Fathers also underwent MRI brain scans while viewing photos of an unknown adult, an unknown child and their own child with happy, sad or neutral expressions.

Fathers of daughters had stronger responses to their daughters' happy expressions in areas of the brain associated with processing emotions, reward and value.

Researchers say the results should encourage dads to be emotionally open with boys.

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

The full study is published this week in the journal Behavioural Neuroscience.

Images: Rex

Fathers pay more attention to daughters than sons, new study shows