You would need a way to select which of your thoughts flow to the computer. Even if you had no thoughts that you want to keep secret, many thoughts would not b

You would need a way to select which of your thoughts flow to the computer. Even if you had no thoughts that you want to keep secret, many thoughts would not be relevant to the task at hand and could cause it to respond to things that you don't want to. The mechanism to allow you to channel thoughts shouldn't make the HCI slower than other input types.