Differential Psychology:
Diversity & Consilience
A research review
Timothy C. Bates
Macquarie University
Sydney Australia
Personality & Cognition:
Extraversion (Bates & Rock 2004)
Personality & Cognition:
Openness (Bates & Shieles 2003)
Raven’s
.85
Inspection
Time
-.66
g
.68
Knowledge
.34
Openness
Differential Psychology

L.J Cronbach (1957; 1975)

The two disciplines of scientific psychology

… a fundamental component of research in psychology. (Yerkes, 1913;
Terman, 1923)

“Individual psychology is one of the chief witnesses to the value of
experiment. It furnishes the key to many, otherwise inexplicable
differences of result, and it promises to allay many of the outstanding
controversies. . . . There can be no doubt that it will play a part of
steadily increasing importance” (Titchener,1910)
Three areas in more depth:

General ability


Schizotypal personality and reduced
representational fidelity


Why are Auditory Inspection Time, Creatine levels,
and Fluctuating Asymmetry associated with IQ?
A risk factor for schizophrenia?
Genetic approaches to Language

Genetic evidence for two distinct disease processes
in Dyslexia
Part I: Ability differences

Speed, Sustain, Control, Direct

Reaction time, Inspection Time, ANT
•

(Bates & Eysenck, 1992; … Bates, 2005a)
Biology

Spectroscopic analysis of neural function
•

Creatine in Vegans
•

(Rae et al., 2003;2004)
(Rae et al., 2004)
Fluctuating Asymmetry & mutation load
•
(Bates, 2005b)
1: Cognitive basis of ability
Brain size, Creatine, Myelination, Fluctuating Asymmetry
Inspection Time
Working Memory
1
Parietal
attention shift system
Auditory Inspection Time
(AIT: Bates, 2004)

Visual Inspection time (VIT)

The stimulus exposure duration required for
a subject to reliably discriminate two
alternative stimuli
• (Vickers, Nettelbeck, & Willson, 1972)

Reliably predicts 25% of IQ-test variance
• (Deary & Stough, 1996; Grudnik & Kranzler,
2001).
Auditory IT

New methods may allow testing competing
psychological hypotheses

g as the speed of attended computations
• (Bates & Eysenck, 1993; Bates & Shieles, 2003)

Or …protection of information from interference
• (Engle, Kane, & Tuholski, 1999)

Epiphenomenon of developmental stability
• (Miller, 2000)

Method to assess the integrity and biological
mechanism of information processing
Parker, Crawford, and Stephen
(1999)

Early auditory IT research used the pitchdimension

Discriminating the higher of two tones correlated
0.23 and 0.45 with IQ (Deary, Head, & Egan, 1989)
• Many subjects (20-40%) couldn’t perform task

Parker used a phase shifted stereo signal



Generates left and right apparent locations
AIT correlated 0.37 with Raven’s
Most subjects could report location of the tone
Experiment 1: AIT & Raven
Subjects: 59 Students
 IQ: Ravens SPM
 AIT:

Stimulus: 100ms 40° phase stereo tone
 Mask: 500ms 450Hz square wave
 Estimator: 17 reversal Garcia-Perez stair

Experiment 1: AIT & Raven

Does AIT correlate with Raven’s?


Yes: r = -0.53, p < .001
Can all subjects complete the task?

All but two subjects completed the task
• Both failures due to mistaking the task instructions
(headphones on in reverse)
Experiment II: Reliability
2.5
log phase repeat
2.25
2
1.75
1.5
1.25
1
.75
.5
.25
0
0


.25
.5
.75
1
1.25 1.5 1.75
log phase
2
2.25 2.5
N= 24
Repeat reliability = .88. No learning
Two ways to decode location

Inter-aural phase shift

Precise:
• ± 0.69 milliseconds between stimuli appearing full left or full
right.

