Quotations about

Are there any identifiable psychological or physiological bases for human individual differences in measured intelligence? Despite the passing of some eighty summers since the invention of IQ tests, and despite ceaseless calls for psychology to 'go beyond' IQ to identify 'what the tests test', there is still little consensus in and around cognitive and differential psychology as to the nature and bases of intelligence itself. Intelligence has stimulated many attempts to specify its essence-e.g. 'learning ability', 'abstract reasoning ability', 'information processing ability' or just 'the capacity to adapt'; but no one such approach has caught on.
Hardened psychology-watchers will say there is nothing new in this. For psychologists have established no certain research method for proceeding to undertake such fundamental psychological analysis of any human ability or propensity. On the one hand there is macroscopic 'behaviour' (including test performances) that is too big and itself requires explanation in terms of its 'bases'; on the other hand there are (presumably, somewhere) the much-sought-after microscopic processes of low-level neuropsychology and computational cognitivism. What is hard is to find with any scientific authority is a level in between-a level at which talk of operating characteristics, goals and strategies (cf. abilities, desires and intentions) seems natural.
It is pretty easy to see what sort of research to do if it is desired to 'measure' an ability, to discover a treatment for a neurotic condition, or to enquire to what degree genetic and/or environmental factors furnish the developmental 'origins' of human psychological differences. Such psychometric, psychotherapeutic and psychogenetic questions present themselves together with straightforward methods relevant to answering them: count and correlate; experiment and observe; follow twins and adoptees. It is precisely psychology that is hard to do convincingly.
This difficulty may arise because 'folk psychology' already does quite a lot of the job so well (see Quotes VII).) Some may thus think it no shame to be uncertain about 'what intelligence really is'. Moreover, psychologists also draw a blank about what underpins or provides any basis for extraversion, authoritarianism, self-monitoring, sexual orientation and other important characteristics that are perfectly 'measurable' (given a little co-operation). Still, intelligence differences are arguably rather special amongst human psychological differences in being especially readily and reliably measured {see Quotes VIII}, in having had their origins very fully researched {see Quotes X}, in being demonstrably important {see Quotes XI} and in having understandably excited the interest of 'cognitive' and developmental psychologists {see Quotes XII and XIII}. To that extent, continuing uncertainty about its essential nature must remain something of a puzzle.
In part, the problem is that psychological fashions of explanation have changed repeatedly because of doubts as to the adequacy of any of them. Explanations invoking brain bumps, innate proclivities, types of conditioning, 'black boxes', neurotransmitters and 'interaction effects' have all worn thin. In addition, sustained application to explaining differences is hard to find within any of psychology's major explanatory paradigms or schools of thought. Nevertheless, in recent years (beginning with Hans Eysenck's classic theoretical paper about IQ and reaction time (1967, Brit.J.Educ.Psychol.)) increasing effort has been made to trace IQ differences to underlying differences in 'basic information processing abilities'. (More strictly, the effort relates to g differences, for g increases through childhood as well as distinguishing between children and between adults of the same chronological age-see Quotes VIII, X.) In particular, g has been linked to 'mental speed' of various kinds:
1) to overall speed of reaction to stimuli (RT);
2) to speed of choice- or decision-making (DT-which is choice RT minus the 'motor' component of how long it takes a subject to respond to the onset of a simple stimulus that does not require any choice to be made); and
3) to speed of intake of elementary perceptual information (especially 'inspection time' (IT)).
Broadly, the idea of Hans Eysenck, Arthur Jensen, Mike Anderson, Ian Deary, Con Stough and much of the rest of the 'London School' of psychology has been:
(i) that such speed differences are probably central to individual differences in 'fluid intelligence' (gf, the ability to solve new problems); and
(ii) that these differences in speed (and/or fidelity) of elementary information processing express themselves gradually, over the course of development, into further differences between people in 'crystallized general intelligence' (gc, knowledge and skills).
[Normally gf and gc correlate substantially, but gf declines in the average person from perhaps age 27 onwards (and markedly after age 55), while gc 'holds' relatively well-see Quotes XXI.]
Confronting such 'simplistic' theorizing about intelligence is a wide range of experts in subjects outwith differential psychology. Some are social environmentalists who balk at any story of g that lends itself to postulating substantial genetic origins for g differences. Other objectors are cultural relativists who suppose that cross-cultural comparisons in intelligence are odious and impossible because cultures are so different-thus intelligence can necessarily have no 'basis' in anything so cross-culturally measurable as 'mental speed' or performance on 'elementary cognitive tasks'. Some objectors are developmental psychologists who think of intelligence as a multi-faceted 'construction'-more like gc than gf (see Quotes XII). Still others are cognitive psychologists who liken the human mind to a computer, study memory and language in psychology students, decline to insist on reliable tests for use with the general population, and thus claim that they alone are pursuing the question of what intelligence really is (see Quotes XIII).


For more coverage of the psychology of intelligence,
and in particular of 'inspection time', see:
BRAND, C.R. (1996). The g Factor.
Chichester : Wiley DePublisher.
[The book was first issued, in March, but then withdrawn by the 'publisher' because it was deemed to have infringed modern canons of
'political correctness.']

For a Summary of the book, Newsletters concerning the
de-publication affair, and others' comments
and reviews, see the Internet URL sites:

For Chris Brand's 'Get Real About Race!'-his popular exposition of his views on race and education in the Black
hip-hop music magazine 'downlow' (Autumn, 1996)-see:



(i) The problem of finding a research-based or scientific answer to the question 'What is intelligence?' 5

(ii) Some answers. - g is not alone! 7

(iii) Is intelligence (whether operationalized as IQ, Mental Age or g) associated with faster reaction times (RTs)? 10

(iv) Is g associated not so much with 'output' as with 'intake' speed? 15

(v) What progress, if any, has been made towards linking intelligence differences to physical parameters
- and especially to central nervous system structure and function? 22

(vi) Might 'cognitive psychology' provide the answer? 28


(i) The problem

"Three or four years ago we tested fifty members of the American Association for the Advancement of Science with the ordinary laboratory tests in sense discrimination, memory, accuracy of movements and the like. They did not do as well as ordinary college students. ....As I understand you now, your view is that if we got an accurate measure of the common element in all varieties of sense discrimination, it would correlate perfectly with intelligence, the fact being that the different varieties of sensory activity agree together only in a general core or kernel of intellect itself. If this were the case, I should interpret it as follows: that in measuring any sensory activity we measured a complex of the mere sensory capacity and of the capacity to understand instructions, to be attentive and ambitious, and to use all the clues that might be available in making the sensory judgments."
E.L.THORNDIKE, 1904, letter to Charles Spearman, published in
R.B.Joynson, The Burt Affair. London : Routledge, 1989.

"[I have not meant to say] that general intelligence was based on sensory discrimination, if anything vice versa. I take both the sensory discrimination and the manifestations leading a teacher to impute general intelligence to be based on some deeper fundamental cause."
C.SPEARMAN, circa 1908, quoted by C.Burt, 1909-10,
British Journal of Psychology 3.

"Observationally, one can say little more about intelligence than that it is what the tests test."
Helen PEAK & Edwin BORING, 1926.

"Since the beginning of the present century, a somewhat heated, and not a little confusing, controversy has been going on among psychologists regarding the nature of intelligence."

