The critical factor is the function of the mind that decides if new information is either true or not true, or at least worthy of significant doubt. That which is deemed to be untrue still enters your Subconscious Mind, but it goes into that Database of Information. This new information is then known to the Subconscious Mind, but given little or no credibility. There, it is unlikely to ever change the existing beliefs or habits. That which is deemed to be “true” reinforces the long-standing habits and beliefs inside of us.
It is the responsibility to the critical factor to keep what is in the subconscious mind consistent. This saves a great deal of mental energy, if the Subconscious Mind had to regularly rearrange its contents, especially habits and beliefs, constantly reorganizing it would be mentally exhausting.
So, unless the Critical Factor is provided convincing information, so strong that it is able to overcome existing beliefs and habits, new information is simply recorded, but not integrated into our personality and consistent behaviors. It just resides in the subconscious database, not to be acted upon.
This is where hypnosis comes in. If you remember the definition of hypnosis, it causes a bypass of the critical factor. This allows someone in hypnosis to accept suggestions at both the subconscious and unconscious levels of the mind.
The essence of the critical factor is that of being protective, and as long as the suggestions that are given to the subject are not going to endanger him/her the Critical Factor will remain in a state of bypass so that the subject can easily accept suggestions. There is no state of hypnosis that can overcome this protective function.