Dads are more attentive to their toddler daughters than their toddler sons, according to new research which suggests unconscious gender biases could influence the way parents treat their children.

The study found that not only did fathers act differently in their daily interactions, but there were noticeable differences in brain scans depending on whether they had a boy or girl.

While previous studies have shown differences in the way parents treat their children, most have been done in labs. This study aimed to tackle the issue in a real-world setting.

The study recruited 52 dads and monitored their interactions with their children using an electronic activated recorder. The fathers would wear the device two days a week and it would record ambient sound every nine minutes.

The researchers found that dads with little girls spent about 60 per cent more time responding to their child, they sang more with girls and spoke more openly about emotions. Fathers with daughters also used more words associated with the body, like “belly”, “cheek”, or “fat”.

In contrast, fathers of sons spent more time engaged in “rough-and-tumble” play and were more likely to use words related to achievement and power, such as “proud”, “win” or “best”.

"We should be aware of how unconscious notions of gender can play into the way we treat even very young children," lead researcher from Emory University Jennifer Mascaro said in a statement.

"The fact that fathers may actually be less attentive to the emotional needs of boys, perhaps despite their best intentions, is important to recognize," she said. "Validating emotions is good for everyone — not just daughters."

The study also used functional MRI scans to look at how the brain responded when shown pictures of adults interacting with children as well as their own children in various emotional states.

Researchers found that fathers’ brains responded more strongly when their daughters showed happy facial expressions. In contrast, fathers with sons showed a more brain activity when their sons showed neutral facial expressions.

"It appears that men's brain responses to their children may be related to their behaving differently with sons compared to daughters," said Mascaro.

According to Mascaro it is still unclear if the differences observed in the study are biologically or evolutionarily ingrained in father’s behaviour or rather a by-product of cultural and societal expectations of adult gender roles.

“We need to do more research to try to understand if these subtle differences may have important effects in the long term," she said.