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Mechanisms of second-order conditioning with a backward conditioned stimulus
1Department of Psychology, University of Winnipeg, Manitoba, Canada.
Summary
Backward conditioning can create a secondary reinforcer, similar to forward conditioning. This study found excitatory second-order conditioning (SOC) occurs when the unconditioned stimulus (US) and conditioned stimulus (CS1) overlap, regardless of pairing order.
Area of Science:
- Behavioral psychology
- Animal learning
- Conditioning and associative learning
Background:
- Secondary reinforcers are stimuli that gain reinforcing properties through association with primary reinforcers.
- Understanding the conditions under which secondary reinforcers develop is crucial for explaining complex learned behaviors.
- Backward conditioning, where the conditioned stimulus follows the unconditioned stimulus, is typically less effective than forward conditioning.
Purpose of the Study:
- To investigate the conditions under which backward pairings of a conditioned stimulus (CS1) can establish it as a secondary reinforcer.
- To compare the effectiveness of forward and backward conditioning in establishing second-order conditioning (SOC).
- To examine the role of the unconditioned stimulus-conditioned stimulus (US-CS1) interval in backward conditioning.
Main Methods:
- Five conditioned suppression experiments were conducted using rats as subjects.
- Rats were exposed to different pairing schedules and US-CS1 intervals during first-order conditioning.
- The ability of the first-order conditioned stimulus (CS1) to act as a secondary reinforcer was assessed through subsequent conditioning trials.
Main Results:
- Excitatory second-order conditioning (SOC) was observed when the US-CS1 interval was 0 s, indicating stimulus overlap, compared to a 3 s interval.
- The levels of SOC were comparable whether CS1 was presented in forward or backward pairings with the US.
- Extinction of CS1 after SOC did not affect the levels of SOC, suggesting robustness.
Conclusions:
- Backward pairings can effectively establish a CS1 as a secondary reinforcer, similar to forward pairings, particularly when there is US-CS1 overlap.
- The findings suggest a common mechanism underlies SOC for both forward and backward conditioning.
- The results question the necessity of complex cognitive mechanisms like memory integration to explain these conditioning phenomena.