Which ethical principle relates to the trustworthiness of psychologists in all interactions?

The ethical principle that relates to the trustworthiness of psychologists in all interactions is integrity. Integrity emphasizes the importance of honesty and adherence to moral and ethical principles in professional practice. Psychologists are expected to provide information and services that are accurate and truthful, thus fostering trust both with clients and within the broader community. This trust is foundational for effective therapeutic relationships and for maintaining the profession's reputation.

While the other principles, such as justice, beneficence, and fidelity, are also crucial in the field of psychology—dealing with fairness, the obligation to help others, and loyalty or promise-keeping respectively—they do not focus specifically on the notion of trustworthiness in the same way. Integrity encompasses a broader commitment to ethical behavior, which is essential for psychologists to uphold their credibility and the ethical standards of their profession.