There is a fairly simple but important point to be made when analysing the behavioural stream. What is happening inside an organism at the moment of observation is not to be treated as an explanation for that observation.

That is to say, the data observed at any point in time are to be treated as data, nothing else.

Strange as it may seem, though, this point is often ignored, with serious consequences for the development of explanations of behaviour. It is often the case, for instance, that events inside an organism are treated as explanations and not as data.

The cover picture above illustrates this way of thinking as the "wall of mentalism" stands in the way of a full "analysis" of behaviour.

Movie 3.1 summaries this point. When this basic argument is ignored the analysis of behaviour is additionally blocked by the circular reasoning of a language trap.

The next series of movies was designed to illustrate examples of circular reasoning that is the hallmark of mentalism. This time the focus is on you. We will show you how easy it is to slip into a mentalistic analysis. Watch Adam and Julia (Movie 3.2) and jot down a few words you might use to talk about the cartoon character called Adam as he interacts with Julia.

Now compare your words with those obtained from a class of 100 undergraduate students. Movie 3.3 was edited and we inserted the words that were used most often by these students.

The most obvious conclusion is that a lot of words were generated after watching the choreography of a very simple animation. Your own words may or may not have appeared. However, the words you used will have a bearing on how your own learning history has led you to use them when summarising your observations. Movie 3.4 picks up this point and shows you that the words used are called ‘summary labels’.

Movie 3.5 shows the circular reasoning that is typical of a mentalistic analysis. The mistake in mentalism as it applies to Adam in this scene is to use the same words to both describe and explain his behaviour. For example, firstly Adam’s behaviour might be described as ‘cheeky’ and then his behaviour is subsequently explained by saying that he behaves that way because he is ‘cheeky’. In other words, it is said that Adam was cheeky because he was cheeky!

Clearly this is nonsense, but it is a powerful illusion nonetheless, and one that most of us fall prey to when explaining behaviour. Think, for example, of a time you may have noticed a child in a shop having a temper tantrum at the check-out because his mother wouldn’t buy some sweets. You could say that this is an example of ‘spoilt’ behaviour, but it would be a mistake to try and explain that same behaviour by saying the child behaved that way because he is ‘spoilt’. Another example might be a case where you watch a professional potter turning a beautiful vase. You could describe her doing this as an example of ‘skilful’ behaviour, but it would be a mistake to explain her behaviour by saying she did this because she was a ‘skilful’.

In each of these examples, notice what has happened as a result of the circular reasoning. The search for an explanation has halted prematurely. It appears as if you’ve gotten your explanation so there is no need to ask any further questions, for example, about the quality of training the potter had undergone.

Another aspect of the mistake of mentalism concerns the way we put explanations ‘inside a person’. We tend to ‘mind read’ and yet we know that nobody can really read another person’s mind. We don’t notice that it is our own thoughts we are ‘reading’, not those of another person; of course, we can feel empathy, but this is different from actually ‘reading’ another person’s mind. By way of illustration, look again at the lesson from the animation with Adam.

In Movie 3.6 the argument against looking inside an organism for an explanation is very striking. There is absolutely nothing inside this cartoon character (i.e., no nervous system, no brain). Consequently, it seems obvious that the use of these words in the attempt to explain his behaviour tells us more about the education of the people who used these words than about what is going on in Adam’s head; and if you used any of these words, or similar words, this conclusion applies to you also.

When this simple animation was designed there were two goals. One was to create something that stimulated the production of words by you! The second was to provide a context that alerted you to the role played by the learning history of the observer in a scientific analysis; more on this later. This argument holds true even if Adam had been a real person. Even if we had all the information we might ever need about what is happening inside a person at the moment of observation, in the context of the behavioural stream we would have to conclude that these data themselves would require explaining because they constitute part of the process of change recorded at that moment in time.

Movie 3.8 summarises the process involved in generating mentalistic explanations of behaviour.

Mentalism is perhaps the greatest obstacle to the uptake of a Natural Science of behaviour.

Every introductory textbook in Psychology pedals myths about behaviour analysis because of the lack of training in the role of mentalism in science discourse. There are two common ones.

• It is said that the science promotes the notion that people are born as blank slates, and the most misguided and offensive one is the suggestion that behaviour analysis promotes the idea that people are empty Black Boxes.

• It is said that behaviourism considers 'what is happening inside' as unimportant. This view stems from a failure to appreciate that criticisms of mentalism are synonymous with criticisms of a failure to recognise circular arguments in the development of explanations.

Movie 3.9, 'Black Box', was designed to tackle head on the nonsense that is part and parcel of training for most undergraduate Psychology students. Movie 3.10 emphasises the problem with explanatory fictions.