"Psychology now seems to find itself in the paradoxical position of devising and advocating tests for measuring intelligence, and then disclaiming responsibility for them by asserting that "nobody knows what the word really means"."

"The short answer to the question, 'What is intelligence?' is that we are just not sure."
D.W.PYLE, 1979.

"Experimental psychologists, who claim to study the human mind, have been strangely loath to tangle with the concept of intelligence." N.J.MACKINTOSH, 1981.

"We may be able to measure intelligence, but we don't know what it really is."

"We have no really adequate theory of intelligence."
E.J.PHARES, 1984.

"....there has never been a measure that has been so ardently endorsed and widely validated and yet so pervasively controversial as IQ."
S.CECI, 1991, Developmental Psychology.

"Nothing in The Bell Curve angered me more than the authors' failure to supply any justification for their central claim, the sine qua non of their entire argument, that the number known as "g", the celebrated general factor of intelligence....captures a real property in the head."
S.J.GOULD, 1994, 'Curveball.' The New Yorker, 28 xi, p.143.

(ii) Some answers

"[Herbert Spencer's (e.g. 1855, The Principles of Psychology) view of the ontogeny, or individual development, of intelligence in humans, from birth to maturity, is that it has three main aspects: (a) an increase in the accuracy of inner adjustments to outer demands, (b) an increase in the number of items of simple knowledge, and (c) an increase in the number of items of consciousness of the external environment. The idea of accuracy of perceptions was likely a precursor of Francis Galton's (1912-1911) emphasis on sensory discrimination as a measure of intelligence...."
A.R.JENSEN, 1987, In J.A.Glover & R.R.Ronning, Historical Foundations of Educational Psychology. New York : Plenum.

"Geniuses are commonly believed to excel other men in their power of sustained attention. - But it is their genius making them attentive, not their attention making geniuses of them."
William JAMES, 1890.

"What we call intelligence in the narrow sense of the term consists of two chief processes: first, to perceive the external world, and then to re-instate the perceptions in memory, to rework them and to think about them."
Alfred BINET, 1890.

"The present results support the hypothesis....that the efficiency of a man's equipment for the specifically human task of managing ideas is only loosely correlated with the efficiency of the simpler sensori-motor apparatus which he possesses in common with other species." E.L.THORNDIKE, W.LAY & P.R.DEAN, 1909, American Journal of Psychology 20.

"[Intelligence-test scores] tell us the extent to which a person has become familiar with the vocabulary, the preferred thinking styles, and the current intellectual problems of western, middle-class society."
Jerome KAGAN, 1975.

"I regard the attempt to identify the "essence" of a g factor as hopeless."
J.B.CARROLL, 1976.

"....the search for a 'true', single information-processing function underlying intelligence is likely to be as successful as the search for the Holy Grail."
Earl HUNT, 1980, British Journal of Psychology 71.

"Mental testing is in fact a subject devoid of scientific interest."

"....regarding IQ tests as measures of 'intelligence' is nonsensical. ....The Jensen data on reaction times seem to me inherently implausible."
L.J.KAMIN, 1981.

"I did not expect impressive correlations of latency parameters from very simple tasks with global or factor scores from very complex [IQ] tests, and the correlations have not, in fact, been impressive. They have generally been at the same meagre level - roughly from .20 to .40 - as the so-called "personality coefficients"(Mischel, 1968) that have plagued the literature on relationships between personality tests that supposedly measure the same or similar things."
R.J.STERNBERG, 1981, Journal of Educational Psychology.

"Many a researcher has wasted his life in pursuit of a "speed" measure of intelligence."
J.P.DAS et al., 1981, in M.Friedman, J.P.Das & N.O'Connor,
Intelligence and Learning. New York : Plenum.

"Correlations between psychometric measures of ability and information-processing operations have hovered around .30."
L.A.COOPER & D.T.REGAN, 1982, in R.J.Sternberg, Handbook of
Human Intelligence
. Cambridge University Press.

"If we ignore "g" and its relatives, I think they will go away."
D.K.DETTERMAN, 1982, Intelligence 6.

"Just a few years ago, students were being taught that measures of basic processes did not correlate with intelligence.... ....there can now be little doubt that basic cognitive tasks do correlate substantially with more traditional measures of intelligence."
D.K.DETTERMAN, 1984, Contemporary Psychology.

"Intelligence is mental self-government. ....Intelligence must legislate, execute and evaluate. ....My own triarchic theory would probably best be characterised as a modified, federated oligarchy."
R.J.STERNBERG, 1986, in R.J.Sternberg & D.K.Detterman,
What is Intelligence? Norwood, New Jersey : Ablex.

"Analytically, intelligence appears to be a metaphor of heterogeneous capacities, abilities and performance (i.e. problem-solving, language and learning ability, mental states or others), rather than something per se."
A.FASOLO & G.MALACARNE, 1986. Paper read to the NATO Conference on the Evolutionary Biology of Intelligence, Poppi, Italy.

"Intelligence is not an entity within the organism, but a quality of behaviour. ....Within the human species, intelligence comprises that combination of cognitive skills and knowledge demanded, fostered and rewarded by the particular culture within which the individual becomes socialized."
Anne ANASTASI, 1986, in R.J.Sternberg & D.K.Detterman,
What is Intelligence? Norwood, New Jersey : Ablex.

g is not alone!

"There is no single theory of heat, but two rather different theories, the thermodynamic and the kinetic.... There is no unified theory of heat, and ultimately heat is defined in terms of the measuring instruments used - very much as intelligence is.... Furthermore, different ways of measuring temperature do not give the same results.... The measurement of intelligence is beset with the same problems and difficulties as the measurement of heat or any other physical quality."
H.J.EYSENCK, 1981.

"No-one has yet been able to say what electricity is."
H.C.FUNK, 1982, Milton Weekly Tribune.

"What is light? What is matter? ....a recently completed experiment goes so far as to indicate that these questions might have no answers at all."

"We are frequently warned of the danger of reifying g, but it is never made very clear just what this might mean. Is there a danger of reifying the physicist's concept of energy, which is also an abstract theoretical construct? One and the same energy is assumed to be manifested in various forms, such as "kinetic", "chemical" and "potential" energy. Is the physicist guilty of reification when the concept of gravitation enters into his explanation of certain physical events? For nearly a century the gene was a hypothetical construct, quantitative genetics and population genetics ere developed entirely in terms of this construct."
A.R.JENSEN, 1985, at Buros-Nebraska Symposium on Testing.

"....intelligence is observable. It is not a capacity. Height measures taken during the period of physical development are not interpreted as a fixed capacity for growing in stature."
L.G.HUMPHREYS, 1985, in B.Wolman, A Handbook of Intelligence. New York : Wiley DePublisher .

"Gould denies the reality of g on the grounds that g isn't literally a thing in the brain, but this argument confuses reality with thinghood. Solubility, after all, is an empirically real property of sugar cubes although it is not a "thing" spatially inside them.... We now identify solubility with a certain arrangement of atoms, but we have little idea of the arrangements of neurons with which intelligence is to be identified. This no more shows a weakness in our present idea of intelligence than ignorance of atomic theory centuries ago implied weakness in the then current idea of solubility."
M.LEVIN, 1990, Journal of Social, Political and Economic Studies 15.

