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How We Get Our ETA Right or Wrong

How We Get Our ETA Right or Wrong

To get to work on time, people tend to rely on estimates of how long the drive took last time. But different outside influences such as how many songs played on the radio last time can skew our perception of time, causing even the best-laid plans to go awry, according to time-management researchers at Washington University in St. Louis.

“Our results suggest time estimates of tasks that we need to incorporate into our later plans, like a drive to an appointment, are often based on our memory of how long it took us to perform that same drive previously,” said Dr. Emily Waldum, principal author of the paper and a postdoctoral researcher in psychological and brain sciences.

“Even if you think you estimated the duration of events accurately, external factors unrelated to that event can bias time estimates,” she said. “Something as simple as the number of songs you heard play on your phone during a run can influence whether you over- or under-estimate the duration of the run.”

Furthermore, growing older appears to alter one’s “prospective memory,” a term psychologists use to describe the process of remembering to do something in the future.

Waldum and co-author Dr. Mark McDaniel, a professor of psychological and brain sciences, designed this study to tease out differences in how people young and old approach a challenge that requires them to plan ahead and complete a series of time-based tasks by a specific deadline.

The study involved 36 college undergraduates and 34 healthy older adults in their 60s, 70s, and 80s. It aimed to simulate the complicated time-based prospective memory (TBPM) challenges that people old and young experience in everyday life.

First, participants were asked to keep track of how long it took to complete a trivia quiz. The quiz always ran 11 minutes, but participants had to estimate the time without access to a clock. Some completed the quiz with no background noise, while others heard either two long songs or four short songs.

Next, the volunteers were asked to put together as many pieces of a puzzle as possible while still leaving enough time to complete the same quiz before a 20-minute deadline.

The study showed that each age group used surprisingly different strategies to estimate how much time they would need to repeat the quiz and finish the next phase of the experiment on deadline. Furthermore, contrary to previous research, the older people completed the tasks at about the same rate as the college undergraduates.

One important finding was that older adults tended to ignore the songs playing in the background, and relied instead on an internal clock to estimate how long it would take to complete the first quiz.

Consistent with other research on internal clocks and time perception, seniors in this experiment were more likely to underestimate time taken on the first quiz. This led them to spend a little too much time on the puzzle and to finish the second quiz a bit beyond deadline.

Interestingly, older adults performed about the same, regardless of whether they heard songs or not. For young people though, background music played a big role in whether they were too early or too late, Waldum said.

“When younger adults heard two long songs during the first quiz, they performed a lot like older adults, underestimating the quiz duration and winding up a bit late,” Waldum said. “When they heard four short songs, younger adults overestimated how much time they would need to repeat the quiz leading them to finish it too early.”

While the challenges of being on time may remain largely the same throughout a lifetime, this study suggests that the tricks we use to stay on schedule may evolve as we age.

The study is published in the Journal of Experimental Psychology: General.

Source: Washington University in St. Louis


How We Get Our ETA Right or Wrong

Traci Pedersen

Traci Pedersen is a professional writer with over a decade of experience. Her work consists of writing for both print and online publishers in a variety of genres including science chapter books, college and career articles, and elementary school curriculum.

APA Reference
Pedersen, T. (2018). How We Get Our ETA Right or Wrong. Psych Central. Retrieved on November 28, 2020, from
Scientifically Reviewed
Last updated: 8 Aug 2018 (Originally: 31 Dec 2016)
Last reviewed: By a member of our scientific advisory board on 8 Aug 2018
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