Skinner B. F.

Skinner also researched schedules of reinforcement. His two main schedules were ration and interval reinforcement. "Ratio is based on the number of responses and interval means the reinforcement is given at intervals of time" (Milhollan & Forisha, 1972). Either type can be fixed or variable. A fixed interval is when the response is reinforced after a specified amount of time. In a fixed ratio design, reinforcement occurs after a certain number of responses are given. A variable interval or ratio is when the time interval or number of response is not fixed but may vary around some average or mean. Multiple schedules may be used in research design. Skinner found that a ration schedule had a high level of response and is higher for variable ratio. Interval schedules have a lower frequency of response in either variable or fixed form.

Skinner also found that reinforcement and operant conditioning contain several contingencies as he outlined in his 1969 book Contingencies of Reinforcement and the Design of Cultures: -Escape.

A rat presses a lever to reduce the intensity of the light in the apparatus. The lever is pressed more quickly when the light appears.

Avoidance. A lever is pressed to postpone a shock which is delivered every 20 seconds. The frequency of lever pressing increases.

Stimulus Discrimination. Food is obtained by pressing the lever only when the light is on. Food is obtained when the light is off. Frequency of lever pressing is higher when the light is on.

Response Differentiation. Food is obtained only when the lever is pressed with a given force. Frequency of leverpressing at the determined force increases.

Superstition.Every 20 seconds food is dispensed regardless of the organism's behavior. Whatever the organism was doing immediately prior to the appearance of food will be reinforced.

In relating his research to humans, Skinner said there is no point in trying to control behavior because behavior is already controlled by reinforcement. The question should not be if behavior can be controlled, but how it should be controlled (Lieberman, 1993). Skinner says behavior can be controlled by altering the environment because the environment is what ultimately controls behavior because it is only temporary. The suppressed behavior often resurfaces after the punishment is removed. Skinner's key to behavior alteration and modification is through reinforcement both positive and negative as well as reinforcement's contingencies.

Skinner denies the existence of free will or human freedom. Skinner defines these values as "self control" which he believes humans do not possess.

Skinner has been labeled one-sided by many critics because he fails to consider any options other than what is "easily observed and manipulated" (Schellenberg, 1978). Skinner focuses strictly on behavior and reinforcement, but gives no thought or research toward biological, sociological, or even neurological causes of behavior. Skinner bases too much of his research on the probability of responses. Actual frequency of response is never the same as the prior probability of response (Schellenberg, 1978). Skinner's focus on the environment as the primary reinforcer ignores "internal contingencies." This is possibly because external factors are more easily manipulated. While Skinner does not believe in free will or human freedom, he never works to disprove such theories, he simply rejects them (Machon, 1974).