Reinforcer devaluation by extinction depends on the food restriction protocol

Area of Science:

• Behavioral neuroscience
• Animal behavior

Background:

• Reinforcer devaluation studies investigate how changes in an unconditioned reinforcer's value affect behavior controlled by its associated conditioned reinforcer.
• New associative learning is a common mechanism for inducing such devaluation.

Purpose of the Study:

• To investigate the role of extinction in inducing conditioned reinforcer devaluation within a heterogeneous chain schedule.
• To examine how different food restriction protocols influence the effectiveness of conditioned reinforcer devaluation.

Main Methods:

• Rats were trained on a heterogeneous chain schedule where lever pressing produced a light (conditioned reinforcer) signaling food availability.
• Extinction of chain pulling was used to induce new learning about the conditioned reinforcer.
• Two food restriction methods were compared: daily 1-hour meal duration and 80% body weight restriction.

Main Results:

• Extinction successfully produced conditioned reinforcer devaluation, irrespective of the food reinforcement density schedule (continuous vs. variable-ratio).
• Meal duration restriction resulted in greater devaluation effects on lever pressing compared to body weight restriction.
• Body weight restriction significantly diminished or eliminated the devaluation effect.

Conclusions:

• The effectiveness of conditioned reinforcer devaluation is sensitive to the specific food restriction procedure employed.
• Differences in food restriction protocols can lead to divergent interpretations of devaluation effects, even when underlying associative learning remains intact.
• Meal duration restriction may be more effective in producing devaluation effects due to its greater impact on reducing body weight.