Forgetting Curve
What is the Forgetting Curve?
The forgetting curve is a psychological model that describes how information is lost over time when there is no attempt to retain it. Forgetting isn’t a linear process but a predictable decay shaped by several factors: the strength of the original encoding, the method of learning, emotional salience, and the frequency of review. The curve highlights the brain’s natural tendency to prioritize efficient storage, meaning information that isn’t used or recalled is quickly de-prioritized or pruned.
The Basic Idea
You stare at your phone. You know you had something important to do, a meeting? A message to reply to? The thought was there a second ago, then slipped away like steam off a mirror. You scroll, retrace your mental steps, even check your calendar, but nothing. That ghost of a memory haunts you all day, just out of reach. This frustrating yet universal experience isn’t just forgetfulness. It reflects a well-studied psychological process: the gradual decline of memory over time. Psychologists call it the forgetting curve: a steep drop-off in how much we retain if information isn’t actively reinforced. Understanding how this curve works isn’t just academically interesting; it’s essential for designing better learning environments, work habits, and even public policy.
The forgetting curve describes the rate at which information fades from memory when it’s not actively reinforced. Introduced by the German psychologist Hermann Ebbinghaus in 1885, the model illustrates how memory decays exponentially. Forgetting happens fastest shortly after learning, while the rate slows with time.1 This decline is not random. It follows a measurable pattern, which reveals that memory requires deliberate care to remain intact.
To understand how the forgetting curve functions, it’s useful to think of memory as a system shaped by time, exposure, and retrieval. When something is learned for the first time, a memory trace is formed. Unless it’s strengthened, this trace is unstable. Without reactivation through use, reflection, or review, the memory begins to deteriorate.
This insight is more than theoretical. In applied behavioral science, the forgetting curve helps explain why training programs lose impact over time, why health habits lapse, and why long-term intentions often fade without support. People forget not because they are careless, but because memory weakens unless maintained. Interventions that acknowledge this pattern tend to perform better. Instead of a one-time instruction, successful systems offer reminders, feedback, or spaced repetition at intervals that align with the curve's shape.
The metaphor of a leaky bucket can be helpful here. Learning fills the bucket, but without periodic attention, it slowly drains. The curve provides the timing that shows when reinforcements are most needed. This insight allows us to intervene with precision, improving recall without overloading learners. Rather than treating forgetting as failure, the forgetting curve frames it as a predictable process that can be managed through thoughtful design.
“If memory is the residue of thought, then students will remember incorrect ‘discoveries’ as much as they will remember the correct ones.”
— Daniel T. Willingham, Professor of Psychology, University of Virginia2
About the Author
Adam Boros
Adam studied at the University of Toronto, Faculty of Medicine for his MSc and PhD in Developmental Physiology, complemented by an Honours BSc specializing in Biomedical Research from Queen's University. His extensive clinical and research background in women’s health at Mount Sinai Hospital includes significant contributions to initiatives to improve patient comfort, mental health outcomes, and cognitive care. His work has focused on understanding physiological responses and developing practical, patient-centered approaches to enhance well-being. When Adam isn’t working, you can find him playing jazz piano or cooking something adventurous in the kitchen.
