 But of course, there is so much scrutiny on this, given all the questions about the president's mental fitness. President Biden, for his part, has said that he doesn't need to take a cognitive test, that his doctors have told him as well that he does not need to take one. The president defiant, saying that he takes a cognitive test every day doing this job. ABC's Selena Wang. Less than a week to the Republican convention, the party has a platform.