We developed a Virtual Shopping Test for realistic cognitive assessment using virtual reality technology. The objective of this study was to investigate differences in task performance, brain activation, and subjective assessments in relation to the task difficulty level. Subjects were asked to buy two specific items in Task 1, four items in Task 2, and six items in Task 3 at a virtual mall. The tasks and questionnaires were conducted by convalescent brain-damaged patients and healthy adults. Hemodynamic changes in the prefrontal cortex (PFC) during activation due to the tasks were examined using functional near-infrared spectroscopy. The mean total time was longer for the patients than for the healthy subjects in all tasks. PFC responses in the patients were greater in Task 2 than in Task 1. The patients subjectively evaluated these tasks as more difficult than healthy adults. Although task performance as well as PFC responses were not significantly changed in the healthy adults, they could subjectively evaluate differences between the three task levels, whereas the patients could not, which indicated that patients could not clearly distinguish between differences in the difficulty of the tasks performed. Taken together, the results suggest that the difficulty of the 4-item shopping task may have been sufficient to cause brain activation in the brain-damaged patients.
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