-off between executing eye-movements and building an internal representation of our world is based on an adaptive mechanism, governed by cost-efficiency.