Four groups of 10 humans each participated in an eye-blink conditioning experiment. In Group 1, a 0.5-second tone was followed by a puff of air to the eye on every trial (Group 100%); in Groups 2, 3, and 4, the tone was followed by the airpuff on 75%, 50%, and 25% of the trials only. The US never occurred in the absence of the CS (i.e., the US did not occur during the 1-minute intertrial intervals). For each group, the experimenter counted the number of people who blinked to the tone.

In the space below, draw a learning curve for each group and explain your reasoning using the concept of contingency. [Hints: Remember, when plotting a learning curve, you always need to consider two variables -- the rate of learning and the asymptote. Also, you need to take into account two probabilities -- i.e., P(US|CS) and P(US|No CS) -- and infer the rates and asymptotes of learning for each group according to the difference between the two probabilities. Finally, you need to determine the dependent and independent variables to plot the learning curves.]