The necessity of motoric engagement in enhancing route memory.

The relative contribution of decision-making and motor engagement at encoding, on route memory, was examined using virtual reality (VR). During encoding, participants explored 12 virtual environments for 40 s each. Navigation strategy during encoding was manipulated within-subjects. On Active trials, participants made decisions about their route of travel. On Guided trials, they followed a pre-determined path overlaid on the road, removing the need for decision-making. On Passive trials, participants simply viewed a set route, without initiating decision-making nor engaging movement during encoding. Following exploration of each environment, participants were asked to 're-trace their steps' using the exact route they had just travelled. We also manipulated type of VR implementation (Desktop VR, Headset VR) between subjects. Movement in a Desktop-VR group was controlled via keyboard input, limiting motoric engagement. Movement in a Headset-VR group occurred using a VR-compatible steering wheel, requiring relatively greater motoric engagement. We found an effect of navigation strategy only in the Headset-VR group: route memory was significantly better following Active and Guided relative to Passive trials. Memory did not differ following Active relative to Guided trial types, suggesting that decision-making does not underlie the memory benefit. We suggest route memory is enhanced when initiating physical movement during encoding.