Only of use for tones > 1500 Hz
• Wavelength must exceed binaural difference in travel time

Intensity (volume) cues


Closer ear is louder
Useful independent of frequency
Experiment II:
Phase vs. volume
avg log phase
2.5
2
1.5
1
.5
0
1.6

1.7
1.8
1.9
2
2.1 2.2
avg log vol
r = 0.746 (p<.0001)
2.3
2.4
2.5
How do we do this task?

1° auditory cortex organized tonotopically
(Merzenich, Knight, & Roth, 1975)

Orthogonally, neurons organized in columns
(Schreiner et al., 2000)

Represent phase and intensity
• Imig & Adrián, 1977; Razak & Fuzessery, 2000.

Subjects report information represented in
caudal temporal cortex


Information lost in more rostral structures
g reflects speed of 1°Auditory Cortex cell
assemblies
Auditory IT

New method may aid testing competing
psychological hypotheses

g as the speed of attended computations
• (Bates & Eysenck, 1993; Bates & Shieles, 2003)

Or …protection of information from interference
• (Engle, Kane, & Tuholski, 1999)

Epiphenomenon of developmental stability
• (Miller, 2000)

Method to assess the integrity and biological
mechanism of information processing
2: Metabolic basis of ability
Inspection Time
g & Working Memory
1
Parietal
attention shift system
2
3
Brain size, Creatine, Myelination, Fluctuating Asymmetry
Mental work costs ATP

Imposition of mental work induces a
cascade of metabolic response


Fuel is hydrolysis of high energy
phosphate chemical bonds


Restores chemical species to steady state
Mainly ATP
fMRS allows imaging bio-energetic
response
Mental work (Rae et al, 2002)
4sec flicker
 26 sec dark
recovery

QuickTi me™ and a
Graphics decompr essor
are needed to see thi s pi ctur e.
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Mental work costs ATP
(Rae et al, 2002)
ON
OFF
Phosphocreatine (arb units)
6
5
4
3
0
2
4
6
8
10
TIME (S)
12
14
16
18
Can supporting metabolism
raise ability?
45 Vegans
 6g/day for 6 weeks
 Double blind placebo controlled
 Working memory, Raven

Supporting metabolism raises g
(Rae et al, 2003. Proc R Soc
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Creatine
ATP
3: Building the machine
Inspection Time
g & Working Memory
1
Parietal
attention shift system
2
3
Brain size, Creatine, Myelination, Fluctuating Asymmetry
Developmental Instability (DI)

In the expression of developmental design,
stability is
“a lack of noisiness in development”
•

Waddington, 1957.
An accessible measure of DI is fluctuating
asymmetry (FA)

Subtle, random, departures from symmetry in
normally symmetrical bilateral traits
•
Ludwig, 1932; Palmer & Strobeck, 1986; Van Valen,
1962.
Experiment 1: Fluctuating
Asymmetry and Raven’s


Sixty-seven subjects (43 female)
Intelligence


Raven SPM un-timed computerized.
Fluctuating asymmetry:




Width of the palm, length of each of
the four fingers excluding the thumb,
ear height and width, and the widths of
the ankle and elbow.
All measures were made using digital
calipers accurate to 0.1 mm.
Each body part was measured twice
and averaged.
FA = Sum( |(left–right)/(left+right)| )
Previous work


Furlow et al. (1997) assessed symmetry in body parts

Independent samples of 111 and 123 students

Cattell’s Culture Fair test of intelligence r -0.2 & -0.27
Prokosch (2005)


Correlation linearly proportional to g-loading of test
-0.40 correlation with Ravens
Experiment 1: Results
R2 = 0.17 (F(1,63)=13.04, p<.0006)
56
51
Raven Score

46
41
36
31
26
0
.005
.01
.015
.02
FA
.025
.03
.035
.04
Experiments II & III
Bivariate Scattergram with Regre ssion
Bivariate Scattergram with Regre ssion
60
40
55
35
50
45
30
25
35
IQ
Rave ns
40
30
20
25
15
20
15
10
10
5
5
0
.1
.2
.3
FA
.4
Ravens = 44 .434 - 43 .269 * FA; R^2 = .147

