Anticipating pleasure or pain before tasting hot sauce appears to influence how the brain responds to the spicy flavour.
鈥淭his has broader implications beyond spicy food,鈥� says at East China Normal University. 鈥淯nderstanding how positive and negative expectations influence perception can inform approaches in medicine, such as enhancing placebo effects in treatments.鈥�
Luo and her colleagues recruited 47 volunteers 鈥� roughly half liked spicy foods and half didn鈥檛 鈥� to receive squirts of both low-intensity and high-intensity hot sauce in their mouths while lying inside an fMRI brain scanner. Computer-controlled syringe pumps outside the main room delivered liquefied versions of mild and hot salsa, along with cleansing sips of water, through a bundle of three 8-metre-long tubes into participants鈥� mouths.
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The researchers conducted one round of experiments without setting expectations. But in the second run, they signalled to participants what intensity hot sauce they would get using different-coloured chilli pepper shapes. An image of two red peppers, for example, signalled the hottest sauce, while one red and one blue pepper signalled the mildest.
The brain scans showed that, for heat haters, the negative expectation of receiving a spicy sample amplified activity in brain regions that process pain, including the somatosensory cortex, thalamus, insula and amygdala. This provides a 鈥渃ritical warning鈥� for how medical patients鈥� negative expectations could intensify pain, says at the University of Maryland.
By comparison, the positive expectation of receiving a spicy treat boosted a pleasure signature in the brain of hot sauce lovers 鈥� but only for the mild version. Such disjunction represents 鈥減arallel subjective realities鈥� in people鈥檚 brains, says at Wake Forest University in North Carolina, a study co-author.
Future studies could investigate how strongly such brain patterns track subjective experiences of pain or pleasure, says at Dartmouth College in New Hampshire.
PLOS Biology
