The Other Condition

So how can we change the first memory without creating a new memory? Here is a second condition in the experiment. We’re going to call this group the “10-Minute Group,” and we’ll explain why shortly.

The first step involves the same process as in the control group and involves conditioning the subject to “fear” a yellow box.

Day 1 – 10-Minute Group

Day 1 for this new group is exactly the same as Day 1 in the Control Condition. We teach participants to “fear” the yellow box.

Now let’s go to Day 2. Remember from the control group that Day 2 involves extinction, which is the process of unlearning the fear response. But for this new group, we’re going to try something different to see if we can replace their original memory without creating a new memory.

Memory Reactivation

This time, before we begin the process of extinction, we are going to get the person to think about the shock experience—that is, we want them to retrieve the full fear memory—before they start extinction. Once the full memory is reactivated, there is a 10-minute delay, and then the subjects go through the same extinction trials that the Control Group subjects experienced on Day 2.

This reintroduction of the yellow box on Day 2 is the one event that did not happen in the control condition you read about earlier. It turns out that this reactivation step is crucial to preventing spontaneous recovery.

Day 2 – 10-Minute Group

After the extinction process has been completed on Day 2, the question is this: will the person show spontaneous recovery of the fear response on Day 3? If they do show spontaneous recovery, then our new procedure (reinstatement of the memory on Day 2) has failed to produce the change in memory that we hoped for.

The last step is to again test for spontaneous recovery.

Day 3 – 10-Minute Group

The procedure on Day 3 for this group is exactly the same as it was for the Control Group. What is different are the subjects’ responses. There is NO SPONTANEOUS RECOVERY for this group. The fear response is gone. The experimenters attribute this lack of a fear response to a changed memory, one that now associates the yellow box with no shock.

So far, the experimenters have shown that fear can be learned (Day 1), extinguished (Day 2), and then spontaneously recover (Day 3) for the control condition. By contrast, the reactivation condition shows that, if the full memory is activated on Day 2 just before extinction, then the fear response does not spontaneously recover.

However, our journey is not quite complete. The experimenters claim that a reactivated memory acts like a new memory: it is open to change for only a brief time and then it becomes stable again. So the Day 2 extinction process should only work to change the original memory for a short while—at most, a few hours. If the memory is reactivated, but extinction is delayed for a few hours, then the memory should not be changed because it has had time to reconsolidate. Let’s see if this was the case.

The Delay Group

The final experiment tests this idea. The only difference between this new group and the last group is the time delay on the second day. Rather than waiting 10 minutes between reactivating the memory and extinction, the experimenters waited 6 hours. After 6 hours, the fear memory should no longer be active and extinction should not change the memory.

Day 1 – 6-Hour Group

Day 1 for this new group is exactly the same as Day 1 for both of the previous groups. We teach participants to “fear” the yellow box.

Day 2 – 6 Hour Group

Day 2 is very similar to Day 2 for the 10-Minute group. The only difference is that the delay has been increased to 6 hours.

Day 3 – 6-Hour Group

When we test the 6-Hour Group on day 3, we see that spontaneous recovery HAS occurred:

This experiment is important because it serves as a control to help us determine if “rewriting a memory” is actually the correct interpretation of the results. In this experiment, the memory is reactivated (just like in the 10-minute group), but the memory is then allowed to deactivate over a 6-hour delay. If there is no spontaneous recovery in this condition, then rewriting memory is not a particularly convincing explanation for the results. If there is spontaneous recovery of fear, then the theory that we are actually rewriting a memory is more convincing.

So let’s see what happens.

The procedure on Day 3 is the same for all three groups, but the responses are different. Participants in the two control conditions (control group and 6-hour group) both act the same: they both show spontaneous recovery of the fear response. Those in the reconsolidation treatment condition (the 10-minute group), however, show no spontaneous recovery of the fear response.