The world of brain research has a secret flaw. For decades, studies into how the mind works have been carried out primarily by English-speaking scientists on English-speaking participants. Yet their conclusions have been branded as universal. Now, a growing body of work suggests that there are subtle cognitive differences between populations who speak different languages—differences in areas like perception, memory, mathematics, and decision-making. Generalizations we make about the mind might, in fact, be wrong.

In a study published in the journal Trends in Cognitive Science, Asifa Majid, a professor of cognitive science at the University of Oxford, has outlined the deficit in understanding that has stemmed from ignoring languages other than English. “We can’t take for granted that what happens in English is representative of the world,” she says.

Take, for example, the Pirahã, an indigenous people of the Brazilian Amazon. They count by approximation—what scientists call a “one-two-many” system. And as a result, they don’t perform well in arithmetic experiments compared to, say, speakers of languages like English, with a vocabulary that encapsulates large cardinal numbers—20, 50, 100. “The way that your language expresses numbers influences how you think about them,” says Majid. “It’s having number words themselves that allow us to think exact large quantities. So 17 or 23, that doesn’t seem to be possible without having words in your language.”

If you’re reading this, you speak (or can understand) English. That’s not surprising, because it’s the most widely used language in human history. Currently, about one in six people speaks English to some degree. Yet there are over 7,150 living languages today, and plenty of them make meaning in completely different ways: They vary widely in sound, vocabulary, grammar, and scope.

When English is used to carry out research into how the human brain works, scientists formulate questions based on the elements English expresses, making assumptions about what the mind, knowledge, or cognition are according to how the language describes them—not what they might represent in other languages or cultures. On top of this, participants in cognition studies tend to be “Weird”—Western, educated, industrialized, rich, and democratic. But the majority of the world’s population doesn’t fall into this category. “There is this bias in academic research, partly because of where it is done, but also because of the meta-language of talking about the research,” says Felix Ameka, professor of ethnolinguistics at the University of Leiden in the Netherlands, who was not involved in Majid’s work.

“If I ask you now, ‘How many senses are there?’ I suspect your answer is gonna be five,” Ameka says. But in the West African language Ewe, spoken by over 20 million people, including Ameka, at least nine senses are culturally recognized—such as a sense focused on being balanced physically and socially, one focused on how we move through the world, and one revolving around what we feel in our body. Yet despite this being well known, it doesn’t permeate what’s classed as scientific fact. “Western science has this huge wall,” Ameka says.