Learning

Activity . factors influencing learning a CR are described below: . T ime Relations between Stimuli : The classical conditioning procedures, discussed below, are basically of four types based on the time relations between the onset of conditioned stimulus (CS) and unconditioned stimulus (US). The first three are called forward conditioning procedures, and the fourth one is called backward conditioning procedure.

The basic experimental arrangements of these procedures are as follows: a) When the CS and US are presented together, it is called simultaneous conditioning . b) In delayed conditioning , the onset of CS precedes the onset of US. The CS ends before the end of the US. c) In trace conditioning , the onset and end of the CS precedes the onset of US with some time gap between the two.

d) In backward conditioning , the US precedes the onset of CS. It is now well established that delayed conditioning procedure is the most effective way of acquiring a CR. Simultaneous and trace conditioning procedures do lead to acquisition of a CR, but they require greater number of acquisition trials in comparison to the delayed conditioning procedure. It may be noted that the acquisition of response under backward conditioning procedure is very rare.

. Type of Unconditioned Stimuli : The unconditioned stimuli used in studies of classical conditioning are basically of two types, i.e. appetitive and aversive . Appetitive unconditioned stimuli automatically elicits approach responses, such as eating, drinking, caressing, etc.

These responses give satisfaction and pleasure. On the other hand, aversive US, such as noise, bitter taste, electric shock, painful injections, etc. are painful, harmful, and elicit avoidance and escape responses. It has been found that appetitive classical conditioning is slower and requires greater number of acquisition trials, but aversive classical conditioning is established in one, two or three trials depending on the intensity of the aversive US.

O PERANT /I NSTRUMENTAL C ONDITIONING This type of conditioning was first investigated by B.F. Skinner. Skinner studied occurrence of voluntary responses when an organism operates on the environment. He called them operants .

Operants are those behaviours or responses, which are emitted by animals and human beings voluntarily and are under their control. The term operant is used because the organism operates on the environment. Conditioning of operant behaviour is called operant conditioning . Skinner conducted his studies on rats and pigeons in specially made boxes, called the Skinner Box .

A hungry rat (one at a time) is placed in the chamber, which was so built that the rat could move inside but could not come out. In the chamber there was a lever, which was connected to a food container kept on the top of the chamber (see Figure . ). When the lever is pressed, a food pellet drops on the plate placed close to the lever.

While moving around and pawing the walls (exploratory behaviour), the hungry rat accidentally presses the lever and a food pellet drops on the plate. The hungry rat eats it. In the next trial, after a while the exploratory behaviour again starts. As the number of trials increases, the rat takes lesser and lesser time to press the lever for food.

Conditioning is complete when the rat presses the lever immediately after it is placed in the chamber. It is obvious that lever pressing is an operant response and getting food is its consequence. response. They include its types – positive or negative, number or frequency, quality – superior or inferior, and schedule – continuous or intermittent (partial).

All these features influence the course of operant conditioning. Another factor that influences this type of learning is the nature of the response or behaviour that is to be conditioned. The interval or length of time that lapses between occurrence of response and reinforcement also influences operant learning. Let us examine some of these factors in detail.

Types of Reinforcement Reinforcement may be positive or negative. Positive reinforcement involves stimuli that have pleasant consequences. They strengthen and maintain the responses that have caused them to occur. Positive reinforcers satisfy needs, which include food, water, medals, praise, money, status, information, etc.

Negative reinforcers involve unpleasant and painful stimuli. Responses that lead organisms to get rid of painful stimuli or avoid and escape from them provide negative reinforcement . Thus, negative reinforcement leads to learning of avoidance and escape responses. For instance, one learns to put on woollen clothes, burn firewood or use electric heaters to avoid the unpleasant cold weather.

One learns to move away from dangerous stimuli because they provide negative reinforcement. It may be noted that negative reinforcement is not punishment. Use of punishment reduces or suppresses the response while a negative reinforcer increases the probability of avoidance or escape response. For instance, drivers and co-drivers wear their seat belts to avoid getting injured in case of an accident or to avoid being fined by the traffic police.

It should be understood that no punishment suppresses a response permanently. Mild and delayed punishment has no effect. The stronger the punishment, the more lasting is the suppression effect but it is not permanent. Sometimes punishment has no effect irrespective of its intensity.

On the contrary, the punished person may develop dislike and In the above situation the response is instrumental in getting the food. That is why, this type of learning is also called instrumental conditioning . Examples of instrumental conditioning abound in our everyday life. Children who want to have some sweets in the absence of their mother learn to locate the jar in which mother hides the sweets for safekeeping and eat it.

Children learn to be polite and say ‘please’ to get favours from their parents and others. One learns to operate mechanical gadgets such as radio, camera, T.V., etc. based on the principle of instrumental conditioning. As a matter of fact human beings learn short cuts to attain desired goals or ends through instrumental conditioning.

Determinants of Operant Conditioning You have noted that operant or instrumental conditioning is a form of learning in which behaviour is learned, maintained or changed through its consequences . Such consequences are called reinforcers . A reinforcer is defined as any stimulus or event, which increases the probability of the occurrence of a (desired) response . A reinforcer has numerous features, which affect the course and strength of a Fig.

. : Skinner Box hatred for the punishing agent or the person who administers the punishment. Number of Reinforcement and other Features It refers to the number of trials on which an organism has been reinforced or rewarded. Amount of reinforcement means how much of reinforcing stimulus (food or water or intensity of pain causing agent) one receives on each trial.

Quality of reinforcement refers to the kind of reinforcer. Chickpeas or pieces of bread are of inferior quality as compared with raisins or pieces of cake as reinforcer. The course of operant conditioning is usually accelerated to an extent as the number, amount, and quality of reinforcement increases. Schedules of Reinforcement A reinforcement schedule is the arrangement of the delivery of reinforcement during conditioning trials.

Each schedule of reinforcement influences the course of conditioning in its own way; and thus conditioned responses occur with differential characteristics. The organism being subjected to operant conditioning may be given reinforcement in every acquisition trial or in some trials it is given and in others it is omitted. Thus, the reinforcement may be continuous or intermittent . When a desired response is reinforced every time it occurs we call it continuous reinforcement .

In contrast, in intermittent schedules responses are sometimes reinforced, sometimes not. It is known as partial reinforcement and has been found to produce greater resistance to extinction – than is found with continuous reinforcement. Delayed Reinforcement The effectiveness of reinforcement is dramatically altered by delay in the occurrence of reinforcement. It is found that delay in the delivery of reinforcement leads to poorer level of performance .

It can be easily shown by asking children which reward they will prefer for doing some chore. Smaller rewards immediately after doing the chore will be preferred rather than a big one after a long gap. Key Learning Processes When learning takes place, be it classical or operant conditioning, it involves the occurrence of certain processes. These include .

In classical conditioning, the responses are under the control of some stimulus because they are reflexes, automatically elicited by the appropriate stimuli. Such stimuli are selected as US and responses elicited by them as UR. Thus Pavlovian conditioning, in which US elicits responses, is often called respondent conditioning. In instrumental conditioning, responses are under the control of the organism and are voluntary responses or ‘operants’.

Thus, in the two forms of conditioning different types of responses are conditioned. . In classical conditioning the CS and US are well-defined, but in operant conditioning CS is not defined. It can be inferred but is not directly known.