(iii) Is intelligence speed of reaction?

"If intelligence is conceived of as speed of information processing, then simple reaction time [recognizing the arrival of one particular stimulus], involving zero bits of information, should not correlate with intelligence, but the slope of the regression line, showing increase of reaction time with amount of information processed, should correlate (negatively) with intelligence... Experimentally, the prediction has been tested.... Reaction time experiments, properly interpreted, do not appear to contradict a theory of intellectual functioning based on the notion of mental speed."
H.J.EYSENCK, 1967, British Journal of Educational Psychology 37.

"University students show faster reaction time (RT) than vocational college students, who are in turn faster than unskilled factory workers, who are faster than the mentally retarded.... It already appears that something approaching half the total variance in g can be accounted for purely in terms of individual differences in RT (and in its associated intra-individual variability) to a few elementary cognitive tasks."
A.R.JENSEN, 1984, Behavioral & Brain Sciences 7.

"The sensitivity of simple oculomotor Reaction Time to presumed neuropathological status supports the hypothesis that RT performance accesses a cardinal functional dimension of the central nervous system."
F.J.PIROZZOLO & E.C.HANSCH, 1981, Science 214.

"The N-weighted mean [of 35 correlations from 29 independent samples, involving a total N of 1,558] between RT slope and "IQ" is -.117.... To be sure, these are small correlations, although they are significant beyond the .001 level."
A.R.JENSEN & P.A.VERNON, 1986, Intelligence 10.

"The twelve WISC-R subtests' correlations with RT slope were correlated +.80 with the subtests' g loadings...."
A.R.JENSEN, 1987, in S. & C. Modgil, Arthur Jensen:
Consensus and Controversy
. Brighton : Falmer.

"[R.L.Thorndike's (1987, Person.&Indiv.Diffs.8) finding of a g-loading of .58 for discrimination reaction time] indicates the central role which reaction time plays in whatever is common to tests of cognitive ability, certainly no-one would have predicted on the basis of current environmentalistic theories of intelligence, emphasizing social learning, that discrimination reaction time would be a better measure of general ability (as measured by the Guilford tests) than would be reading, comprehension, general information, or judgement! Findings such as these demand an explanation in theoretical terms, and it is interesting that this important finding has been completely disregarded by writers in the field up till now." H.J.EYSENCK, 1988, Intelligence 12.

"A correlation between speed of information processing, as measured by reaction time on various elementary cognitive tasks and....psychometric g is now well established. ....The average speed of information processing on [a Semantic Verification Task - checking whether the letter 'A' precedes 'C' in screened displays of three letters] is about thirty per cent greater in the gifted than in their siblings...." A.R.JENSEN et al., 1989, Personality & Individual Differences 10.

"In the early 1970's many investigators conducted studies of various cognitive tasks given in conjunction with more conventional paper-and-pencil cognitive ability tests. Illustrative work may be cited: Hunt et al.'s (1973, in G.Bower, The Psychology of Learning and Motivation) correlational studies of several cognitive tasks as related to performance on verbal and quantitative sections of the Scholastic Aptitude Test, and later a major factor-analytic study by Hunt, Lunneborg and Lewis (1975, Cognitive Psychology 7), Chiang and Atkinson's (1976, Memory & Cognition 4) study of two short-term memory tasks as related to S.A.T. scores, Hundal and Horn's (1977, Applied Psychological Measurement 1) factor-analytic study of mental abilities and short-term memory performances, and Jensen's (1979, Creative Science & Technology 2) study of simple and choice reaction times as related to intelligence test scores."
J.B.CARROLL, 1993, Human Cognitive Abilities.
Cambridge University Press.

"....in the year of publication of his work On the Origin of Species, Charles Darwin wrote...."I suppose I am a very slow thinker." His son Francis remarks that Charles Darwin "used to say of himself that he was not quick enough to hold an argument with anyone, and I think this was true."
J. R. BAKER, 1974, Race. Oxford University Press.

"Binet found that his daughters and their small friends had average reaction times about three times longer than typical adults', but with greater variability. On some trials, the children responded just as quickly as adults, but on others they were slower. Since the children could sometimes match the adult speed, Binet concluded that the crucial factor differentiating children from adults was not reaction time per se, but rather the ability to sustain attention to the task."
R.E.FANCHER, 1985, The Intelligence Men. New York : Norton.

"....mean reaction time is an almost worthless measure for assessment of individual differences."
P.M.A.RABBITT, 1982.

"[Apparently] few age differences in speed of processing for simple visual forms exist from kindergarten to adulthood."
F.J.MORRISON, 1982, Journal of Experimental Child Psychology 34.

"....Jensen forgets the problem of positive bias inherent in any meta-analysis: studies that do not result in rejection of the null hypothesis are not as likely to be submitted for publication, and, if they are submitted, they are not likely to be published."
L.E.LONGSTRETH, 1986, Intelligence 10.

"Factor analytic studies of the WAIS-R subscales reveal the existence of a performance or nonverbal (visual motor, space-perception, etc.) organisation component (Wechsler, 1958). A significant portion of the variance in the relation between Decision Time and IQ [here found to be -.34 in 28 college students] may be due to this factor."
M.A.SMALL et al., 1987, Journal of Genetic Psychology 148.

"One can only conclude that the evidence for relations between reaction time(RT) and motor time(MT) variables and intelligence is mixed and incomplete. ....My hunch is that many [of Jensen's] RT and MT findings can be explained by supposing that lower-IQ individuals are less capable of meeting the attentional requirements of the RT-MT task."
J.B.CARROLL, 1987, in S. & C. Modgil, Arthur Jensen:
Consensus and Controversy
. Brighton : Falmer.

"Recent claims of linear relationships between mean RTs and RT variance, and between both of these factors and chronological age and IQ test scores, fail to replicate after very intensive testing. ....[Other experiments] show that while IQ test scores correlate strongly with practised performance on complex interactive video-games, these associations mainly reflect individual differences in rates of acquisition of complex control relationships, and differences in strategic management of complicated scenarios. They only very weakly reflect individual differences in simple information processing rate. The implications of these data for models of individual differences in skilled performance, and for recent re-evaluations of theories of intelligence, are discussed with some relish."
Patrick RABBITT, 1988, to 24th International Congress of
Psychology, in Sydney (S492).

"[Our] correlations between Scholastic Aptitude Test (SAT) scores and Reaction Time (RT) and Motor Time(MT) intercept and slope estimates are consistent with the hypothesis that correlations between Hick parameter estimates and measures of mental ability or achievement occur because of ability-related differences in automatization of responding to the task, rather than being due to ability-related differences in rate of execution of elementary mental operations. The results from the present study call into question the typical interpretation of findings related to the Hick paradigm...."
K.F.WIDAMAN & J.S.CARLSON, 1989, Intelligence 13.

"[In view of the reports by Kyllonen & Christal (1989, Intelligence 14) and Carpenter et al. (Psychol. Rev. 97)] one is allowed to speculate....whether the general factor presumably measured by the Raven Progressive Matrices test is principally a measure of the capacity of working memory.... [However,] as yet there has not been sufficient work on measuring working memory, and the validity and generality of the concept have not yet been well established in individual difference research."
J.B.CARROLL, 1993, Human Cognitive Abilities.
Cambridge University Press.

