Personality and individual differences

In 1865 Francis Galton began to study heredity, after reading his cousins (Charles Darwin’s) publication the

organs of species

Following this work Galton became interested in studying variations in human ability and in particular,

intelligence. In his book hereditary Genius 1869 he was convinced that higher intelligence was due to

superior qualities passed down to children through heredity.

Galton felt that intelligent people show the ability to respond to a large range of information experienced

through the senses. People of low intelligence have problems dealing with information gained through the

senses and was show less response to sensory information such as being able to distinguish between heat

and cold and being unable to recognise pain.

Galton suggested several methods to determine intelligence through responsiveness to stimuli;

Reaction time

Keenness of sight and hearing

Ability to distinguish between colours

Eye judgement

Strength

In 1884 he tested people at his Anthropometric Laboratory. Some of Galton's ideas of measuring intelligence lack reliability and validity by todays standards. Clearly poor eyesight does not determine intelligence, but instead is the result of the eyes. However, some measures that Galton developed such as reaction time are still used today.

Clark Wissler (1901) criticised Galton by saying that variations of sensory and motor tests did not correlate on college students.

Galton recognised the limitations of his methods, and believed the question could be better studied by comparisons of twins. His method involved testing to see if twins who were similar at birth diverged in dissimilar environments, and whether twins dissimilar at birth converged when reared in similar environments. He again used the method of questionnaires to gather various sorts of data, which were tabulated and described in a paper The history of twins in 1875. In so doing he anticipated the modern field of behavior genetics which relies heavily on twin studies. He concluded that the evidence favored nature rather than nurture. He also proposed adoption studies, including trans-racial adoption studies, to separate the effects of heredity and environment.

Alfred Binet and Theodore Simon created the first ever intelligences test in 1905 naming it the Binet-Simon

scale. To develop their tests Binet and Simon choose a series of 30 short tasks related to everyday life. Some of

the tasks used in the intelligence tests were;

Following a lighted match with your eye

Shaking hands

Naming body parts

Counting coins

Recalling digits

Word definitions

Filling in missing words in a sentence

The test questions were arranged in an increasing degree od difficulty to indicate levels of intelligence. The

easiest of all tasks was whether a child could follow a lighted match with their eyes, these tasks were expected

to be completed by all children. Harder tasks included asking children to name body parts or repeat simple

sentences. The hardest tasks involved finding rhymes for difficult words and repeating seven random digits.

The Binet-Simon test was used for children aged between 3 and 10 to determine their mental age. In 1911 the

final publication test was released which now had for tests for the ages of 12 and 15 as well as for adults.

In 1916 modifications were made to this scale transforming it into the Standford-Binet scale. The modification

provided English translations for the French items as well as new items. Despite other available translations,

Terman is noted for his normative studies and methodological approach. Age 4-14 Terman tested 1000

children.

The Stanford-Binet intelligence test used a single number, known as the intelligence quotient (or IQ), to

represent an individual's score on the test. This score was calculated by dividing the test taker's mental age by

their chronological age, and then multiplying this number by 100. For example, a child with a mental age of 12

and a chronological age of 10 would have an IQ of 120 (12 /10 x 100).

At the outset of World War I, American Army officials were faced with the monumental task of screening an

enormous number of army recruits. Yerkes aim was to be able to develop group intelligence testing.

In 1917, as president of the APA and chair of the Committee on the Psychological Examination of Recruits,

psychologist Robert Yerkes developed two tests known as the Army Alpha and Beta tests.

The Army Alpha was designed as a written test, while the Army Beta was administered orally in cases where

recruits were unable to read. The tests were administered to over two million soldiers in an effort to help the

army determine which men were well suited to specific positions and leadership roles

The alpha test battery for literates included the testing of a variety of cognitive abilities by examining the

persons knowledge base in both oral and written language. The alpha test included eight tests of individual

ability to;

Follow oral directions, involving the comprehensions of simple and complex oral language directions

Arithmetic

Show practical judgement, involving the ability to make the correct choice on a scenario

Use synonyms and antonyms, knowledge of the same and opposite words

Rearrange, disarranged sentences

Complete an uncompleted series of numbers (1,2,4,8,16,…)

See analogies, which require the ability to see similarity between two things that are otherwise dissimilar

Demonstrate information, an examination of the persons everyday knowledge base

The administration was designed to be completed within a certain time

The beta tests was an intellegience test comparable to the Alpha but freed from the influences of literacy and

the English language. Non-English speakers and people who had spoken the language for less than 6 years

were sent for Beta testing. Also those who had tried the Alpha test but were considered to be poor readers

were also sent for Beta testing. Instructions were given by the testor and their aides by makig hand signals. The

examiners recorded their responses. The Beta test included seven tests of ability in which the individual had to;

Complete a maze task

Complete a cube analysis, by counting cubes in a graphic representation

Read an X-O series of graphic displays in left to right sequences

Complete a test using digit symbols, requiring scanning and matching of numbers to symbols

Complete a test using number symbols, requiring matching of symbols to numbers

Complete a picture )like a (jigsaw)

Undertake geometrical construction, which involved working with graphics information and mentally

rearranging it to construct a figure

Administration of Beta testing was t be completed at a certain time