N = 98 & 164
.5
.6
0
.02
.04
.06
.08
.1
FA
IQ = 25.0 28 - 54.7 97 * FA; R^2 = .08 8
.12
.14
.16
.18
Results: FA & other IQ
correlates

IQ correlates with
height, health,
longevity, and a range
of other physical traits
including brain
volume.
IQ correlates 0.4 with
brain volume and
around .2 with head
size.
35
30
25
IQ

Bivariate Scattergram with Regre ssion
40
20
15
10
5
510
520
530
540
550
560
570
Head Size
580
590
600
IQ = -14.8 28 + .06 5 * Head Size; R^2 = .0 45
Head size, significant
alone, but not if FA
entered
610
620
Conclusion

Intelligence may be very hard to achieve


Metabolically demanding
Intrinsically vulnerable to mutation load and pushing
the limits of development
• Matt Ridley “Mendel’s Daemon”

IQ may function as a fitness indicator:

Selected to be sensitive to a wide variety of alleles
correlated with survival, rather than aiding survival
itself.
• Geoffrey Miller
Part II: Personality Disorder
research

Schizotypal Personality Disorder
Structure
 Eye tracking
 Mixed handedness
 Sensory fidelity

Sensory Imprecision &
schizophrenia (Bates, 2005)

Schizophrenia


Serious and relatively common illness
Since Kraepelin often thought of in terms of 3
component traits:



Perceptual aberration
Disorganization
Social withdrawal
Liddle, 1987
Schizophrenia as inability to
represent

Pan-modal sensory imprecision

Schizophrenic patients require as much as
19% difference in pitch to reliably
discriminate tones
• Strous et al., 1995; Javitt et al., 1999

Effect size between 0.5 and 2.0
• Rabinowicz et al., 2000
What is Pitch Discrimination: A
practical example - tuning

A (440 Hz)

A# (466.16 Hz)

B (493.88 Hz)

A & A±∂
Imprecision in people at risk for
schizophrenia?

Would suggest that low-fidelity
representation is a trait not a state

Potentially causal

Existing prior to intervening medication or
chronicity effects
Experiment 1

Subjects



N: 73 students and community members (37 male)
Age: Mean age 29 years (SD 14)
Psychometrics


Raine Schizotypal Personality Questionnaire
Three components
1. Cognitive-perceptual symptoms
2. Social withdrawal
3. Disorganization
Raine, 1996; Wuthrich and Bates, under revision

Information increased with Lickert scale
Wuthrich, V., & Bates, T. C. (2005).
Experiment 1 Results…


500ms
Log (% difference pitch threshold)
100ms
Adjusted R2=0.21,
F(1,72)= 20.55,
p<.0001)
No effect of sex
100ms
3
2.5
2
1.5
1
.5
0
-.5
-1
-1.5
-2
-2.5
0
10
20
30
40
50
Raine SPQ Total Score
60
70
Experiment 1: Discussion

Reduced auditory precision in a high-function pre-morbid
population



Not an artifact of illness/treatment
Pre-morbid (Causal?) factor in schizophrenia
Limitations: Alternate interpretations



Distractibility (i.e, Deutsch, 1970)
Rapid decay of memory traces (i.e, Harris, 1952)
Slower-than-normal accumulation (i.e, Vickers)
Neurally…Triple dissociation

Sensory precision = PAC
• Zatorre, Belin, & Penhune, 2002
• Tramo, Shah, & Braida (2002)

Delayed matching = Auditory association cortex
• Colombo, Rodman, & Gross (1990)

Distraction = Prefrontal cortex
• Chao & Knight (1995; 1998)

Lesions in any of these may reduce pitch
discrimination
• Alain, Woods, & Knight, 1998
Experiment II: Method

Subjects:


28 subjects from experiment 1 retested
Procedure
∆Hz was individually determined from
experiment 1
 Tested with 4 and 10 second delay from s1 to
s2

Results & Discussion
Main effect of delay, with % correct
decreasing at the longer delay
 No main effect of SPQ and no interaction
effect (F<1).


