Mmm, Baby.. That's Spicy!

Whenever I’m out at a Chinese restaurant with my family, my brothers and I always argue about how much chilli we should put in the soy sauce. I like putting a little, but they like having way more chilli than soy sauce- and my tongue can’t handle that! In fact, I find that my family, and most people in general, have an all-or-nothing attitude when it comes to anything spicy in their meals – you either use the Extra Hot Tabasco, or you don’t use Tabasco at all. I think it’s probably why Mildly Hot Tabasco is so unpopular; if you’re going to put hot sauce, you might as well go all the way!

This might make those who hate the spicy feeling wonder – why do people love spicy foods so much? Psychologists can answer this. You might think that the answer lies somewhere in the study of our taste buds and taste receptors, but spicy foods are actually more related to our pain receptors.

Skip ahead to 10:40 in the below video to see a little bit of the research chef Heston Blumenthal did on chilli and pain (or just watch the whole video to see his take on Chili Con Carne – just make sure you’re not hungry! J)

Heston Blumenthal In Search Of Perfection-Chilie Con Carne

(Bonus: at 15:00 he conducts a little perception psychology with our friends Kiki and Buba, and on 20:00 we get to see one of the many uses of gas chromatography!)

To expand a little more on what they’ve said: Basically, chilli and spicy foods stimulate receptors in our tongue – specifically, pain receptors or nociceptors. Nociceptors respond to different things, like mechanical simulator, chemical simulation, and thermal simulation. The more capsaicin there is in the chilli (or the higher the Scoville level, the measure of spiciness/heat that Blumenthal keeps talking about, if you have a hard time deciphering his accent), the more the nociceptors are stimulated. For reference, the regular Tabasco brand hot sauce hits from around 2,500 to 5,000 SHU (Scoville Heat Units); in the video, they used capsaicin levels of over one million!

Scientists still aren’t completely sure how exactly the process goes from our nociceptors to our brain, although a bunch of models have been proposed, such as the gate control model. The idea behind this model is that the pain signals begin in the spinal column, and then travel through different “gates” or pathways to get to the brain – and that opening or closing these gates controls the strength of the pain signal. Although it is a good model, research today suggests that it is a lot more complex.

What scientists do know is that pain activates a lot of areas in the brain – in the video, the fMRI clearly shows a number of different areas being activated across the whole of the brain, not in just one area. This is what researchers refer to as the pain matrix, and it includes the hypothalamus, the amygdala, the thalamus, areas in the cortex, and prefrontal cortex... there is no one single “pain center” in the brain; it’s all spread out.

Of course, this only partly answers our question – if pain is supposed to be avoided, then we shouldn’t like spicy foods at all! But, as it turns out, a lot of people do – in the same way that a lot of people like getting massages, or biting down on a painful tooth, or scratching your legs after a long day in jeans...but this isn’t to say that if you like spicy foods, you’ll like getting shot in the foot! The Scoville levels of almost all chilis and spicy foods are low enough not to cause true pain; this is just a tiny burn... and a lot of people like that, and nobody is really sure why (yet!). Call them adventurous, intrepid, or masochistic - they just like spice!

Reference: 

Goldstein, E. B. (2010). Sensation and Perception. Belmont, CA: Wadsworth, Cengage Learning.