While your split test is running, the response overview page of that campaign only has one tab, and it reads 'Split Test.' The rest of the response data shows up as you know it after the test is complete.
The page is laid out in timeline format. The bottom box shows the starting time and data. Next up you have the test status. The main focus is on the open rates and the option to complete the test right away. Below that, you've got more details: the time remaining, the test style (autosend or manual) and your options at the moment.