Why Do We Forget Thoughts? Brain Limitations Behind Memory Loss Explained

Forgetting what we were just thinking about is a familiar experience. Whether it’s walking into a room and forgetting why we’re there or starting to speak and losing track of the thought—our brain seems to slip now and then. This everyday phenomenon is deeply connected to how the brain processes and juggles information, with much of the cause being attributed to the limits of working memory.

How Memory Functions

To grasp why we forget, it’s essential to understand memory itself. According to Susanne Jaeggi, Professor of Psychology at Northeastern University, memory is not a singular process but involves various components. It can be broadly divided into long-term and working memory. Long-term memory holds experiences, skills, and knowledge, while working memory temporarily handles thoughts, allowing us to process information in real-time.

What Is Working Memory?

Earl K. Miller, a Professor of Neuroscience at MIT, describes working memory as a sketchpad where our conscious thoughts exist. It’s highly limited, only capable of holding four to seven chunks of information at once. The brain constantly moves from one thought to another, and this constant shifting makes it easy for some thoughts to slip through the cracks.

Why Do We Forget?

The main reason we forget is that working memory is not designed to multitask. It is forced to juggle multiple ideas, often dropping one when attention is diverted. Miller explains that this juggling is even more prone to failure when we’re tired or under the influence of alcohol. Additionally, age plays a role in how efficiently working memory functions, with its peak performance happening in our twenties before declining later in life.

Retrieving Forgotten Thoughts

One effective way to retrieve a forgotten thought is to recreate the environment where it was formed. Jaeggi suggests returning to the place or retracing your steps, as this can provide the brain with the necessary context to recall what was lost. This technique helps because the brain often relies on environmental cues to trigger memory retrieval. In short, understanding how working memory operates can help us be more mindful of its limitations and take steps to avoid unnecessary forgetfulness.