Sensitivity to a change in reward has been studied in a range of species, from bees to birds, and the change in reward can either be in the quality, quantity or frequency of the reward. We can measure an animal’s reward sensitivity in a few ways. One way is to measure how hard the animal is prepared to work in order to get the reward – for example pressing a lever, performing a hand touch, or running down a runway. Alternatively, we can measure how much of the reward an animal consumes in a set period of time.
Studies of reward sensitivity typically consist of two groups of animals. One group only ever gets the same low quality reward (‘Unshifted’) whereas the other group (‘Downshifted’) initially receive a high value reward, are then switched to the low value reward, before receiving the high value reward once again. It is the ‘Downshifted’ animals’ response to the unexpected switch from a high to a low quality reward that we are most interested in.
The studies are typically split into three parts – ‘preshift’ trials (where animals in one group receive the high value reward and in the other group receive the low value reward), ‘post-shift’ trials (where all animals receive the low value reward), and a final ‘recovery’ trial (where animals in the experimental group receive the high value reward).
The way an animal responds to a change in reward has been found to be affected by their affective state. Read more here.
Some examples of studies of SNC can be found here.