Proactive inhibition, or proactive interference, explains the psychological phenomenon of individuals who are unable to learn a new skill set that is counterintuitive to a previously learned skill set. According to the Encyclopedia Brittanica, proactive inhibition states that an individual's old memories interfere with the way she retains new information.
Retroactive inhibition is the opposite of proactive inhibition. In the case of retroactive inhibition, an individual is unable to recall previously learned knowledge after learning a new skill or piece of knowledge that interferes with those old memories.
An individual learns that George Washington discovered the world was flat. Later, she reads evidence that George Washington was the first president of the United States and did not propose the world was round. For a short while, she may recall that George Washington did not propose the world was round, but will forget, because her previous teachings with come to the forefront of her memory.