Personalisation strategies, such as posts showing the politician at the local soccer field or at home with a pet, seemed to help drive interaction, said researcher Yilang Peng, Assistant Professor at University of Georgia in the US.
"Faces are a very important vehicle to extracting emotions," Peng.
"In general, people are paying attention to posts that feature faces, and especially faces of people they recognise."
Using computer vision methods, Peng analysed over 59,000 images published on Instagram of 159 US politicians, including presidential candidates, governors, senators and Cabinet members.
Peng identified four broad categories to classify the setting of the politicians' images.
These are professional/political setting, such as press conferences, offices, rallies and protests; text/illustration, such as graphics and test-based messages; personal setting, showing individuals in private or nonpolitical settings such as restaurants, homes or gyms; and architecture/landscape, featuring views of buildings or landscapes, often without people.
Roughly 60 per cent of the posts analysed fell into the professional/political setting category, showed the findings published in the International Journal of Press/Politics.
"These kinds of posts are generally not that successful in terms of attracting comments or likes," Peng said.
On average, images in the personal setting category received about 20 per cent more likes on Instagram compared to the professional setting and text/illustration categories.
Images with only the politician's face, as opposed to the politician with other people or images without faces, also attracted more likes and comments.
"In summary, faces drove audience engagement," Peng said.