Fig. 1. The experimental set-up and visual patterns. Yellow patterns were used in the training and learning test in the morning at Maze B; blue patterns were used in the training and learning test in the afternoon at Maze A; black patterns were used in experiment 1, the transfer tests at Maze A and B. Various transfer tests were conducted at Maze C: (a) experiment 2: yellow training patterns in the morning and blue training patterns in the afternoon; (b) experiment 3: blue and yellow vertical patterns in the morning and blue and yellow horizontal patterns in the afternoon; (c) experiment 4: black horizontal and vertical patterns in the morning and in the afternoon. The rewarded patterns were denoted by (+) and the unrewarded patterns were denoted by (–). See text for further details.