Whenever we perceive something, we make an instant judgement on whether what we see, hear, taste, smell or feel is positive or negative. This subjective colouring of our perceptions is such a pervasive aspect of human experience that we are almost unable to sense anything without automatically valuing it according to its pleasantness or unpleasantness. Taking in the world this way means that even when we observe the same object or situation, we each form a unique and personal impression of it. Compared to other aspects of perception, the dimension of individual feeling is far less well understood.
Adam Anderson, associate professor at Cornell University, has led a research group focusing on the way in which subjective evaluation of the outside world shows up in the brain. The results suggest that not only is there a common pathway that deals with this type of emotional response across the various physical senses, but that it works the same way for all of us.
“Despite how personal our feelings feel, the evidence suggests our brains use a standard code to speak the same emotional language,” says Anderson.
Together with researchers from the University of Toronto and the University of Cambridge, Anderson discovered that an individual’s subjective feeling is represented by fine-grained patterns of neural activity within the orbitofrontal cortex, an area of the brain associated with emotional processing.
“If you and I derive similar pleasure from sipping a fine wine or watching the sun set, our results suggest it is because we share similar fine-grained patterns of activity in the orbitofrontal cortex”.
Anderson’s findings show that the human brain generates a code for the whole spectrum of feelings ranging from pleasant to unpleasant. This code can be read as a “neural valence meter”, with certain groups of neurons leaning in one direction when the emotion is a positive one, and in the opposite direction when an unpleasant feeling arises. This means that the popular theory that the experience of ‘good’ and ‘bad’ feelings corresponds with activity in distinct parts of the brain, seems to have been disproved.
According to Anderson, our personal feelings are the last frontier of neuroscience. In order to venture into this relatively unchartered territory, he asked the participants in his study to rate a series of complex images and tastes, whilst observing the patterns of activity which arose in their brains. As well as identifying the sensory-independent emotional codes in the orbitofrontal cortex, the researchers found that distinct sensory-specific emotional areas were involved for vision and taste. The authors indicate that this combined pattern of activity demonstrates that our subjective emotional response is an integral and inseparable aspect of human perception.