Turnitin will most likely adjust the AI detector as AI advances (for example, with the popular ChatGPT). However, AI is developing at such a rapid pace that instructors should accept the AI detector score with some skepticism, as false-positive results are possible. Veteran Turnitin users know that setting an arbitrary percentage for the similarity score regardless of the assignment or the student reduces the likelihood that this information will be used to inform a meaningful conversation about the student's writing. Due to system restrictions, students cannot see either the AI writing detection indicator (percentage) or the report (highlighted text).
The educator's own knowledge about the student and their work is as crucial to understanding the AI writing score as the percentage itself...
