Errorless learning

Errorless learning

Errorless learning is a procedure introduced by Herbert Terrace (1963) which allows discrimination learning to occur with few or even with no responses to the negative stimulus (abbreviated S-). A negative stimulus is a stimulus associated with undesirable consequences (e.g., absence of reinforcement). In discrimination learning, an error is a response to the S-, and according to Terrace errors are not required for the learning of a discrimination.

A simple discrimination learning procedure is one in which a subject learns to associate one stimulus, S+ (positive stimulus), with reinforcement and another, S-, with extinction. For example, a pigeon can learn to peck a red key (S+), and avoid a green key (S-). Using traditional procedures, a pigeon would be initially trained to peck a red key. When the pigeon was responding consistently to the red key, a green key would be introduced. At first the pigeon would also respond to the green key but gradually responses to this key would decrease so that they occurred on few or no trials.

Terrace (1963) found that a discrimination can occur without errors when the training begins early in operant conditioning and visual stimuli (S+ and S-) are used that differ in terms of brightness, duration and wavelength. He used a fading procedure in which the brightness and duration differences were decreased progressively leaving only the difference in wavelength. In particular, he introduced the S- early in training, within 30 seconds after the pigeon had made its first peck to the red key. When first introduced, however, S- was presented only for 5 seconds and was a dark key, not green. Over successive trials (set of events that constitute a session) the duration of the S- and its brightness were gradually increased until the keylight was green.

The errorless learning procedure is highly effective in reducing the number of responses to S- during training. In Terrace’s (1963) experiment, subjects trained with the conventional discrimination procedure averaged over 3000 S- responses during 28 sessions of training; whereas subjects trained with the errorless procedure averaged only 25 S- responses in the same number of sessions.

Later, Terrace (1972) has claimed not only that the errorless learning procedure improves long-term discrimination performance, but also that: S- does not become aversive and so does not elicit "aggressive" behaviors, as it often does with conventional training; S- does not develop inhibitory properties; and that positive behavioral contrast to S+ does not occur. In other words, Terrace has claimed that the "by-products" of conventional discrimination learning do not occur with the errorless procedure.

However, some evidence suggests that errorless learning may not be as qualitatively different from conventional training as Terrace initially claimed. For example, Rilling (1977) in a series of experiments has demonstrated that these "by-products" can occur after errorless learning, but that their effects may not be as large as in the conventional procedure; and Marsh and Johnson (1968) found that subjects given errorless training were very slow to make a discrimination reversal.

Interest from researchers in basic psychology for errorless learning decreased after the 70’s. However, errorless learning attracted the interest of researchers in applied psychology, and studies have been conducted with both children (e.g., educational settings) and adults (e.g. Parkinson’s patients).

REFERENCES

• Mazur, J. E. (2006). Learning and behavior. 6th edition. Upper Saddle River, NJ: Prentice Hall.
• Rilling, M. (1977). Stimulus control and inhibitory processes. In: W.K. Honing & J.E.R Staddon (Orgs.), Handbook of operant behavior (pp.432-480). Englewood Cliffs, NJ: Prentice-Hall.
• Terrace, H. S. (1963). Discrimination learning with and without "errors". Journal of the Experimental Analysis of Behavior, 6, 1-27.
• Terrace, H. S. (1972). By-products of discrimination learning. In G. H. Bower (Ed.), The psychology of learning and motivation (Vol. 5). New York: Academic Press.