Inspection time
Encyclopedia
Inspection time refers to the exposure duration required for a human subject to reliably identify a simple stimulus. Typically a stimulus made up of two parallel lines differing in length and joined at the tops by a cross bar is presented (similar to the Greek letter Pi
). The ability to quickly detect the identity of a stimulus is moderately heritable
and correlates with the subject's IQ.
after a short period of time, the proportion of correct responses declines as the exposure duration reduces, and reliable individual differences emerge in the percent identified correctly at different intervals.
The task itself was proposed by Doug Vickers as a measure the rate of accumulation of information. Ted Nettelbeck, Chris Brand
and others demonstrated it related quite strongly to psychometric intelligence, especially across the lower part of the IQ range
suggesting that differences in intelligence may reflect, in part, differences in the rate of information processing
- a theory proposed by Arthur Jensen
.
One version of the inspection time stimuli is shown below (1) with the stimulus (short left given as an example), which is replaced by a mask (2). (3) indicates the opportunity for the subject to report which stimulus they saw at their leisure.
. This work on the heritability of IT from Nick Martin
's group also demonstrated, however, that perceptual speed does not have a causal role in intelligence
, but rather that IQ and IT are distinct reflections of some shared biological processes.
Pi (letter)
Pi is the sixteenth letter of the Greek alphabet, representing . In the system of Greek numerals it has a value of 80. Letters that arose from pi include Cyrillic Pe , Coptic pi , and Gothic pairthra .The upper-case letter Π is used as a symbol for:...
). The ability to quickly detect the identity of a stimulus is moderately heritable
Heritability
The Heritability of a population is the proportion of observable differences between individuals that is due to genetic differences. Factors including genetics, environment and random chance can all contribute to the variation between individuals in their observable characteristics...
and correlates with the subject's IQ.
Overview
If asked which of the two lines in the figure below is longer; the left or the right, almost all non-visually impaired subjects can answer correctly 100% of the time. If, however, the stimulus is backward maskedBackward masking
Backward masking has several meanings:*The original meaning of the term, in psychoacoustics, refers to temporal masking of quiet sounds that occur moments before a louder sound....
after a short period of time, the proportion of correct responses declines as the exposure duration reduces, and reliable individual differences emerge in the percent identified correctly at different intervals.
The task itself was proposed by Doug Vickers as a measure the rate of accumulation of information. Ted Nettelbeck, Chris Brand
Chris Brand
Christopher Richard Brand is an English psychological and psychometric researcher who gained media attention for his controversial statements on race and intelligence and pedophilia. He went to Queen Elizabeth's, Barnet, and is a graduate of The Queen's College, Oxford, and a fellow of Nuffield...
and others demonstrated it related quite strongly to psychometric intelligence, especially across the lower part of the IQ range
suggesting that differences in intelligence may reflect, in part, differences in the rate of information processing
Information processing
Information processing is the change of information in any manner detectable by an observer. As such, it is a process which describes everything which happens in the universe, from the falling of a rock to the printing of a text file from a digital computer system...
- a theory proposed by Arthur Jensen
Arthur Jensen
Arthur Robert Jensen is a Professor Emeritus of educational psychology at the University of California, Berkeley. Jensen is known for his work in psychometrics and differential psychology, which is concerned with how and why individuals differ behaviorally from one another.He is a major proponent...
.
One version of the inspection time stimuli is shown below (1) with the stimulus (short left given as an example), which is replaced by a mask (2). (3) indicates the opportunity for the subject to report which stimulus they saw at their leisure.
Genetics
Inspection time is moderately heritableHeritability
The Heritability of a population is the proportion of observable differences between individuals that is due to genetic differences. Factors including genetics, environment and random chance can all contribute to the variation between individuals in their observable characteristics...
. This work on the heritability of IT from Nick Martin
Nick Martin
Nicholas Gordon Martin is a leading behavior geneticist who has published over 600 peer-reviewed articles on topics as diverse as the heritability of religion and intelligence to medical disorders such as endometriosis...
's group also demonstrated, however, that perceptual speed does not have a causal role in intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
, but rather that IQ and IT are distinct reflections of some shared biological processes.