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Effects of intertrial reinforcers on rats' timing behavior
D M Wilkie1, L A Symons, R C Tees
1Department of Psychology, University of British Columbia, Vancouver, B.C. Canada V6T 1Y7.
Behavioural Processes
|June 5, 2014
Summary
Non-contingent reinforcers presented during the intertrial interval (ITI) disrupt rats' duration discrimination. This disruption, observed in timing tasks, suggests pre-trial reinforcement priming negatively impacts complex behavioral performance.
Area of Science:
- Behavioral neuroscience
- Animal cognition
- Learning and memory
Background:
- Intertrial interval (ITI) reinforcers can influence operant conditioning and cognitive tasks.
- The precise mechanisms by which ITI reinforcers affect timing discriminations remain unclear.
Purpose of the Study:
- To investigate the impact of non-contingent ITI reinforcers on rats' ability to discriminate between different durations of a light stimulus.
- To determine if the disruptive effects of ITI reinforcers are specific to trials immediately following reinforcement or a more general phenomenon.
Main Methods:
- Two experiments using rats were conducted to assess duration discrimination (2s vs. 8s light).
- Non-contingent reinforcers were delivered during the ITI in Experiment 1.
- Experiment 2 compared performance on trials following ITI-reinforcer trials versus empty ITI trials within the same session.
Main Results:
- ITI reinforcers significantly disrupted duration discrimination in rats.
- Disruption occurred irrespective of whether the preceding trial was short (2s) or long (8s).
- Disruptive effects extended to trials following empty ITIs when ITI-reinforcer trials were present, though to a lesser extent.
Conclusions:
- ITI reinforcers negatively impact timing discriminations in rats, similar to their effects in classical conditioning and matching-to-sample tasks.
- The underlying mechanisms for ITI reinforcer disruption may differ across various behavioral paradigms.
- Pre-trial reinforcement priming appears to disrupt, rather than facilitate, performance in complex tasks like duration discrimination.
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