Fig. 1. Virtual navigation task and behavioral data.

(A) Associative object-location memory task during virtual spatial navigation. At the beginning of the experiment, patients collected eight different objects from eight different locations within the virtual environment. Afterward, patients completed variable numbers of retrieval trials, during which they were first presented with one of the eight objects serving as cue (“cue presentation”). Patients then navigated to the remembered location of that object (“retrieval”) and made a response. Following this response, patients received feedback via an emoticon (“feedback”) and had to collect the object from its correct location (“re-encoding”). (B) Overhead view of the virtual environment (diameter, 9500 vu). Goal-directed navigation occurred after cue presentation, when patients started (“S”) navigating to the assumed object location. Starting locations were identical with ending locations from preceding trials and thus varied from trial to trial. The trial-wise drop error was calculated as the Euclidean distance between the response location (“R”) and the correct location (“C”). (C) Histogram of drop errors across all trials and all patients. Red dashed line, overall chance performance. (D) Change in mean drop error across objects between the first and the last trial. Gray lines, patient-wise data; thick red line, average.