"It is generally agreed by philosophers of science that important contributions which have a revolutionary impact on science are often methodologically inadequate, reveal many anomalies, and may indeed be factually erroneous."
H.J.EYSENCK, 1987, replying to J.B.Carroll (1987) {above} in S.& C.Modgil, Arthur Jensen: Consensus and Controversy. Brighton : Falmer.

"In his "specificity of mind" view, Ceci (1990) asserts that relationships between microlevel processes (measured by elementary cognitive tasks (ECT's)) and macrolevel processes (assessed through psychometric intelligence tests) are only due to their sharing a common knowledge base....[We found that] high speed of information processing in ECTs is related to high psychometric intelligence. All three ECTs involving different knowledge bases (verbal, numerical, figural) correlated significantly with all three content factors in the Berlin Model of Intelligence Structure (BIS). This rather supports the "singularity of mind" view."
A.C.NEUBAUER & V.BUCIK (Karl-Franzens University, Graz), 1995, 'The mental speed - IQ relationship: singularity or specificity of mind?' From the abstract of an address to International Society for the Study of Individual Differences, meeting in Warsaw.

(iv) Is intelligence related to speed of 'intake' of information
- i.e. to 'sensory reaction time' or 'inspection time'?

"Aquinas made the interesting but questionable observation that 'those who have the best sense of touch have the best intelligence.' It is interesting to note that Spearman, in his first investigation into intelligence [1904, Am.J.Psychol.] found that sensory discrimination, including tactile discrimination, correlated well with general intelligence."
L.S.HEARNSHAW, 1987, The Shaping of Modern Psychology. London : Routledge.

"The trials I have as yet made on the sensitivity of different persons confirm the reasonable expectation that it would on the whole be highest among the intellectually gifted."
Francis GALTON, 1883.

"The discovery that there were individual differences in the time needed to perceive a stimulus was made by James McKeen Cattell while he was carrying out investigations for his Ph.D. in Leipzig. ....Cattell's concern was that the reaction time was too 'motor' and that the elements of the reaction time would reveal more about the timing of mental events. Cattell devised his "perception time" as the time needed to make a single discrimination, i.e., the time needed to see, freed of all constraints to respond quickly....
[He reported] "I tried to make the determinations on two rather obtuse porters, but their consciousness did not seem able to take up at all such delicate impressions. They required three times as long as educated people to read a word."
I.J.DEARY, 1988.

"A reasonable conclusion from the research on visual masking [in adulthood] is that the rate of processing visual stimuli is slower with increased age."
T.A.SALTHOUSE, 1982, Adult Cognition: an Experimental Psychology
of Human Ageing
. New York : Springer.

"Dempster (1981, Psychol.Bull.) examined ten possible sources of individual and developmental differences in [memory-span] performance. ....His conclusion was that only item identification [i.e. recognition speed] appeared to be a major source of such differences."
M.S.HUMPHREYS, 1983, Individual Differences in Cognition 1.

"Amongst young children (of ages six to twelve years), recent studies....have found correlations of about -.60 between Inspection Time and raw scores [i.e. Mental Age] on Cattell's Culture Fair Test of Intelligence. ....At least it is clear that the reported IT/IQ correlations do not lend themselves to being explained as socio-cultural constructions that reflect Western capitalism's demands for and differential stimulation of intelligence."
C.R.BRAND, 1984, in C.J.Turner & H.B.Miles, The Biology of Human
. North Humberside : Nafferton Books.

"....perhaps psychologists would have come to understand g earlier if they had considered that, in English, the term 'intelligence' has particular reference to information-gathering (as in its classic military usage) rather than to the final use of such information, which is often distorted by features of motivation and temperament."
C.R.BRAND, 1984, in J.Nicholson & Halla Beloff,
Psychology Survey 5. Leicester : British Psychological Society.

"....measures of 'inspection time' (IT) for extra-elementary displays continue to show strong correlations (of around -.60) with measures of IQ and mental age."
C.R.BRAND, 1985, Behavioral & Brain Sciences 8.

"Several studies (Bornstein & Sigman, 1986; Rose & Slater, 1986) have established that looking time [the duration for which novel material is inspected by an infant] is strongly [inversely] related to....later IQ. It is a curious relationship, given the simplicity of the earlier ['looking time'] measures and the very general nature of the IQ test."
P.E.BRYANT, 1992, Nature, 27 viii.

"Inspection Time may reflect subtle cognitive factors, associated with the encoding of stimulus elements, that can influence mental speed."
Quarterly Journal of Experimental Psychology 34A.

"What we fear is that research on attentional contributions to intelligence could experience a fate similar to that of some of the research on basic information-processing determinants of ability: namely, establishing that individual differences exist, but not knowing what those individual differences really mean."
L.A.COOPER & D.T.REGAN, 1982, in R.J.Sternberg,
Handbook of Human Intelligence. Cambridge University Press.

"Inspection Time appears to be a threshold variable which can successfully distinguish retarded and non-retarded samples, while within either group, or at least within a group of above-average intelligence, it does not appear to correlate with measures of intelligence nor with other measures of cognitive processing."
P.A.VERNON, 1983, Intelligence 7.

"Brand and Deary (1982) have reported some extremely high correlations (around -.80) between IQ and a measure derived from reaction time needed to indicate the longer of two vertical lines. They refer to the time needed to do this task as "inspection time". Although these correlations seem most impressive at first, they were derived from very small samples of subjects, who often differed extremely widely in IQ, ranging from the mentally retarded to the gifted. Using more typical samples, other investigators, such as Nettelbeck (1982, Qu.J.Exptl Psychol.), have obtained the more typical level of correlation for tests of choice reaction time (about -.30)."
R.J.STERNBERG, 1985, in R.J.Sternberg, Human Abilities.
New York : Freeman.

"....our impression is that the relation between intelligence and IT is not very clear, particularly due to the great variability in results."
Marie-Paule LUBIN & Jose Muniz FERNANDEZ, 1986,
Personality & Individual Differences 7.

"Reports of very high (.60) correlations between IQ and measures of timed performance have not been substantiated and can usually be attributed to the inclusion of disproportionate numbers of retarded subjects in the samples."
N.J.MACKINTOSH, 1986, British Journal of Psychology 77.

"If anything, the essence of intelligence would seem to be in knowing when to think and act quickly, and knowing when to think and act slowly."
R.J.STERNBERG, 1987, in S. & Celia Modgil, Arthur Jensen:
Consensus and Controversy.
Brighton : Falmer.

"Inspection Time was not significantly related to IQ or to any of the WAIS subtests among strategy users [i.e. among subjects who could 'penetrate the backward mask']. In the non-users, however, Inspection Time was highly correlated with Performance IQ and with scores on two of the subtests."
B.MACKENZIE & Elizabeth BINGHAM, 1985,
Australian Journal of Psychology 37.

"We are 'Doubting Thomases' no more. The association between visual inspection accuracy as measured in a backward-masking paradigm and IQ appears to be more than the predictable consequence of small and heterogeneous samples."
L.E.LONGSTRETH et al., 1986,
Personality & Individual Differences 7.

