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Developmental Influences on Adult IntelligenceThe Seattle longitudinal study$

K. Warner Schaie

Print publication date: 2005

Print ISBN-13: 9780195156737

Published to Oxford Scholarship Online: September 2007

DOI: 10.1093/acprof:oso/9780195156737.001.0001

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Cross-Sectional Studies

Cross-Sectional Studies

Chapter:
(p.62) chapter four Cross-Sectional Studies
Source:
Developmental Influences on Adult Intelligence
Author(s):

K. Warner Schaie

Publisher:
Oxford University Press
DOI:10.1093/acprof:oso/9780195156737.003.0004

Abstract and Keywords

This chapter describes the pilot studies that led to the selection and validation of the measures used in the Seattle Longitudinal Study. The 1956 baseline study is presented and its findings are compared with the six cross-sectional replications. For purposes of an orderly presentation, the basic cognitive battery that is common to all study cycles is analyzed. Data for the fifth, sixth, and seventh cycles for the extended cognitive battery and the practical intelligence measures are then presented. Finally, the cross-sectional findings for the measures of cognitive style (Test of Behavioral Rigidity, TBR) are discussed.

Keywords:   Seattle Longitudinal Study, intellectual development, intelligence measures, cross-sectional studies, practical intellegence, cognitive style, primary mental abilities

T HIS CHAPTER BEGINS WITH A DESCRIPTION of the pilot studies that led to the selection and validation of the measures used in our research program. I then present the 1956 baseline study and compare its findings with the six cross-sectional replications. For purposes of an orderly presentation, I begin with the analyses of the basic cognitive battery that is common to all study cycles. I then present data for the fifth, sixth, and seventh cycles for the extended cognitive battery and the practical intelligence measures. Finally, I consider the cross-sectional findings for the measures of cognitive style (Test of Behavioral Rigidity, TBR).

The Pilot Studies

Our inquiry began by questioning whether factorially defined measures of intellectual abilities would show differential age patterns. Before this question could be examined parametrically, it was necessary to examine the applicability of the Primary Mental Abilities (PMA) test to an older population, with respect to both its level of difficulty and whether the low correlations among abilities observed in childhood would continue to prevail for adults. Two pilot studies concerned with these questions are described in this section. In addition, our interest in cognitive style as a concomitant of intellectual aging required the development of a set of psychometrically sound measurement instruments for the multiple dimensions of rigidity-flexibility. A third pilot study was concerned with demonstrating the construct validity of the resultant measure (the TBR).

Study 1: Suitability of the Primary Mental Abilities Tests for Adults

Sixty-one study participants, gathered from the geriatric practice of a family physician and from the membership of the small first cohort of the San Francisco (p.63) Senior Citizen Center, were given the PMA tests under standard conditions. For purposes of analysis, participants were arbitrarily divided into four approximately equal groups: ages 53 to 58, 59 to 64, 65 to 70, and 71 to 78. In the absence of adult norms and to permit comparison across the five abilities measured by the test, raw scores were converted into percentiles employing norms for 17-year-old adolescents (L. L. Thurstone & Thurstone, 1949). Thus, for example, if our participants, on average, were at the 50th percentile, this would imply that their level of functioning would be similar to that of 17-year-olds.

The results of this study are shown in figure 4.1. For the group in their 50s, stability is suggested for Verbal Meaning and Number (performance is slightly above the adolescents' 50th percentile), but performance appears to be substantially lower for the other three tests. Indeed, it was lowest for Spatial Orientation and Inductive Reasoning, measures of the kind of ability later to be termed fluid by Cattell (1963). The differential pattern was observed for all age groups, with some further lowering of scores into the 60s and apparent maintenance of the lower level for the group in their 70s (Schaie et al., 1953).

On the off chance that the differential pattern might be caused by unequal effects of the slightly speeded instructions for the performance of older individuals, four of the tests were administered to 31 participants without a time limit. Results shown in figure 4.2 indicate that, if anything, differential performance levels were greater and in the same order as under the standard conditions of instruction.

The first pilot study also investigated the construct validity of the PMA 11–17 when used with older individuals. Intercorrelations between the tests were computed and were quite low, ranging from .07 for the correlation between Spatial Orientation and Number to .31 for the correlation between Spatial Orientation

                   Cross-Sectional Studies

figure 4.1 Age Differences in Primary Mental Abilities for the Adult Pilot Sample.

(p.64)
                   Cross-Sectional Studies

figure 4.2 Age Differences in Primary Mental Abilities Under Unspeeded Conditions of Test Administration.

and Inductive Reasoning. These correlations did not differ significantly from those obtained for an adolescent comparison group (Schaie, 1958d). Split-half reliabilities computed under the power test condition were also quite satisfactory, with all above .92 after Spearman-Brown correction.

