25+ B phase Introduction of IV % s A phase = 20 Baseline H [ L 154 y o > 2 10 @ 3 o 5 L o 2P 0 T T I I T 1 3 5 9 11 1l3 15 17 19 21 23 Days -~ Figure 4 Hypothetical example of the step-wise change in frequency in behavior when using the changing-criterion design. Notes: The baseline is recorded for 6 days. On day 7, the IV is introduced. Abbreviation: IV, independent variable