218 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”leading to the increase or decrease in the frequency of that behavior,
depending on whether the stimulus is desirable (positive reinforcement)
or undesirable (negative reinforcement) to the animal. Unlike in clas-
sical conditioning, in which a reflexive bodily response is modified by
an antecedent stimulus, in operant conditioning a voluntary behavior is
modified by a stimulus subsequent to the behavior. For example, the fre-
quency of bar pressing (by a rat) increases when the action is rewarded
by food. Conversely, the frequency decreases if the action triggers an
electric shock. In a different setup, bar pressing can be designed to sup-
press an anticipated electric shock. Since operant conditioning involves
manipulation of a gadget, it is also called instrumental conditioning.
A well-known instrument for testing operant conditioning is the Skinner
box. Unlike classical conditioning, which is strictly implicit in nature,
operant conditioning has an explicit component.
Both classical and operant conditionings imply a rudimentary sense
of causality in the experimental animal, though not necessarily at the
conscious level.
Declarative (explicit) memory of the episodic type can be tested in
lower animals, though it requires more elaborate and ingenious design.
For example, rodents can be tested for space memory with the aid of
visual cues. These include the Morris water maze and Barnes maze tests.
The former requires an animal to swim in shallow water to reach a par-
tially submerged platform, whereas the latter requires it to find a correct
escape hole on a circular surface. Both depend on the integrity of the
hippocampus.^9
10.5 On Abstract Memory
No memory is strictly abstract. Memory is usually rooted in some-
thing concrete — experience related to sensation or musculoskeletal
movement. Take telephone numbers for example. When I try to recall
a phone number, I subconsciously use several cues at the same time,
among them: (1) visual appearance of the digits on a piece of paper or
in my mental “blackboard”; (2) tongue movements when calling out