Negative (positive) contrast effect

Negative and positive contrast are used in regard to the amount of reinforcement a subject or participant receives in a given situation. Negative contrast is when a subject starts out with a large reinforcement and then after awhile, are suddenly shifted to a smaller reinforcer, thereby decreasing their behavior. Positive contrast on the other hand is when a subject or participant is given an ok or small reward and then is suddenly shifted to a larger reward, which then increases the behavior. This theory is important in the understanding of learning. If someone is given a small reward when the learning is first presented, but then later on given a larger reward, they will show more desire to continue learning.

History of Negative (positive) contrast effect
In 1942, Crespi did a study to understand the magnitude of reward of white rats. What he discovered was that the greater the magnitude of reward, the faster the rat would run to get the reward In the middle of his experiment, on trial 20, Crespi shifted some of his animals from a low reward to a high reward. The other animals he shifted from a high reward to a low reward. The high to low animals decreased their behavior rapidly, while the low to high reward animals ran even faster than they had before. He originally called these effects elation and depression effects In 1949, Zeaman suggested changing the terms from elation and depression effects to positive contrast and negative contrast effects respectively. In 1981, Bower discovered that there can be a ceiling effect when looking at positive contrast effect. Therefore the low reward needs to be significantly less than the ceiling in order for there to be an opportunity for a greater reward. In 1996, Flaherty suggested that negative contrast effect was related to frustration. The presentation of the lower reward in the middle of the trial causes frustration for the person or the animal. This frustration interferes with the behavior the subject is performing.

Negative (positive) contrast effect in operant conditioning
In the behavioral theory of operant conditioning, the negative contrast effect is evident when an attempt to reinforce a particular behavior through reward; when the rewards are finally withdrawn or reduced the subject is even less likely to exhibit that behavior than if he/she had never been rewarded. The theory is that the subject will view the task as work, for which he is only temporarily rewarded, rather than enjoyable or an end in itself, such as play. For example, rewarding children for reading may be counter-productive in the long run, as they may view it as a chore.

Conversely, the positive contrast effect is that when rewards are increased, the subject shows an even greater frequency of the behavior than subjects who had been rewarded with the higher quantity all along.

These effects only last for a short period of time. After a while, the behaviors will start to return to the track they would have been on if the reward had never changed.

Negative (positive) contrast effect in relationships
In the assessment of interpersonal relationships, this would be the tendency for an individual to utilize the history of performance (by an individual or a process) to determine their expectations relative to a current level of performance—a form of behavioral "compare and contrast", in that if an individual's history of a particular behavior improves (increases), this will be perceived by the receiving individual as a positive contrast effect. If a person's behavior (or some process) diminishes or is degraded in any fashion historically related to a similar event or set of events, this will be perceived as a negative contrast effect.

For example, at the beginning of a relationship one partner made significant efforts in supplying love, care or attention to another person and the receiving party enjoyed and reacted positively to these efforts. However, at a later date, these practices diminished or were omitted to some degree (the expectation of the other partner not being met or the behavior not persisting or increasing), causing the receiving partner to experience a negative contrast effect.

However, if the reverse was to happen and the partner started out with a lesser degree of love, care or attention and were to increase the practice over time, the receiving person would experience a positive contrast effect.