A new study from Northwestern University suggests that brief periods of forgetfulness, known as transient memory lapses, may be a natural part of the brain's memory formation process. Beverly Wright, a researcher at the School of Communication, led the study that challenges traditional views on human memory retention.

The research builds on work from 1957 by American psychologist Leon Kamin, who identified a U-shaped learning-retention curve in rats. This pattern showed that while rats remembered tasks soon after training and hours or days later, their retention was poor one hour after training. Such lapses have been noted across various non-human species and are believed to signify transitions between different phases of memory formation.

"We reasoned that if transient memory lapses reflect fundamental processes in memory formation in animals, they should also occur in humans," Wright explained.

To test this hypothesis, Wright analyzed data from previous studies involving 192 young adults tasked with sound localization exercises. These participants were tested at different times post-training. The findings revealed similar transient memory lapses occurring between one and three hours after training.

"While experiencing a transient memory lapse, it can seem that you have forgotten the learned task, but you really haven’t. It’s just temporarily locked in your mind," said Wright.

Published in "npj | Science of Learning," the study suggests these lapses could represent transitions between short-term, intermediate-term, and long-term memory phases identified in animals. "The idea is that transient memory lapses occur when there are time gaps between the end of one memory phase and the beginning of another," Wright stated.

These findings may offer insights into the molecular underpinnings of human memory formation. Transient lapses might assist the nervous system during long-term memory formation by acting as choice points between maintaining current knowledge and adapting to new experiences.

Wright's study highlights the importance of considering these lapses when assessing human memory in clinical and research settings. "We hope these findings will spark new investigations into the phases of human memory formation," she added.

Ruijing Ning, a former PhD student in Wright’s lab now at Linköping University in Sweden, co-authored the study.