“Historical Foundations”

The nature of the human intellect has fascinated scholars for centuries. The earliest work, ranging from Plato and Aristotle to Itard and Esquirol, formed the foundation for modern explorations of intelligence (i.e., the theories developed over the past 200 years).


Plato (ca. 428/42-348/347 BCE)
Aristotle (384-323 BCE)
Augustine (354-430 AD)
Aquinas (ca. 1225-1274)
Huarte (ca. 1530-1592)
Hobbes (1588-1679)
Pascal (1623-1662)
Thomasius (1655- 1728)
Smith (1723-1790)
Kant (1724-1804)
Duff (1732-1815)
Esquirol (1772-1840)
Itard (1775-1838)


Time Period 1
“Modern Foundations”

During this time period, psychology began to emerge as a discipline separate from philosophy, mathematics, and biology. However, individuals from these diverse fields continued to influence psychological discourse and the study of intelligence.


Locke (1632-1704)
LaPlace (1749-1827)
Gauss (1777-1855)
Mill (1806-1873)
Darwin (1809-1882)
Galton (1822-1911)
Charcot (1825-1893)

Time Period 2
“The Great Schools”
This period in history witnessed the advent of several prominent European schools of psychology. Some of the American psychologists profiled on our site studied overseas, then returned home to establish influential psychology programs in the United States. The study of intelligence gained popularity during this era, bolstered by the work of Wilhelm Wundt, James McKeen Cattell, G. S. Hall, and Hermann Ebbinghaus.


Wundt (1832-1920)
James (1842-1910)
Hall (1844-1924)
Ebbinghaus (1850-1909)
Freud (1856-1939)
J M.Cattell (1860-1944)
Wissler (1870-1947)
Edison (1847-1931)

Time Period 3
“The Great Schools’ Influence”
As the students of the Great Schools began to form their own programs, the number of theoretical and empirical investigations of intelligence increased.. A milestone during this time period was the development of the United States’ Army Alpha and Beta testing program, established under the direction of Robert Mearns Yerkes. This massive project gave rise to the first group intelligence tests and provided a fertile training ground for many psychologists who would become influential in the ensuing decades.


E. L. Thorndike (1874-1949)
Binet (1857-1911)
Pearson (1857-1936)
Spearman (1863-1945)
Goddard (1866-1957)
Stern (1871-1938)
Simon (1873-1961 )
Yerkes (1876-1956)
Terman (1877-1956)
H. Hollingworth (1880-1957)
L. Hollingworth (1886-1939)
Goodenough (1886-1959)
Vygotsky (1896-1934)
Piaget (1896-1980)
Cox (1890-1984)

Time Period 4
“Contemporary Explorations”
The enthusiasm generated by the formation of the Great Schools and the Army Alpha and Beta testing program laid the foundation for the work done during this period. New statistical techniques and modern experimental designs helped to make standardized testing of intelligence and achievement a way of life in most Western countries. Although g-centric theories dominated, theories of “multiple intelligences” began to appear in the work of Thurstone and Guilford.


Burt (1883-1971)
L L Thurstone (1887-1955)
P. Cattell (1893-1989)
Wechsler (1896-1981)
Guilford (1897-1988)
T. Thurstone (1897-1993)
Vernon (1905-1987)
Hunt (1906 – 1991)
Anastasi (1908-2001)
R. Thorndike (1910-1990)
Inhelder (1913 – 1997)
Taylor (1915-2000)
Eysenck (1916-1997)

Time Period 5
“Current Efforts”
Current trends in intelligence theory and research involve the formation of more complex multiple intelligence theories and a deemphasis on the use of standardized testing to measure intelligence. At the same time, the availability of relatively cheap computers has promoted advances in statistical analysis, providing new perspectives on the measurement of intelligence. The emergence of reliable genetic and neurological research methodologies is creating a new area of study in which environmental, biological, and psychological aspects of intelligence are studied simultaneously.


R. Cattell (1905-1998)
Carroll (1916- )
Jensen (1923 – )
Kamin (1924 – )
Renzulli (1936 -)
Gardner (1943 – )
Sternberg (1949-)
A. Kaufman (1944 – )
Carol S. Dweck (1946 – )
Simonton (1948 – )