Study 2: Suitability of the Primary Mental Abilities Tests for Older Adults

A second pilot study was conducted in 1954 as part of an investigation of community-dwelling older persons (more completely described in Schaie & Strother, 1968a, 1968d). A campus and community appeal resulted in the selection of 25 men and 25 women, all college graduates with professional careers, ranging in age from 70 to 88 years (mean age 76.5 years). These study participants were all in fair-to-superior health and free of diagnosable psychiatric symptoms. The differential ability pattern shown in the first pilot study was replicated, with performance on Number, Word Fluency, and Verbal Meaning substantially above (p.65) that observed for Spatial Orientation and Inductive Reasoning. Also noteworthy was the finding that some of the octogenarians in this study still equaled or exceeded the adolescent mean on some of the verbal tests, even though it was most likely that this performance represented a decrement from previously higher levels, suggested by the unusually advantaged demographic characteristics of this sample. In this study, findings also indicated sex differences in favor of the males for the Spatial Orientation and Number abilities and in favor of the females for Verbal Meaning, Inductive Reasoning, and Word Fluency (Strother et al., 1957).

Study 3: Construct Validity of the Test of Behavioral Rigidity

The third pilot study was concerned with demonstrating the construct validity of a set of measures defining the multiple dimensions of rigidity-flexibility. This study began as my master's thesis (Schaie, 1953), in which I factor-analyzed a number of tests representing the functional, structural, and attitudinal approaches to the study of rigidity-flexibility (see Chown, 1959). Although use of an unorthodox method of rotation (Horst, 1956b) made the result of the initial analysis somewhat tenuous, it provided the basis for selecting the variables to be included in the more definitive construct validation study (Schaie, 1955). Because I intended to use the final battery for studies of aging, only those tests were included that could be adapted for use with both adult and elderly populations. For practical reasons, only tests suitable for group administration were retained, and those tests were selected that were minimally influenced by social status and education in the initial study.

The measures included in the construct validity study, for what eventually became the TBR (Schaie & Parham, 1975), are described in the section that discusses measures of cognitive style in chapter 3. Not described there are the Jar test (Luchins, 1942) and the Alphabet test (Bernstein, 1924), which were subsequently dropped from the final battery. The Jar test involves participants correctly identifying the use of jars of different sizes in measuring a given quantity of water, with different methods of solution appropriate at various times. The so-called Einstellung effect is tested by first conditioning the participant to employ a complex method of solution. Critical problems are then presented for which a more direct solution is available. The rigidity measure then becomes the number of problems unnecessarily solved in the more complex manner. The Alphabet test involves the letter combinations abode and Imnopq first written forward and then backward.

The validation sample consisted of 216 participants who were drawn from day and evening classes at the University of Washington (Seattle), from a social club for older people, from the membership of a liberal church, from a Rotary club, and from a group of YMCA members. The sample ranged in age from 17 to 79 years, with a mean age of 38 years. Educational level ranged from 4 to 20 years, with a mean of 14.2 years. The participants' occupational levels averaged 6.3 on a 10-point scale from unskilled to professional. For purposes of cross-validation, (p.66) a second sample of 200 participants was drawn from a restricted population of college students between the ages of 19 and 26 years, with a mean age of 21.4 years.

The correlation matrix for the first sample was factored using a simplification of Thurstone's multiple group method (Horst, 1956a; L. L. Thurstone, 1947, pp. 170 ff). Note that this approach is an early forerunner of modern confirmatory factor analysis. The first hypothesis specified the existence of a single rigidity factor and a motor speed factor. This hypothesis had to be rejected, and instead a three-factor combination emerged that, on appropriate oblique rotation (Horst & Schaie, 1956), yielded an acceptable simple structure solution (see table 4.1).

Factor I was originally named Motor-Cognitive Speed (the current term is Psychomotor Speed [PS]), Factor II was identified as Personality-Perceptual Rigidity (now called Attitudinal Flexibility [AF]), and Factor III was thought to be a representation of Motor-Cognitive Rigidity (now called Motor-Cognitive Flexibility [MCF]). These factors were next cross-validated by factoring the correlation matrix for the second sample and rotating it to the same factor pattern. As indicated by table 4.1, the resulting pattern replicates that obtained for the original sample. The major difference between results from the two samples can be seen in the factor intercorrelations. All three factors are moderately correlated in the heterogeneous sample, whereas the factor correlations are quite small in the homogeneous sample of college students.

table 4.1 Factor Loadings and Factor Intercorrelations After Oblique Rotation

Factor Pattern

PS

AF

MCF

Tests

S1

S2

S1

S2

S1

S2

Capitals–NR

.66

.74

−.02

.03

−.12

−.06

Alphabet–NR

.66

.68

−.03

−.02

−.03

−.06

Opposites–NR

.46

.49

.09

−.01

.14

.09

Water Jar test

.00

.00

.31

.28

−.05

.05

P Scale

.00

−.09

.50

.57

.07

.01

R Scale

.05

.09

.56

.58

−.01

.04

Opposites–R1

.05

.04

.00

−.02

.55

.69

Opposites–R2

.05

.03

−.10

−.02

.64

.64

Capitals–R

−.04

−.09

.07

.02

.39

.25

Alphabet–R

−.07

−.01

.03

.10

.25

.30

Factor Intercorrelations

I. Motor-Cognitive Speed

.427

−.049

.508

.075

II. Attitudinal Flexibility

.422

.148

III. Motor-Cognitive Flexibility

Note. AF, Attitudinal Flexibility; MCF, Motor-Cognitive Flexibility; PS, Psychomotor Speed; S1, Sample 1; S2, Sample 2.

