What principle is in effect if a puppy learns not to jump against the owner's legs due to the owner ignoring it?

The principle at work here is extinction, which occurs when a behavior that was previously reinforced no longer receives reinforcement, leading to a decrease in that behavior over time. In this scenario, the puppy's jumping behavior is likely motivated by attention from the owner. When the owner ignores the puppy, they stop providing the reinforcement (the owner's attention) that may have encouraged the jumping.

As the puppy continues to jump but receives no response, it learns that this behavior does not lead to anything positive, which eventually diminishes the likelihood of jumping against the owner's legs in the future. Extinction is a gradual process where the absence of reinforcement leads to a decline in the frequency of the behavior. This situation exemplifies how ignoring a behavior can lead to its extinction.