Individual Differences

Meaning of Individual Differences
 Are deviations of individuals from the average or from one another?
 Is a trait by which and individual may be distinguished from other individuals.

Nature of Individual Differences
Individuals vary in physical as well as psychological characteristics. Variability range from intra-variability to inter-variability

 Intra-variability – concerns differences within the individual. It is also referred to as Trait-variability.
 Inter-variability – concerns differences among individuals or between individuals with regards to environment.

Characterization of Individual Differences
1. Variability and Normality – Virtually all measures of individuals manifest characteristics that can be distributed in the form of a normal probability curve.
2. Differential rates of growth and learning – These variations can be seen in cognitive abilities, in physical, emotional and moral aspects of growth.
3. Interrelation of traits – the growth of personality for instance, is the result of the continuing interaction of many factors.
4. Hereditary and environmental factors – The Hereditary and environmental contributions can never be completely separated because they are in continuous interplay in the production of every physical and psychological trait.

Factors Affecting Individual Differences
1. Physiological factors – the effects of drugs and alcohol are well-known to alter personality, to influence control and judgement.
2. Cultural influences – these norms affect individual self-concepts as well as social adjustments.
3. Interaction between biological and social factors – An individual being a complex product of many interaction variables is really more than the simple sum of different influences.

Measurement and Evaluation of Individual Differences

 Standards or Norms – are based on massive data collected concerning different kinds of behavior. It serves as a basis against which to interpret individual measurements under given circumstances.
 Sampling – is the process of choosing a selected portion which is representative for the whole.
 Reliability – refers to the dependability of test as reflected in the consistency of its scores upon repeated measurements of the same group.
 Validity – is a property of measure device, say a test, in measuring in fact, what it is intended to measure.

Tests – are techniques used in psychological assessment to sample individual or group behavior.

Different Kinds of Tests
1. Intelligence Tests – as well as specialized aptitude and achievement tests may be divided into:
1.1a Individual Tests – are given to a single testee by another person, say, a trained psychologist.
1.1b Group Tests – are given simultaneously to large numbers of testees.

1.2a Verbal Tests – require the use and understanding of language to either oral or written work.
1.2b Performance Tests – make minimal use of language and may require the use of concrete nonverbal materials

2. Aptitude Tests – are designed to measure capacity to learn.
3. Achievement Tests – identify what a person can do now or his already accomplished skills.
4. Interest Tests or Inventories – are instruments designed to measure an individual’s interest in a variety of activities.
5. Personality Tests – are tests designed to measure personality traits.

Most Popular Personality Test
1. The Rorschach or Inkblot Tests – is a projective technique in which the subject is shown ten plates or cards containing bi-symmetrical inkblots.
2. The TAT (Thematic Apperception Test) – is a projective technique in which the subject is asked to tell a story suggested by each of a series of nineteen picture which are relatively unstructured and are thus suitable material into which the subject can project his own needs, emotions, conflicts, etc.