The preference is more personal, which is much harder to be modified. Even if you are whispered a new way of thinking directly in the brain, your emotion does not accept it easily. You still can choose from many alternatives by comparing their pros and cons, even under the electromagnetic irradiation.
Although, your emotion is also controlled by the radiowave. If your positive and negative is manipulated when the thought is directly irradiated to your brain, you are more maneuvered by the wave. In another case, your anger is controlled while the though is sent to your brain, you should dislike its object as a result. In this way, your behavior can be manipulated by the wave, though it is not a simple electromagnetic control.
If you have been affected by this control for a long time, there is a possibility that your preference is completely changed. This holds true to the philosophy and you might be brainwashed especially when you are not stubborn on your thought. This also holds true to the radical idea that you might become an extremist especially when you have no strong political opinion. Generally speaking, you can make a radical believer just by the physical manipulation, but the electromagnetic wave can function secretively to create one of them.
It is not concluded yet but it should be necessary for manipulators to believe the radical idea, even for a conversion through the electromagnetic wave. If they do not believe, it is hard for the subject to believe its radical idea. This implies there are many radicals in the league of manipulators as there have been many brainwashes to convert the subject. That is, there should be many radicals within the intelligence organization and their assets.
The radiowave also creates a short-term influence on the thought. For example, your fear is enhanced with the stomach ache to escalate the anxiety. If there is an additional wave to remind someone or some events in the brain at the same time under the anxiety, you are likely to feel something is wrong about that. If the negative feeling is added on top, you might have a delusion that it is definitely wrong.
Although, the delusion might be more at the positive side. When your positive feeling is enhanced with heating up your brain temperature, you are likely to believe the thought sent directly into your brain. If your aggression is enhanced at this time moment, you might be angry with that distorted thought. This process reinforces your delusion and prepares for the further action. It is not a positive thought, but it is an extension of the positive feeling to believe something emotionally.