Associate Professor of Psychology and Neuroscience; Stanford University
Future Self-Continuity

Five years from now, what will your future self think of your current self? Will you even be the same person?

Over a century before the birth of Christ, Bactrian King Milinda challenged the Buddhist sage Nagasena to define identity. The Buddhist responded by inquiring about the identity of the king’s chariot: “…is it the axle? Or the wheels, or the chassis, or reins, or yoke that is in the chariot? Is it all of these combined, or is it apart from them?” The king was forced to concede that his chariot’s identity could not be reduced to its’ pieces. Later, Greek scholar Plutarch noted that the passage of time further complicates definitions of identity. For example, if a ship is restored piece by piece over time, does it retain its’ original identity? As with Theseus’ reconstructed ship, the paradox of identity applies to our constantly regenerating bodies (and their resident brains). Flipping in time from the past to the future, to what extent can we expect our identity to change over the next five years?

Considering the future self to be an entirely different person could have serious consequences. Philosopher Derek Parfit worries that people who regard the future self as distinct should logically have no more reason to care about that future self than a stranger. By implication, they should have no reason to save money, maintain their health, or cultivate relationships. But perhaps there is a middle ground between self and stranger. To the extent that someone imagines their future self to be similar to their present self, this sense of “future self-continuity” might predict their willingness to at least consider the interests of the future self.

Here, I argue that beyond rekindling philosophical debates, future self-continuity is a critical (and timely) scientific concept, for a number of reasons. First, future self-continuity can be measured. Remarkably, neuroimaging research suggests that a medial part of the frontal cortex shows greater activity when we think about ourselves versus strangers. When we think about the future self, the activity falls somewhere in between. The closer that activity is to the current self, the more willing individuals are to wait for future rewards (or to show less “temporal discounting” of future rewards). More conveniently, researchers can also simply ask people to rate how similar or connected they feel to their future selves (e.g., in five years). As with neural measures, people who endorse future self-continuity show less temporal discounting, and have more money stashed in their savings accounts.

Second, future self-continuity matters. As noted, individuals with greater future self-continuity are more willing to wait for future rewards—not just in the laboratory, but also in the real world. Applied research by Hal Hershfield and others suggests that adolescents with greater future self-continuity show less delinquent behavior, and that adults with greater future self-continuity act more ethically in business transactions. Future self-continuity may even operate at the group level, since cultures that value respect for elders tend to save more, while nations with longer histories tend to have cleaner environments.

Third, and most importantly, future self-continuity can be manipulated. Simple manipulations include writing a letter to one’s future self, whereas more sophisticated interventions involve interacting with digital renderings of future selves in virtual reality. These interventions can change behavior. For example, adolescents who write a letter to their future selves make fewer subsequent delinquent choices, and adults who interact with an age-progressed avatar later allocate more available cash towards retirement plans. While the active ingredients of these manipulations remain to be isolated, enhancing the similarity and vividness of future self representations seems to help. Scalable future self-continuity interventions may open up new channels for enhancing health, education, and wealth.

The need for future self-continuity continues to grow. On the resource front, people are living longer while job stability is decreasing. In the face of increasing automation, institutional social safety nets are shrinking, forcing individuals to bear the full burden of saving for their futures. And yet, in the United States, saving has decreased to the point where nearly half of the population would have difficulty finding $400.00 to cover an emergency expense. On the environmental front, global temperatures continue to rise to unprecedented levels—along with attendant droughts, increases in sea levels, and damage to vulnerable ecologies. Human choice has a hand in these problems. Perhaps increased future self-continuity—in individuals as well as policymakers—could generate solutions.

The dawn of a new year is as good a time as any to take the perspective of your future self. Imagine yourself in five years. Did you do everything you could today to make the world a better place—both for your present and future selves? If not, what can you change?