"The most important point to emerge from these three studies is that inspection time is related to IQ differences in children. Further, the relationship holds across four chronological years and when the effects of Mental Ages (MA) are removed.... It must be emphasized that the sample is composed of normal school children and that this effect cannot be attributed to the inclusion of any mentally retarded subjects.... [The results suggest that] the reason for the IT/IQ correlation is that both measures are related to fundamental aspects of information processing, rather than the contents of knowledge structures."
M.ANDERSON, 1986, Personality & Individual Differences 7.

"The apparent independence of Inspection Time from the effects of previous experience, its impressively high reliability of .87 in the whole sample, and its substantial correlation of .66 with the measure of intellectual level in a specifiable part of the whole subject sample, jointly confirm the promise of the measure as a tool for experimental research on intelligence."
Personality & Individual Differences 7.

"....it is not clear that low-IQ subjects suffer from commonplace attentional failures that could simply lengthen their ITs: even mentally subnormal subjects are quite capable of near-perfect performance on IT-like tasks so long as target stimuli are exposed for more than a fifth of a second."
C.R.BRAND, 1987, in S. & Celia Modgil, Arthur Jensen:
Consensus and Controversy.
Brighton : Falmer.

"Results [of our experiments] indicate that college students differ in performance on a very simple auditory recognition task, and that as much as 25% of this variability is predictable from differences in IQ. Given the simplicity of the task, little room remains for variability related to differences in reasoning or strategy selection.... Galton's (1883) suggestion of an important link between 'the avenue of the senses' and good sense may be not as far-fetched as previously supposed."
Personality & Individual Differences 8.

"....inspection time (a paradigm invented by T.Nettelbeck & M.Lally, 1976, Brit.J.Psychol.) is highly correlated (negatively) with IQ, enabling high-IQ subjects to correctly perceive very simple precepts presented very rapidly, such as the respective length of two lines. The most recent studies (unpublished) on the topic indicate that correlations in the .50's can be obtained from large random samples."
H.J.EYSENCK, 1987, in S. & C. Modgil, Arthur Jensen:
Consensus and Controversy.
Brighton : Falmer.

"....evidence [from some thirty studies] suggests a correlation of -.50 between IT and IQ among normal adults - higher than has generally been found between IQ and [other] laboratory procedures for measuring speed of information processing. Results from children are not clear with respect to an IT-IQ correlation, but strongly support the theory that mental speed increases with mental age. In broad terms, therefore, the outcome is consistent with Brand's theory but does not support speculation that IT might supplement or replace existing psychometric procedures."
T.NETTELBECK, 1988, in P.A.Vernon, Speed of Information-
Processing and Intelligence
. Norwood, New Jersey : Ablex.

"....IT presents many advantages as a test of basic processing speed. IT shows little practice effect and may be used in repeated testing.... IT continues to remain one of the few correlates of general mental ability that has not been accused of some kind of bias. Unlike RT, IT has the appearance of a task that indexes one basic process: the speed of intake of sensory information. Unlike Average Evoked Potential {see below}, IT may be tested relatively quickly by workers using non-specialist equipment."
I.J.DEARY, 1988, Human Evolution 3.

"Despite....only moderate reliability in the measuring procedures, the correlation between IT and raw scores on the WISC-R [in 47 six-year-old children of mean IQ 113, s.d. = 10] was -.57.... We believe that control processes are involved, so that the "mental speed" indexed by IT is probably not a primary characteristic of some sampling mechanism but, instead, a secondary consequence of less efficient information processing."
Personality & Individual Differences 10.

"[My] conclusion is that there are attentional influences on IT performance, but they detract from, rather than induce, the relationship between IT, age and intelligence." M.ANDERSON, 1989, Personality & Individual Differences 10.

"An association between g and encoding speed can account for many of the cognitive correlates of g, such as the Posner NI-PI measure (Keating & Bobbitt, 1978), inspection time, and even digit span, which appears to depend on speed of item identification (Dempster, 1981)."
G.MATTHEWS & Lisa DORN, 1989, Intelligence 13.

"[Our] results challenge Mackintosh's (1986, Brit.J.Psychol.), Todman and Gibb's (1985, Brit.J.Psychol.) and Vernon's (1986, Person.& Indiv.Diffs.) suggestions that the IT-IQ correlation depends on the inclusion of retarded subjects. When the IT-IQ correlations were corrected for restriction of ability range, the correlations became slightly larger than the -.50 result predicted by Nettelbeck (1987, in P.A.Vernon, Speed of Information-Processing and Intelligence)."
Personality & Individual Differences 10.

"In general, the pattern of correlations of subjects' IT estimates with the parameters of the P200 and P300 components of their Average Evoked Potentials of the brain {see below} to the IT stimuli....argues strongly for the view that the IT measures the speed of that stage of information processing at which the stimulus is encoded or transferred into Short Term Memory from a sensory register...."
Personality and Individual Differences 10.

"The information-processing implications of habituation [to a novel stimulus] and its individual differences and reliability together suggest that habituation in infancy may harbor concurrent or predictive validity for cognitive functioning in childhood.... Infants and young children who habituate efficiently tend also to prefer complexity, show advanced sensorimotor development, explore their environment more rapidly, play in relatively sophisticated ways, solve problems quickly and attain concepts efficiently, and excel at oddity identification, picture matching, and block configuration in traditional tests of intelligence. Further, infants who are expected to differ in intelligence in later life show commensurate individual differences in habituation of attention. Perinatal risk adversely affects habituation, and trisomy-21 is associated with less efficient habituation."
Marc H. BORNSTEIN, 1989, Seminars in Perinatology 13.

"Inspection Time was measured {in 91 testees of IQ's ranging quite widely around 110} using a curve-fitting procedure that was less susceptible to variable task performance. IQ correlated significantly with I.T. (r = - .624), and Odd-Man-Out decision time (DT = .365) as well as with CRT DT (r = .28)."
T.C.BATES & H.J.EYSENCK, 1993, Intelligence 17.

"It is not known for certain what the noncognitive component of RT consists of, most of it is probably variance in the purely sensorimotor aspects of RT performance. This may also account for the generally higher g loading - about -.50 - of inspection time (i.e. the speed of making simple visual or auditory discrimination, which involves no motor component) than of RT based on any single elementary cognitive task."
A.R.JENSEN, 1994, 'Phlogiston, animal magnetism and intelligence.'
In D.K.Detterman, Current Topics in Human Intelligence 4: Theories of Intelligence. Norwood, NJ: Ablex.

"....when scores {of 107 secondary schoolchildren, IQ = 11} on the first unrotated principal component extracted from three auditory [discrimination] tests were correlated with the scores on the first unrotated [IQ] component extracted from the Mill Hill and Raven IQ's Pearson's correlation was .52."
I.J.DEARY, 1994, 'Intelligence and auditory discrimination.' Intelligence 18.

"[Richard] Gregory suggests that if visual perception is seen as involving active (though unconscious) decision-making, and not simply the passive registering of input, then we can attribute higher intelligence to perception."
Annette KARMILOFF-SMITH, 1994, Times Higher Educational Supplement, 21 x. (Reviewing Jean Khalfa(ed.) , What is Intelligence?, Cambridge University Press.)

