that they respond to pair wise comparisons of differential rewards. 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.