The researchers discovered that the neurons' firing rates reset between the two sessions. In the first session the maximum firing rate corresponded to the option of two drops of juice, and in the second it corresponded to 10 drops of juice. In other words, the same change in how rapidly the neuron fired corresponded to a fine distinction in value when the range was narrow, and a coarse distinction when the range was broad. "As we adapt to large values, we lose some ability to consider smaller values," Padoa-Schioppa said. "This is why salesmen try so hard to sell you upgrades when you're buying a car. Spending $100 to add on a radio seems like no big deal if you're already spending $20,000 on a car. But if you already have a car and you are thinking of spending $100 for a radio, suddenly it seems like a lot. They know that people don't come back and buy the radio later." - www.sciencedaily.com