The general concept of a graded sequence of stimuli from mild to intense used in training is:

• A. Hierarchy of Intensity
• B. Intensity Gradient
• C. Hierarchy
• D. Hierarchy of Severity

Answer: (D)

In training, you build a ladder of stimuli that increases in how aversive or challenging they are, so the dog can progress from easy to harder tasks while staying under control. The best term for this is a hierarchy of severity because it conveys both the ordered progression (a hierarchy) and the differing levels of stimulus seriousness (severity). This framing matches how trainers design sessions: start with the least severe form and only move up to more severe stimuli as the dog demonstrates reliable responses. The other options are less precise: a generic hierarchy doesn’t specify that the steps vary in how severe the stimulus is; an intensity-focused term suggests a continuous scale rather than a set of labeled levels; and a simple hierarchy doesn’t explicitly emphasize the relative aversiveness that drives graded exposure.