(p.67) As a result of this study, we decided to retain the four subtests (Capitals, Opposites, R scale, P scale) that provided the best factor definition for inclusion in the final version of the TBR used throughout the SLS.

The 1956 Baseline Study

In our effort to determine the pattern of age differences, we sampled 500 individuals from our health maintenance organization population frame distributed evenly by gender and 5-year age interval from 21 to 70. For ease of comparison, we standardized all variables across the entire sample to T -score format (M = 50, SD = 10). We have followed this procedure throughout, always restandardizing on the basis of the largest total sample of individuals' scores at first test (entry into the study). Age difference findings from the baseline study are shown in figure 4.3.

What is most noteworthy about the baseline study is that, although negative age differences are found on all five abilites, peak ability ages occur generally later than had been observed in the previous literature (see Jones & Conrad, 1933; Wechsler, 1939), and that the differential ability patterns noted in our first pilot study could be confirmed in this reasonably representative and age-continuous investigation.

More specifically, we noted that peak levels of the abilities were reached for Reasoning by the 21- to 28-year-old group, for Space, Verbal Meaning, and Word Fluency by the 29- to 33-year-olds, but for Number only at ages 43–49. Similarly,

                   Cross-Sectional Studies

figure 4.3 Baseline Age Differences on the Primary Mental Abilities.

(p.68) there are differences among abilities for the first occurrence of a significant age difference from performance at the peak age. Such significantly lower average performance levels were observed for Verbal Meaning, Space, Reasoning, and Word Fluency with respect to the 36- to 42-year-olds, but for Number only for the 50- to 56-year-olds. Differences were found also in the absolute magnitude of the age difference between the group at peak age and the oldest observed group (ages 66–70). This difference amounted to 1.5 SD for Verbal Meaning, Space, and Reasoning, but slightly less than 1 SD for Number and Word Fluency. The absolute differences between the youngest and oldest age groups was greatest for Reasoning (1.5 SD), next largest for Space and Verbal Meaning (1.2 and 1 SD, respectively), and smallest for Word Fluency and Number (0.6 and 0.2 SD, respectively). These differences could be interpreted as of substantial magnitude for Reasoning, Space, and Verbal Meaning; moderate for Word Fluency; and near trivial for Number.

Cross-Sectional Replications

This section begins with the basic cognitive data collected throughout the study. I then turn to the expanded battery and consider the age difference patterns within ability domains as well as the age difference patterns in the factor scores for the latent ability constructs. Finally, cross-sectional results are provided for the measure of practical intelligence and the measures of cognitive style.

Basic Cognitive Data

Given the 7-year interval between our data cycles, all data were reorganized into 7-year age intervals. Thus, the baseline study for purposes of comparison with the subsequent replications contains seven age groups, with mean ages from 25 to 67 years. In the second cross-sectional sample (1963, N = 998), we included eight age groups, with mean ages from 25 to 74 years. The third sample (1970, N = 705) and the remaining three cross-sectional samples (1977, N = 609; 1984, N = 629; 1991, N = 691; and 1998, N = 719) include nine age groups, with mean ages from 25 to 81 years.

Again, for ease of comparison, all raw scores were converted to T scores with means of 50 and standard deviations of 10 based on the entire set of 4,851 observations at first test.

Differential Ability Patterns Mean scores by age and gender for the five PMA subtests and the two composite measures of Intellectual Ability and Educational Aptitude are presented in table 4.2. For a more dramatic presentation of differences across abilities in age difference pattern, we graphed mean values by gender for the first (1956) and last (1998) cross-sectional comparisons (see figure 4.4).

Age difference patterns for males have remained relatively constant over the course of the study, with the exception that peak ages for Verbal Meaning and Number shift to age 60 and Word Fluency shifts to the late 30s. For the female (p.69)

table 4.2 Means and Standard Deviations for the Basic Ability Battery by Sample and Gender

Age

25

32

39

46

53

60

67

74

81

Verbal Meaning

1956

Male

50.68

52.55

51.28

49.54

48.29

41.11

41.89

(9.46)

(9.50)

(10.23)

(10.11)

(10.01)

(9.74)

(8.46)

Female

52.50

55.27

50.43

55.73

47.71

45.16

40.68

(7.35)

(7.15)

(10.87)

(7.45)

(9.01)

(8.74)

(87.31)

Total

51.59

53.99

50.86

52.40

48.00

43.19

41.29

(8.47)

(8.39)

(10.48)

(9.44)

(9.46)

(9.40)

(8.36)