Schizotypal impairment not due to decay
Experiment III

Examines artifacts of:



Slower-than-normal accumulation of sensory information into
the representational system
Increased backward masking effects from subsequent stimuli
Auditory inspection time task

Adapted from Parker, Crawford, & Stephen (1998).
Results: AIT & SPQ


F=1.37, p = 0.25
No difference in
interference given
discriminable
stimuli.
True too of
schizophrenia

(Knight, Elliott, &
Freedman, 1985;
March et al., 1999)
70
60
50
SPQ B Total

40
30
20
10
0
.5
1
1.5
2
2.5
3
phase_loc log
Y = 40.925 - 2.31 * X; R^2 = .022
3.5
4
4.5
SPQ & Representational Fidelity
Conclusions

Deficit in representation



May extend into frontal systems required to support
organized, planned behavior.
Affected by Ketamine
Doesn’t explain thought disorder


Appears to be related to simpler measures of
distractibility
Dopamine connection
Part III: Communication &
Comprehension

Are there different kinds of dyslexia?

Different genes for different dyslexias?

Did reading evolve or is it parasitic on other abilities, like
language?

How is reading linked to autism, SLI, ADHD, IQ?


Does SLI cause dyslexia?
Are genes for reading pleiotropic for language or reasoning?
Twin Studies
•Can quantify the importance of
genetic factors on a behaviour.
A
C
E
•Can quantify environmental factors,
distinguishing between:
–Common environmental effects
–Effects which are shared by siblings
in a family, such as SES, home
environment, and, perhaps, schooling
–Unique effects
–Everything else (usually including
error in measurement).
“Phenotype”
A = Additive genetic
C = Common (family)
environment
E = Unique effects
Heritabilities

A = 2*( r MZ — r DZ)
C = (r MZ — A)
E = 1 — r MZ

In practice, we use path modeling


A
C
E
“Phenotype”

Heritability (A) for reading ≈ 0.75 (Olson et al, 1994)
Dyslexia:
Failure of Print to Speech

Two tasks in reading
aloud:

Lexical access
Abstract letter units

Orthographic
lexicon

Letter-sound
conversion
Phonological
lexicon
• (e.g. GOP)

Nonlexical decoding


Phoneme units
Activate known words from a
store “lexicon”
Fails for nonwords
Produce phonemes
corresponding to letters: “GPC
rules”
Fails for irregular words
• (e.g. YACHT)
A Single Disorder Model
A
Irregular
Reading
C
E
Nonword
Reading
Theory-driven modeling: A dualroute genetic model
E
Abstract letter units
E
C
A
Lexicon
E
C
A
C
A
Letter-sound
conversion
Phoneme units
Irregular
Reading
Nonword
Reading
Subjects

1382 Twins and Siblings

Age:12-23 yr (mean 17.6 yrs,SD=3.0)
Pairs
Male
MZ
DZ same sex
DZ opposite sex
97
127
229
Female
116
122
Measures: Reading

Components of Reading Examination
• (CORE: Castles, Bates & Coltheart, 2004)

Lexical skills
• 40 irregular words

Nonlexical skills
• 40 nonwords
Best-fitting model of reading
Ag
Airr
= .77=
.38
(.31-.44)
(.39-.50)
Eirr
.33
(.39-.23)
(.73-.80)
Nonword
Reading
Irregular
Reading
.44
Anon
.26
.49
(.18<.33)
=
=
Eg
(.43-.54)
Enon
2(3) difference from saturated model (ACE) = 4.0, p= 0.26
Genetics of spelling

Very little is known about genetic and
environmental influences on processes in
spelling:


(Defries et al 1991)
Dual Route Model of Spelling

Proposes separate lexical and nonlexical
spelling processes
 e.g. Ellis (1982)
The Dual Route Model of
Spelling

Two basic processes in
spelling:

