Wednesday, 2 November 2011

How walking through a doorway increases forgetting

Like information in a book, unfolding events are stored in human memory in successive chapters or episodes. One consequence is that information in the current episode is easier to recall than information in a previous episode. An obvious question then is how the mind divides experience up into these discrete episodes? A new study led by Gabriel Radvansky shows that the simple act of walking through a doorway creates a new memory episode, thereby making it more difficult to recall information pertaining to an experience in the room that's just been left behind.

Dozens of participants used computer keys to navigate through a virtual reality environment presented on a TV screen. The virtual world contained 55 rooms, some large, some small. Small rooms contained one table; large rooms contained two: one at each end. When participants first encountered a table, there was an object on it that they picked up (once carried, objects could no longer be seen). At the next table, they deposited the object they were carrying at one end and picked up a new object at the other. And on the participants went. Frequent tests of memory came either on entering a new room through an open doorway, or after crossing halfway through a large room. An object was named on-screen and the participants had to recall if it was either the object they were currently carrying or the one they'd just set down.

The key finding is that memory performance was poorer after travelling through an open doorway, compared with covering the same distance within the same room. "Walking through doorways serves as an event boundary, thereby initiating the updating of one's event model [i.e. the creation of a new episode in memory]" the researchers said.

But what if this result was only found because of the simplistic virtual reality environment? In a second study, Radvansky and his collaborators created a real-life network of rooms with tables and objects. Participants passed through this real environment picking up and depositing objects as they went, and again their memory was tested occasionally for what they were carrying (hidden from view in a box) or had most recently deposited. The effect of doorways was replicated. Participants were more likely to make memory errors after they'd passed through a doorway than after they'd travelled the same distance in a single room.

Another interpretation of the findings is that they have nothing to do with the boundary effect of a doorway, but more to do with the memory enhancing effect of context (the basic idea being that we find it easier to recall memories in the context that we first stored them). By this account, memory is superior when participants remain in the same room because that room is the same place that their memory for the objects was first encoded.

Radvansky and his team tested this possibility with a virtual reality study in which memory was probed after passing through a doorway into a second room, passing through two doorways into a third unfamiliar room, or through two doorways back to the original room - the one where they'd first encountered the relevant objects. Performance was no better when back in the original room compared with being tested in the second room, thus undermining the idea that this is all about context effects on memory. Performance was worst of all when in the third, unfamiliar room, supporting the account based on new memory episodes being created on entering each new area.

These findings show how a physical feature of the environment can trigger a new memory episode. They concur with a study published earlier this year which focused on episode markers in memories for stories. Presented with a passage of narrative text, participants later found it more difficult to remember which sentence followed a target sentence, if the two were separated by an implied temporal boundary, such as "a while later ...". It's as if information within a temporal episode was somehow bound together, whereas a memory divide was placed between information spanning two episodes.
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ResearchBlogging.orgRadvansky, G., Krawietz, S., and Tamplin, A. (2011). Walking through doorways causes forgetting: Further explorations. The Quarterly Journal of Experimental Psychology, 64 (8), 1632-1645 DOI: 10.1080/17470218.2011.571267

Post written by Christian Jarrett for the BPS Research Digest.

15 comments:

  1. I've done this experiment lots of times. I walk into a room and then can't remember what I went in for.

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  2. @Dan H: Me too! But walking *back* to where I came from will often immediately trigger the reason for the original trip. So I think context must have some effect, as well as doorways. Great study!

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  3. Perhaps a virtual room with no distinct sensory environment, such as distinct smell, distinct lighting level & tone, or distinct colors; no associations with physical movement, objects, people, experiences; etc is less likely to trigger context dependent memory. A room or environment which holds alot of existing associations (including fears or novelty for an unfamiliar place) may be better at holding and triggering such contextual memories. Good study...I like the inventive way they challenged context dependent memory. Contextual and episodic memory do not seem to be incompatible to me either.

    Bart Schuster
    OnlineGraduateSchool.tripod.com
    Twitter.com/arrive2_net

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  4. Many people experience this and it appears that much formal training and education - which requires a lot of walking in/out of doors - creates episodic dissonance which acts as a barrier to immediate and long term recall.

    At Retenda we're tackling this head on by providing an easy to administer method to reinforce and remind learners of key points once they've walked out the door, using a variety of mobile media including email, text messages, video and digital personalised printing.

    Take a look at http://www.retenda.com - would very much welcome feedback and comment.

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  5. Anonymous7:31 pm

    Does the study address the factor of time? If you pass through two doors instead of one, more time will have elapsed (which might have a hand in how easy or hard it is to recall something).

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  6. hi anonymous (7.31pm): the doors were open and the distance travelled was the same when comparing between memory within a large room and memory after passing through a doorway. So time/distance cannot be the causal factor.

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  7. Doug Scott12:05 am

    To me, this is the "forget trivia" mechanism happening at the time of a context switch. The brain doesn't need to recall trivial details once the subject has left the room, so discards it. This would explain why, on returning to the room, the subject can't re-create the memory - it has gone.

    Nice experiment, showing how highly efficient the brain's memory mechanism is.

    Doug

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  8. S.Williams3:16 pm

    This is very interesting but quite understandable. The information taken in when entering a new room would push out the information stored in the short term about the previous room. It is nice to see an experiment to test this theory as a previous commenter stated they often forget why they went into a room. This is a modern everyday example of this "boundary" effect.

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  9. It's about the only thing I'm really good at!

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  10. I had something interesting to say about this, but because the comment box opened in a new window, I forgot. Perhaps windows and doors have this in common?

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  11. Anonymous3:26 am

    @paul lol. I'll cross few doors before I take any exam.

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  12. This may be why you can only find your keys when you go back to the room you actually left them. And they're never where you thought you left them, because that's the room you're in now.

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  13. Anonymous4:45 pm

    I wonder if by repetition, you could train your memory to retain multiple rooms or even a whole house as a single frame. In a simplistic way, sort of like using a child's memory card game and have each person walk into 2 rooms before each turn. Of course it doesn't replicate any of these studies, but would a person get more adept at it with time.

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  14. Anonymous10:23 pm

    A few years ago there was a web-inar that claimed: the first 20 days of any month you will recall what you needed in what room. The remainder days (ie, 21 through 31) of the months you will need to talk outloud as you walk to the other room or lock a door.

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  15. I wonder...does it make a difference if you close your eyes before you go through a door way? Does the brain get tricked that easily?

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