LONG ANSWER 5

Describe in detail the retardation tests:

The retardation test: is if the suspected CS- really signals that no US will occur, the CS- should be slow to be transformed into a CS+ if it is later reinforced alone in a test stage. If a stimulus is truly inhibitory, it should be slow to turn that stimulus into it’s opposite (it will take 8 steps as opposed to a normal 4). In an experiment, it would take the subjects longer to learn to fear an aversive CS, as they will have to make it to neutral before they begin to be excited (before they can even begin to fear).

Describe in detail the summation test:

The summation test:  is if the suspected CS- signals that no US will occur, it should suppress responding to a different CS+ other than the original one the first time they are presented together. For example, we get a new excitatory cue and do a test trial where C is presented in compound with inhibitory B; if B was neutral, it would have no impact on C; but if B was inhibitory, C would be presented similar to the AB- trial (original trial), which would show the inhibition of B. If B is inhibitory in the experimental group, it should suppress a CR that might otherwise occur to C. In test, CB should be less than C. C is called the transfer excitor, while A is the original excitor.

Why did Rescorla recommend both should be passed before declaring a CS- to be inhibitory?

Both retardation and summation tests must be passed in order to declare a stimulus as being inhibitory, as there could be potential for sampling error.

Example of retardation test

After conditioning a fear response to a light, if the light is then presented with a CS-inhibitor that has never been paired with shock, the conditioned inhibitor will take longer to become excitatory than a neutral stimulus would