1963

Male

51.43

52.29

53.92

49.65

46.05

43.74

39.92

38.03

(8.63)

(8.64)

(8.03)

(9.30)

(10.25)

(9.54)

(9.37)

(9.53)

Female

52.98

53.63

52.58

51.79

48.12

47.45

42.75

38.60

(8.48)

(7.79)

(7.68)

(8.56)

(9.51)

(10.44)

(8.86)

(9.14)

Total

52.33

53.06

53.21

50.70

47.22

45.69

41.32

38.32

(8.54)

(8.16)

(7.85)

(8.98)

(9.86)

(10.16)

(9.19)

(9.28)

1970

Male

51.81

51.39

53.15

53.51

54.48

53.18

42.86

37.04

35.73

(8.27)

(9.15)

(7.64)

(8.14)

(7.41)

(9.68)

(7.67)

(7.57)

(8.67)

Female

53.72

53.93

52.90

54.33

52.67

49.57

45.10

40.27

36.96

(7.84)

(8.31)

(7.76)

(8.21)

(7.54)

(8.45)

(8.73)

(5.87)

(7.88)

Total

52.89

52.83

53.00

53.92

53.48

51.29

44.07

38.55

36.32

(8.03)

(8.71)

(7.66)

(8.14)

(7.49)

(9.18)

(8.29)

(6.98)

(8.24)

1977

Male

53.07

54.31

53.11

52.59

52.90

49.91

43.91

38.22

34.32

(7.73)

(7.17)

(10.01)

(9.33)

(9.79)

(10.20)

(8.98)

(9.17)

(7.05)

Female

54.21

56.12

54.97

50.49

40.78

49.37

46.55

41.00

34.19

(9.84)

(7.02)

(8.06)

(10.40)

(9.97)

(9.17)

(8.95)

(10.33)

(6.99)

Total

53.64

55.27

54.03

51.46

51.88

49.63

45.29

39.53

34.25

(8.78)

(7.09)

(9.08)

(9.90)

(9.87)

(9.61)

(9.00)

(9.76)

(6.96)

1984

Male

53.29

55.37

56.13

55.50

52.27

51.08

46.55

41.72

39.92

(8.25)

(6.14)

(6.52)

(6.37)

(8.17)

(8.33)

(8.81)

(6.80)

(9.39)

Female

55.11

52.61

55.82

57.15

55.43

51.86

48.43

44.69

38.78

(7.40)

(8.59)

(6.57)

(6.17)

(6.69)

(7.88)

(8.38)

(8.35)

(7.91)

Total

54.50

53.96

53.96

56.49

53.85

51.51

47.51

43.15

39.33

(7.70)

(7.56)

(6.50)

(6.26)

(7.58)

(8.05)

(8.59)

(7.68)

(8.59)

1991

Male

51.89

55.32

56.97

56.03

54.05

53.16

49.40

47.15

39.17

(8.14)

(6.72)

(6.41)

(6.27)

(7.46)

(8.69)

(9.07)

(8.58)

(7.59)

Female

54.27

52.78

57.10

56.49

57.08

51.83

52.60

47.77

41.94

(6.87)

(8.62)

(6.06)

(6.66)

(6.68)

(8.26)

(8.51)

(9.35)

(10.02)

Total

53.20

53.88

57.04

56.30

55.60

52.41

51.22

47.46

40.54

(7.50)

(7.91)

(6.19)

(6.47)

(7.19)

(8.49)

(8.85)

(8.93)

(8.91)

1998

Male

53.56

54.26

55.23

54.19

54.74

55.43

51.67

47.88

45.47

(6.29)

(6.90)

(6.66)

(8.03)

(8.85)

(7.09)

(8.21)

(8.47)

(7.48)

Female

52.92

53.56

52.79

55.81

55.36

52.73

51.54

49.29

44.33

(6.93)

(7.65)

(8.01)

(7.33)

(6.86)

(8.44)

(6.95)

(8.71)

(8.31)

Total

53.17

53.94

53.89

55.01

55.08

54.21

51.62

48.66

44.90

(6.61)

(7.21)

(7.50)

(7.70)

(7.81)

(7.79)

(7.73)

(8.56)

(8.03)

Spatial Orientation

1956

Male

56.87

56.18

54.39

52.37

49.63

47.97

45.92

(9.54)

(10.29)

(6.84)

(8.12)

(9.50)

(9.82)

(7.78)

Female

50.97

53.49

49.74

47.67

45.60

42.49

41.34

(9.65)

(7.84)

(7.91)

(10.48)

(7.02)

(8.21)

(6.15)

Total

53.92

54.76

52.10

50.20

47.61

45.15

43.63

(9.99)

(9.11)

(7.70)

(9.51)

(8.54)

(9.38)

(7.34)

1963

Male

58.95

56.48

56.39

54.01

50.87

49.05

45.16

42.97

(8.41)

(7.90)

(7.84)

(8.50)

(7.21)

(8.55)

(7.85)

(6.46)

