Related Experiment Video

Updated: Aug 24, 2026

Three Laboratory Procedures for Assessing Different Manifestations of Impulsivity in Rats
09:12

Three Laboratory Procedures for Assessing Different Manifestations of Impulsivity in Rats

Published on: March 17, 2019

Reinforcer concentration effects on a fixed-interval schedule

Frances J Blomeley1, C F Lowe, J H Wearden

  • 1University of Wales, Bangor, UK.

Behavioural Processes
|June 9, 2004
PubMed

Insights

Higher condensed milk concentrations delayed rat responding and shifted peak response times on a fixed-interval schedule. This study explores timing behavior and reinforcement effects in rats.

Area of Science:

  • Behavioral neuroscience
  • Animal behavior and cognition
  • Psychology

Background:

  • Understanding interval timing is crucial in behavioral science.
  • Reinforcement value can influence temporal control of behavior.
  • Previous models of timing do not fully account for reinforcement effects.

Purpose of the Study:

  • To investigate how variations in reinforcer concentration affect interval timing in rats.
  • To examine the impact of different fixed-interval (FI) schedules on response patterns.
  • To test predictions from Scalar Expectancy Theory, the Behavioural Theory of Timing, and the Tuned-trace model.

Main Methods:

  • Four rats were trained on a mixed fixed-interval (FI) 30-s and FI 150-s schedule, with levers associated with different intervals.
  • Reinforcer concentration (condensed milk) was varied (10%, 30%, 50%, 70%) during testing.
  • Behavioral measures, including response initiation and peak response location, were recorded from the FI 30-s lever.

Main Results:

  • Increased reinforcer concentration significantly lengthened the time to initiate responding within an interval.
  • Higher concentrations shifted the peak response location on the FI 30-s lever, often beyond the programmed 30-s interval.
  • Peak response rate and the spread of the response rate function showed minimal changes with varying concentrations.

Conclusions:

  • Reinforcer concentration plays a significant role in modulating interval timing, affecting response initiation and temporal accuracy.
  • Findings challenge some assumptions of current timing theories regarding the influence of reinforcement magnitude.
  • Further research is needed to refine timing models to incorporate the effects of reinforcement value.

More Related Videos

A Method for Evaluating the Reinforcing Properties of Ethanol in Rats without Water Deprivation, Saccharin Fading or Extended Access Training07:50

A Method for Evaluating the Reinforcing Properties of Ethanol in Rats without Water Deprivation, Saccharin Fading or Extended Access Training

Published on: January 29, 2017

Novel Apparatus and Method for Drug Reinforcement07:32

Novel Apparatus and Method for Drug Reinforcement

Published on: August 20, 2010

Related Concept Videos

Reinforcement Schedules01:24

Reinforcement Schedules

Positive reinforcement is a powerful method for teaching new behaviors to both animals and humans. B.F. Skinner demonstrated this with his experiments using rats in a Skinner box. When a rat pressed a lever, it received a food pellet. This immediate reward encouraged the rat to repeat the behavior. This method, where a reward follows every instance of the behavior, is known as continuous reinforcement. It is highly effective for establishing new behaviors quickly.
Once a behavior is learned,...
Timing and Consequences on Behavior01:08

Timing and Consequences on Behavior

In operant conditioning, the timing of reinforcement is crucial. For animals like rats and cats, immediate reinforcement (within a few seconds) is much more effective than delayed reinforcement. For example, a food reward for a rat needs to follow within 30 seconds of pressing a bar to be effective. 
Humans, however, can respond to delayed reinforcers. We often make decisions between immediate small rewards and delayed larger rewards. This ability to delay gratification is a significant factor...
Operant Conditioning01:21

Operant Conditioning

Operant conditioning, a key concept in behavioral psychology, involves using reinforcement and punishment to alter the likelihood of a behavior being repeated. B.F. introduced this type of conditioning. Skinner focused on voluntary behaviors and the consequences that follow them, influencing whether these behaviors will be strengthened or diminished.
Reinforcement in operant conditioning can be positive or negative, both of which serve to increase the likelihood of a behavior. Positive...
Primary and Secondary Reinforcers01:23

Primary and Secondary Reinforcers

In psychology, reinforcement is a key concept in behavior modification. B.F. Skinner demonstrated this with his experiments involving rats in what is known as a Skinner box. The rats learned to press a lever to receive food, a primary reinforcer that fulfilled their innate need for nourishment.
Effective reinforcers for humans vary depending on the individual and the context. Primary reinforcers, such as food, water, sleep, shelter, and pleasure, have inherent value and satisfy basic biological...
Reinforcement01:23

Reinforcement

Positive and negative reinforcement are key concepts in operant conditioning, a learning process where the consequences of a behavior affect the likelihood of that behavior being repeated.
Positive reinforcement occurs when a behavior is followed by the presentation of a rewarding stimulus, increasing the frequency of that behavior. For example:
Law of Effect01:06

Law of Effect

B.F. Skinner, a prominent figure in behavioral psychology, introduced operant conditioning by emphasizing the role of consequences in shaping behavior. This theory builds upon the law of effect proposed by Edward Thorndike, which posits that behaviors followed by satisfying outcomes are likely to be repeated. In contrast, those followed by unsatisfying outcomes are less likely to recur.
Edward Thorndike's foundational work involved studying learning in animals, particularly using puzzle boxes...