The following essay is reproduced with permission from The conversationan online publication covering the latest research.
You know that feeling when you walk into a room and immediately forget why you came in? Maybe you were there to collect your keys. As you headed to the room, you thought about getting your keys. But once you arrive, your keys have completely disappeared from your mind.
This is sometimes called the effect carriesbecause it often hits when you walk into a new room. Why does this happen? The answer has a lot to do with a skill called working memory. Information is stored in working memory when we need it for tasks we are engaged in at the moment (like remembering to get your keys).
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What makes working memory so intriguing is its close connection to consciousness. The portal effect suggests that when information is removed from working memory, it appears to immediately leave consciousness. This also suggests that it is easy to forget information in working memory.
The link between working memory and consciousness has received increasing attention in psychology, philosophy, and neuroscience. Could working memory somehow give rise to consciousness? In my new bookI explore the complex relationship between the two.
Working memory: both rich and poor
To understand the gate effect, we’ll need to know a little more about working memory. What makes working memory so special is that it is so rich, both in terms of the information it has access to and its processing power. According to recent models of working memoryit can extract information from sensory channels (vision, touch, smell, etc.), as well as other memory systems such as long-term memory and also the brain’s language processing system. In other words, working memory is where much of your brain’s information comes together.
Once working memory has this information, it can do a lot with it. Inside working memory are a host of smaller systems for specific tasks, including visual and spatial reasoning (like solving a Rubik’s cube) and storing chunks of information (like a phone number). There is even a “central executive” system (my favorite). The executive is like a ruthless boss, assigning tasks to the different working memory systems and keeping everything under control.
In another way, what makes working memory so special is that it is very poor at the same time. Despite the wealth of information available to this, working memory cannot really store a tiny amount of information at a time.
In one classic experiment reported in 1997People were asked to look at a screen with several colored shapes, which they had to remember. The shapes then disappeared for about a second and a new set of colored shapes appeared. One of the new shapes might have changed color. Participants were asked to determine whether there were any changes between the two sets of shapes. This is called “change detection”.
People were almost perfect at this when there were only 1 to 3 shapes involved in each set, but it steadily got worse as the number of shapes increased from 4 to 12. The experimenters argued that this was because it became more difficult to store information as the number of shapes increased. This is because the capacity of working memory is not large enough to store a large number of shapes. The experimenters concluded that the capacity of working memory is only about four “slots.” Once these locations are occupied, working memory is full: there is simply no more room for new information.
The idea that working memory has “slots” is closely related to what is called “fragmentation.” Here are two strings of letters (nine each). Try to memorize them both:
BBC FBI WWF
ZQK EWP WLJ
I bet you find the first string of letters easier to remember. This is because they are familiar and your brain naturally sorts them into three pieces. They can then be stored in the form three different pieces in working memory. For this reason, the first set only occupies three locations in working memory. The second string of letters is unfamiliar and therefore requires us to store all nine letters as individual chunks. This is difficult because working memory quickly runs out of locations.
But like many features of working memory, its capacity is a highly controversial issue. A growing number of scientists rejected the idea that it has “time slots”, arguing instead that its capacity is more of a flexible resource that can be distributed differently among different pieces of information. According to this view, working memory capacity, far from being four rigid slots, might be more like a reservoir of water to use for watering your garden: you can give a little water to many different areas, or a lot of water to just one or two areas.
Similarly, working memory might be able to store some information about many objects, or very detailed information about just one or two of them.
A 2004 study supports this flexible view of resources on the locations view. This experiment also used change detection with shapes.
Above all, experimenters tried this with different types of shapes. Sometimes they used only very simple shapes, sometimes very complicated shapes. They found that people seem able to store information about a larger number of the simplest shapes in their working memory. They were much worse at storing information about complex shapes. In fact, experimenters suggest that the working memory capacity for a very complicated object (like a cube with many different colored faces) might only be between 1 and 2.
This seems to show that working memory capacity is much more “sucked up” when trying to remember very complicated objects. This suggests that working memory does not have a fixed number of locations, but that its capacity depends on the complexity of the information you are trying to store.
For me, there is something romantic about how rich working memory is in terms of the amount of information available, and how poor it is in terms of its small capacity. It is as if he can always see the vast riches at his disposal, but can only taste a tiny part of it at a time.
