Lateralization of Brain Function - Advantages of Brain Lateralization

Advantages of Brain Lateralization

The widespread lateralization of many vertebrate animals indicates an evolutionary advantage associated with the specialization of each hemisphere. In one experiment, baby chicks were lateralized before hatching by exposing their eggs to light. These chicks were set to a task of picking out food from a bed of pebbles. Neither the lateralized, nor the non-lateralized chicks had a problem with this task, but the lateralized chicks only used the eye on the side of which they were lateralized to pick up the pebbles. When presented with a second task of watching for a cutout of a predatory hawk, the discrepancy between lateralized and non-lateralized chicks became evident. Lateralized chicks could pick food out of the pebbles with one eye and one half of the brain while using the other eye and other half of their brain to monitor the skies for predators. Not only could non-lateralized chicks not complete the two tasks simultaneously, but their performance of the single task deteriorated. This suggests that the evolutionary advantage of lateralization comes from the capacity to perform separate parallel tasks in each hemisphere of the brain.