What best describes an operant conditioning technique?

Operant conditioning is a learning process through which the strength of a behavior is modified by reinforcement or punishment. The correct choice describes a technique where a falconer encourages the bird to perform a desired behavior—jumping to the fist—by using a variable reward system. This method not only reinforces the desired behavior but also maintains the bird's interest and motivation, because it introduces unpredictability in the reward system.

The use of varying rewards, such as treats or praise at different intervals, helps to engage the bird and encourages it to repeat the action, as it learns that there is a chance of receiving a positive outcome. This technique is effective because it capitalizes on the principles of reinforcement and keeps the training dynamic.

In contrast, other options describe techniques that are either punitive or not aligned with the principles of operant conditioning. For instance, pinching the bird's toe or withholding food both employ aversive stimuli that could instill fear or anxiety rather than a learning response. These methods may lead to avoidance behaviors rather than encouraging desired actions through positive reinforcement, which is central to effective training and operant conditioning.