We’re all familiar with this experience: you’re finally sitting on the couch, ready to watch your favorite TV show. Just after you’ve made yourself comfortable, you realise that you forgot your snacks! You could just accept the situation and watch the TV show anyway, but let’s be honest, it’s just not the same. So you get up, annoyed, and set out for the long journey to your kitchen, still thinking about the last episode of the show. When you get there, you find yourself wondering why you were there again. You wanted to get something, right? But what was it?
This situation can be described by Event Segmentation Theory (EST), which states that people make sense of their environment by segmenting the continuous stream of information that we perceive into separate events (1). This allows us to anticipate future events as we adaptively encode what an actor will do next. Based on that, we can select our own actions. In this way, we use less processing resources (2).
According to EST, we form event models, which are representations in our working memory that capture what is happening now. When those predictions are accurate, event models are maintained. However, when perceptual or conceptual features of an activity change, prediction becomes more difficult and errors in prediction tend to increase. In this case, event models are updated based on currently present information (1). This changes the information that is currently actively maintained, and the event model is then usually replaced by a new model.
The shift from one event model to the next is marked by event boundaries. Event boundaries are often marked by a change in context. When something salient happens in our environment that we did not predict, we need to adapt to this new situation in order to be able to make valid predictions of the environment again. Let’s return to the current example – imagine you are watching TV and suddenly a giraffe walks in. Clearly, there is a change in context and you need to be able to make new predictions about what happens next. A change in context is not always visual, it can also be an auditory change or a change of location. Because of the update of information that occurs at event boundaries, previously maintained information is freed enabling orientation to new perceptual information.
Back to your TV night. What happened? You entered the kitchen: a change in context! Our brain believes that the thoughts we had while sitting in front of the TV are no longer relevant in this new situation. The event model that was actively maintained is now replaced by a new one, and the goal of getting snacks is no longer actively remembered.
So, you head back to your couch and as soon as you sit down you suddenly remember: the snacks! Crazy, right? When you returned to the context of the previous event model, your memory of that specific context also came back. So, you go to the kitchen again. Hopefully your working memory can withstand the shift in context this time! Although you may once again end up in the kitchen with no clue of what you were doing, at least now you know why.
1) Kurby, C. A., & Zacks, J. M. (2008). Segmentation in the perception and memory of events. Trends in cognitive sciences, 12(2), 72-79.
2) Schütz-Bosbach, S., & Prinz, W. (2007). Prospective coding in event representation. Cognitive processing, 8(2), 93-102.