Female

56.19

52.50

50.06

48.58

46.84

45.19

41.51

39.85

(9.12)

(8.11)

(7.78)

(8.26)

(8.66)

(7.68)

(6.34)

(5.38)

Total

57.35

54.20

53.06

51.35

48.59

47.02

43.35

41.37

(8.89)

(8.23)

(8.40)

(8.79)

(8.28)

(8.30)

(7.34)

(6.10)

1970

Male

60.97

59.75

57.21

56.19

52.98

51.79

46.74

42.47

42.62

(10.87)

(6.66)

(9.38)

(8.25)

(8.29)

(8.68)

(5.96)

(7.98)

(6.34)

Female

55.38

55.27

50.76

51.67

48.76

46.95

41.00

39.80

37.42

(10.30)

(9.68)

(8.99)

(8.96)

(8.12)

(6.43)

(7.12)

(5.93)

(5.95)

Total

57.82

57.20

53.37

53.93

50.65

49.25

43.65

41.23

40.12

(10.84)

(8.74)

(9.64)

(8.86)

(8.42)

(7.91)

(7.18)

(7.18)

(6.63)

1977

Male

58.36

56.17

57.35

54.31

53.68

49.37

47.89

43.46

41.57

(8.39)

(6.40)

(7.95)

(7.25)

(8.19)

(10.13)

(8.02)

(7.38)

(6.80)

Female

51.75

55.94

52.50

50.84

48.11

45.63

46.89

40.70

36.94

(7.91)

(7.64)

(7.60)

(8.70)

(8.23)

(8.32)

(8.81)

(7.13)

(6.64)

Total

55.05

56.05

54.96

52.45

51.00

47.42

47.37

42.16

39.14

(8.74)

(7.03)

(8.10)

(8.19)

(8.62)

(9.36)

(8.40)

(7.34)

(7.06)

1984

Male

58.57

54.52

56.43

54.00

51.52

51.47

46.02

43.79

41.88

(11.07)

(8.64)

(9.51)

(10.42)

(8.79)

(8.51)

(8.53)

(7.88)

(6.84)

Female

53.95

53.86

50.45

53.95

48.42

45.58

42.95

40.61

39.30

(10.04)

(7.33)

(11.59)

(7.83)

(8.06)

(9.84)

(8.89)

(8.72)

(6.90)

Total

55.49

54.18

53.01

53.97

49.97

48.27

44.45

42.24

40.54

(10.56)

(7.93)

(11.09)

(8.88)

(8.51)

(9.66)

(8.80)

(8.39)

(6.93)

1991

Male

60.26

57.26

59.92

56.88

54.84

51.50

49.14

45.95

40.62

(8.10)

(8.29)

(8.26)

(7.51)

(8.99)

(7.12)

(7.38)

(8.38)

(7.21)

Female

59.45

54.02

53.38

52.10

50.35

47.24

43.76

41.00

38.42

(8.05)

(8.49)

(8.15)

(9.10)

(9.73)

(6.81)

(8.57)

(7.63)

(8.33)

Total

59.82

55.42

56.61

54.06

52.54

49.11

46.09

43.42

39.54

(8.01)

(8.50)

(8.79)

(8.76)

(9.59)

(7.22)

(8.47)

(8.34)

(7.80)

1998

Male

63.50

58.97

57.83

54.06

52.91

53.05

50.20

45.08

44.10

(8.34)

(7.89)

(7.06)

(8.50)

(8.46)

(7.68)

(8.15)

(8.50)

(6.88)

Female

58.52

54.06

53.78

50.71

50.58

48.88

45.91

42.68

39.53

(6.56)

(7.80)

(10.88)

(10.24)

(8.98)

(7.33)

(7.68)

(7.25)

(6.39)

Total

60.46

56.73

55.61

52.38

51.66

51.06

48.62

43.75

41.82

(7.62)

(8.17)

(9.52)

(9.53)

(8.77)

(7.76)

(8.20)

(7.85)

(6.98)

Inductive Reasoning

1956

Male

52.79

52.70

48.89

49.74

46.63

39.46

40.84

(8.38)

(9.31)

(8.64)

(9.19)

(8.77)

(6.89)

(7.32)

Female

55.42

55.05

50.97

51.43

47.43

42.68

40.66

(9.04)

(8.28)

(9.41)

(8.16)

(10.04)

(7.01)

(7.07)

Total

54.10

53.94

49.92

50.52

47.03

41.11

40.75

(8.76)

(8.79)

(9.03)

(8.70)

(9.37)

(7.09)

(7.15)

1963

Male

56.83

53.17

53.18

47.75

44.81

42.17

38.94

40.03

(7.31)

(8.32)

(8.45)

(7.92)

(8.38)

(7.58)

(6.71)

(6.83)

Female

58.12

56.27

52.39

50.20

45.64

44.49

39.81

37.00

(7.91)

(6.92)

(7.46)

(9.18)

(8.23)

(9.35)

(6.78)

(4.77)

Total

57.58

54.95

52.77

48.95

45.28

43.44

39.37

38.47

(7.65)

