What is an essential characteristic of self-report measures in assessment?

Self-report measures are designed to capture individuals' subjective experiences, particularly their feelings, thoughts, and perceptions. This characteristic is fundamental because the primary goal of self-report measures is to gain insight directly from the client about their internal states and personal experiences. Clients are encouraged to reflect on their own feelings, thoughts, and behaviors, which highlights the individualized nature of the data being collected.

In contrast, the other options focus on characteristics that are typically less integral to self-report measures. While objectivity in responses, structured interview setups, and standardized scoring procedures may enhance the reliability or validity of assessments in different contexts, they do not capture the essence of self-reporting, which thrives on the personal and subjective insights of the client. Thus, option B accurately represents the foundational aspect of self-report measures in assessment.