Though exact details are highly proprietary, AI detection tools typically assess some combination of perplexity, burstiness, and brevity in the text of a document. Perplexity is a measurement of the unpredictability of a sequence of text. Similarly burstiness is variation in sentence structure and length. Low levels of perplexity or burstiness can sometimes indicate use of a generative AI tool since those tools often produce less varied sentence length and structure when compared with typical human writing. High levels of brevity, or language that comes off as a vague summarization, are also a red flag for AI detection tools.
It bears repeating here that this guide is not an endorsement of any particular tool. AI detection tools have been plagued by low accuracy rates and even once leading tools like OpenAI’s classifier tool have quietly shut down.
Turnitin, a leading academic anti-plagiarism company launched Turnitin AI checker in early 2023. Turnitin AI checker is available under USD’s subscription to Turnitin can be turned on in any assignment that is submitted to Canvas. Note however, due to the challenges imposed by false positives, many educational institutions have chosen to ban or disable Turnitin’s AI detection tool. iThenticate is another product under the Turnitin umbrella, also with AI detection features. iThenticate is a separate license that assists faculty and researchers during manuscript drafting, peer review, and publishing.
GPTZero launched in January 2023 and later that year announced a partnership with the American Federation of Teachers. It has tiered pricing with the basic level available for free, essential $8.33/month, premium $12.99/month, and professional for $24.99/month.
Created specifically for educators and publishers. Like Turnitin and GPTZero it incorporates a plagiarism checker and percentage score. It also allows for the ability to scan handwritten documents. Users can try the tool for free for up to 2,000 words. After that pricing starts at $12/month (80,000 words) or $19/month (200,000 words)
Originality.AI is inexpensive and easy to use though some claim a high rate of false positives meaning that it is incorrectly labeling human-written text as AI-generated. Originality.ai relies on grammar, spelling, and syntactic errors to accurately identify human-written text. After a free trial, it costs $0.01 per credit (1 credit scans 100 words).
Copyleaks easily integrates with some of the most popular learning management systems (LMS) used by instructors, including Canvas and Blackboard and claims a 99.12% detection rate accuracy, but admits that the accuracy to detect AI-generated creative writing is typically lower than other content styles. Copyleaks is a subscription service for $7.99/month.