Fig. 6. Results of transfer tests with fish 1 (blue) and fish 2 (red), during which the size of the S+ (cone) was varied. In pair 2, the big cone was moved further away from the gate (3 cm instead of 0.5 cm) than during all other trials. Each bar depicts the choice frequency for the cone (S+). `Ratio' gives the volume ratios of the cube (S–) divided by the respective cone. Asterisks above each graph indicate significant differences from random choice conditions: ^**P<0.01; n.s., non significant.