Why independent cultures think alike when it comes to categories: It’s not in the brain

Imagine you gave the exact same art pieces to two different groups of people and asked them to curate an art show. The art is radical and new. The groups never speak with one another, and they organize and plan all the installations independently. On opening night, imagine your surprise when the two art shows are nearly identical. How did these groups categorize and organize all the art the same way when they never spoke with one another?

The dominant hypothesis is that people are born with categories already in their brains, but a study from the Network Dynamics Group (NDG) at the Annenberg School for Communication has discovered a novel explanation. In an experiment in which people were asked to categorize unfamiliar shapes, individuals and small groups created many different unique categorization systems while large groups created systems nearly identical to one another.


If people are so different, why do anthropologists find the same categories, for instance for shapes, colors, and emotions, arising independently in many different cultures? Where do these categories come from and why is there so much similarity across independent populations? “If I assign an individual to a small group, they are much more likely to arrive at a category system that is very idiosyncratic and specific to them,” says lead author and Annenberg alum Douglas Guilbeault (Ph.D. ’20), now an Assistant Professor at the Haas School of Business at the University of California, Berkeley. “But if I assign that same individual to a large group, I can predict the category system that they will end up creating, regardless of whatever unique viewpoint that person happens to bring to the table.”

The explanation is connected to previous work conducted by the NDG on tipping points and how people interact within networks. As options are suggested within a network, certain ones begin to be reinforced as they are repeated through individuals’ interactions with one another, and eventually a particular idea has enough traction to take over and become dominant. This only applies to large enough networks, but according to Centola, even just 50 people is enough to see this phenomenon occur.

Adapted and abridged from Source

Guilbeault, D., Baronchelli, A. & Centola, D. Experimental evidence for scale-induced category convergence across populations. Nat Commun 12, 327 (2021). https://doi.org/10.1038/s41467-020-20037-y

Sound Beaming

Imagine a world where you move around in your own personal sound bubble. You listen to your favorite tunes, play loud computer games, watch a movie or get navigation directions in your car — all without disturbing those around you. That’s the possibility presented by “sound beaming,” a new futuristic audio technology from Noveto.

The technology uses a 3-D sensing module and locates and tracks the ear position sending audio via ultrasonic waves to create sound pockets by the user’s ears. Sound can be heard in stereo or a spatial 3-D mode that creates 360 degree sound around the listener. The company expects the device will have plenty of practical uses, from allowing office workers to listen to music or conference calls without interrupting colleagues to letting someone play a game, movie or music without disturbing their significant others. The lack of headphones means it’s possible to hear other sounds in the room clearly.

Adapted and abridged from Source

Keeping time more precisely with a new type of atomic clock

Atomic clocks are the most precise timekeepers in the world, which use lasers to measure the vibrations of atoms. They keep time with such precision that, if they had been running since the beginning of the universe, they would only be off by about half a second today. Still, they could be even more precise. If atomic clocks could more accurately measure atomic vibrations, they would be sensitive enough to detect phenomena such as dark matter and gravitational waves, which would give answers to questions like what effect gravity might have on the passage of time and whether time itself changes as the universe ages.

The researchers Pedrozo-Peñafiel et al. report in the journal Nature that they have built an atomic clock that measures not a cloud of randomly oscillating atoms, as state-of-the-art designs measure now, but instead atoms that have been quantumly entangled. Their findings would lead to clocks being less than 100 milliseconds off. To keep perfect time, clocks would ideally track the oscillations of a single atom, but they are subject to the Standard Quantum Limit that introduces an uncertainty when measuring at such small scales.

The solution would be quantum entanglement which describes a nonclassical physical state, in which atoms in a group show correlated measurement results, even though each individual atom behaves like the random toss of a coin. The team reasoned that if atoms are entangled, their individual oscillations would tighten up around a common frequency, with less deviation than if they were not entangled. In this way, the researchers quantumly entangle the atoms, and then use another laser, similar to existing atomic clocks, to measure their average frequency. When the team ran a similar experiment without entangling atoms, they found that the atomic clock with entangled atoms reached a desired precision four times faster.  

This version was adapted and abridged from the original MIT article

Original paper: Pedrozo-Peñafiel, E., Colombo, S., Shu, C., Adiyatullin, A.F., Li, Z., Mendez, E., Braverman, B., Kawasaki, A., Akamatsu, D., Xiao, Y. and Vuletić, V., 2020. Entanglement on an optical atomic-clock transition. Nature588(7838), pp.414-418. Online