Primary Reinforcement
Trace conditioning is defined by a temporal gap between conditioned-stimulus offset and unconditioned-stimulus onset.
Learning Across a Gap
Learning can occur even when a conditioned stimulus has already ended before the unconditioned stimulus begins. This timing pattern is called trace conditioning. The central problem is the interval between the two events: if the original stimulus is no longer present, what allows the earlier event and the later unconditioned stimulus to remain connected?
The defining feature is not simply that two stimuli occur at different times. It is specifically that the conditioned stimulus ends first, followed by a temporal gap, and then the unconditioned stimulus begins.
What Remains After Offset
A stimulus trace is a continuing nervous-system trace of a stimulus after that stimulus has ended. In trace conditioning, the conditioned stimulus is no longer physically present during the gap, but a trace of it can continue in the nervous system. That continuing trace provides a basis for understanding how learning can extend from the earlier conditioned stimulus to the later unconditioned stimulus.
Two Explanations for Delayed Learning
Stimulus traces and secondary reinforcement explain different parts of learning across delays. A stimulus trace concerns what remains from the earlier conditioned stimulus after it ends. Secondary reinforcement concerns what happens to stimuli that occur during the delay: through association with a primary reinforcer, those delay-period stimuli can acquire reinforcing value.
| Feature | Stimulus trace | Secondary reinforcement |
|---|---|---|
| What it concerns | The earlier conditioned stimulus | A stimulus occurring during the delay |
| When it matters | After the conditioned stimulus has ended | During the delay before the unconditioned stimulus |
| Main role | Preserves a nervous-system trace of the earlier stimulus | Gives a delay-period stimulus reinforcing value through association with a primary reinforcer |
| Relationship to delayed learning | Helps explain how learning can bridge the gap | Helps explain why delay-period stimuli can become reinforcing |
A Delayed-Reinforcement Walkthrough
Separating the Trace from the Delay Stimulus
Imagine a learning sequence in which a conditioned stimulus ends, a temporal gap follows, and an unconditioned stimulus then begins. During the gap, another stimulus is presented.
Identify the conditioned stimulus: The first stimulus is the conditioned stimulus because it occurs before the temporal gap and ends before the unconditioned stimulus begins.
Locate the trace interval: The interval between conditioned-stimulus offset and unconditioned-stimulus onset is the trace interval. The conditioned stimulus is no longer physically present during this interval.
Apply the stimulus-trace account: A continuing nervous-system trace of the conditioned stimulus can remain after offset. This trace provides a basis for learning across the gap.
Identify the delay-period stimulus: The additional stimulus presented during the gap is not the lingering trace of the original conditioned stimulus. It is a separate stimulus occurring during the delay.
Apply the secondary-reinforcement account: Because the delay-period stimulus is associated with a primary reinforcer, it can gain reinforcing value through secondary reinforcement.
The stimulus trace explains what can remain from the original conditioned stimulus after it ends. Secondary reinforcement explains how a separate stimulus presented during the delay can acquire reinforcing value through association with a primary reinforcer.
The most important diagnostic question is whether you are discussing the earlier conditioned stimulus continuing as a nervous-system trace, or a different stimulus that occurs during the delay and gains reinforcing value through association. Both ideas can be relevant to delayed learning, but they refer to different events and different explanatory roles.
Check the Mechanism
What do you think happens?
A conditioned stimulus ends before an unconditioned stimulus begins. During the gap, a separate stimulus is presented. Which statement best distinguishes the two mechanisms?
Reveal answer
Answer: The stimulus trace is the continuing nervous-system trace of the original conditioned stimulus, while secondary reinforcement concerns reinforcing value acquired by the delay-period stimulus.
Trace conditioning includes a gap after conditioned-stimulus offset. A stimulus trace refers to what remains from the earlier stimulus in the nervous system. Secondary reinforcement refers to reinforcing value acquired by a stimulus occurring during the delay through association with a primary reinforcer.
Explain in your own words why the gap between conditioned-stimulus offset and unconditioned-stimulus onset matters. Then identify which part of your explanation refers to a stimulus trace and which part refers to secondary reinforcement.
Hints
- Start by naming what happens to the conditioned stimulus before the unconditioned stimulus begins.
- Ask what remains from the earlier conditioned stimulus during the gap.
- Separately consider whether another stimulus occurs during the gap and gains reinforcing value through association with a primary reinforcer.
Treating trace conditioning as though the conditioned stimulus remains physically present until the unconditioned stimulus begins.
Trace conditioning is defined by the conditioned stimulus ending before the unconditioned stimulus begins, with a temporal gap between offset and onset.
Fix:
State clearly that the conditioned stimulus has ended and that a stimulus trace may continue in the nervous system.Calling every event during the delay a stimulus trace.
A stimulus trace is the continuing nervous-system trace of the earlier stimulus. A separate delay-period stimulus is a different event.
Fix:
Distinguish the lingering trace of the original conditioned stimulus from a separate stimulus that occurs during the delay.Using stimulus trace and secondary reinforcement as interchangeable terms.
The two are distinct accounts: the trace concerns persistence of the earlier stimulus, while secondary reinforcement concerns reinforcing value acquired by a delay-period stimulus through association with a primary reinforcer.
Fix:
Identify whether the explanation is about persistence of the earlier stimulus or acquired reinforcing value of a later delay-period stimulus.
Key Takeaways
- Trace conditioning has a temporal gap between conditioned-stimulus offset and unconditioned-stimulus onset.
- A stimulus trace is a continuing nervous-system trace of a stimulus after that stimulus has ended.
- The stimulus trace provides a basis for understanding learning across the gap.
- A stimulus occurring during the delay can gain reinforcing value through association with a primary reinforcer; this is secondary reinforcement.
- Stimulus traces and secondary reinforcement are distinct but complementary explanations of learning across delays.
Key Takeaways
- Trace conditioning is defined by a gap between conditioned-stimulus offset and unconditioned-stimulus onset.
- A stimulus trace can preserve a nervous-system trace of the conditioned stimulus after it has ended.
- Delay-period stimuli can acquire reinforcing value through association with a primary reinforcer.
- The stimulus trace concerns persistence of the original stimulus, whereas secondary reinforcement concerns acquired value in a stimulus occurring during the delay.