Take a look at your desk—is it full of junk? If so, you may be thinking that, while it’s not an ideal situation, your messy desk isn’t so bad. Sure, it takes you a little longer to find stuff, but you know where the important things are, right? But when you stop and think about it, how do you actually feel when your desk or room is cluttered? Do you find it harder to focus, maybe even irritable? Even you “organized clutter” folks probably feel this way from time to time. As you might have guessed, these negative feelings may be related to how our brain responds when there’s just too much stuff—but how does this happen? And is clutter really that bad?
When we look around our environment, it doesn’t take much effort to get a sense of our surroundings. But even though seeing feels easy, we actually have limited access to the visual world. Consider your cluttered desk—can you really see everything on the desk at once? You might be able to discriminate the objects at some vague level—maybe there’s something dark in one corner, a bunch of papers in the middle, and a box-shaped item on the left side. But if someone asked you about the details of any particular item (i.e., is your stapler pointing leftwards or rightwards?), you wouldn’t have a clue unless you actually focused your attention on that item. Thus, the visual system is limited in the sense that we’re not very good at seeing details of multiple things at one time. This illustrates how visual perception is limited—but why is it limited in the first place?
To answer this question, scientists have turned to the brain to see what happens in the visual system when we encounter multiple objects. You might think that seeing more objects would increase activity in the brain’s visual areas because there’s more information to deal with, but the opposite happens: seeing multiple items at once actually reduces visual brain activity (e.g., Desimone & Duncan, 1995). It’s analogous to what happens when you try to hear what four kids are saying when they’re all screaming at once—all you hear is meaningless noise. In a similar way, objects compete with one another for the chance to be seen in greater detail.
So if objects are constantly competing with one another, how do we see anything? Like any competition, there is potential for one item to “win” if it is prioritized over the other items—in fact, there are multiple ways for an object to beat out the others. Back to the screaming kids analogy, suppose one kid was yelling twice as loud as the other kids—she would grab your attention automatically. In general, the more an object stands out relative to other objects, the more likely it will get priority access in the brain. This is why it’s easy to see a red M&M in a group of yellow ones, even if there are twenty M&M’s. We can also prioritize objects by focusing attention on things that we care about—so if four kids are yapping at you, but one of the kids is your son, you can tune out the other kids to focus in on what your son is saying. Similarly, we are able to pick out the blue M&M’s in a group of multi-colored candies if the blue ones are our favorite. Whether an object wins the competition because it’s easy to see or because we care more about it, the way it gets prioritized in the brain is the same: visual activity for that object increases.
Now, here’s a twist: how does the visual system prioritize an object when we combine how easy it is to see and whether it’s relevant or not? In the yelling kids scenario, suppose your son is the quietest of the bunch—you’d really need to focus in order to hear what he’s saying. But if he’s the shrieker, well, he’s done the work for you—his voice has already won the competition. Thus, the amount of focus required to see an object may depend on how easy an item is to see to begin with.
This is precisely what McMains & Kastner (2011) found using functional magnetic resonance imaging (fMRI). Their subjects viewed pacman shaped objects that were arranged either in an organized or disorganized way, as shown in the figure below.
These four shapes are analogous to the four screaming kids; when the shapes are presented at the same time, it’s harder to make sense of them individually than if they are presented one at a time. But do you think that the displays are equally difficult to see? You’ll probably agree that the displays in the top row (called “Strong Perceptual Group”) are easier to see all at once than the displays in the middle and bottom rows. To control the visibility of the shape displays, the authors used a perceptual concept called grouping . Grouping is a way of arranging objects so that they combine to form a single object. For example, do you see a black shape in the centers of the top row displays? There isn’t really a black square there, but the pacman shapes are organized in such a way that, when combined, they form a square-like shape. Effectively, this arrangement makes the pacman shapes easy to see all at once because they form a single, organized group—and, importantly, the pacman shapes no longer compete with one another as strongly. In contrast, for the “No Grouping” display, there should be strong competition among the pacman shapes when they are presented at the same time–thus, this arrangement will be more difficult to see.
The authors also varied whether subjects cared about the pacman arrangements by having them ignore the whole display (by doing another task at a different location) or pay attention to the lower left corner of the display. They then measured visual brain activity to this lower left pacman for each of the grouping displays, either with or without attention to the display. When subjects ignored the pacman display, the brain response to the display’s corner was highest when it was in the context of the strong perceptual group display. In other words, the display that had the lowest amount of competition had priority access in the brain, even when subjects weren’t paying attention to the shapes. When subjects did pay attention to the lower corner pacman, brain activity to this pacman increased, but the amount of increase depended on the grouping of the pacman display. When the display had strong grouping (low competition among the shapes), attention only increased the brain response a little bit. In contrast, when the display was disorganized and had no grouping (high competition among the shapes), attention increased the brain response to a much greater extent. This result confirms that the need for focusing does depend on how easy things are to see to begin with, especially when we are trying to see multiple objects at the same time.
What are the implications of this finding? For starters, it means that we may not have full control over how our attention is deployed over the environment; it depends on how organized, salient, or otherwise easy-to-see objects are to begin with. So if an object is already easy to see, paying close attention to it may not help you see it any better, and if it’s hard to see, it will automatically recruit as much attention as it needs to win the competition. Second, because highly cluttered displays automatically require more attention to see what you care about—and since more attention means more effort—cluttered displays could end up draining your mental resources, leading to loss of focus, irritability, etc. So even if you don’t realize it, just looking at your cluttered desk may be using up resources. One more reason to keep that desk organized!
Desimone, R., & Duncan, J. (1995). Neural Mechanisms of Selective Visual Attention Annual Review of Neuroscience, 18 (1), 193-222 DOI: 10.1146/annurev.ne.18.030195.001205
McMains S, & Kastner S (2011). Interactions of top-down and bottom-up mechanisms in human visual cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31 (2), 587-97 PMID: 21228167