Operant Conditioning

Definition: Operant conditioning (also called "instrumental conditioning") is a type of learning in which 

(a) the strength of a behavior is modified by the behavior's consequences, such as reward or punishment, and 

(b) the behavior is controlled by antecedents called "discriminative stimuli" which come to signal those consequences.

Operant response - a response or behaviour of an organism that is voluntary and not associated with a particular stimulus. This response acts on or modifies the environment. For example, e.g. a person picking up a book to read.

Reinforcer - the reward given for a response in order to strengthen it and increase the likelihood of the response occurring again.

Positive reinforcer - a reward which strengthens a response by providing a pleasurable consequence such as praise or a chocolate bar.

Negative reinforcer - a reward which strengthens a response by removing or reducing an unpleasant stimulus such as taking away a house chore or homework.

Schedules of reinforcement: This refers to the frequency in which a response is reinforced in operant conditioning. There are different schedules of reinforcement within this type of learning.

Continuous reinforcement - when a satisfying response is reinforced every time.

Partial reinforcement - reinforcement which does not occur continuously. The reinforcement may be administered in the following ways:
Fixed ratio schedule - a satisfying response is reinforced after a set number of responses have been made, e.g. every fifth response.
Fixed interval schedule - a satisfying response is reinforced at regular time intervals e.g. every five minutes.

Classical Conditioning

Definition: Classical conditioning (also known as Pavlovian or respondent conditioning) refers to a learning procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a bell).

Introduction: Van Petrovich Pavlov was a Russian scientist who investigated the digestive system of dogs by presenting them with meat powder and measuring the amount of saliva they produced. Pavlov found that the dogs began to salivate even before the meat powder was presented as they associated the feeder with the meat powder. This led Pavlov to conclude that the dogs were conditioned to respond to the feeder through the process of classical conditioning.

Important Definitions And Terms

Some key terms in classical conditioning include:

Neutral stimulus (NS) - a stimulus which, prior to conditioning, would evoke no response. This always becomes the conditioned stimulus, e.g. the bell in Pavlov's experiments.

Unconditioned stimulus (UCS) - a stimulus which innately produces a response or reflex, such as the meat in Pavlov's experiments.

Unconditioned response (UCR) - an unlearned response elicited by an unconditioned stimulus, e.g. the dog involuntarily salivated at the meat (UCS).

Association - a connection between two events which results in learning. Pavlov's dogs learned to associate the ringing of the bell and the presentation of the meat so that they eventually learned to salivate at the bell alone.