Many birds don't appear to be motivated by food at all. Some stubborn individuals might have to be half starved before they will take food from the human hand and eat it. While a few of these birds are demonstrating alienation, the overwhelming majority, especially cockatoos and many domestic handfeds are simply so crazy about people that they would rather play or cuddle rather than eat when humans are present. Training or correcting problem behaviors in these birds sometimes proves more difficult for new parrot owners because there is so little instruction available in the use of non-food rewards as a behavior modification tool. I suspect this situation exists not because food rewards are more effective, but rather because non-food rewards are so difficult to explain.
Most birds respond emotionally to melodious voices in soothing tones.
The bird may pinpoint or display in response to this type of verbal caress. Be careful not to overdo verbal praise, for too much adoration can come to seem like a courtship song to a sex-starved companion parrot. It is not unusual for a bird to abuse a human who talks sweetly but fails to reinforce an effective authority-based relationship. If the bird doesn't see a particular human as dominant, then that human might be treated as territory, possession, or rival. I believe that a successful relationship between human and companion bird casts the human in the role of loving parent.