Shadowing: what it is and how it is used in classical conditioning

In psychology, a good part of the behavioral phenomena described by this science have to do with learning.

Overshadowing is one of the concepts that refer to how we learn through classical conditioning, and in this article we will see what it consists of. Let's start with the basics.

What is classical conditioning?

Basic psychology explains, describes and defines the laws that govern the organism, understanding it as behavior, and the processes underlying it. Within it, we find the psychology of learning and, more specifically, classical conditioning.

He classical conditioning (CC) or Pavlovian conditioning is a central theme in the psychology of learning, as well as one of its basic principles.

This kind of learning involves automatic or reflex responses, not voluntary behavior (In this it differs from operant or instrumental conditioning).

CC consists of creating a connection between a new stimulus and an already existing reflex; It would therefore be when an originally neutral stimulus, which does not provoke a response, reaches provoke it thanks to the associative connection of this stimulus with the stimulus that normally causes said answer.

CC allows children to be taught to perform desired behaviors associating stimuli to other unconditioned stimuli that already generate the target behavior in the child (for example, associating a timbre (EC) with the fact of begin recess (EI), so that the children prepare to go out to the playground when they hear the doorbell.

This type of learning will allow the establishment of routines that help children to anticipate the behaviors they have to carry out. This learning is of vital importance when working with children who have special educational needs, since these routines prevent them from becoming disoriented and the appearance of anxiety.

Shadowing: the importance of salience

From classical conditioning we can differentiate different complex phenomena. One of them is the shadowing (overshadowing).

This was initially described by Ivan Pavlov in 1927, and consists of the joint presentation of two stimuli that differ in salience (prominence) followed by an unconditioned stimulus (IS).

This sequence implies a conditioned response (CR) of greater intensity to the most salient stimulus. Thus, if A is more salient than B, he will be conditioned more quickly than the latter, and also will make it difficult to condition B.

In this way, the more the CS stands out from the rest of the stimuli present during the acquisition (which can be one or several), the better the conditioning.

Shadowing experiments

A typical shadowing experiment would include two groups of subjects and two stimuli, one high intensity (A) and one low intensity (b).

For the shadowing group, the two stimuli are presented together (Ab) as a compound cue and paired with reinforcement during conditioning. For the control group, only the low intensity stimulus (b) is presented during conditioning.

Tests are carried out for each group presenting only the weakest element of the stimulus (b). These tests show fewer responses (RC's) to b in the shading group than in the control group.

Thus, it is observed how the presence of A alters the control of behavior by the weaker stimulus, b. In more precise terms, we will say that A has deprived B of the power of association with the reinforcer.

But, what are the characteristics of salience? One of them would be the intensity of the stimulus, and, although there are others, for research purposes we neutralize the other variables that determine salience and only the intensity is varied.

Thus, logically, of two environmental elements (neutral stimuli) paired with EI, we will pay more attention to the most outstanding, to the one that most attracts our attention, and this will lead to a greater conditioned response.

An example

We can think of an example to visualize this type of procedure; traffic signs.

A sign painted on the ground will be less protruding than a sign on a pole, and therefore less effective. In this case, the protrusion will also have to do with the location of the sign and our position when driving (the post sign will be more visible to us, more striking).

In addition, as an addition, we know that the sign on a pole has preference over a graffiti in the dream, in the case of finding a contradiction between the two.

Differences Between Shadowing and Blocking

We should not confuse shadowing with a similar but not identical phenomenon, the blocking effect.

This also consists of a phenomenon of classical conditioning, and it is that a conditioned stimulus (EC1) is paired with an unconditioned stimulus (IS) in a first phase, and in a second phase both EC1 and a new conditioned stimulus (EC2) are paired together with the IE; all this causes obstacles to EC2 learning.

That is to say, the conditioning of a first EC (EC1) makes it difficult for a second EC (EC2) to be learned later.

Thus, we see that in both shadowing and blocking, one stimulus causes another to lose associative power, although for different reasons (shadowing due to the salience of the stimulus, and blocking due to EC1 preexposure).

Bibliographic references:

• Pérez, V., Guitérrez, M., Gracía, A., and Gómez, J.(2017). Basic psychological processes: a functional analysis. Madrid (Spain): UNED.
• Domjan, M. (2009), Principles of learning and conduct, Madrid (Spain): Thomson.