At Science Gallery London, we were immersed in blood as we worked on our current exhibition. We also brushed up on our first aid as we expected some visitors to exhibit a particular response to the material we presented. But why do people faint at the sight of blood?
The Diagnostic and Statistical Manual of Mental Disorders (DSM) has historically treated blood, injection or injury phobia as a specific sub category, for good biological reason. With many other phobias, exposure to the stimulus (a picture of a spider, say) results in an increase in heart rate. But with blood, this is followed by a sudden decrease in heart rate and blood pressure, which can lead to fainting. This latter element is similar to the disgust response and is opposite to pure fear. In evolutionary terms, this may be useful if it’s you who’s been injured, since it might stop you from losing blood. And some have wondered whether it’s an automatic version of ‘playing dead’. If someone in your group has been badly injured, it may be worth keeping your head down. Whatever its origins, it certainly adds an interesting layer to an exhibition experience.
Dr Daniel Glaser is director of Science Gallery at King’s College London
