return trip effect

(名詞) 回程效應:認為回程所花的時間比最初的行程短的錯覺 (即使去程和回程的距離及所花的時間完全一樣)。

What causes this so-called "return trip effect"? You might guess that it has something to do with knowing the route — on the way back, you see landmarks that help you better gauge when you're close to your destination. Well, you'd be wrong! According to this study, the return trip effect (which makes the return trip seem 17-22% shorter on average!) is seen even when people take different routes on the outward and return trips.
—"Flashback Friday: Why the return trip always seems shorter," Discover, July 4, 2014

In past years, researchers have suggested that it has to do with the way our bodies experience and measure time as it passes, or the way we remember the trips we take after the fact, or perhaps a bit of both. On Wednesday, a team in Japan released a new report in the journal PLOS ONE detailing the latest effort to solve the mystery. This group's take? That the return trip effect is created by travelers' memories of their journeys — and those memories alone.
—Eryn Brown, "The trip back home often seems to go by faster — but why?," Los Angeles Times, June 10, 2015