How does the narrator in "exhalation" plan to discover the cause of the clock discrepancy?

Exhalation is a science fiction short story by author Ted Chiang. The story is presented as a scientist's journal entry. It tells the story of a race of mechanical beings, which the scientist belong to. One day, he discovers that clocks appear to be going faster than usual. In order to find out why this is the case, he decides to dissect his own brain. The scientist discovers that it is not that clocks are going faster, but that brains are computing more slowly due to increased atmospheric pressure.

3 is blunder, i’m not sure about the last one but the first two look correct