The psychometric approach considers intelligence as an aggregate of abilities. It expresses an individual's performance in terms of a single index of cognitive abilities.

(i) Alfred Binet conceptualized intelligence as consisting of one similar set of abilities which can be used for solving all problems in individual's life. This theory of intelligence is called Uni or one-factor theory of intelligence.

(ii) Charles Spearman introduced the two-factor theory of intelligence employing a statistical method called factor analysis.

— He said that intelligence consisted of a general (g-factor) and some specific factors (s-factor).

— The g-factor includes mental operations which are primary and common to all performances.

— In addition to the g-factor, he said that there is an s-factor which is not common and help the individual to excel in a particular field.

(iii) Theory of primary mental abilities was proposed by Louis Thurston.

— It says that intelligence consists of seven primary abilities. Each ability is relatively independent from others.

These ability are — (i) Verbal comprehensions, (ii) Numerical Abilities, (iii) Spatial Relations, (iv) Perceptual Speed, (v) Word fluency, (vi) Memory, (vii) Inductive Reasoning.

(iv) Arthur Jensen proposed a hierarchical model of intelligence, consisting of abilities operating at two levels.

Level-I: associative learning in which output is more or less similar to the input.

Level-II, called cognitive competence, involves high order skills as they transform the input to produce an effective output.

(v) Structure-of-intellect-model: Proposed by J.P. Guilford.

(vi) He classifies intellectual traits among three dimensions — operations, contents and products.

(vii) Operations are what the respondent does, e.g., memorization of a poem.

(viii) Contents refer to the nature of materials or information on which intellectual operations are performed, e.g., poem is familiar or unfamiliar, learner using a particular sense modality, method use.

(ix) Products refer to the form in which information is processed by the respondent. e.g., understanding and application of the theme of poem.

The situationist perspective views human behaviour as resulting from interaction of external and internal factors. It is product of traits and environmental factors.

This approach believes that external factors play more important role to determine individual differences.

(i) Individual differences refer to distinctiveness and variations among people's characteristics.

(ii) Different traits can exist in varying degrees in an individual.

(iii) Each one of us is unique as we possess a novel or typical combination of various traits.

(i) Individual differences make the world beautiful, purposeful and goal directed.

(ii) Different people have different needs and to satisfy the different needs, different types of skills are required. That is why variability is a fact of nature which helps in adaptation.

The behaviour of an individual varies from situation to situation because although our behaviours are influenced by our personal traits but it is also influenced by situational factors.

Situations and circumstances in which one is placed influences person's behaviour.