Some people are gifted with natural abilities to pierce this Veil. Some just trained hard to look to the Other Side. Vision is not the only sense that can be enhanced to look beyond this reality. There are people with the ability to hear, smell, taste and feel these entities from beyond. We Filipinos are rather gifted with the ability to feel these beings from beyond since I think we are just so connected with the Natural/spirit world. We have a lot of Filipino "Espiritista", "Albularyos" and "Mangkukulam" each claimed to have connections to the Other world.
I think the ability to pierce this Veil is enhanced by our awareness that these worlds outside our own exist. With our natural affinity to sense these worlds beyond, training our senses to feel these beings would really help people who are into this field to effectively communicate with them. With the ability to communicate with these beings, a psychic/medium can learn a lot of things from beings who are not bound by the laws of time and space. They can give us information about things that we won't normally know. However, we must be very careful as some of these entities are also capable of lying.
*** pic from the www.spaceclear.com