Can you recognize two words at once?

What is it about?

When you look around, you see a world full of objects. But can you truly identify multiple things at once, or are you limited to focusing on one at a time? This study investigates that limit using a simple test: participants view one or two items flashed on a screen and must quickly identify if a 'target' category is present. The logic is straightforward: if the human brain can process two things simultaneously, having two targets on the screen should lead to a faster response than having just one. We specifically applied this to word recognition. By testing whether people can identify two written words at the same time, we gain insight into the mechanics of reading: can we process words in parallel, or is it better to move our attention sequentially, one word at a time?

Featured Image

Photo by Patrick Tomasso on Unsplash

Photo by Patrick Tomasso on Unsplash

Why is it important?

This question has long been debated by psychologists and neuroscientists for two primary reasons: 1. Real-World Performance: It determines how we handle complex tasks like driving or reading. If we can process multiple items in parallel, we have a significant advantage. However, if dividing attention causes 'interference'—making us slower or more prone to errors—then focusing on one thing at a time is actually the more efficient strategy. 2. Brain Architecture: While our eyes send visual information about many objects to the brain simultaneously, we don't yet know if the 'identification' centers of the brain work the same way. Is there a single bottleneck that processes one word at a time, or a distributed system that can decode multiple meanings at once? To solve this, we used computational models to simulate human performance. These models compare parallel processing (simultaneous) against serial processing (one-at-a-time). Interestingly, our research reveals a surprising prediction of the serial model: when searching for a 'target' (like a real word among nonsense letters), a person will actually be slower when two targets appear together than when only one target appear. In four experiments, we confirmed that this prediction holds true when trying to recognize multiple words at once. We also show that a certain type of parallel processing model, in which multiple words interfere with each other in the brain, can also account for the data.

Perspectives