Visual illusions are often attributed to complex psychological processes. However, new research suggests that these illusions are actually caused by limits in the way our eyes and visual neurons work. Scientists have debated whether these illusions are a result of neural processing in the eye and low-level visual centers in the brain or involve higher-level mental processes. Dr Jolyon Troscianko from the University of Exeter co-developed a model that suggests simple limits in neural responses explain these illusions. The model combines the “limited bandwidth” of neural responses with information on how humans perceive patterns at different scales and assumes that our vision performs best when looking at natural scenes. It was initially developed to predict how animals see color but was also found to correctly predict many visual illusions seen by humans. This challenges long-held assumptions about how visual illusions work and sheds light on how our eyes and brains handle high contrast levels, as seen in high-definition televisions. The study’s model shows how neurons with limited contrast bandwidth can combine signals to allow us to see enormous contrasts, though the information is “compressed” resulting in visual illusions. This research demonstrates how our neurons are precisely evolved to use every bit of capacity, allowing us to perceive contrasts larger than 10,000:1. The paper, titled “A model of color appearance based on efficient coding of natural images,” was published in the journal PLOS Computational Biology.