Sensory Liking: How Nervous Systems assign Hedonic Value to Sensory Objects

Sensory liking is a biological process by which biological organisms compute how liked or disliked a sensory stimulus is. The purpose of this process is to tag the sensory objects an organism encounters in its physical environment as either conducive or threatening to survival. Objects that are deemed likeable elicit appetitive behaviour, whereas objects that are encoded as dislikeable elicit aversive behaviour. In this chapter, I review an extensive body of neuroscientific work that shows that, in vertebrates, evaluations of sensory liking are computed by neural mechanisms located in the mesocorticolimbic reward circuitry. However, evidence from numerous experiments also shows that these processes are modulated by input from interoceptive, perceptual, cognitive, and executive mechanisms that represent endogenous and exogenous conditions that are of relevance to the organism’s physiological needs and current behavioural circumstances. As a result, the hedonic value it assigns to a given stimulus is determined not just by information inherent to the stimulus but also these stimulus-external factors. Focusing on human sensory liking, I demonstrate how liking and disliking outcomes are caused not by fixed reactions to sensory stimulation but by flexible evaluation events that integrate computational outputs from a distributed network of mechanisms.