"....habituation-based measures [of 'infant intelligence'] obtained from babies at ages ranging from three months to a year, are significantly correlated with the intelligence test scores of the same children when they get to be 2 or 4 or 6 years old (e.g. Columbo, 1993, Infant Cognition). A few studies have found such correlations even at ages 8 or 11 (Rose & Feldman, 1995, Develop. Psychol. 31). A....meta-analysis, based on 31 different samples, estimates the average magnitude of the correlations at about .36."
Extract from Intelligence: Knowns and Unknowns - Report of a Task Force established by the Board of the Scientific Affairs of the American Psychological Association, 1995. Washington, DC : APA Science Directorate.

(v) What could be the physical basis of intelligence (in the nervous system)?

"In the mentally defective the nerve cells are few in number, they have relatively few branches, and, as seen under the microscope, they are arranged in a relatively unsystematic and higgledy-piggledy fashion."
Cyril BURT, circa 1970, in C.James, Modern Concepts of
. 94, Chatsworth Road, Croydon : R.S.Reid.

"A .78 correlation (p<.005, one-tailed) was found between the edited String Length 256 [a measure of Average Evoked Cortical Potential-cf. D.E. & A.E. Hendrickson, 1980, Person.& Indiv.Diffs.] for ten subjects [having satisfactory inter-electrode resistances] and their total raw scores on the Alice Heim 4 Test of General Intelligence [across an IQ range of approximately IQ 105-140."
I.C.FRASER, 1984, Edinburgh University : Psychology Honours Thesis.

"I regard mental speed as a secondary consequence of differences among individuals in ability to process information accurately, inaccurate processing leads to delays and thus to longer latencies."
H.J.EYSENCK, 1984, Behavioral & Brain Sciences 7.

"The distinction between stimulus evaluation stages [of information processing] and response selection stages has been supported by brain event related potential (ERP) studies. The latency of the P300 component of the ERP is sensitive to changes in stimulus complexity but not to changes in response complexity...."
H.NAYLOR et al., 1985, Psychopharmacology 86.

"....the findings of the present study indicate that ACTH 4-9 may reduce temporal thresholds of recognition of single letters presented with a tachistoscopic technique. The results can be interpreted to indicate a beneficial effect of the peptide on automatic, pre-attentive levels of information processing involved in the transfer of information from the peripheral icon to the cortical centres, i.e. from iconic storage to short-term memory."
G.D'ELIA et al., 1985, Neuropsychobiology 13.

"....we should accept that elementary cognitive tasks such as choice reaction times, inspection times and EEG evoked potentials show stronger positive correlations with g than was previously believed."
Philip E. VERNON, 1985.

"Height, weight, cranial size, brain size, various blood groups, serum level in the blood, and basal metabolic rate are some of the researched [physical] correlates of IQ.... Intellectually gifted children, on average, are found to be much more myopic than their less gifted siblings.... Gifted children have more allergies than their siblings."
A.R.JENSEN, 1986, at a conference in Blackwood, Virginia.

"Intelligence, as the sum total of all cognitive processes, entails planning, coding of information, and attention / arousal. ....The structural basis for planning is the frontal lobes. ....The structural base for [coding] processes is the posterior part of the human brain.... An adequate level of arousal and attention is a prerequisite for coding and planning. The function is located in the brain stem."
J.P.DAS, 1986, in R.J.Sternberg & D.K.Detterman,
What is Intelligence? Norwood, New Jersey : Ablex.

"Changes of simple visual reaction time were analysed in two groups of unilaterally brain-damaged patients in order to evaluate to what extent properties of lesions, clinical parameters and experimental variables might influence speed of motor response. The results confirmed that brain damage, independent of its site, produces a retardation of speed."
A.TARTAGLIONE et al., 1986, Neuropsychologia 24.

"A most exciting recent discovery is the genetic link between Alzheimer's disease and Down's syndrome. G.C.Glenner and his colleagues....[have] demonstrated that the amyloid beta protein (a major component of the neurofibrillary plaque that accumulates in the brains of individuals with Alzheimer's disease) is identical with the protein that accumulates in apparently identical lesions in the brains of all individuals with Down's syndrome who are over 35 years old."
D.PATTERSON, 1987, Scientific American 257, viii.

"[In Alzheimer and control patients (Chase et al., 1984)] the correlations between overall resting cortical glucose use and IQ scores were [.68 for Full Scale IQ, .61 for Verbal IQ, and .56 for Performance IQ]."
I.J.DEARY, 1988, Mensa Research Journal(USA), No.24.

"A well-known drug, nicotine, was reported [at a conference of pharmacologists in Athens - see also Brit.Med.Journal, August 1991] to enhance certain aspects of test performance in patients early in the course of Alzheimer's disease. [Other results] indicate significant [nicotine-] dose-related improvements in performance in young volunteers and in [patients suffering Alzheimer-type dementia] [on a] test of rapid information processing."
T.W.ROBBINS, 1988, Nature 336, 17 xi.

"Performance on the Raven's Advanced Progressive Matrices showed significant negative correlations [around -.75, p <·05] with cortical metabolic rate. ....The results (with young adults)....suggest that there is an inverse relationship between abstract reasoning and glucose use in the brain as a whole."
R.J.HAIER et al., 1988, Intelligence 12.

"Willerman et al. (1989, paper to 19th Annual Meeting of Behavior Genetics Association, Charlottesville, Virginia) have reported a substantial relationship between magnetic resonance imaging (MRI) measurements of brain size and mental test scores in a college sample, controlling for sex and overall body size." A.R.JENSEN, 1989, draft paper 'Understanding g
in terms of information processing.'

"An analysis of IQ in relation to head size (and, by inference, brain size) was performed on some 14,000 children....at ages 4 and 7 in the National Collaborative Perinatal Project. Within each race x sex group, IQ is significantly correlated {at around .25} with head [circumference], age and body size having been partialled out..... There are both race and sex differences in head size, although the sex difference in IQ is nil."
A.R.JENSEN & F.W.JOHNSON, 1994, Intelligence 18.

"Over the past 3½ million years the brains of our hominid ancestors have more than quadrupled in size. The earliest australopithecine brain was not much larger than a modern chimpanzee's, little more than 400 cc. From then onwards there has been a more or less steady increase in brain volume through Homo sapiens and Homo erectus to modern Homo sapiens, which averages not much under 1800 cc in some populations. And stone artefacts indicate that human material culture has been increasing in complexity in step with the increase in brain volume."
C.B.GOODHART, 1995, The Galton Institute Newsletter, No. 16, iii.

"Thinking in terms of physiological processes is extremely dangerous in connection with the clarification of conceptual problems in psychology. Thinking in terms of physiological hypotheses deludes us sometimes with false difficulties, sometimes with false solutions. The best prophylactic against this is the thought that I don't know at all whether the human I am acquainted with actually have a nervous system."
L.WITTGENSTEIN, Remarks I 1063, cited by A.J.Ayer,
Ludwig Wittgenstein. London : Weidenfeld and Nicholson, 1985.

"....there are no data to indicate....that the brain is....a thinking and controlling organ and the locus of intelligence. The brain is no more responsible for an individual's psychological activity than the heart, lungs, stomach or endocrine system."
S.W.BIJOU & E.DINITZ-JOHNSON, 1981, Psychological Record 31.

"Even if IQ correlated perfectly with some physiological measure, what would this correlation tell us about (a) the cognitive processes that underlie intelligent behaviour, (b) what constitutes intelligent behaviour, or (c) why IQ tests themselves are so imperfect as predictors of intelligent behaviour in the real world? ....intelligence should be studied at multiple levels, with our goals being the ultimate linkage of these levels."

