It is now established that orbital frontal cortex neuron activity
in monkeys enables them to discriminate between
rewards that are directly related to the animals ’ relative
(as distinct from absolute) preference among food item
such a cereal, apples, and raisins (in order of increasing
preference) ( Tremblay and Schultz, 1999 ). Thus, if A is
preferred to B is preferred to C, then neuronal activity
is greater for A than for B when the subject is comparing
A and B, and similarly for B and C when comparing
B and C.