Measuring Individual Differences

Individual differences theory: Consequences of individual differences

Individual differences concern the traits within humans that affect human behaviours.

There are consequences of individual differences; different opinions may separate and divide people. The individual differences theory explores and explains various aspects of human behaviours in psychology by examining these traits. To do this, psychologists need to measure the various aspects of individual differences accurately.

Cultural differences

Our culture shapes our lives to a great extent. It influences many things about us, from behaviours to thought patterns. It consists of normal or acceptable behaviour in that particular culture. While there are many different cultures, they can generally be divided into two main groups, individualistic cultures (value the individual) and collectivist cultures (value the group).

Gender differences

Gender describes the concepts of masculinity and femininity and how they apply to individuals within the context of culture. It can influence many aspects of a person's life, including behaviour, relationships, and physical and psychological health.

Developmental differences

Whichever way we look at development, either nature, nurture or both (interactionist approach), it is clear that every individual is vastly different. Since everyone has different genes and environments whilst they're growing up, each individual will have different abilities, attitudes, behaviours, and everything else mentioned.

Personality differences

Our personalities are one of the most significant factors that set us apart. Whilst culture and gender do differentiate us, we share those with a large number of people that are part of the same group. It is different for everyone and makes us all unique, and it influences how people interact with each other and their surroundings in different situations.

Different theories about personality exist, including trait theory, the psychodynamic theory, the social cognitive perspective, the humanistic approach, and the big 5 personality traits (O.C.E.A.N - openness, conscientiousness, extraversion, agreeableness, neuroticism).

Fig. 1 The Big 5 describes our different personalities.

Measurement of Individual Differences in Cognitive Abilities

Overall, multiple methods can measure individual differences in cognitive abilities. These include:

• Problem-solving tasks
• Psychometric tests
• Tests assessing maths, language, and memory skills
• Repeated testings (when using the above methods)

Methods of assessing individual differences

There are multiple key areas where individual differences are particularly prominent in people worldwide, which can be examined on a wider scale using assessment methods developed by influential psychologists. These areas of interest include:

• Cultural differences
• Gender differences
• Personality differences
• Developmental differences

Individual Differences Theory: The key studies

There are two key studies you need to know for your exams, and we have explanations discussing them in more depth. Consider the following overviews of Gould (1982) and Hancock et al. (2011).

Classic Study - Intelligence

Everyone has different levels of intelligence from each other, and each person also has different levels of the different types of intelligence, e.g. IQ (Intelligence quotient), emotional intelligence, etc. Gould (1982) carried out a famous study measuring individual differences in intelligence, in which he reviewed and critiqued the largest intelligence test carried out by Yerkes (1917), testing 1.75 million army recruits, in an attempt to measure intelligence in a scientific way.

Gould's aim was to reveal the problems in measuring intelligence that Yerkes had in his research. Yerkes developed three main intelligence tests which measured native intelligence, that he claimed were not affected by culture or education level:

1. Alpha test, which had eight parts, was for literate recruits and is similar to today's IQ tests.

2. Army Beta test, a pictorial test for illiterate people who failed the alpha test.

3. Individual Examinations (spoken) test, an oral test for those who failed the beta test too.

Yerkes found different average mental ages for people from different countries: white Americans (13.04), then Russian immigrants (11.34), Italian immigrants (11.01), Polish immigrants (10.74), then Black Americans (10.41). The results determined which role the recruits got. Yerkes' study resulted in serious consequences for immigrants to America, e.g. Jews who were fleeing from Hitler.

Gould (1982) pointed out several issues with Yerkes' intelligence research, which lowered its validity:

• That it was culturally biased and disadvantaged immigrants, so it didn't measure native intelligence, e.g. some questions in the alpha test included testing knowledge about American culture rather than literate ability.

• The beta test was pictorial, but recruits would still need to know how to write/draw numbers.

• Those doing the beta and alpha tests didn't get as much time as was specified, so they missed questions.

• Due to too many recruits lining up for the beta test, a lot got tested with the alpha test, which meant their scores were very low.

• Also, many who failed the beta test weren't called back for the individual test.

The question, therefore, arises about whether or not we can accurately measure intelligence?

The answer to this based on the conclusions of Gould's study would be that it has been found that IQ tests are not developed to measure innate intelligence, which is what we want to measure when it comes to intelligence, but rather they reflect practices of that specific culture, which reduces the tests' accuracy and questions their ability to correctly measure intelligence.

Contemporary study - Language of psychopaths

Psychopathic traits are an individual difference because not everyone is a psychopath. Those classed as psychopaths are different from the rest of the population.

Therefore, to measure this individual difference, Hancock et al. (2011) decided to analyse the language of psychopaths to see:

• Whether they use different linguistic features that reflect their worldview

• Whether their language indicates differences in which needs they emphasise from Maslow's Hierarchy of Needs (basic, physiological or higher needs).

• Whether their language reflects their lack of emotion.

They found that psychopaths used more words like 'since' or 'because' (subordinating conjunctions) because they describe their murders in a cause and effect way since they see their murders as goal-oriented and logical. Also, psychopaths used two times as many words describing their physiological needs as non-psychopaths, who talked more about higher needs, e.g. religion, family, etc.

Psychopaths described their murders using more past tense verbs, which showed their distance from the crime. They also used language that wasn't fluent ('uh'/'um'), indicating that it was difficult for them to describe such an emotional event to someone. The higher their psychopath score, the less emotional and positive their language was.

These findings show how psychopaths view the world differently and think in such a different, rational, and primitive way. Psychopaths use language and word patterns that lack fluency, are psychologically distant and are more rational than emotive.

Comparison of Gould (1982) and Hancock et al. (2011)

There are several aspects that these two individual differences studies have been compared on. Overall, Gould (1982) is a review of a classic study (Yerkes, 1917), which analysed the issues with conducting mass intelligence tests due to the levels of individual differences within populations. This relates both to culture and social upbringing.

Individual diversity

Hancock et al showed that it is possible to measure behaviour in order to establish which factors cause individual differences. This contemporary research is different from Gould's review of general intelligence as more specific measures of abnormal behaviour are taken.

Social diversity

Gould's research was a review of a large study with a huge sample size, so it tells us about intelligence of the general population and social diversity. Since Hancock et al only focused on 52 men who were in prison for murder, his research cannot really tell us much about the general population, so has little social diversity.

However, it can tell us a good amount about the specific group of individuals who are likely to have a similar background (based on offending research). This means Hancock et al.'s research was able to explain an important problem, which can potentially help in reducing offending in society, in the future.

Cultural diversity

Gould's study included participants from 6 different ethnicities, so had good cultural diversity. However, Hancock et al.'s study focused on Canadian prisoners, so there is little cultural diversity. This research could be improved by conducting it in different cultures with different languages.