The low capacity of working memory can help us understand why the information it stores is so easily forgotten, such as in the gate effect. There isn’t much room in working memory, so when new information comes in, the old information has to go.
As I mentioned at the beginning, research suggests that the very action of walking through a door can trigger forgetting. An experiment showed that people have a harder time remembering things when they walk through a door, compared to people who walk the same distance but don’t cross a threshold. When we enter a new room, it’s as if the brain clears old facts from working memory, to prepare for new information we may need in our new environment.
From an evolutionary perspective, the gate effect makes sense: it is important to forget old information to help us remain open and attentive to new information in the new environment.
Thinking about working memory capacity can help understand why it’s so easy to forget things, even when we barely think about them for a second. But there is an even more tempting possibility here. When we forget things like our keys, they seem to disappear from our awareness completely. This raises the suggestion that working memory and consciousness could go hand in hand.
Working memory and consciousness
Consciousness is perhaps the greatest mystery facing science and philosophy today. By “consciousness” I mean the subjective experiences we have of the world. Consciousness includes the visual image of a beautiful sunset or the taste of chocolate, as well as emotions like love and anger.
A lot philosophersAnd scientists I thought that working memory can help us understand consciousness.
The strong connection between consciousness and working memory is evident in some of the leading theories of consciousness in psychology and neuroscience today. Personally, I’m a big fan of global neural workspace theorywhich suggests that consciousness arises as a result of the “broadcast” of information in a “global workspace” in the brain. This workspace is like a central information bankwhich can process information and distribute it globally to many different systems in the brain.
Does this sound like working memory to you? If so, it is not a coincidence: the global workspace and working memory are similar notions. Their similarity is even visible in the brain. There are still many open questions about where is working memory located in the brain but one important area is the prefrontal cortex. It’s at the front of your brain, just above your eyes and behind your forehead. The same domain also appears to be important for the type of worldwide distribution what global workspace theorists think responsible for consciousness.
Scientists favor global neural workspace theory suggested that When we pay attention to information stored in working memory, this information increases in volume and is broadcast throughout the brain – and this is what makes it conscious. According to this view, consciousness arises when working memory and attention work together.
The idea that attention and working memory might both be important for consciousness seems to fit with our own experience. When you try to remember a phone number in your head, your attention stays on the phone number and you are aware of it. If someone distracts you by asking you a question, your attention is diverted from the number phone and it is immediately deleted from your consciousness. According to this photo, no attention = no awareness.
The importance of working memory and attention is also consistent with experimental data. One of my favorite experiences was studying people walking across a yard on a spring afternoon. It was found that 75 percent of people who used their cell phones I totally failed to spot a purple and yellow clown riding a unicycle in the yard. This is even though the clown could have crossed their path, potentially causing a dangerous collision. They were on the phone, their attention was elsewhere, so the clown did not enter their consciousness. Again, this suggests that no attention = no awareness.
I’ve always been afraid of clowns. The idea that there might be a clown nearby that I just haven’t spotted scares me. (I mean come on, they are clearly terrifying.)
But like everything related to consciousness, the link between consciousness and working memory is controversial. Some think there is simply too much awareness to fit in working memory. Others say that some elements of working memory are not conscious at all. Let’s take a look at these arguments.
Is working memory too small for consciousness?
We have seen that working memory has a small capacity. This raises an obvious question: If working memory is responsible for consciousness, doesn’t that mean that consciousness must also have a small capacity?
This can be a difficult idea to swallow. Imagine you are watching a countryside scene. You see rolling hills, bright sunshine and a herd of cows. You hear the birds, smell the freshly cut grass and feel the wind on your skin. You are probably aware of this whole scene at once. But we know that working memory has far too small a capacity to hold all of this information at once. If consciousness arises from working memory, then how can I be aware of all of this at the same time?
Indeed, some philosophers And scientists we argued in this way, saying that consciousness overflows working memory capacity. If true, this would pose a problem for those who believe that consciousness arises from working memory.
In response to this problem, proponents of the link between working memory and consciousness have argued that consciousness is not as great as one might think. With the campaign scene you could think that you are aware of all these sights, sounds and smells together. However, according to this view, you are actually only aware of a few bits at a time. The reason why feels as if you are aware of more, it is because, every time you pay attention to something, that attention brings the information up into consciousness.
