Asymmetry of memory

When it comes to the workings of our minds, one of the most fascinating aspects is the surprising asymmetry between two functions which are unmistakably related and still show significantly difference performance: recognition and recall. The first one implies identifying an item (an object, a word, a sound) as something that we have experienced in the past, just in the way you recognize the words you are reading: you identify them and even understand their meaning. Recall, on the other hand, is what I am doing as I write, where I have a certain (possibly fuzzy) idea of the meaning that I want to convey and I have to find the way to put it into words. As this page explains it, it is like the difference between a police line-up (recognition) and describing the suspect's face to the sketch artist.

In spite of the obvious connection, their capabilities are significantly different: in linguistic terms they are called the passive (recognition) and the active (recall) vocabularies and although the measurements provide widely different results it is not uncommon to see conclusions that the active vocabulary is somewhere between 50 and 75% of the passive one for native speakers, while for non-native ones this difference is even bigger. They understand less words than a typical native speaker, but their use is even lower, so they end up hearing a lot of words that they are perfectly able to understand but do not use on a regular basis.

Photo: Hernán Piñera

However, words are only one aspect of the dichotomy, there are many other elements that show the same difference even if they have been study much less extensively. Think about odors, colors, noises, images: they are all very easy to recognize but extremely difficult to reproduce or even to describe. I mentioned in a previous post how I was able to recognize motorbikes of the same make as mine even at a distance just by its noise, but there is no way I could tell you what the sound is, so that you could learn it from me instead of from the actual motorbike. However, this is somewhat understandable because this impression happen in media that we are not supposed to produce at will: we cannot produce images or odors at will and even our noises only have a limited range. But words, especially in our own language, is something that we all can produce at will and in great variety, so why the difference?

Last weekend we were having dinner with some friends and they started streaming on their sound system old pop music from the 90s. Unsurprisingly, I was not only able to recognize most of the songs, but in many cases I was able to even sing along. And it was not the case that they picked my favorite band or anything of the sorts: the words probably got stuck in my mind decades ago and now, primed by the song, my memory was able to retrieve them with an accuracy way beyond my expectations (although certainly not perfect). It also happened that I liked most of them, even if I would never have thought of naming any of the songs if anyone had asked. But the recognition was there to assist me and I had a great time.

The last few days I have also discussed the matter with my kids with respect to studying for their exam. In particular, I have mentioned many times that looking at their notes and checking "I know this, I know this, I know this" is not a good enough guarantee of success in the exam, because most of the time they will be asked to recall things ("Name the parts of a cell") not to recognize them ("Is the cytoplasm a part of a cell?"). In other words, I have told them that, once they have checked their notes, they should put them away and try to write the same content from memory, just as they might be asked to do at the exam. I have to admit that I have not been very successful, but no one can deny that I have warned them many times, so whatever success or failure they harvest will be entirely theirs.

The funny part is that recognition does not even have to be literal: a certain memory can be evoked or inspired by a related stimulus, just like you remember a joke that someone told you because the situation was similar. But this phenomenon, called association, should better be left for another day, because this post is starting to run long. Until then, you can keep this promise in your memory so that you recognize it whenever I decided to make good on it. Have a nice evening.