Men kissing
The state of 'gay panic' isn't a real thing according to science See-ming Lee / Flickr

The visceral and violent reaction to displays of gay affection dubbed ''gay panic'' has no basis in biology, scientists have found.

Gay panic has been used as a defence in cases of hate crimes against LGBTQ people. It's described as a momentary insanity when someone flies into a rage at seeing romantic or sexual behaviour between men. The defence has been used repeatedly in criminal cases, albeit mostly unsuccessfully.

"These men [who commit attacks] argue that it's out of their control and that it's something completely innate. It's likened to reverting to a natural fight-or-flight defence mode because they've seen something dangerous," Karen Blair, a researcher at St Francis Xavier University in Canada, told IBTimes UK.

But homophobic men have a stress reaction no different to men who are neutral towards gay relationships when they view pictures of men kissing, according to Blair's research, published in the journal Psychology and Sexuality.

Blair and her colleagues decided to test whether there was a biological response that could be called a ''gay panic'' state. They tested the saliva of about 120 men in Utah for a stress response while watching a slideshow of images. Some of the images showed men and women kissing, some showed men kissing other men, some were neutral everyday things like paperclips, and some were disgusting things, like maggots.

They tested amount of salivary alpha-amylase – a digestive enzyme linked to stress – while the men were viewing the images. The levels in people who tolerated gay relationships were the same as those who were found to hold homophobic views.

"This blows a big hole in that argument that people who react very violently to same-sex public displays of affection are somehow not in control," Blair said.

"There is no difference in the stress response based on attitudes. So it doesn't make sense to say that those people who are reacting violently are doing so because of some biological response."

However, the levels of salivary alpha-amylase were higher across all groups of men – homophobic and tolerant – than when viewing the neutral images. This could be due to internalised homophobia even among men who are accepting of gay relationships, Blair said.

"Perhaps this is a sign of some of this historic social conditioning that has been taking place. We have been raised for generations to believe that homosexuality is wrong and that it is disgusting. That is built into the internalised homophobia that gay people have themselves," she added.

"So perhaps what this is pointing to is that we are still physiologically experiencing a disgust response, regardless of our views."

Further research will be necessary to see if the results can be replicated with a larger sample. The approach also has yet to be tested in non-Americans. But the evidence that aggressive homophobia is not driven by an innate biological response offers hope, Blair said, and could spur on interventions to reduce such behaviour.