(7.68)

(7.93)

(8.62)

(8.27)

(8.61)

(6.73)

(6.02)

1970

Male

59.00

56.61

53.62

52.30

49.20

49.76

40.55

37.68

37.12

(7.51)

(8.63)

(7.72)

(9.18)

(8.08)

(8.88)

(7.36)

(5.39)

(6.91)

Female

58.58

57.46

52.70

52.70

50.27

47.19

41.53

38.66

37.08

(7.12)

(7.70)

(7.42)

(8.42)

(8.31)

(7.82)

(7.54)

(5.38)

(4.62)

Total

58.76

57.09

53.07

52.50

49.79

48.41

41.08

38.14

37.10

(7.24)

(8.06)

(7.51)

(8.76)

(8.18)

(8.39)

(7.43)

(5.38)

(5.86)

1977

Male

56.00

55.97

55.08

50.72

51.42

47.74

42.77

39.38

36.48

(8.09)

(6.69)

(8.97)

(8.29)

(8.73)

(8.70)

(6.84)

(5.75)

(4.44)

Female

59.93

57.21

55.97

52.05

49.38

46.66

44.87

39.67

38.32

(7.73)

(7.42)

(7.07)

(8.41)

(8.39)

(7.74)

(8.68)

(6.57)

(8.08)

Total

57.96

56.63

55.52

51.43

50.44

47.18

43.86

39.51

37.47

(8.09)

(7.06)

(8.05)

(8.32)

(8.57)

(8.17)

(7.87)

(6.10)

(6.65)

1984

Male

58.64

57.78

56.50

52.81

49.18

49.83

43.59

42.34

38.20

(6.86)

(7.07)

(7.15)

(6.58)

(8.34)

(7.67)

(7.12)

(6.70)

(6.18)

Female

59.14

57.75

56.98

56.64

54.79

49.93

48.02

44.82

37.22

(7.60)

(8.13)

(6.01)

(7.58)

(6.69)

(8.48)

(7.51)

(7.96)

(4.84)

Total

58.98

57.76

56.77

55.11

51.98

49.89

45.89

43.51

37.69

(7.33)

(7.56)

(6.48)

(7.39)

(8.02)

(8.07)

(7.61)

(7.38)

(5.49)

1991

Male

58.81

58.06

57.69

56.00

52.82

49.53

47.14

44.41

39.55

(7.47)

(5.70)

(7.56)

(7.89)

(8.11)

(4.82)

(7.40)

(8.46)

(4.88)

Female

61.55

58.46

58.50

58.02

55.28

50.20

50.15

46.44

39.42

(5.78)

(7.05)

(5.13)

(7.18)

(7.91)

(7.16)

(7.98)

(7.48)

(5.63)

Total

60.32

58.29

58.10

57.19

54.08

49.90

48.85

45.45

39.48

(6.68)

(6.47)

(6.42)

(7.50)

(8.05)

(6.21)

(7.84)

(7.99)

(5.23)

1998

Male

63.12

58.74

58.06

54.55

53.81

54.20

48.28

44.60

43.77

(5.75)

(6.85)

(6.00)

(6.38)

(8.08)

(7.46)

(7.09)

(6.91)

(6.20)

Female

61.36

59.78

57.93

56.78

54.94

51.97

49.11

45.77

42.97

(4.39)

(6.54)

(6.95)

(7.32)

(7.27)

(6.79)

(6.79)

(6.71)

(5.69)

Total

62.05

59.21

57.99

55.67

54.42

53.19

48.59

45.25

43.37

(4.97)

(6.68)

(6.51)

(6.93)

(7.63)

(7.21)

(6.96)

(6.76)

(5.91)

Number

1956

Male

48.00

53.88

53.17

56.80

53.86

48.34

47.61

(8.30)

(10.24)

(10.53)

(8.76)

(9.91)

(8.64)

(9.66)

Female

50.61

50.78

50.46

51.30

52.97

47.84

46.18

(10.27)

(8.67)

(10.46)

(8.48)

(11.65)

(7.51)

(9.46)

Total

49.30

52.24

51.83

54.26

53.41

48.08

46.89

(9.37)

(9.50)

(10.51)

(9.00)

(10.75)

(8.03)

(9.52)

1963

Male

51.12

55.88

57.25

53.57

51.60

49.84

47.28

46.82

(8.03)

(12.42)

(10.44)

(10.66)

(10.96)

(13.53)

(10.40)

(9.15)

Female

51.48

53.33

52.94

53.70

49.25

49.05

44.51

42.32

(8.38)

(9.46)

(10.21)

(10.38)

(10.87)

(11.09)

(9.73)

(9.62)

Total

51.33

54.42

54.98

53.63

50.27

49.43

45.91

44.51

(8.20)

(10.85)

(10.51)

(10.49)

(10.93)

(12.26)

(10.13)

(9.60)

1970

Male

52.97

58.82

54.59

56.47

55.42

56.84

49.14

44.32

43.88

(9.65)

