I don’t really have much to add to the post that was published on the British Psychological Society’s Research Digest blog, but the study they wrote about bears more than just simply passing along the link, I think. The post, “How walking through a doorway increases forgetting,” concerns a study out of Notre Dame that sought to get to the bottom of how the mind carves experience up into episodic memory. If you think back to what you did this morning your recall will present the events from getting up to leaving the house sequentially, if all goes well. Instead of fits and starts where you are putting on a sock then suddenly are back in bed, then perhaps coughing up scrambled eggs, then in the shower then back to bed again, the sequence of the memories should follow the way they unfolded in reality, from bed to shower to sock to eggs.
But how does the mind carve what can be categorized as one single event — “Getting Ready this Morning,” — into a series of smaller components. What, in the mind’s opinion, differentiates the process of getting dressed as discretely different from taking a shower? The Notre Dame researchers hypothesized it was the act of walking through a door that cut a memory in two like a circular saw through a warm thigh.
To test the hypothesis, the Notre Dame crew created a virtual series of rooms connected by doorways that study participants wandered through. In each room they were asked to pick up an object from one table and leave another object. Once in a while the program asked the participants about an object — what is what they were holding, had it been something they’d just put down? The object no longer being visually accessible once picked up, the participants had to answer from memory.
The study found that when asked questions about objects that had been handled within a room while the participant was still in that room participants displayed the highest rates of accurate recall. Once they’d gone through a door, however, those rates dropped. And even after exiting through a door and being brought back into the previous room, answers about objects handled in that room showed less accuracy than when the questions were asked before the room had ever been exited. The same results held up in a similar, real-life environment constructed by the study researchers.
It can be assumed that the trigger need not be a door. Doors are a fairly ancient invention, although they have been frequently improved; Old Kingdom Egyptians had locking doors around 2,000 B.C., about 2,000 years later, Heron of Alexandria described pneumatic doors. The revolving door was invented in 1888, and automatic sliding doors first came about in 1954. Episodic memory, one imagines, is far, far older than doors and so anything that signals a change in environment could be useful. I wonder if people who lived prior to the advent of the cities that arose from sedentary agricultural communities had longer memory tranches. With less of a built environment they would have had fewer cues to separate an experience into episodes. If that is the case, it must be fairly certain that the creation of doors led to a pronounced effect with how we humans view our lives and our world.