A course that lasts “2 hours and 59 minutes” feels longer than one that lasts “3 hours,” even though it is a minute shorter. Marketing researchers call this the added-unit effect: adding a smaller unit of time to a larger one makes the whole duration seem longer.
The study, Every Minute Counts: The Added-Unit Effect In Time Perception, by Tatiana Sokolova, Deepak Sirwani and Maximilian Gaerth, was published online in the Journal of Marketing Research on September 6, 2026. Sokolova is listed in Tilburg University’s marketing research group.
Hours plus minutes feel longer
The authors combined data from an online course aggregator platform with nine preregistered experiments. Across them, describing time with a larger and a smaller unit, such as “by 8 PM on June 30” instead of “by the end of day on June 30,” increased how long people thought something would take.
The effect appeared across several combinations: dates with hours, hours with minutes, and minutes with seconds.
Many small pieces
The researchers trace the effect to mental representation. Adding a smaller unit leads people to picture time as a collection of more numerous, smaller pieces, which makes the total feel bigger.
That shift has practical consequences. The studies show effects on interest in online courses, on judgments of how well a product works, on how people set time-based goals and on trade-offs between time and money.
For anyone writing delivery promises or course descriptions, the takeaway is simple: a round number in one unit tends to sound shorter than the same span spelled out in two.
Study Details:
- Title: Every Minute Counts: The Added-Unit Effect In Time Perception
- Authors: Tatiana Sokolova, Deepak Sirwani, Maximilian Gaerth
- Journal: Journal of Marketing Research
- Publication Date: September 6, 2026
- DOI: 10.1177/00222437261488297