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# Classification and Quantitative Judgement

## Details

**Authors** Tajfel and Wilkes

**Year** 1963

**Publisher** British Journal of Psychology

**Discipline** Cognitive Science

[Read it at the publisher](https://doi.org/10.1111/j.2044-8295.1963.tb00865.x) 
10.1111/j.2044-8295.1963.tb00865.x

## In authors' words

### Abstract

The investigation is concerned with the effects on judgement of some relations between the manner in which stimuli of a series are classified and the magnitudes of the stimuli. It is shown that when the classification stands in a direct and predictable relation to a physical scale, the stimuli belonging to different classes are judged as farther apart on that scale than in an unclassified series. A classification which is not coherently related to the physical scale does not affect judgement in this manner. There is also evidence in the results that, as a function of past experience with the classification, an increase occurs in the apparent differences between stimuli belonging to different classes, and in the apparent similarity of stimuli belonging to the same class. The relevance of these findings to the general problem of stereotyping is discussed.

### What they set out to do (purpose)

How does the act of classification affect judgement?

### What they found (results)

When classification is imposed on participants, the judgments people made were altered.

## Commentary

### In short

The way that one thinks about an idea, person, or thing has an impact on the resulting mental model. Being aware of the way your patterns of thinking affect you can only lead to increased metacognition and allows one to try to mitigate their biases.

### In more detail

Tajfel and Wilkes (1963) found that classification has an increased effect on the behavior of judgement, when the experience is repeated throughout the experimental session. The purpose of their experiment was to examine the effect classification had on quantitative judgements. This was accomplished through judging the length of a collection of lines, so that the judgement (in this case, length) would be simple. After presenting the lines one by one in a sequential order, their results showed that when classification is imposed on participants, the judgments people made were altered. They postulated that this could be due to the repeated and frequent experience of the same class of stimuli, which could then strengthen the association to it. This includes an increase in both the subjective difference between classes, and the subjective similarities among classes of stimuli. This pattern is exemplified by stereotyping—when humans tend to highlight the differences of the other, and the similarities of the group they identify with. The more experience a person has with one class of stimuli, the more judgemental they are towards other classes.

**Patterns it shows** D

**How to cite this** Tajfel and Wilkes (1963). Classification and Quantitative Judgement. British Journal of Psychology.