"A most promising development has been the correlation of some aspects of the auditory evoked potential with measures of intelligence. ....The size of [Blinkhorn & Hendrickson's, 1982] correlations (from .50 to .75 [between IQ and AEP]) is of the same order of magnitude as correlations between the subtests of an intelligence test. ....[However] this finding remains highly controversial. The relatively small size of the samples involved and the continuing lack of any confirmation of their two reports does not inspire confidence."
J.A.C.EMPSON, 1986, Human Brainwaves. London : Macmillan.

"There's no difference between your brain and the brain of an Einstein or a Mozart or a Shakespeare."
Stated in the first broadcast of the 'Open College' on
UK TV Channel IV, September, 1987.

"....the existence of manifest individual differences in speed or choice reaction time, whether in Jensen's task or others, does not imply isomorphic underlying differences in speed or reaction time at the neurological level."
R.J.STERNBERG, 1987, in S. & Celia Modgil, Arthur Jensen:
Consensus and Controversy
. Brighton : Falmer.

"....'natural frequency' [of electro-encephalographic patterns], expressed as radians per second, is a direct measure of the speed of thalamocortical transmission, and it is clear from the present findings that an intermediate speed of neural transmission is associated with higher IQ. Consequently, it seems that the speed of neural transmission would not provide a basis for explaining the frequently small but consistently negative correlations between RT and IQ or between IT and IQ."
D.L.ROBINSON, 1989, International J. Neuroscience 46.

"For neuroscientists, exploring the microscopic intricacies of the most complex object we know, attributing significance to gross measures of size is frankly vulgar. ....Rushton (1995, Race, Evolution & Behavior, Transaction) cites correlations [between brain size and IQ] of .38, .40 and .43. He does not, however, mention that the researchers who obtained the last of these figures found that correcting for age reduced it to .22, and further corrections for sex and head size made it all but vanish completely (Raz et al., 1993, Intelligence 17). The others provide more authentic support for his views, though that is unsurprising in the case of the .40 figure, since it was generated by colleagues of his at the University of Western Ontario."
Marek KOHN, 1995, The Race Gallery: the Return of Racial Science. London : Jonathan Cape.

"Now that links between features of the AEP and IT and IQ have been clearly established, it should be easier to argue productively about the mechanism underlying the correlations that have been observed."
Y.ZHANG, P.G.CARYL & I.J.DEARY, 1989, Person. & Indiv.Diffs. 10.

"The cortical event-related potential (ERP) waveform path length (string measure) - previously found by Hendrickson (1982, A Model for Intelligence) to correlate very highly with psychometrically assessed intelligence - was found in the present study to correlate significantly positively [though at a more modest .41] with intelligence test scores."
D.G.GILBERT, et al., 1991, Personality & Individual Differences 12.

"We found significant correlations between IQ and [the size of] many of the [brain] structures that were measured [in 67 normal Iowa adults of mean Wechsler IQ 116, standard deviation 14]. In all analyses, height was [partialled out] in order to correct for individual differences in body size. A significant positive [partial] correlation was observed between intracranial volume and....full-scale IQ (r = .38, p<.01).... Within subcortical brain regions, there was a differentiation between subcortical structures that subserve functions such as memory or language and those that subserve habit formation, motoric function, or emotional function. That is, a significant [partial] correlation was observed between intelligence and hippocampal volume [c. r = .37], but not between IQ and the volume of the caudate [c. r = .07, n.s.]."
Nancy C. ANDREASEN et al., 1993, Amer. Journal of Psychiatry 150.

"A variety of measures of EEG and of average evoked responses correlate with intelligence.... [However,] it is unlikely that any single index of brain electrical activity will provide a "biological measure of g" which can replace conventional tests of intelligence."
I.J.DEARY & P.G.CARYL, 1993, 'Intelligence, EEG and Evoked Potentials.' In P.A.Vernon, Biological Approaches to the Study of Human Intelligence, Norwood, NJ : Ablex.

"In the Daily Record of March 8, 1994 (definitely not April 1), an item entitled "Your Brains Are in Your Bum, says Doc" describes how psychologist Milton Sternes (ho ho) of Chicago, after a five-year study into intelligence and body shapes, has discovered that "people with ample behinds score an average 26 points higher on IQ tests" and has reported this in his book "Big Butt, Bigger Brains.""
Bill McPHILLIMY, 1994, 'Media Watch', Bulletin of the Scottish Branch
of the British Psychological Society.

"Further research [into the physical basis IQ differences] should be led on the right track by disentangling the cause of the confirmed correlation between glutathione peroxidase and IQ."
V.WEISS, 1995, from the abstract of an address to International Society for the Study of Individual Differences, meeting in Warsaw.

"Recent research on the relationship between brain volume (measured via magnetic resonance imaging, or MRI) and IQ has indicated a moderate positive correlation of about .40 between the two variables. The purpose of the present research is to further replicate this finding in a sample of 100 healthy adult males comprising 50 pairs of brothers...In 62 subjects (31 pairs of brothers) collected to date, it was found that brain volume correlated significantly with IQ (r = .277, p < .05...."
J.C.WICKETT, P.A.VERNON & D.H.LEE, 1995, from the abstract of an address to International Society for the Study of Individual Differences, meeting in Warsaw.

"Using data from magnetic resonance imaging (MRI), autopsy, endocranial measurements and other techniques, we show that (1) brain size is correlated with cognitive ability about .44 using MRI; (2) brain size varies by age, sex, social class and race; and (3) cognitive ability varies by age, sex, social class and race. ....it is clear that the direction of the brain-size/cognitive-ability relationships described by Paul Broca (1824-1880), Francis Galton (1822-1911) and other nineteenth-century visionaries is true, and that the null hypothesis of no relation, strongly advocated over the last half century, is false. ....Rushton & Osborne (1995, Intelligence 20) studied genetic and environmental contributions to cranial size among 236 pairs of adolescent twins [....and found the] genetic contribution to cranial size....ranged from 38% to 51%"
RUSHTON, J.P. & ANKNEY, C.D. (1996). 'Brain size and cognitive
ability: correlations with age, sex, social class and race.' Psychonomic Bulletin & Review 3, 1, 21-36.

(vi) Will cognitive psychology explicate g if other approaches have failed? {See also Quotes XIII.}

"Cognitive psychology, so called, is little more than a promise to pay, without evidence that there is any balance in the bank to meet creditors' demands."
H.J.EYSENCK, 1980.

"Research conclusions in artificial intelligence have shown that intelligence is equivalent to comprehension, i.e. the acquisition or construction of linguistic structures appropriate to the world of objects they represent. It has also shown that comprehension and learning are basically similar because both are mechanisms to build linguistic representations of meaningful information.... Intelligence is an information-gathering process as much as it is a search process.... Intelligence is the production of new information, i.e. to find new elements and relations to be added to the data bases stored in memory."
F.FRISCHKNECHT, 1986, Behavioural Science 31.

