Final answer:
The missing element in the four sources of confidence according to performance psychology is vicarious experience, not self-efficacy, social support, cognitive appraisal, or motivation.
Step-by-step explanation:
The four sources of confidence associated with performance psychology are personal experience, physiological state, verbal persuasion, and vicarious experience. The missing element in the list provided by the student is vicarious experience, which refers to observing someone else perform a task successfully which, in turn, can increase one's belief in their own ability to succeed at the task. This is different from self-efficacy, which is a person's belief in their own capability to complete a task and is not the answer to the question.
For example, seeing a peer deliver a great presentation can boost your own confidence in your public speaking abilities. Other factors like social support and cognitive appraisal, which are important in overall performance, are not specifically listed as sources of confidence in performance psychology according to Bandura.