Jelmer Tiemessen

Who they are

At the time of the thesis, Tiemessen was a master's student in information sciences at Radboud University in the Netherlands. The thesis is dated 15 July 2022 and was supervised by Hanna Schraffenberger, with Gunes Acar as second supervisor. The experiment was reviewed and approved by the research ethics committee of the university's Faculty of Science. A short version appeared in 2023 in the extended abstracts of the CHI conference on human factors in computing systems, with both supervisors as co-authors. His affiliation in that paper is Radboud University.

The experiment asked 245 people recruited through the Prolific research platform to choose an office chair from a fictional webshop under a work budget. Both chairs cost $260. In a control group neither carried an offer. In a second group the grey chair showed an original price of $320. In a third it showed the same markdown and a seven-minute countdown timer that restarted whenever the page was refreshed. The grey chair was chosen by 17 per cent of the control group, 56 per cent of the markdown group and 46 per cent of the timer group, and the study could not tell the last two apart.

The thesis lists its own limits: the money was imaginary, the setup might not have worked entirely as intended, and the sample did not match the population of online shoppers. Its abstract calls for a ban on deceptive countdown timers, which is the authors' position and is reported here as such. This page records nothing about him beyond the cited work.

How the experiment was set up, and why that matters

The design isolates one variable at a time. Because the control group saw no offer, the markdown group saw a markdown only and the timer group saw the markdown plus a clock, the comparison between the second and third groups is the clean test of whether the timer adds anything. The first comparison, no offer against markdown, shows that the offer itself matters: 17 per cent of the control group chose the grey chair against 56 per cent of the markdown group. The grey chair in the timer group was chosen by 46 per cent, a gap from the markdown group that the study could not tell from chance.

Colour was a confound the design had to live with. With no offer on, more than four in five people chose the black chair, and colour was the reason participants gave most often. That is why the experiment fixed the price of both chairs at $260 and varied only the offer, so that any shift toward the grey chair could be read as a response to the offer.

The free-text answers add a second layer. Nobody in the timer group named the timer as a reason for choosing. Ten people in the markdown group said a chair on sale must be worth more, a reading that does not depend on any deadline. Five in the timer group said they had avoided the offer because it looked fake. All 245 participants were also asked whether countdown timers influence them: 93 said yes, 38 said sometimes and 108 said no, with several of the no answers giving distrust as the reason.

What the study cannot tell a seller

The timer was false by design, since it restarted when the page was refreshed, so the experiment says nothing about an honest timer on a true offer. The money was imaginary, the product was one chair, and the authors describe the study as exploratory. The authors read the result as the markdown doing the work and the timer doing none that could be detected. A reader should take it as a careful first test of one deceptive timer in a lab, and not as a measure of what timers do in shops.

Key papers

Tiemessen, J., Schraffenberger, H., & Acar, G. (2023). "The Time is Ticking: The Effect of Limited Time Discounts on Consumers' Buying Behavior and Experience." Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems, 1-11. doi:10.1145/3544549.3585735.

Tiemessen, J. H. (2022). "The Time is Ticking: The Effect of Deceptive Countdown Timers on Consumers' Buying Behavior and Experience." MSc thesis, Radboud University.

Key ideas

The discount, not the clock, appeared to do the work. Among people who took the discounted chair, reported fear of missing out was higher in the timer group than in the group that saw no offer. In free-text answers, several participants said they distrusted the timer, and nobody in the timer group named it as a reason for their choice. See Deceptive Countdown Timers and Fear of Missing Out.

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