general mental ability john manning. overview history of general mental ability definition, models...
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General Mental Ability
John Manning
Overview History of General Mental Ability
Definition, Models Measures of GMA Applications
GMA and Job Performance Individual Differences
Race, Gender, Age Alternatives?
What is GMA? It goes by many names: g, general mental
ability, IQ, intelligence A general measure of cognitive functioning
that should work across several different domains
First proposed by Francis Galton (1888), an English geneticist and relative of Darwin
Spearman (1904) proposed “g”- a general underlying intelligence factor that accounted for correlations between different areas on measures of intelligence.
It remains one of the most studied of all human characteristics
Spearman’s g Model and later models
Just how positively correlated are these subdimensions?
1 2 3 4 5 6 7 8 9 10Science 1.00Arithmetic 0.73 1.00Word knldg 0.82 0.72 1.00Paragraph 0.72 0.70 0.82 1.00Numeric 0.57 0.63 0.65 0.64 1.00Coding 0.51 0.55 0.60 0.61 0.72 1.00Auto+shop 0.68 0.59 0.61 0.51 0.38 0.33 1.00Math knldg 0.70 0.82 0.69 0.67 0.62 0.54 0.47 1.00Mech comp 0.71 0.70 0.64 0.57 0.45 0.41 0.75 0.62 1.00Electronic 0.77 0.68 0.72 0.63 0.47 0.42 0.76 0.60 0.75 1.00
Source: National Longitudinal Study of Youth ASVAB Scores, sample size is 11878 test takers
Factor Eigenvalue Difference Proportion Cumulative1 6.40 5.64 0.91 0.912 0.76 0.54 0.11 1.023 0.22 0.08 0.03 1.054 0.14 0.16 0.02 1.07
Correlation between the supposedly distinct ACT and SAT?R=0.91; R2=0.82
General mental ability and stability
The genetic inheritance of GMA Two statistics:
h2 (genetic effect) c2 (shared effect)
The effects of heredity only get stronger with age
Correlates of GMA Childhood outcomes
Average r=0.50 with school performance However, children in Japan and China know
more math than American children even though IQ scores are very similar
Average r=-0.19 with juvenile crime General psychomotor skills
Reaction speed r=.30 Judgment speed r=.55
GMA and Stability Is it really a trait? Is it stable?
Test re-test Age 6 to 18=0.77 Age 12 to age 18=0.89 Even higher correlations if tests are given on multiple
occasions What does this mean?
It means that rank order is very stable over time It does not mean that an average (100 IQ) 6 year old
can do what an average 18 year old can do
Correlation of GMA (1980) with life outcomes (1990)Sample size = 8891 (NLSY)
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
Education Income Self-esteem Weeksunemployed
Criteria
Co
rrel
atio
n
Data clearly show that general mental ability as measured by the ASVAB is correlated with education levels, income, self-esteem, and weeks of unemployment even with a 10-year gap between measures
Measures of GMA General Aptitude Test Battery (GATB) Wonderlic Personnel Test Armed Services Vocational Aptitude Battery
(ASVAB) IQ Tests (WAIS-IV, Stanford Binet, etc.)
Examples of items from the Wonderlic Personnel Test
Examples of items from the GATB
Examples of items from the GATB
Overall it seems like GMA is a perfect selection tool It’s very stable over time It’s related to measures of learning ability
and adaptability It’s one of the best predictors of job
performance available The tests are cheap (about $2.00 per
applicant tested) It really doesn’t matter which test you use
since they all measure the same thing But…
…there are potential problems with GMA test scores The subtests show differences for gender
Women score higher on verbal intelligence Men score higher on visual-spatial intelligence
and the math section of the SAT These differences are not very great and there
are massive overlaps However, overall IQ scores are basically
equivalent for men and women
GMA Scores and Race/EthnicityThere are clear differences in GMA scores based on ethnicity African-Americans scored about 1
SD below Whites, although more recent data suggests this difference is closer to 0.6 to 0.7 SD
Latinos score between Whites and African-Americans
Asians score slightly higher than Whites
Ashkenazi Jews score about ½ SD higher than other White groups
Returning to our conception of biased from earlier
GMA tests predict just as well for both groups, but one group gets lower scores
This passes the equity standard, but not equality
There is no factual or logically rigorous reason to say this is okay or not
GMA for selection
Job complexity
Proficiency ratings
Training success
General job familiesHigh (synthesizing/coordination) 0.59 0.50 15%Medium (compiling/computing) 0.51 0.57 63%Low (comparing/copying) 0.40 0.54 18%
Industrial job familiesHigh (setup work) 0.56 0.65 3%Low (feedback/offbearing) 0.23 n/a 2%
GATB Validity for: % of U.S. Workers in these
occupations
GMAEverything
else
Nuclear weapons specialist 77.3% 0.8%Air crew operations specialist 69.7% 1.8%Weather specialist 68.7% 2.6%Intelligence specialist 66.7% 7.0%Fireman 59.7% 0.6%Dental assistant 55.2% 1.0%Security police 53.6% 1.4%Vehicle maintenance 49.3% 7.7%General maintenance 28.4% 2.7%
Percentage of training success explained by:
The Relation Between General Mental Ability (GMA) and Performance in Job Training and on the Job: Representative Findings From Meta-Analyses Performance measuresStudy Occupation On the job In
trainingHunter and Hunter (1984) Medium complexity .51 .57
Pearlman et al. (1980) Clerical .52 .71
Hirsh et al. (1986) Law enforcement .38 .76
McHenry et al. (1990) Military—enlisted .63b NR
McHenry et al. (1990) Military—enlisted .65c NR
Hunter (1986) Military—enlisted NR .63
Ree et al. (1994) Military—enlisted .45 NR
Ree and Earles (1991) Military—enlisted NR .60
Schmidt et al. (1979) First-line supervisors .64 NR
Schmidt et al. (1979) Administrative clerks .67 NR
Schmidt et al. (1980) Computer programmers .73 NR
Callender and Osburn (1981) Refinery workers .31 .50
Applicant reactions to GMA tests In general, results suggest applicants tend
to find GMA tests acceptable They especially like tests that are called
“personnel tests” They like tests more when they are paired
with individual interview information They usually like tests of knowledge and
abilities more than they like personality tests or biodata.
Bobko, Roth, & Potosky:Cognitive Ability and Alternative Predictors
Their meta-analytic matrix shows that structured interviews, conscientiousness, and biodata all have much lower d-scores than cognitive ability in terms of prediction, and many of these alternatives have good correlations with job performance
Validity vs. Value GMA is the single strongest predictor of
performance Value of interviews, collecting biometric data,
etc.?
To wrap it up… GMA is the totality of mental processes
involved in adapting to the environment. Underlying component of all different aspects
of intelligence. Stable over time, strong genetic/heredity
component Strong predictor of future job performance,
especially with complex and technical jobs. People like GMA tests. Value of alternatives?