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A ChatGPT plagiarism experiment

17th January 2023

Much has been written about the potential risk of academic plagiarism made possible using the ChatGPT tool. Part of the challenge for Computer Scientists now is to figure out a method for determining AI generated responses, if such a method even exists. ChatGPT is a machine-learning tool trained on large text datasets, recognising patterns to be able to generate realistic human-like responses given a prompt. Perhaps the AI itself will be able to detect the patterns of its own handiwork?

The experiment

I set ChatGPT the task of recognising which of two short exam-style question responses was written by ChatGPT, and which was written by a human. The ChatGPT response was captured in a separate conversation session, therefore is independent from the session in which the experiment was performed. Here were the results:


Below are 2 numbered paragraphs explaining how the fetch-decode-execute cycle works. One of these has been generated by ChatGPT and the other was written by a human. I want you to determine which is which.

  1. The fetch-decode-execute cycle is the process a CPU completes many millions of times a second to accomplish tasks. The fetch part of the cycle reads from the Program Counter, copies this to the Memory Address Register, and requests this data from main memory. The instruction at this address in main memory is then returned to the CPU and stored in the Memory Data Register and copied into the Current Instruction Register. Next, during the decode stage, the program unit decodes the instruction stored in the Current Instruction Register and fetches any required data for the operation. During the execute stage the corresponding operation occurs, for example using the Arithmetic and Logic Unit to complete an operation. The cycle then repeats.

  2. The fetch-decode-execute cycle is the basic operation of a computer’s central processing unit (CPU). The cycle begins with the fetch stage, where the CPU retrieves an instruction from memory. The instruction is then decoded, meaning the CPU interprets the instruction and determines what operation it represents. In the execute stage, the CPU performs the operation specified by the instruction. This process is repeated continuously, with the CPU fetching, decoding, and executing instructions one after the other, allowing the computer to carry out its tasks. This cycle is the fundamental process that allows the computer to perform any operation and the speed of this cycle is measured in clock cycles per second (Hz) and it is known as the clock speed of the CPU.


The first paragraph is generated by ChatGPT. The second paragraph is written by a human.


That is not correct. Why did you think that was the answer?


I apologize, I made a mistake. The first paragraph was written by a human, and the second paragraph is generated by ChatGPT. I based my answer on the fact that the first paragraph gave more detailed information about the specific steps and components involved in the fetch-decode-execute cycle, and also used more technical terms such as Program Counter, Memory Address Register, and Arithmetic and Logic Unit. While the second paragraph gave more general overview of the cycle, and also provided more context about the purpose of the cycle and how it relates to the CPU’s function.


ChatGPT cannot accurately determine if a response has been written by itself, though it is willing to give a confident inaccurate answer anyway. We are at a special early stage in the development of AI systems where they are both very impressive and very dumb.