Most of our lives are recorded in “Standard Definition.” We remember the gist of our commute, the general flavor of our lunch, and the basic outline of our workday. To save energy, the brain operates as a prediction machine; it guesses what will happen next based on what happened yesterday. When those predictions are right, the brain stays on autopilot. But the moment you are confidently wrong, your brain’s “Save” button gets smashed in high definition.
Why Do We Remember Surprises?
According to a 2021 study in Learning & Memory, these moments are Mnemonic Prediction Errors. Researchers found that when reality violates a strong expectation, our memory doesn’t just record the event, but supercharges the details.
In the study, researchers trained participants to expect certain patterns, like a man’s face followed by a basketball. Once they set the expectations, researchers replaced the second image with something entirely new, such as a clock.
In psychology, this is a typical “prediction error.” But the participants not just remember the “idea” of surprise, but also fine-grained details. Researchers retested the memories of surprised objects using similar-looking clocks. The surprised participants could distinguish the identical ones from “similar fakes” with a 70% hit rate. (Related: Do We All Have a Built-in Fortune Teller?)
The Overwrite Problem
Intuitively, if we learn something new that contradicts an old habit, the new info might “overwrite” the old memory.
This is interference, an important concept in multiple information processing. However, the study found that a “prediction error” (such as a surprise) can actually prevent this from happening. During unexpected events, the brain recognizes that the old rule (“A leads to B”) and the new reality (“A leads to C”) are two different things. Instead of deleting the old file, it simply creates a brand-new folder for the surprise. And by doing so, rather than forcing a permanent change, the brain ensures we will not repeat the same mistake out of illusion.
Therefore, we are able to update our internal maps in a timely and flexible manner without losing the history. You can remember that your friend usually hates spicy food (the old rule), but also has a crystal-clear, high-definition memory of the one time they ordered the “extra hot” wings on a dare (the surprise).
Note
This theory holds up when you’re already certain before the surprise; a weak expectation doesn’t boost memory as much. That said, if you already suspect your friends are going to throw you a surprise birthday party, a sudden request to lead you somewhere might simply confirm your assumption. But if you stay focused on work and go home with no expectations, the lights, the “surprise,” and the room full of gifts and balloons will almost become an epic.
*What is Daily Insight? An ongoing series of quick, bite-sized brain snacks. Every week, there are three research-based factual reports and three research-informed reflective notes.
