You’re not alone - I had to read it out loud to see the pattern :)

I wonder if people have a range of sensitivity to what one might call the "mind's voice" - by analogy to the recent discovery of aphantasia, which revealed that different people's experience of the "mind's eye" ranges from vivid imagery to nothing at all.

Some people say they don't have a mind voice, and grow up thinking nobody does. Other people, with a mind voice, grow up thinking everyone does.

I've been in the room when people compared notes as adults, and were mind-blown to discover the other type of person exists. The one without a mind voice had never thought people really heard a voice in their heads.

Each additional university math course makes the puzzle harder ;)

Continue sequence: one, 1, two, 1, three, 2, four, 1,