Individual differences and assessment

No two people are exactly alike. Individual differences are the distinct variations among people in their characteristics and behaviour: some are calm, some anxious; some quick with numbers, some with words.

Do people behave the same way in every situation? Trait views say our behaviour comes mainly from stable qualities inside us. Situationism stresses the circumstances: the same person may be shy in class but lively with friends. Most psychologists accept that both matter.

Assessment means measuring and evaluating a person's attributes using some standard of comparison.

• Informal assessment: everyday judgements ('she seems clever'). It is subjective and can vary from person to person.
• Formal assessment: objective, standardised and organised, so that results are the same whoever does it.

The main domains (areas) assessed:

• Intelligence: the ability to understand, think rationally and adapt to the environment.
• Aptitude: the potential to learn a particular skill.
• Interest: preference for certain activities.
• Personality: relatively stable patterns of thinking, feeling and acting.
• Values: enduring beliefs about an ideal way of behaving.

Methods of assessment:

• Psychological tests: standardised, objective measures.
• Interview: talking with the person.
• Case study: an in-depth study of one person's psychological history.
• Observation: systematically watching behaviour.
• Self-report: the person describes himself or herself, often on a questionnaire.

Psychological attributes are multi-dimensional: like a box with length, breadth and height, not a simple line. Intelligence, for instance, has many parts. So assessment is the first step to understanding a person, not the last.