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Instrumental learning normally clearly depends on a contingency between response and reinforcement, but must this always be the case? Normally, if a contingency is not present - if responding has no effect on whether reinforcement is obtained, then no learning occurs. There is, however, the possibility that a contingency is perceived where, in fact, there is none. To truly assess the contingency between response and reinforcement we need to know both the chances of obtaining a reinforcer if we respond and the chances of obtaining a reinforcer if we don't respond. If we never evaluate the latter probability because we are responding all the time then we may attribute a contingency to responding where there is none. The opposite can also occur. An extreme example of this is 'learned helplessness'. In the first part of a learned helplessness experiment an animal is subject to unavoidable shocks - there may be a potential path to escape, for example a wall to jump over, but escape is impossible, for example because the wall is too high. Soon the animal learns that escape is impossible and ceases attempting it. If the animal is now moved to a different situation in which escape is possible it will, nevertheless, fail to learn. Because it never performs escape behavior it does cannot discover that the chances of being shocked when it makes an escape attempt now are different from those it experience when not behaving. The lack of contingency perceived between behavior and shock is illusory. In these circumstances then conditioning is really being controlled by the contiguity of response and reinforcer not their contingency. It should, however, be emphasised that, in general, the effectiveness of instrumental learning depends on contingency.
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