A new study explains why humans evolved large brains.

According to researchers at the University of Bath, bigger brains help humans perceive more information from their visual fields and help reduce visual illusions.

The research adds weight to the idea that size of certain brain areas such as the visual cortex played an important role in human evolution. The team found that the brain region dedicated to vision varies in size among primates, apes and humans. And, this size is associated with visual processing.

Researchers said that overall brain size can't be tied with intelligence. However, size of specific brain areas can increase efficiency at a given task.

"Primates with a bigger visual cortex have better visual resolution, the precision of vision, and reduced visual illusion strength. In essence, the bigger the brain area, the better the visual processing ability," Dr Alexandra de Sousa of the University's Department of Psychology explained.

"The size of brain areas predicts not only the number of neurons (brain cells) in that area, but also the likelihood of connections between neurons. These connections allow for increasingly complex computations to be made that allow for more accurate, and more difficult, visual perception," de Sousa added, according to a news release.

Last year, a separate team of researchers had found that dedicating a big area in the brain to process visual information led to the fall of Neanderthals. Humans, researchers said, devoted more brain area to understand social cues, which helped them survive.

Dr Michael Proulx, Senior Lecturer (Associate Professor) in Psychology at Bath said that the study ties anatomy of brain and behavior and presents it in a single framework.

Future behavioural research and neuroanatomical data on other sensory systems could help scientists understand how ancient animals sensed the environment, Proulx added.

The study is published in the journal Frontiers in Neuroanatomy.