Many of us have collected things at some point in our lives, whether it’s coins, records, CDs, or stuffed animals. You might be surprised by the range of weird and wonderful things that people like to collect. Some examples I’ve seen around the internet include sugar packets, traffic cones, and umbrella covers.
Visually, collections are something of an overwhelming sight. At first glance, if you look at one of these photos, it all seems like a lot to take in at once; there’s a lot of cluttered “stuff” in these images. And yet, at the same time, it’s easy for you to make some sense of what you’re seeing; you can say, “This is a bunch of fridge magnets” without too much effort.
These sorts of complex visual scenes are common in our everyday lives. Redundancy is everywhere in your environment, and not just in the knickknacks gathering dust on your shelf. If you go for a walk outside, you’ll see blades of grass and leaves on a tree, or walking around a city, you’ll see faces in a crowd, windows on a building, and cars in a parking lot.
How does the brain deal with all of this visual information? It would take a lot of effort to process every detail of every face in a crowd to conclude that you’re seeing a large group of people. Fortunately, there are a number of ways in which the brain reduces the information we receive to something more manageable. One potential consequence of this is something called redundancy masking, a phenomenon that Fazilet Zeynep Yildirim-Keles, Daniel Coates, and Bilge Sayim investigated in a recent paper in the Psychonomic Society journal Attention, Perception, & Psychophysics.
According to the authors, redundancy masking is a phenomenon in peripheral vision (i.e., vision away from your point of gaze), in which we estimate fewer items than there are. In the photo below, look at the white ceramic pot on the left. Without moving your eyes, can you figure out how many books there are on the right?
How did you do? There are actually seven books, but chances are, you estimated fewer. The authors gave participants a similar task in the lab, by showing them displays like the ones below. Participants looked in the middle of the screen and saw a set of lines appear briefly in their peripheral vision, in one of the eight possible locations shown in the left panel. The lines varied in number, from three to seven, and each time, participants estimated how many lines they saw.
It seems as though people should do this fairly easily, right? You’d be surprised! The authors showed that participants consistently underestimated the number of lines that they saw (for example, if four lines were shown, they might say three). This effect was also strongest with just three lines in the display – people would frequently report that there were two lines.
So, what actually causes redundancy masking? One possibility is that it is a limitation of our attention. If we’re not paying attention to something, we might miss it entirely. This is something you may have encountered behind the wheel of a car; for example, you may have been so focused on your GPS while driving that you failed to notice a pedestrian. Readers familiar with the classic gorilla study will appreciate just how easily an object can fall out of our awareness. Could this account for redundancy masking?
To test whether inattention could explain why we seemingly “miss” items due to redundancy masking, the authors had participants estimate the number of lines under three different conditions, as shown below. In one condition, participants knew ahead of time the location where the lines would appear. This was indicated to them using an arrow cue, shown just before the lines were to appear (left panel). In another, participants knew that the lines could appear in one of two possible locations (indicated with two arrows; middle panel). The authors also tested a condition in which no cue was presented, so there was an equal chance that the lines would appear in one of eight possible locations.
People were most accurate in the single cue condition (left), compared to the double cue (middle) and no-cue conditions (right). However, redundancy masking was still strong in the double-cue and no-cue conditions. What does this mean? Even when attention was divided across all locations, participants still underestimated the number of lines. Together, these results suggest that while attention can impact redundancy masking, inattention alone can’t explain why these objects seemingly drop out of our awareness.
Importantly, this phenomenon highlights some key limits of our peripheral vision. Can we trust our eyes and brain at all? After all, missing an item entirely would be very dangerous if you’re driving down a busy street and completely fail to see a pedestrian on the road.
The good news is that, for one, we can move our eyes to get a more accurate estimate when we need to. And when we do need to rely on peripheral vision, a reduction in the amount of information we get can help us get an overall picture of our environment, without needing to process everything in detail. According to Yildirim-Keles, “the reduction of the amount of information that needs to be consciously processed in redundancy masking has the advantage that the limited processing resources of the human brain are not used for redundant information.”
So, while underestimating the number of objects may seem disadvantageous, it might reflect some shortcuts that the brain takes to make sense of the redundant information in our environment. In other words, seeing less may help us do more.
Featured Psychonomic Society article
Yildirim-Keles, F. Z., Coates, D. R., & Sayim, B. (2024). Attention in redundancy masking. Attention, Perception, & Psychophysics, 1-14. https://doi.org/10.3758/s13414-024-02885-8
