Abstract
Interacting with our surroundings involves the interpretation and storage of visual information, as well as the updating of visual representations of the environment. That is, active interactions in natural behavior are interlocked with visual memory and its associated cognitive mechanisms. When physical-effort demands are low, we use eye movements to delay the gathering of task-relevant information until just before it is required, rather than holding information in working memory. We investigated the role of increasing metabolic demands in the utilization of working memory for efficient task completion in a temporally extended block-copying task. Our aim was to quantify the cost of encoding and maintaining information in working memory to guide behavior by combining head- and eye-movement measurements in virtual reality as we parametrically manipulated the required locomotive effort of the task. Across a series of studies, participants sorted objects into provided templates under conditions requiring varying movement effort during the information maintenance stage of the task. We show that working memory usage increases as locomotion demands increase. Participants shifted from a pure on-line acquisition strategy when minor head movements were required to maintaining up to 4 items when full body rotations were necessary. This change in strategy is accompanied by intricate gaze dynamics during encoding and maintenance, which allows us to describe the shape of the relationship between locomotion effort and working-memory utilization, i.e. quantify the energetic cost of loading working memory. The utilization of cognitive resources is a cornerstone of ecological behavior, and we argue that it should be investigated under the light of available actions and by encompassing naturalistic complexities such as behavioral goals, locomotion, and object interaction, rather than ignoring them.