Our effectiveness as a companion to parrots is not easily measured, and often very difficult to determine. Being the intelligent creatures they are, they are constantly evaluating our actions both directly related to them, as well as actions less subjective. Through this observation, they come to a decision where exactly we fit into their social hierarchy. Through meaningful interaction, patience, a willingness to alter our behavior towards them with respect to their wishes, we can often work our way "up the ladder" to a position of increased acceptance, but again they are always watching/evaluating our behavior.
There are many other factors that weigh in, when considering their behavior towards us, such as diet and the energy levels inherent in poor diets (high sugar and fat can lead to unnecessary stress and anxiety), foraging opportunities and mental stimulation through the aid of toys and puzzle solving games, and a show of respect towards their wishes when interacting. In truth, our relationship with our companion bird is always evolving, and while the foundation may never actually change, levels of acceptance and willingness to interact in a previous manner can often alter based on mood, situation changes (moving furniture around to unfamiliar placements, presence of unfamiliar persons in the vicinity, etc...) and these factors must be always be kept in mind.
While parrots are welcome guests in our lives/homes, it must be considered that we invited them without them actually ever expressing a wish to be brought into a situation so completely outside the frameworks of their natural instincts. Can it work: yes; does it require patience and a willingness to adapt on the part of the human: absolutely. Parrots are wonderfully intelligent and highly capable of adapting, but their wishes and needs must be met - not just our own - in order for there to be a suitable companion lifestyle. Too many people bring them home expecting to have a feathered dog who can talk but also obeys their wishes, and doing so set themselves up for complete failure leaving only the parrot to suffer once relegated to a position outside of the "flock" it has been forced into.
Please spread the word and knowledge of companion parrot advocacy far and wide, and let us all contribute to a better understanding of what companion parrot care is so that all companion parrots may find a safe and happy home.