(2Dのほうが探しやすい [1, 2]) [1] A. Cockburn and B. McKenzie, "Evaluating the Effectiveness of Spatial Memory in 2D and 3D Physical and Virtual Environments," Proc. CHI '02, ACM, pp. 203‒210, 2002. doi:10.1145/503376.503413 [2] G. Robertson, M. Czerwinski, K. Larson, D. C. Robbins, D. Thiel, and M. van Dantzich, "Data Mountain: Using Spatial Memory for Document Management," Proc. UIST '98, ACM, pp. 153‒162, 1998. doi:10.1145/288392.288596