"There is really little argument among cognitive psychologists about the existence of a g or general intelligence factor. They would also support the existence of various narrower factors such as spatial ability. Any or all of these factors may indeed have temporal aspects, the question is how much the difference between high and low ability is manifested in processing time."
J.B.CARROLL, 1987, replying to H.J.Eysenck, in S. & C.Modgil,
Arthur Jensen: Consensus and Controversy. Brighton : Falmer.

"....the hard work is done by neuropsychology and differential psychology....yet cognitive psychology gets the credit."
I.J.DEARY, 1992, Nature 359, 3 ix.
(Reviewing M.Anderson, Intelligence and Development: A Cognitive
. Oxford Blackwell.)

Epilogue - continuing arguments

"....we believe that individual differences in performance on most measures of mental speed are determined more by differences in the quality of meta-componential processing than by differences in speed of performance components."
Diana B. MARR & R.J.STERNBERG, 1988, in P.A.Vernon, Speed of
Information Processing and Intelligence
. Norwood, NJ : Ablex.

"It is argued that the relationship between IQ and IT must be a power function (rather than a linear one), and the correlation between log IQ and log predicted IT was found to vary systematically as a function of the information in the inspected item, the greatest correlation (r = .87; p<.001) being for items containing about 15 bits - that is, items containing approximately the same amount of information as verbal material. This may mean that g is a measure of the time an individual takes to process verbal information."
P.HOLOHAN & H.V.SMITH, 1992, 'Individual differences in immediate
recall, inspection time and intelligence'.
Irish Journal of Psychology 13.

"....we do not, even now, know what intelligence tests measure, and we are equally hard put to say with any coherence what intelligence is."
P.E.BRYANT (Professor of Psychology, University of Oxford),
1992, Nature 358, 20 viii.

"....regarding IT as a 'pure' measure of general intelligence is probably no longer tenable. Nor is the use of IT motion after-effects demonstrably strategic in origin."
V.EGAN, 1994, British Journal of Psychology 85.

"Between 1884 and 1890, Galton operated a laboratory in the South Kensington Museum.... Though Galton never analyzed the data, Johnson et al. (1985, Amer.Psychol.) did and found them to be surprisingly consistent with [recent] data. {However,} Wissler (1901), a graduate student working with McKeen Cattell, was given {Cattell's data on line bisection, auditory RT, least perceptible difference between weights, two-point threshold and color naming in Columbia freshmen} to analyze [and concluded] "While the tests do seem to have some value when applied to children in the lower schools, they tell us nothing as to the general individual worth of college students or of adults." ....Sharp (1898) [a student in Titchener's laboratory] [found] no relationship between test results [memory, imagery, discrimination and attention] and academic performance [in seven fellow graduate students].... The graduate students obviously represented a highly curtailed range of intellectual ability, but no one seems to have recognized that this methodological problem would have substantially reduced the size of the correlations obtained. It is not surprising that Sharp did not realize the problem, because correlation was a new technique. It is surprising that many investigators today still make the mistake of using samples with curtailed ranges even though the effects of restricted ranges on correlation coefficients are well known."
D.K.DETTERMAN, 1994, 'Intelligence and cognitive abilities.'
In D.K.Detterman, Current Topics in Human Intelligence 4: Theories of Intelligence. Norwood, NJ: Ablex.

"Despite hundreds of factor analytic studies on psychometric g, we scarcely know more about its nature than did Spearman seventy years ago. Using elementary cognitive tasks (ECTs) to unpack its properties has also been disappointing, though some modest advances have been made."
L.WILLERMAN, 1995, address to International Society for the Study of Individual Differences, meeting in Warsaw.

"....it may be that bright subjects process approximately the same number of discrete stimuli per unit time (with normal attentional-blocking separating successive stimulus processing and attentional refixation cycles). The greatest advantage in g, then, may lie in high quality processing of stimuli at normal overall rates of presentation and attentional difficulty."
T.BATES (Univ. Auckland), 1995, from the abstract of an address to International Society for the Study of Individual Differences, meeting in Warsaw


(Compiled by Chris Brand, Dept. Psychology, University of Edinburgh.)

For more coverage of intelligence
and in particular 'inspection time, see:
BRAND, C.R. (1996) The g Factor.
Chichester : Wiley DePublisher.

"The nature and measurement of intelligence is a political hot potato. But Brand in this extremely readable, wide-ranging and up-to-date
book is not afraid to slaughter the shibboleths of modern "educationalists". This short book provides a great deal for thought
and debate."
Professor Adrian Furnham, University College London.
The book was first issued, in February, but then withdrawn, in April, by the 'publisher' because it was deemed to have infringed modern canons of
'political correctness.'
It received a perfectly favourable review in Nature (May 2, 1996, p. 33).

For a Summary of the book, Newsletters concerning the
de-publication affair, details of how to see the book for scholarly purposes, and others' comments and reviews,
see the Internet URL sites:

For Chris Brand's 'Get Real About Race!'-his popular exposition of his views on race and education in the Black
hip-hop music magazine 'downlow' (Autumn, 1996)-see:

A reminder of what is available in other Sections of 'P, B & S.'

Summary Index

(This resource manual of quotations about individual and group differences, compiled by
Mr C. R. Brand, is kept on the Internet and in Edinburgh University Psychology Department Library.)
Pages of Introduction
3 - 11 Full Index, indicating key questions in each Section.
12 - 14 Preface. - Why quotations? - Explanations and apologies.
15 - 51 Introduction: Questions, Arguments and Agreements in the study of Personality.
Some history, and a discussion of 'realism vs 'idealism.'
52 - 57 Introductory Quotes about the study of personality.
General problems
1 'Situational' vs 'personological' approaches to human variation.
2 'Nomothetic' vs 'idiographic', 'subjective' and relativistic approaches.
3 Personality dimensions - by factor analysis and otherwise.
4 'Superstructure' and 'infrastructure' - the 'mind/body problem'.
5 Nature vs Nurture? - Or Nature via Nurture?
6 The role of consciousness in personality and 'multiple personality'.
7 The 'folk psychology' of personality components.
8 The measurement of intelligence. - Does g exist?
9 The bases of intelligence. - What is the psychology of g?
10 The developmental origins of g differences. - The nature and nurture of g.
11 The importance of intelligence. - The psychotelics of g.
12 Piagetianism: Kant's last stand?
13 Cognitivism: 'The Emperor's New Mind?'
14 Neurosis, emotion and Neuroticism.
15 Psychosis, psychopathy and Psychoticism.
16 Crime and criminality.
17 Genius and creativity.
Popular proposals - psychoanalytic, phrenological and prophylactic
18 Psychoanalysis: 'Decline and Fall of the Freudian Empire'?
19 Hemispherology: a twentieth-century phrenology?
20 Psycho-social Engineering: therapy, training or transformation?
Group differences
21 Age and ageing - especially, the role of g in 'life-span development'.
22 Psychological sex differences. - Do they exist? Must they exist?
23 Social class. - Does it matter any longer?
24 Racial and ethnic differences. - Their role in 'lifestyles' and cultural attainments.
Ideological issues
25 The psychology of politics and ideological extremism.
26 The politics of psychologists and allied co-workers.
27 Equality and Community: the 'utopian' package of political aims.
28 Freedom and Responsibility: the 'legitimist' package of political aims.
Pragmatic questions
29 Carry on differentializing?
30 Carry on psycho-testing?
Appendix: Factor analysis. - 'Garbage in, garbage out'?


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