Lexical route



Access a memory store or
lexicon of known words
Fails for nonwords (eg gop)
Nonlexical route


Apply learned rules about
correspondence between
sounds and letters
Fails for irregular words
• yacht
Measures: Spelling

Lexical spelling


Spelling 18 irregular words
Nonlexical spelling

18 word regularization test

Give me a spelling for each word so that someone who had never
seen the word could spell it properly. e.g. if I gave you the word
“yacht”, you would say “Y” “O” “T”
Best-fitting model of Spelling
Airr
Agen
Anon
.54
= .61 =
.41
(.35-.67)
(.49-.66)
(.20-.51)
Irregular
Spelling
Eirr
Nonword
Spelling
.47
.65
(.40-.53)
(.59-.72)
Enon
2(4) difference from saturated model (ACE) = 3.65, p=0.46
Multivariate Model: Spelling &
reading
A
A
.25 (19-30)
=
A
.83(69-89)
.39(25-54)
=
=
=
.45 (40-50)
.83 .70
(67-86)
Irreg
Read
Irreg
Spell
(63-74)
Non
Read
Non
Spell
-.26 (-40-01)
C
E
.51 .14 .12 .06
E
.48 .13 .03
E
E
.52 .13
.69
Genes

The next step is genes

Fisher & DeFries (2002)
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Oxford Dyslexia Multivariate
scan (Marlow et al, 2003)


C6p21.3 (Cardon, et al. 1994; Gayan, 1999).
C18p11.2 (Fisher et al, 2002)

Multivariate-linkage suggests that gene(s) in both the C6p22 region participate
in several reading processes (Marlow et al., 2003)
Other regions

2p15 “DYX3” (Fagerheim, 1999)

2q = language delay (Buxbaum et al 2001)

3p12-q13 (Nopola-Hemmi, 2001)

7q31 SPCH1 gene, SLI (Fisher et al. 1998); FOXP2 (Lai
et al. 2001); Autism (Bradford et al, 2001)

15c/15q Dyslexia (Smith et al, 1983; 1991; Taipale,
2003). Also linked to Autism & p50 c/dis)
Reading Linkage
(Bates et al., prep)

18p: First independent replication
7q31: SPCH1 (O’Brien, et al 2003), Autism
4p: novel?
Weaker support for: 1p, 2, 3q, 4p

Note: The SLI sites 13q, 16q & 19q not supported




(Bartlett 2002;2003, SLIC, 2002;2004)
Spelling Linkage
(Bates et al., prep)






2p (DYX3)-> reading, 2q -> language delay
3p -> dyslexia/NWR (Nopola-Hemmi, 2001)
C6 (DYX2) -> dyslexia (Cardon, 1994)
7q31 (SPCH1) SLI (Fisher 2002, Lai 2003)
15c/15q -> dyslexia (Taipale, 2003) (+ autism & p50 c/dis)
C9 & C17. Novel?
Current study:
SLI and semantics
print
Abstract letter units
g
Semantics
Orthographic
lexicon
Letter-sound
conversion
SLI (16q,19q)
Phonological
lexicon
Phoneme units
speech
Behavior Genetics
Tool to dissect behavior
 Evolution
 Development & Aging
 Psychopathology

Cognition, Biochemistry,
Genetics, and Evolution

Cognition: Components of reasoning


Biochemistry: the mind as a muscle


Creatine ALA, Mental work
Evolution: Mendel’s Daemon


Role of attention in ability
Fluctuating Asymmetry & g
Personality

Anxiety genes and interaction with treatment
Collaborators






Queensland Genetic Epidemiology Laboratory
Collaboration
Prince of Wales Medical Research High Field MR
Facility
University of Melbourne
University of New Mexico
Swinburne Neuropsychology Laboratory
Macquarie University Anxiety Research Unit
SLI and semantics
print
Abstract letter units
g
Semantics
Orthographic
lexicon
Letter-sound
conversion
SLI (16q,19q)
Phonological
lexicon
Phoneme units
speech