Acquisition: This refers to the establishment of a response through reinforcement.
THINK – When Skinner’s rat is first placed in the box, when it first starts hitting the lever it is accidental. During the acquisition phase, the rat is learning the appropriate response in order to receive reinforcement.
· The speed at which the establishment occurs depends on whether continuous (constant reinforcement for every response) or partial (fixed-interval, fixed-ratio, etc) reinforcement.
Complex Behaviours (Such as training a pigeon to turn around):
When complex behaviours are required to learnt, SHAPING is used.
Shaping: Refers to a procedure in which reinforcement is given for any response that ultimately leads to the final desired response or target behaviour (Also known as the method of successive approximations).
EXAMPLE: When training the pigeon to turn around in a circle, Skinner first started reinforcing the pigeon whenever it took a step to the left. It would reinforce this behaviour until the pigeon had associated the behaviour with being reinforced, then he would cease reinforcement. The pigeon would then happen to turn slightly more to the left and then the reinforcement would begin again for that behaviour. This process would continue until the pigeon had turn in a full circle.
Extinction: Is the gradual decrease in the strength or rate of a conditioned response (learned response) following consistent non-reinforcement of the response.
SO – in other words, Skinner would stop reinforcing the rat or the pigeon for its response, and eventually the strength or rate of that response would decrease.
· Extinction is less likely to occur when partial reinforcement is used. WHY? Because when continuous reinforcement is used, the organism is used to being reinforced for every single correct response, and when it stops getting reinforced for correct responses the behaviour will extinguish very quickly. Partial reinforcement is more resistant to extinguish because the organism is used to making correct responses without getting reinforced, so they can hold out for longer.
· WHICH IS THE MOST RESISTANT TO EXTINCTION? Variable-Ratio schedule of reinforcement (Think Pokie machines – people will continue to play even thought they rarely get reinforced).
Spontaneous Recovery: Once the response appears to be extinct, the organism will once again show the response in the absence of reinforcement.
EXAMPLE: The pigeon could turn around in a circle again or the rat could push down on the lever again, even though this behaviour/response had been extinguished due to the absence of a reinforcer.
Stimulus Generalisation: This occurs when the correct response is made to another stimulus that is similar to the stimulus that was present when the conditioned response was reinforced.
EXAMPLE: Skinner operantly conditioned rats to press a lever for a reinforcer (food) every time that a light flashed in the Skinner Box. This light could be a variety of colours which flashed at various times. The rat could show stimulus generalisation by pressing the lever for reinforcement whenever any coloured light was flashed.
Stimulus Discrimination: This occurs when an organism makes the correct response to a stimulus and is reinforced, but does not respond to any other stimulus, even when the stimuli are similar.
EXAMPLE: With the rats pressing for reinforcement when lights are flashed, stimulus discrimination could occur if the rat only pressed the lever for reinforcement whenever the ‘red’ light, or a specific colour was flashed and would not respond when other coloured lights were flashed. Skinner was able to do this deliberately by only providing reinforcements when a certain coloured light was flashed.
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