(14.00)

(10.76)

(9.21)

(12.61)

(10.97)

(8.95)

(8.95)

(9.63)

Female

51.10

50.57

51.88

54.58

54.69

55.07

47.51

44.73

38.12

(8.63)

(9.28)

(8.59)

(9.93)

(10.90)

(11.81)

(8.01)

(7.92)

(6.17)

Total

51.92

54.12

52.98

55.52

55.02

55.91

48.26

44.51

41.12

(9.07)

(12.17)

(9.56)

(9.57)

(11.63)

(11.38)

(8.45)

(8.44)

(8.58)

1977

Male

49.36

49.69

51.84

49.12

55.02

51.77

50.71

44.89

42.21

(9.79)

(8.86)

(10.11)

(9.81)

(13.18)

(10.90)

(10.93)

(9.41)

(9.10)

Female

50.14

52.67

51.61

48.14

48.86

50.13

49.95

44.88

42.03

(9.95)

(8.29)

(8.88)

(9.08)

(8.04)

(10.79)

(10.51)

(10.50)

(8.39)

Total

49.75

51.27

51.72

48.59

52.06

50.92

50.32

44.89

42.12

(9.79)

(8.62)

(9.46)

(9.37)

(11.38)

(10.80)

(10.64)

(9.87)

(8.66)

1984

Male

50.50

53.63

48.60

51.92

48.79

52.69

48.42

48.44

44.71

(9.32)

(10.59)

(7.71)

(6.72)

(11.23)

(9.99)

(9.73)

(8.36)

(6.46)

Female

47.77

48.71

49.95

52.26

50.21

47.77

49.69

46.28

39.11

(7.84)

(8.06)

(8.47)

(7.86)

(8.95)

(9.43)

(9.48)

(7.70)

(9.09)

Total

48.68

51.13

49.37

52.12

49.50

50.01

49.07

47.40

41.75

(8.41)

(9.62)

(8.12)

(7.37)

(10.10)

(9.94)

(9.56)

(8.07)

(8.38)

1991

Male

47.89

49.26

51.44

53.56

52.03

49.22

51.21

48.61

45.06

(6.77)

(7.91)

(9.72)

(9.50)

(10.01)

(8.11)

(8.03)

(11.58)

(10.76)

Female

48.18

47.39

50.20

50.80

50.28

49.56

49.04

50.07

48.18

(7.35)

(7.20)

(7.71)

(10.05)

(8.61)

(9.26)

(8.42)

(8.16)

(8.67)

Total

48.05

48.19

50.81

51.93

51.13

49.41

49.98

49.36

46.62

(7.04)

(7.52)

(8.73)

(9.87)

(9.30)

(8.72)

(8.28)

(9.94)

(9.82)

1998

Male

52.31

48.18

50.50

49.58

50.35

51.92

48.83

48.24

47.73

(10.27)

(8.81)

(9.31)

(10.23)

(10.86)

(8.76)

(8.55)

(8.61)

(7.86)

Female

47.96

48.59

48.28

48.03

49.24

47.58

47.80

48.55

44.67

(7.74)

(6.12)

(6.85)

(8.87)

(6.59)

(8.03)

(6.53)

(8.64)

(9.49)

Total

49.66

48.37

49.28

48.80

49.75

49.96

48.45

48.41

46.20

(8.95)

(7.65)

(8.09)

(9.56)

(8.79)

(8.66)

(7.84)

(8.55)

(8.77)

Word Fluency

1956

Male

53.87

53.76

53.36

54.14

53.57

48.77

48.50

(9.57)

(9.92)

(9.04)

(10.63)

(11.30)

(10.96)

(11.18)

Female

53.53

58.78

54.83

58.87

57.14

50.78

47.03

(10.57)

(10.91)

(10.27)

(9.47)

(10.12)

(8.97)

(10.43)

Total

53.70

56.41

54.08

56.32

55.36

49.81

47.76

(10.02)

(10.69)

(9.62)

(10.31)

(10.80)

(9.97)

(10.76)

1963

Male

50.86

49.15

52.30

49.42

45.69

46.83

43.94

44.74

(8.32)

(9.11)

(9.00)

(9.65)

(9.50)

(7.59)

(9.42)

(8.17)

Female

53.00

54.66

51.10

51.80

48.81

50.80

44.92

44.18

(8.04)

(8.88)

(7.57)

(9.41)

(8.37)

(10.53)

(9.11)

(8.15)

Total

52.10

52.31

51.67

50.59

47.46

48.91

44.43

44.45

(8.19)

(9.35)

(8.27)

(9.58)

(8.98)

(9.43)

(9.24)

(8.11)

1970

Male

52.36

47.64

48.88

51.40

52.00

50.32

42.38

39.74

41.19

(8.07)

(9.05)

(8.08)

(8.78)

(10.40)

(10.04)

(8.49)

(8.12)

(9.73)

Female

53.78

52.73

51.00

53.51

53.23

50.10

45.20

43.15

43.54

(8.18)

