Walk Backward to Better Memory
Backward motion through physical space can improve our recall of the past.
Posted December 31, 2018
Whenever we’re remembering some incident from our past, it’s not uncommon for us to say we’re “thinking back” on it, figuratively attributing spatial characteristics to non-spatial time. We know that space and time are separate entities, but when we think of our relationship to time, we often picture ourselves traveling along a timeline with the future extending in front of us and the past stretching out behind us. We look “forward” to the future and “back” to the past. While thinking of time in terms of spatial dimensions is, of course, purely figurative, a recent study in England suggests that thinking of time in terms of physical space offers unexpected and potentially useful benefits when it comes to remembering the past. Through a series of experiments designed to test the effect of backward travel through space on the recall of events occurring in the recent past, Aksentijevik et al. demonstrated that thinking “back” — or more specifically thinking “backward” — to the past can improve our memory of what we experienced there.
In a series of six experiments, participants were presented with either a video of a staged crime, a word list, or a set of pictures, and were later tested on the accuracy of their recall of the video, words, and pictures. Between the presentation and the test, the participants engaged in one of three different activities designed to measure the effect of backward motion, forward motion, or no motion on their ability to answer questions about the video or recall the words and pictures. In a “physical motion” activity, participants either walked forward toward a target, walked backward toward a target, or stood still for two minutes — approximately the amount of time it would have taken them to receive instructions and walk to the target. In an “imaginary motion” activity, participants closed their eyes and imagined themselves walking either forward or backward to a target, or stood still for two minutes. In an “optic flow” activity, participants watched a video filmed from the back platform of a moving train. Some participants watched a forward version of the video, which moved backwards from the observers’ perspective, while others watched a reverse version of the video, appearing to move forward form the observers’ perspective. A control group of participants stood still for two minutes.
Throughout the series of experiments, participants in the backward motion conditions — whether real, imaginary, or virtual — exhibited better recall than the participants in either the forward motion or no motion conditions. This correlation between backward motion and improved recall suggests “some form of temporal indexing” through which related memories “are ordered on the subjective timeline and stored in a temporal sequence or a time-indexed spatial cluster.” The mental experience of moving backwards through space appeared to carry the participants’ minds backward along that subjective timeline toward the point at which the remembered information was encoded, thus improving their recall.
Aksentijevic et al. have labeled the observed effect of “motion-induced mental time travel” on memory as the “Mnemonic Time Travel Effect.” While their research on the phenomenon is admittedly in its early stages, they believe that it shows promise for potentially developing “motion-based mnemonic aids," which, among other possible applications, could prove beneficial to the elderly and people with dementia. Whatever the practical applications of the “Mnemonic Time Travel Effect” may turn out to be, the results of the present study offer compelling evidence for the dynamic relation of memory to the entirety of human experience. Rather than being “an enclosed domain whose task is to retain information and make it available,” memory is but a component of a larger “embodied system which brings together perception, thinking and action.”
The embodied nature of memory blurs the line between space and time, and, where descriptions of memory are concerned, between literal and figurative language. The timeline upon which we traverse the course of our lives is thus a physical as well as a mental construct, and a trip down memory lane is as much an occasion for walking shoes as for a shoebox full of old photographs.
Aksentijevic, Aleksandar, K. R. Brandt, E. Tsakanikos, and M. J. A. Thorpe. “It Takes Me Back: The Mnemonic Time Travel Effect.” Cognition. 2019 January. 182:242-50. Epub 2018 October 24.