"This is a nightmare. It isn't real. It isn't... DON'T TOUCH ME!"
In world-breaking cute news, it turns out that mice are scared of men. Robert Sorge and colleagues decided freak some mice out by seeing whether the gender of the researcher could affect the behavior of mice, and they discovered that mice experienced greater stress in the presence of men compared to women.
Besides being funny to imagine a mouse atop a chair shrieking as a man approaches him and trying to bat him away with a mini broom, it does have some serious implications for not only how we should conduct future research but also in how much confidence we should attribute to past research that hasn't controlled for this factor.
Before discussing the complications this research raises, we'll first look at what the study did and exactly what they found. One of the main measures used in the study was the "mouse grimace scale", which adorably looks like this:
and presumably the judgement of where a mouse fell on the scale simply involved a group of researchers huddled around a mouse cooing: "Who's a grumpy mouse? You are! Yes, you're a grumpy mouse!". The pain response (or 'grimace') was used as a proxy for stress and this was associated with an observed "stress induced analgesia" (SIA). SIA simply means that when an individual is stressed, any pain it experiences is effectively numbed - like when an athlete injures themselves during a game but doesn't realise they are in pain until after the game has ended.
I'd love to be able to say that the researchers also used a handful of other semi-anthropomorphic measures, like a tiny mouse-sized Freudian couch where it talks about its feelings, but unfortunately they just looked at body temperature and corticosterone. However, these proxies for stress did support the conclusions reached based on the grimace metric.