Time and Classical Conditioning

Modified: 2020-03-27


What role, if any, does the time between the CS and the UCS play? It plays a very significant role, it turns out.

Delayed conditioning is easily established. Delays of around .5 sec. between the CS and the UCS lead to the strongest conditioning.

In trace conditioning a period of time is allowed to lapse between the CS and the UCS. It is called trace conditioning, because a memory trace is presumably responsible for the conditioning. Traces of up to 12 sec. can be established in pigeons without a great deal of effort. Longer traces are not likely to lead to conditioning. That is why punishing children hours after they commit some infraction does not lead to learning. Below, however, we will see that traces of up to 75 minutes have been established with some pairs of stimuli. (See Taste Aversion)

In backwards conditioning, the UCS precedes the CS. Typically, little or no conditioning results, although some have succeeded in demonstrating backwards conditioning when life-threatening shock was used.

Simultaneous conditioning leads to little or no conditioning as well. Simultaneous conditioning provides us with a glimpse into the logic of conditioning. A CS that does not predict the UCS is of no value.

Temporal conditioning does not use an explicit CS. Rather, the UCS repeats on a regular basis. Some animals may use that repetition to achieve conditioning by timing the interval between UCS onset and offset.

The "Highway Analogy" graphic provides you with a useful analogy, I think. I saw this analogy presented at an APA meeting some years ago, and I created the graphic for it later. I cannot recall who presented it originally. The analogy is useful because it shows how the CS is a signal for the UCS. In this analogy, the sign is the CS, the curve is the UCS. Notice that putting the sign far away from the curve does not lead to conditioning, nor does putting the sign in the curve, or after the curve.


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