Considering side biases in vigilance and fear

Measures of vigilance and fear might be more consistently associated if side biases are taken into account, because the right side of the brain is specialised to detect predators and to express fear responses. In species with eyes positioned laterally and with relatively small binocular fields, this brain asymmetry is manifested as eye preferences because each eye sends most of its input to be processed in the opposite side of the brain. Hence, responses elicited by stimuli on the animal's left side are more likely be associated with fear than are responses to the same stimuli on the animal's right side.