Katie notices there is a new barista at her favorite coffee shop. she also notices that her vanilla latte tastes just slightly sweeter than usual. the taste is right at the threshold.

Difference

Explanation:

The difference threshold, also known as the "just noticeable difference" is the amount that must be changed for a difference to be noticeable at least 50% of the time. Therefore, although the difference is still very small, a person is able to recognize it most of the time. In this case, Katie notices a small change in the sweetness of her latte due to the change in barista. Because the difference is barely perceptible, it is right at the difference threshold.