Mental Chronometry and the Unification of Differential Psychology

Arthur R. Jensen

Yi. Sangyoon

Mental Chronometry

• Measurement of cognitive speed

• Individual’s response time(RT)

• Inspection Time(IT)

• Major aspect of general intelligence - Sir Francis Galton(1822-1911), et, al.

• Sensitive measure of individual difference

History of RT

• First appeared in astronomy Journals– Astronomers showed individual differences in

RT to the star’s transit across the hair line– Astronomer Royal at the Greenwich Observatory

• Tested simple RT on thousands of people– (Galton)

• Related to the nature of intelligence– (Vernon, 1987)

• Conventional Psychometric Measurement

• Mental Chronometry

• Advantages of Chronometry

• Advancement of Differential Psychology

Conventional Psychometric Measurement

• Ordinal Scales– Composed of a number of separate items

on which the subject’s responses are scored either R/W or P/F – Ordinal scales

– Ranking, percentile raks, standardized scores(z, T, IQ), normalized scores …

– norm referenced– Do any kind of transformation of the raw

scores’ rank order represents a true interval scale or a ratio scale??• It’s depends on ASSUMPTION.• Transformed test scores contain no new

information.

Conventional Psychometric Measurement

• Ordinal Scales– Ordinal scales have many shortcomings.– Cannot make really meaningful

statements about many things we want to know in differential and developmental psychology.

X Y

Conventional Psychometric Measurement

• Absence of ratio scales in differential psychology is most unfortunate.

• Reductionist research necessarily be focused on discovering functional relationships

• How one measured variable is related to some other measured variable

• Time MC

Advantages of MC

• Reliability

• Repeatability

• Range of Equivalency

• Sensitivity of Measurement

The Psychometric Misconception of Mental Speed• Speeded tests in given limit time– Score is the number of identifying items

completed within a time– This results have as rather small factor value– Is it minor factor ???

• This kinds of tests are different from the Chronometric methods used to measure RT and IT

• We should realize that distinction between speed and power.

Standardizing Chronometric Methods

• The units of time have been standardized throughout the history of MC ms

• But, testing conditions are not well standardized…– a severe hindrance to differential psychology

• Within vs Between(*)

• standardization is Essential for science field

Chronometry as a Primary Tool for Research on Intelligence

• “Almost entire psychometric literature shows that they are best represented by a hierarchical factor structure.”

– John B. Carroll (1993)– Three-stratum model

The most general component of the common factor variance

Chronometry as a Primary Tool for Research on Intelligence

• g– Cannot be characterized in therms of the information

content of mental test or in terms of any observable types of behavior.

– g is known not by its nature but by the variation in its loadings on a wide variety of mental tests• (Charles Spearman)

– An aspect of individual differences that causes positive correlations between virtually all measurable cognitive abilities

Chronometry as a Primary Tool for Research on Intelligence

• Chronometric and psychometric tests have much the same general factor in common– RT and IT are related to g

• It is not the main purpose of mental chronometry.

• It is a general tool for measuring all aspects of cognition.

Fundamental Findings in the Relationship of Chronometric

to Psychometric g

• The Problematic Meaning of Inter-Trial Variability

Fundamental Findings in the Relationship of Chronometric

to Psychometric g

• The “Worst Performance Rule”