This is called the refrigerator light illusion. Imagine someone who thought their refrigerator light was always on, because every time they open the door to check, the light is on. Obviously the problem is that just opening the door causes the light to turn on.
In the same way, simply checking to see if you are aware of the birdsong causes you to bring your attention to it, which brings the bird song into awareness. According to this view, we are aware of only a few small things at a time, but the ease with which attention can make things conscious promotes the illusion that we are aware of much more.
As if it wasn’t bad enough that doors make us forget, or phones make us ignore clowns on unicycles, we now have to deal with our refrigerators fooling us about our own conscience.
Working memory without consciousness?
Another area where consciousness and working memory might separate involves unconscious information. We know that many processes in our brain occur unconsciously. When it comes to information in the brain, we are only aware of the tip of a large iceberg. Some psychologists suggested that some information in working memory is completely unconscious. If true, this would mark an important difference between consciousness and working memory (since by definition unconsciousness cannot be part of consciousness).
A key experience from 2011 involves showing participants an image of a wavy area, tilted at a specific angle. In the world of psychology, this is called a Gabor patch. This patch was only shown to participants for a moment. It stays on the screen for only 16.67 milliseconds, or about 17 thousandths of a second. That’s about the time it takes for a bee to flap its wings three times.
Flashing the patch on the screen so briefly prevents the patch from being consciously seen. Because of the brevity with which the patch appears, information about the patch enters participants’ eyes, and participants see the patch but are not consciously aware of it. They see it, but unconsciously.
Yet we know that information about things we are not aware of must be processed at a fairly high level in the brain. After the first patch disappeared, they were shown another different patch. This was shown for longer, so that it could be seen consciously. Participants were asked to indicate (by clicking a button) whether this second patch was tilted to the left or to the right relative to the first patch that they had not consciously seen. Surprisingly, they were able to do this at a level above chance. Even if the first patch was unconscious, people could still use information about it to make comparative judgments.
This is crucial for working memory and consciousness. The experimenters claimed that information about the briefly flashed patch should be stored in working memory, even if participants were completely unaware of it. From this, the experimenters concluded that some information contained in working memory is not conscious. If this is the case, the link between consciousness and working memory is weaker than one might hope.
Not an all or nothing thing
Regarding the experience just mentioned, I would like to conclude with some of the ideas that I explored in my book. I think that working memory may not be an all or nothing matter, that information does not necessarily have to be “in” or “out” of working memory.
Sometimes we can fall into the trap of thinking that everything in the human mind must be either one thing or another. This mindset is very natural, but in my book I argue that it must be rejected.
I suggest that there might be information that is not “in” or “out” of working memory, but somewhere in between. I argue that working memory spans a spectrum. Some information is definitely in working memory, some is not. But in between (I argue) is a big gray area where some information in our minds falls between being stored entirely in working memory and that which is not.
This is certainly an unusual suggestion. But I argue that viewing working memory as a spectrum sheds new light on the experiences I discussed above. Remember the patch that appeared in three bee-wing beats – so fast that you couldn’t consciously see it, preventing it from being fully encoded into working memory? I argue that this information falls in the gray area between being entirely in and completely out of working memory.
This raises an interesting possibility regarding consciousness. If we think that working memory is closely linked to consciousness, a obvious question is whether there can be a gray area between something that is conscious and something that is not. Indeed, some philosophers have suggested that there might be such a gray area.
At first glance, the experiences I have described may seem a little strange and obscure. When I talk about these experiences at parties, they sometimes ask me how I can spend so much time thinking about doors, clowns on unicycles, or how we remember random shapes. I’m visibly excited to tell people about all this, and I can almost see them making a mental note not to invite me again.
But these experiences are exciting. To realize this, we must move away from the technical details of these experiments and adopt a broader vision. These experiences and others continue to discover the mechanisms of working memory. There is still much to discover, including where and how it happens in the brainand the ways in which brain injury can impact on working memory. As these mysteries are slowly explained, we may be better positioned to tackle arguably science’s greatest enigma: consciousness itself.
This article was originally published on The conversation. Read the original article.
