Based on PISA 2012 and 2015 data, this paper analyzes students’ perseverance in taking a low-stakes assessment, defined as their ability to maintain a constant rate of correct answers throughout the test. It also investigates the possible effect of the administration mode (paper-and-pencil vs. computerized test) on participants’ perseverance. For that purpose, this research exploits the balanced incomplete block design of PISA 2012 and 2015, and focuses on the answers to the questions posed at each of the four positions. The results show an overall decrease in student performance, regardless of the domain and the cycle, and an increase in variability. However, to the questions asked at the start of the test, the students generally answered better in the 2012 than 2015 cycle. On the contrary, to the questions asked at the end of the test, this trend seems to be reduced or even reversed, which could reflect a greater pupils’ motivation to answer with a computerized test.