It cannot be expected that the use of the CoRT Thinking Lessons will in every case bring about the sort of results that are shown in these sections.

The effect will vary from class to class and from teacher to teacher.

The effect will vary with the background and ability of the students.

The effect will vary with the type of question used in the test situation.

There may well be schools which are unable to show any concrete effects from teaching thinking as a subject. This may be due to the way the subject has been taught or to the inappropriateness of the test.

If students are given a problem about which they have a lot to write, then it is very unlikely that the CoRT group will show any greater number of points than a control group. In fact there may even be a negative effect. This is because a control group can move from point to point whereas the CoRT group is trying to operate within a framework.

Although there may be no difference in the total number of points there may be a difference in the type of points considered.

For instance, a control group often tends towards more egocentric points, whereas the CoRT group ranges more widely and considers the effect of the idea on others and on society in general. In such cases a simple count of points is not appropriate.

With more capable groups, at first sight there may be little difference in the essays from CoRT students. The essays all seem articulate, reasonable and well-argued.

It does require some experience in looking at thinking as distinct from its expression to note the difference, and then it can be very obvious.

For instance, students in a control group tend to take up a position and then use their thinking to defend that position, whereas students in the CoRT group tend to explore the situation before taking up a position.

Finally there are aspects of thinking behaviour (like listening to others and being prepared to think about something) which cannot be examined by a simple point-count of ideas. They come under the heading of general expression, but in fact may be more valuable than the direct count.

It is true to say that new aspects of the effects of the CoRT Thinking Lessons are appearing all the time. At the moment it is not possible to predict all the effects and the differences in effect with students of different ages or abilities.

It seems likely that in the younger groups the effect will be mainly on general thinking behaviour and breadth of thinking.

In the older groups the effect may well be on the style of thinking when the subject is very familiar and on the breadth as well when it is not so familiar.

We can separate the effects of CoRT Thinking Lessons into three types:

1. Behaviour: This concerns the behaviour of students when they are in a thinking situation. This behaviour also includes their response to the thinking of others.

2. Style: This is not easy to define, but covers the way students use their thinking - what they hope to achieve and how they try to achieve it. For example, do they use thinking to defend a position or to explore the situation?

3. Content: This deals with the actual ideas used, the breadth and depth of the thinking, the amount of the scene that is explored, and the number of aspects brought to mind.


In some cases change in behaviour is by far the most striking effect of the CoRT lessons. The change in behaviour can take the following forms:

1. An ingrained refusal to think about anything for which there is not a stock answer or prejudice is changed into a willingness to consider matters which would previously have been dismissed as "Silly," "Ridiculous," "Don't want to bother about that," "That is none of my business," "Why should I think about that?", etc.

There is instead an effort to think about something, even though the quality of the thinking may be poor.

2. Silliness, giggling and embarrassment about having ideas is replaced by a greater confidence in putting forward ideas, even if they are only tentative.

The need to be right with every utterance (and otherwise keep silent) is replaced by a willingness to contribute.

3. Complacency, smugness and prejudice are lessened. It takes a long time for them to disappear, but students are able to acknowledge another point of view even if they do not really accept it.

4. Interaction with others is much improved. This is probably a direct result of the group format in the CoRT lessons.

Initially students tend to attack any differing point of view as "stupid" or "impossible." They tend to shout someone else down and use repetition ot their own argument in place of elaboration of it.

They enlist support for their argument by direct appeal to others in the group and even insist on a vote. In short they rely not on the nature of their thinking, but on the social support they can arouse for it (by enlisting friends, and dismissing opponents as fools).

This is changed by the CoRT lessons, to the extent that students can be heard commenting, "That is a good point," and "Yes, I agree with that."


Style and content will be discussed together and with particular reference to specific experiments. The two are quite closely intertwined but, as in twine, the strands can be unraveled by deliberate analysis. For example, the use of a special operation like a PMI comes under style, but the ideas that are turned up would come under content.


A random half of a group of business executives was asked to consider the proposition that "there should be dated currency (e.g., a 2007 dollar and a 2008 dollar), with an adjustable exchange rate between the different dates." Of these people 35% thought it would be a good idea.

The other random half of the group was asked to consider the suggestion that "marriage should be a five-year contract." Of these people only 23% thought it would be a good idea.

The questions were then switched round, and this time both halves were asked to do a deliberate PMI (which was briefly explained to them) before deciding on the proposals.

This time only 11% approved on the dated currency (a decline from 35% to 11%). on the other question, there was an increase from 23% to 37% of those approving marriage as a five-year contract.

This experiment was a simple one, but it highlights an important point.

Most people claim to consider both the good and bad points of a proposal, when in reality they simply follow their initial reaction of like or dislike.

The dated currency seemed a good idea so it tended to be approved, but a deliberate PMI drastically reduced this approval.

With the marriage contract, the idea seemed outrageous at first, but, with a deliberate PMI, approval for it almost doubled.

This and parallel experiments indicate that when CoRT thinking tools are deliberately used the operations can make a difference in thinking.

It does not indicate that the operations - even if taught - would be used in the ordinary course of events.

To examine that point we have to look at some specific experiments. The following pages present "before and after" results of two experiments involving CoRT Thinking.


Girls' Private School Girls aged 13-14.

One class had done fourteen CoRT lessons.

The control group came from an equivalent class that had not done any lessons.

Unfortunately the control class had to be divided in half to provide controls for two different experiments, so the number of students in the control group was only 16 and that in the experimental group was 32.

For this reason the figures in the table can only be regarded as proportional.

The last line in the "no lessons" group has been multiplied by two to make it comparable with the other group.

The groups were asked to write on the question:

"Should everyone have to do one year's social work after leaving school?"


The above graph 3 (a) indicates the type of points made.

In some categories this increase after the lessons was more marked than in others.

Some indication of this is given in the approximate figures given below.

Egocentric points (P) increased from 174 to 224 (x 1.28)

Points for the idea (F) increased from 90 to 149 (x 1.65)

Points against the idea (A) increased from 98 to 188 ( x 1.91)


Points relating to society (S) increased from 16 to 41 ( x 2.56)

Neutral, exploratory points (Po) increased from 82 to 250 ( x 3.04)

Points relating to other people (O) increased from 28 to 91 ( x 3.25)

Administrative points increased from 46 to 209 ( x 4 54)

As expected, the smallest increase was in the egocentric points and the greatest increase in the practical points.



High School Girls and boys aged 16-18.

The students at this school had been selected for their high general level of ability and could be regarded as well above average.

In a crossover experiment one group tackled the question without having studied any CoRT lessons and the other group tackled the same question after seven of the lessons.

The question was the same as that used in Experiment 3 (a):

"Should everyone have to do one year's social work after leaving school?"

The above graph is constructed on the same basis as for Experiment 3 (a).

This time, however, there were as many students in the control group as in the experimental group.

Egocentric points (P) increased from 108 to 308 (x 2.85)

Points for the idea (F) increased from 122 to 238 (x 1.95)

Points against the idea (A) increased from 59 to 101 (x 1.71)

Points relating to society (S) increased from 18 to 62 ( x 3.44)

Neutral, exploratory points (Po) increased from 45 to 1F)7 (x 2.37)

Points relating to other people (O) increased from 13 to 54 (x 4 15)

Administrative points (Ad) increased from 46 to 131 (x 2.84)

What is unusual in this result is that, although there was an increase in all categories of points for students who had studied CoRT, the egocentric points increased considerably though not as much as the points relating to other people.




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