You get up from the sofa, take a few steps towards the kitchen, go through the door and… total emptiness: “why did I come here?“. It happens to everyone, it is inevitable, and science has discovered that it is precisely the fault brings that you went through. Our brain uses precise mechanisms to organize memories, and forgetting what we were doing is a demonstration of mental efficiency for make space to the new information that the new environment offers us. In practice, if we move from the living room to the kitchen, the brain is too busy processing information from the kitchen to remember the information “thought” in the living room. This so-called “threshold effect” that makes us forget what we were supposed to do when we enter a room is strong enough to come into play even if Let’s imagine changing rooms or, according to the study published in the Psychonomic Bulletin & Review by researchers at Yale University, a few moments before crossing the threshold.
The border between two rooms or two worlds: the threshold effect
Researchers have dubbed this forgetting phenomenon as “threshold effect” (or doorway effect). To understand what happens, we need to think about how we perceive the world. Unlike a continuously recording camera, our brain segments human experience into separate unitscall events.
When we walk through a door, we walk through a physical border which the brain interprets as a mental boundary between different experiences. In the study Walking through doorways causes forgetting: Situation models and experienced spacesome participants had to move around a virtual environment and memorize objects. The results demonstrated that the information becomes less accessible immediately after walking through a doorcompared to walking the same distance within a single room. The door closes one chapter and opens another.
Emptying the brain’s “cache”: the mental updating of the doorway effect
Why does the mind act like this? The answer is nei situational models. As we experience an event, we create a mental map that contains the relevant information in that context. When the environment changeslike when we enter a new room, the spatial model is drastically updated.
It’s a very similar process to “clear cache” function of a computer. As the new environment brings new rules and challenges, the short-term memory cleans up, deleting data associated with the previous room for leave space to the new ones. The intention to take a glass was part of the context in which that intention was thought (perhaps in the living room) and, once we reach the kitchen, it is simply forgotten because it is linked to a different environment.
The power of imagination and anticipation
The connection between boundaries and memory is so deep that it does not require actual physical interaction. The effect occurs even if we limit ourselves to imagine walking through a doorremaining perfectly still with eyes closed. Mere mental transit from one place to another causes the same deterioration of information. Even more surprising: forgetting often occurs not only when we cross a border, but even when we anticipate doing so. Recent tests show that memory suffers a decline already in the immediately preceding moment at the crossing of the threshold, while preparing to cross it. Our brain acts like a prediction engine: knowing that a context change will occur, download old memories in advance to be ready.
On the scope In reality, not everyone agrees about the threshold effect. A recent article published in BMC Psychology claims to have found no significant forgetting effects in 3 of 4 experiments done. The same article comes to the conclusion that we experience the threshold effect much more sporadically than previous studies have stated, and that thefor real reason of this little amnesia is not so much to be looked for in the physical “threshold”, but rather in the cognitive stress of the person who suffers the effect: the more our brain is engaged in “mental multitasking”, that is, it is occupied with multiple tasks at the same time, and the more likely we are to forget the objective of our actions.
Sources
Radvansky and Copeland, 2006, Walking through doorways causes forgetting: Situation models and experienced space. Manning et al., 2016, A neural signature of contextually mediated intentional forgetting. McFadyen et al., 2021, Doorways do not always cause forgetting: a multimodal investigation. Horner et al., 2016, The role of spatial boundaries in shaping long-term event representations. Ongchoco, 2024, Visual event boundaries trigger forgetting despite active maintenance in visual working memory. Wang et al., 2023, Here it comes: Active forgetting triggered even just by anticipation of an impending event boundary. Lawrence and Peterson, 2014, Mentally walking through doorways causes forgetting: The location updating effect and imagination. Pettijohn and Radvansky, 2015, Walking through doorways causes forgetting: environmental effects.
