Why Doesn’t Science Include Pleasure as the Tenth Sense?

Science today considers nine senses: five “traditional” (taste, smell, sight, hearing, and touch) and also nociception (pain), proprioception, thermoception, and equilibrium perception. Why doesn’t science include pleasure as the tenth sense? 

Thomas Neukirch, painter

Answer by Kent C. Berridge:

Some have considered pleasure to be a sensation, but pleasure is not usually included among the classic traditional senses. That is because the pleasure of a sensation is not inherent in any external sensory stimulus, but rather is created by the individual’s brain and mind in response to that stimulus. Pleasure always must be actively generated by the brain, not merely decoded in the stimulus. As the Dutch psychologist Nico Frijda put it, pleasure is a niceness gloss added by the brain to a sensation, not part of the original sensation.

For example, sweetness is usually pleasant. But if eating a new sweet food is followed by nausea, people often develop a learned taste aversion for that food: in future, they may find it disgusting, even if they liked it the first time, and even if their nausea was caused by a stomach virus and not by the food. Conversely, a person’s first taste of bitter coffee or beer is often unpleasant, but many people grow to find these tastes very pleasant. Beyond taste, a dip into a cool pool can be pleasant on a hot summer day, but in winter a hot bath is more inviting. In all cases, the pleasure is not in the sweetness, bitterness, cold or heat per se –but rather in the ‘niceness gloss’ or ‘badness gloss’ that the brain puts on that sensation in its current state.

Biography:

Kent C. Berridge is the James Olds Distinguished University Professor of Psychology and Neuroscience at University of Michigan, Ann Arbor. Berridge completed his bachelor’s degree from the University of California, Davis, and his PhD at the University of Pennsylvania in Philadelphia.

As the Director of the Affective Neuroscience and Biopsychology Lab, Dr Berridge aims to understand the neurobiology of affective states such as pleasure, pain, sorrow, joy and depression, just to name some. He also studies more complex issues like learning, decision-making or addictive behavior.

The research of Berridge and his team has also been key in deciphering some neural bases of addiction, namely the distinction between wanting and liking mechanisms and how the dopamine system fires wanting, and not liking.

Berridge has authored more than 200 scientific publications, and he is also an editor of Pleasures of the Brain, a book that summarizes the most relevant scientific advances in this field to date. Berridge is one of the world’s most cited contemporary psychologists and, in 2018, he was named one of the 50 most influential living psychologists by TheBestSchools.org.