The boldest black-lined rainbowfish are those that are born in the wild. Also more fearless are those that analyze information with both sides of their brains. The preference to analyze and react to information with either the left or right hemisphere of the brain is called cerebral lateralization, and is widespread among vertebrates. Lateralization is seen in the preference of humans or parrots to use one hand or claw over the other or to always turn to the same side when moving around objects.