Differential Psychology: Diversity & Consilience

1. Differential Psychology: Diversity & Consilience A research review Timothy C. Bates Macquarie University Sydney Australia

2. Personality & Cognition: Extraversion (Bates & Rock 2004)

3. Inspection Time Raven’s Openness g Personality & Cognition: Openness (Bates & Shieles 2003) .85 -.66 .68 Knowledge .34

4. 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)

5. Three areas in more depth: • General ability • Why are Auditory Inspection Time, Creatine levels, and Fluctuating Asymmetry associated with IQ? • Schizotypal personality and reduced representational fidelity • A risk factor for schizophrenia? • Genetic approaches to Language • Genetic evidence for two distinct disease processes in Dyslexia

6. Part I: Ability differences • Speed, Sustain, Control, Direct • Reaction time, Inspection Time, ANT • (Bates & Eysenck, 1992; … Bates, 2005a) • Biology • Spectroscopic analysis of neural function • (Rae et al., 2003;2004) • Creatine in Vegans • (Rae et al., 2004) • Fluctuating Asymmetry & mutation load • (Bates, 2005b)

7. 1: Cognitive basis of ability Brain size, Creatine, Myelination, Fluctuating Asymmetry Inspection Time Working Memory 1 Parietal attention shift system

8. 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).

9. 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

10. Parker, Crawford, and Stephen (1999) • Early auditory IT research used the pitch-dimension • 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

11. 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

12. 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)

13. Experiment II: Reliability • N= 24 • Repeat reliability = .88. No learning

14. 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

15. Experiment II:Phase vs. volume • r = 0.746 (p<.0001)

16. 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

17. 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

18. 2: Metabolic basis of ability Inspection Time g & Working Memory 1 Parietal attention shift system 2 3 Brain size, Creatine, Myelination, Fluctuating Asymmetry

19. Mental work costs ATP • Imposition of mental work induces a cascade of metabolic response • Restores chemical species to steady state • Fuel is hydrolysis of high energy phosphate chemical bonds • Mainly ATP • fMRS allows imaging bio-energetic response

20. Mental work (Rae et al, 2002) • 4sec flicker • 26 sec dark recovery

21. Mental work costs ATP(Rae et al, 2002)

22. Can supporting metabolism raise ability? • 45 Vegans • 6g/day for 6 weeks • Double blind placebo controlled • Working memory, Raven

23. Supporting metabolism raises g (Rae et al, 2003. Proc R Soc Creatine ATP

24. 3: Building the machine Inspection Time g & Working Memory 1 Parietal attention shift system 2 3 Brain size, Creatine, Myelination, Fluctuating Asymmetry

25. 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.

26. 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)| )

27. 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

28. Experiment 1: Results • R2 = 0.17 (F(1,63)=13.04, p<.0006)

29. N = 98 & 164 Experiments II & III

30. 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. Head size, significant alone, but not if FA entered

31. 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

32. Part II: Personality Disorder research • Schizotypal Personality Disorder • Structure • Eye tracking • Mixed handedness • Sensory fidelity

33. 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

34. 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

35. What is Pitch Discrimination: A practical example - tuning • A (440 Hz) • A# (466.16 Hz) • B (493.88 Hz) • A & A±∂

36. 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

37. 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 • Cognitive-perceptual symptoms • Social withdrawal • Disorganization Raine, 1996; Wuthrich and Bates, under revision • Information increased with Lickert scale Wuthrich, V., & Bates, T. C. (2005).

38. Experiment 1 Results… • Adjusted R2=0.21, F(1,72)= 20.55, p<.0001) • No effect of sex 100ms 100ms 500ms

39. 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)

40. 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

41. 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

42. 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

43. 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).

44. 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)

45. 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

46. 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?

47. A C E “Phenotype” Twin Studies • Can quantify the importance of genetic factors on a behaviour. • 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). A = Additive genetic C = Common (family) environment E = Unique effects

48. A C E “Phenotype” Heritabilities • A = 2*( r MZ — r DZ) • C = (r MZ — A) • E = 1 — r MZ • In practice, we use path modeling • Heritability (A) for reading ≈ 0.75 (Olson et al, 1994)

49. Abstract letter units Orthographic lexicon Letter-sound conversion Phonological lexicon Phoneme units Dyslexia: Failure of Print to Speech • Two tasks in reading aloud: • Lexical access • Activate known words from a store “lexicon” • Fails for nonwords • (e.g. GOP) • Nonlexical decoding • Produce phonemes corresponding to letters: “GPC rules” • Fails for irregular words • (e.g. YACHT)

50. A Single Disorder Model C A E Nonword Reading Irregular Reading