Could "Severance" Ever Become Reality?

Source: Atsushi Nishijima/Apple TV+

The Apple TV+ series Severance poses an interesting question: What if we could fully separate memories from one part of our life from another part of our life? In the show, characters who undergo the severance procedure (a surgery that involves implanting a chip in their brain) effectively disconnect their work life from their home life. Their work selves (“innies”) are unable to remember anything about their lives outside of the office, and their home selves (“outies”) have no idea what they have been doing at work.

Although the concept may sound far-fetched, the show illustrates some important aspects of memory and raises some provocative questions.

What the show gets right about memory

Our memories are often strongly connected to the contexts that we were in when we formed them. Entering a childhood home for the first time in years may bring back memories that previously seemed to be forgotten. This phenomenon that memories are easier to remember when we are in the same physical context as when they were created is referred to as context-dependent memory. So, in theory, it’s easier for you to remember something from your home life when you are at home rather than at work.

Context-dependent memory was most famously demonstrated by two British psychologists, David Godden and Alan Baddeley. In 1975, Godden and Baddeley asked scuba divers to learn lists of words on land and underwater and then tested them on their memory for the words both on land and underwater. They found that words that were studied on land were remembered better on land and vice versa. In other words, memory was best when the context stayed the same between learning and remembering.

The scuba diver experiment is a classic that any college student who has taken a psychology course on memory is sure to encounter, but context-dependent memory effects are not always so robust. Recently, Yeon Soon Shin and colleagues from Ken Norman’s lab at Princeton University identified some key features that make context-dependent memory effects more likely to occur.

Shin’s participants engaged with two immersive virtual reality environments, one that was underwater and one that was on Mars. They encountered a series of items in the two environments and rated each item on how useful it would be in that particular environment (e.g., flippers would be useful underwater but less useful on Mars). Like the scuba divers, these participants also later remembered items better when they were tested in the same environment, but this was particularly true for items that were judged as useful for that particular context.

Why is this? One possibility is that elements of your environment get tied to the memories that you form, and these same elements can later function as retrieval cues that help bring a memory back to mind. Your dying office plant may remind you of the report you need to finish because you were looking at the plant when you first learned about the report. The stronger the connection between an item and the context, the more likely the context will act as a retrieval cue, which is why items that were deemed useful on Mars were better remembered in a Mars environment.

Severance takes context-dependent memory to the extreme, with “innies” unable to remember anything about their lives or who they are in the outside world, but the underlying concept is scientifically sound.

Where the show strays too far from reality

One of the 20th century’s groundbreaking discoveries in memory research was that memory is not a unitary construct; rather there are multiple memory systems that are separable. This may sound a lot like Severance, but the type of severing that can occur is different than what is depicted in the show.

In real life, the famous neuropsychological Henry Molaison, known as H.M., underwent a surgery that removed a brain structure called the hippocampus. Afterward, H.M. displayed profound amnesia, where he was unable to form new, long-lasting conscious memories, yet other types of memory remained perfectly intact. For example, he knew who he was, he could still remember general knowledge he acquired prior to the surgery, and he could learn new skills.

Severance gets some of this right. A severed character whose “innie” goes by the name of Helly R. is able to remember the name of one of the 50 United States (“Delaware”), even though she cannot remember any events from her life. In other words, her general knowledge, or semantic, memories are intact, but memories of personal experiences, or episodic memories, are impaired.

Memory Essential Reads

Timeless Minds

Memory Training for Modern Minds

However, another severed character, Mark, encounters the same person in both his work life and his home life, and he has a very different emotional response in the two settings. Because emotional responses, or conditioned responses, rely on a different part of the brain than our memories of our personal pasts, Mark’s emotional response to that person should transfer from his “innie” self to his “outie” self. In other words, he should still experience cross-self emotional learning even if his personal event memories are severed, but he doesn’t.

Is the severance procedure coming soon?

Will technology ever get to the place where something like the severance procedure is a reality? The neurosurgeon who was consulted on the show suggests that it may be closer than we think. For example, we have robotic arms that are controlled by chips inside the brain, and patients who are able to communicate via their thoughts through similar devices. Perhaps even a closer parallel would be optogenetic techniques that can be used to turn on and off specific memories in rodents.

Yet, based on what we know about the complexity of memory, completely severing one set of conscious memories from another does not seem likely not only due to scientific limitations but also for ethical reasons.

In the meantime, one only needs to watch Severance to understand the potential fallout of this procedure.