Positive feedback (less wobbling) was given to our participants *only if* their brains would start to represent the shape they were looking at as a stronger member of a specific (neural) category that we chose arbitrarily, instead of how their brains would represent the shape by default.

We ran a 10-day experiment that included 6 days of neurofeedback training. In each training trial, our participants were shown a random wobbling shape from the complex stimulus space we created, and they were asked to “Generate a mental state that will make the shape wobble less or even stop!”.