Final answer:
The theory of planned behavior distinguishes itself from the theory of reasoned action by including perceived behavioral control as a key factor influencing behavior, beyond just attitudes and intentions.
Step-by-step explanation:
The main factor that sets the theory of reasoned action apart from the theory of planned behavior is the inclusion of a component called perceived behavioral control in the theory of planned behavior.
While both theories examine the link between attitudes, intentions, and behavior, the theory of planned behavior acknowledges that an individual's perception of their ability to perform a behavior plays a crucial role in intention formation and the actual behavior execution. This reflects the understanding that even if one has a positive attitude and intention to engage in a behavior, perceived control can facilitate or impede the behavior.