Doppler effect changes time perception

With the sci-fi prospect of a time machine comes the inevitable question: can we go back in time? But how do we know traveling to the past is in fact going back? This is because humans perceive time as one-directional. We think time only moves forward and nothing in the past can be changed or experienced again. Surprisingly, the common perception of time as having a direction has been confirmed by physicists. Furthermore, physicists discovered that our perception of time changes depending on when an event occurred. The distortion in our perception of time is named the temporal Doppler Effect.

This term, “Temporal Doppler Effect” was coined by Eugene Caruso, an associate professor at the University of Chicago. The famous Doppler effect is illustrated by an ambulance passing by on the street and the pitch of it’s siren seems to get higher as it gets closer, then lower as it drives away. Named for it’s analogous characteristics, the temporal Doppler effect describes the changes in time perception as the person move “away” from an event.

Just as the sound wave’s frequency increases as an object moves closer toward the source of sound, humans see future events as more immediate than past events. Because time moves toward the future, people feel that the future is approaching much more quickly while the past is receding. The psychological effect results in the perception that the future is immediate and the past is very distant.

“[The] Temporal Doppler effect is grounded in people’s movement through time and space…the subjective experience of movement through time is analogous to the physical experience of movement through space,” Caruso said.

In order to test the theory of temporal Doppler effect, researchers found hundreds of volunteers and split the subjects into two groups. For the first group, researchers asked a selection of subjects how they would celebrate an upcoming event — in this case Valentine’s Day. Afterwards, the researchers asked the other group how they celebrated the event. The researchers then asked both groups to rate the immediacy of the event on a seven-point scale.

The researchers asked a series of questions about the holiday one week before or after the event. If time perception is temporally universal, the ratings should be similar. However, the group that received the question before the actual event perceived the occasion as being closer. The ratings from the two groups indicate that past events are seen as being more distant than future events.

To further validate their claims, researchers also presented hypothetical situations to both groups in order to determine the correlation. The relationship remained the same —past events seemed more distant than future events.

“Our work suggests … that there is a systematic difference in people’s perceptions of distance to the past and the future,” Caruso asserted.

Despite the human tendency to treat future events as being much closer than past events, the scientists found that the distortion can be ameliorated. In another experiment, subjects were placed in a virtual world. One group saw the projections as moving forward while the other group experienced the sensation of traveling backwards. After their time in the virtual machine, the group that traveled backwards rated past events as being closer than the control group.

“Many … descriptions of time are closely linked to our experiences of moving through space,”  Caruso explained.

In addition to being an interesting phenomena, the implication of temporal Doppler effect has major impacts in many areas. The discovery offers potential breakthroughs to every sub-field of psychology whether it’s social, developmental, cognitive or clinical.

In an effort to describe the importance of this study, Caruso states the possibility of whether manipulations might mitigate the Temporal Doppler effect exacerbate poor planning for and poor decisions about the future. Furthermore, Caruso is also concentrating efforts toward determining whether the Temporal Doppler effect is associated with healthy psychological functioning.