[copsarebastards]

This makes perfect sense based on how tDCS is hypothesized to work.

tDCS is believed to enhance learning by providing more force behind the encoding of memories: it's like pressing harder when writing with a pencil, making it harder to erase. Normally it takes many iterations of practice to encode a complex skill properly, but with more electricity behind the "write" operation it takes fewer iterations.

However, with perceptual reasoning, encoding memories quickly would be counterproductive, because it would cause your first ideas to be firmly encoded, leading you to consider fewer ideas. This would prevent the broader considerations necessary in problem-solving.

I'm not a neuroscientist, so take what I'm saying with a grain of salt. I've just read a lot about tDCS, and have no formal training.