Which type of event can only be observed and verified by the individual performing the behavior?

The correct choice refers to a private event, which can only be observed and verified by the individual experiencing it. Private events encompass internal experiences such as thoughts, feelings, and emotions. These experiences are subjective and cannot be directly observed by outsiders; they are unique to the individual and may influence behavior in significant ways.

In the field of applied behavior analysis, it's essential to understand the distinction between public and private events because it impacts how behavior is studied and interpreted. Public events, on the other hand, can be perceived and verified by others, such as observable behaviors or actions in the environment. Experimental events are systematically manipulated and measured in a structured setting, while natural events occur spontaneously and can often be observed but may not always be controlled or measured scientifically. Therefore, private events are distinct because they are solely accessible to the individual engaging in the behavior, highlighting the intimate connection between thoughts and behaviors.