The only way we can travel through time, of course, is in our mind.

But as we do so — as we contemplate either our past or our future — our body moves ever so imperceptibly with us.

Specifically, we sway slightly backward when we muse about the past and slightly forward when we turn our thoughts to the future.

That’s the curious finding from a new study conducted by a team of researchers at the University of Aberdeen in Scotland and published earlier this month in Psychological Science, a journal of the Association for Psychological Science.

The finding suggests that the invisible process of mental time travel (chronesthesia) elicits an unconscious physical movement — a movement that reflects our metaphor for time (past = back; future = forward).

In other words, our perceptions of time and space may be very closely linked.

Here are the specifics about the study: The scientists fitted 20 young adults with a movement sensor. They then blindfolded the participants and asked them to recall what a typical day was like for them four years earlier or to envision what a day in their life might be like four years in the future. The sensors detected that the participants consistently leaned backward when dwelling mentally in the past and forward when imagining the future.

Are there any other examples of this kind of coupling of thought and subtle physical movement?

Not that he knows of, wrote psychologist Lynden Miles, the study’s lead author, in an email to me earlier this week.

“The closest I know of,” he wrote, “is the link between the experience and expression of emotion — for instance, emotional states (e.g., happiness) can influence our facial expressions (e.g., smiling) and shape the way we move (e.g, walking speed, gait patterns, etc.). While this isn’t a direct coupling of thought to movement, it’s similar to the extent that emotions are essentially invisible until they are overtly manifest, for example, in patterns of movement.”

I also asked Miles if his findings were cultural-specific — in other words, would people in cultures where time isn’t viewed in a straight line show different movements when thinking about the past and the future?

“We don’t know yet,” he answered. “Some research suggests that not all cultures think of the past as being behind them and the future in front of them — for example, speakers of Aymara, an Amerindian language of the Andes, report the reverse mapping (i.e., past = forward, future = backward). However, this evidence comes from patterns of language use rather than movement. As such, it’s an open question as to whether this group would show movements consistent with our participants, or alternatively, consistent with their local patterns of language use.”

The question is an important one, he added: “It may help inform us about the origins of the sorts of effects we are reporting. That is, do we come to associate time with space in particular ways because of repeated exposure to language, (e.g., metaphors) or is the mechanism grounded in more basic, non-linguistic processes?”