Attempts to establish phencyclidine and cocaine discrimination without error

Area of Science:

• Behavioral pharmacology
• Animal models of drug discrimination

Background:

• Drug discrimination studies in pigeons are crucial for understanding drug effects.
• Training procedures can influence the development of stimulus control.

Purpose of the Study:

• To investigate the impact of "training without errors" versus "training with errors" on drug discrimination in pigeons.
• To assess stimulus generalization patterns for phencyclidine (PCP) and cocaine.

Main Methods:

• Pigeons were trained to discriminate phencyclidine (PCP) or cocaine from saline using second-order schedules.
• A "training without errors" procedure involved gradually increasing the intensity of a visual stimulus on the incorrect key.
• Stimulus generalization was assessed by testing with other drugs.

Main Results:

• Initially, "training without errors" reduced errors, but errors increased as stimulus intensity rose.
• No significant differences in stimulus control or generalization curves were found between training methods for PCP or cocaine.
• Cocaine discrimination showed broad generalization to other drugs, suggesting potential lack of stimulus specificity.

Conclusions:

• The choice of training procedure (with or without errors) did not significantly impact the final drug discrimination or generalization in pigeons.
• The cocaine stimulus may lack specificity under certain conditions, as evidenced by broad generalization patterns.