(9.26)

(9.06)

(7.14)

(6.86)

(6.50)

(9.00)

(8.17)

(7.08)

Total

53.11

50.54

50.14

52.45

52.62

50.20

43.90

41.33

42.32

(8.11)

(9.45)

(8.69)

(8.03)

(8.59)

(8.32)

(8.84)

(8.28)

(8.56)

1977

Male

53.21

53.03

50.03

48.84

51.55

48.83

46.37

40.43

38.46

(8.36)

(8.26)

(8.55)

(9.85)

(11.48)

(8.01)

(8.60)

(7.98)

(6.86)

Female

53.32

55.88

53.61

49.84

49.70

50.84

48.47

45.64

44.45

(10.99)

(6.97)

(8.02)

(8.38)

(8.70)

(9.28)

(7.34)

(9.87)

(8.66)

Total

53.27

54.55

51.79

49.38

50.66

49.88

47.47

42.89

41.61

(9.68)

(7.67)

(8.43)

(9.04)

(10.22)

(8.70)

(7.99)

(9.23)

(8.35)

1984

Male

56.00

56.07

55.00

51.27

51.21

46.80

44.78

44.08

39.50

(13.79)

(6.93)

(10.26)

(9.92)

(10.05)

(7.05)

(9.22)

(8.43)

(7.35)

Female

54.33

53.29

54.08

54.59

52.42

48.60

48.67

45.11

42.41

(9.41)

(10.39)

(9.24)

(10.29)

(8.83)

(10.91)

(8.93)

(8.79)

(7.13)

Total

54.89

54.65

54.47

53.26

51.82

47.79

46.78

44.57

41.04

(11.01)

(8.89)

(9.63)

(10.20)

(9.41)

(9.37)

(9.23)

(8.56)

(7.31)

1991

Male

55.41

53.81

55.03

51.03

49.76

50.44

47.07

45.71

42.15

(9.43)

(9.03)

(9.99)

(8.67)

(8.91)

(9.30)

(9.06)

(10.64)

(8.80)

Female

57.33

53.88

53.42

52.78

50.72

50.54

48.76

48.35

43.55

(9.98)

(10.13)

(8.74)

(10.42)

(9.13)

(9.09)

(7.37)

(8.99)

(8.21)

Total

56.47

53.85

54.22

52.06

50.26

50.49

48.03

47.06

42.84

(9.70)

(9.61)

(9.35)

(9.72)

(8.98)

(9.12)

(8.14)

(9.86)

(8.48)

1998

Male

58.94

53.84

54.77

52.58

49.47

47.68

46.55

44.00

40.80

(10.55)

(8.68)

(8.83)

(8.99)

(9.22)

(8.94)

(9.42)

(8.42)

(6.48)

Female

56.24

56.12

54.64

53.03

52.48

49.82

47.29

47.71

41.50

(9.77)

(10.08)

(9.55)

(0.57)

(9.78)

(10.21)

(9.53)

(10.55)

(9.90)

Total

57.29

54.89

54.70

52.81

51.09

48.64

46.82

46.05

41.15

(10.04)

(9.35)

(9.19)

(9.25)

(9.59)

(9.53)

(9.42)

(9.75)

(8.30)

Index of Intellectual Ability

1956

Male

52.47

55.03

52.97

53.97

51.00

43.94

43.66

(8.86)

(10.48)

(9.55)

(8.54)

(9.72)

(8.56)

(8.73)

Female

53.24

55.62

51.60

53.70

50.80

44.81

41.50

(10.19)

(9.14)

(9.21)

(8.88)

(10.80)

(7.70)

(8.77)

Total

52.86

55.34

52.30

53.85

50.90

44.39

42.58

(9.49)

(9.73)

(9.34)

(8.63)

(10.20)

(8.09)

(8.76)

1963

Male

54.60

54.75

56.37

51.39

47.52

45.57

41.30

40.84

(7.53)

(8.51)

(7.71)

(9.29)

(9.11)

(10.04)

(9.54)

(7.40)

Female

55.36

55.44

52.59

52.00

47.20

46.77

40.57

37.52

(8.29)

(8.08)

(7.04)

(8.89)

(9.87)

(10.49)

(8.90)

(7.48)

Total

55.04

55.15

54.38

51.69

47.34

46.20

40.94

39.14

(7.95)

(8.23)

(7.58)

(9.07)

(9.51)

(10.25)

(9.20)

(7.58)

1970

Male

56.71

57.00

54.71

55.40

54.00

53.74

43.07

37.79

37.46

(8.23)

(9.08)

(8.55)

(8.01)

(9.33)

(9.74)

(7.77)

(7.79)

(8.85)

Female

55.50

54.76

52.46

54.53

53.02

50.43

42.73

39.07

35.04

(8.02)

(7.95)

(8.11)

(8.04)

(8.15)

(8.24)

(7.80)

(6.15)

(6.05)

Total

56.03

55.72

53.37

54.97

53.46

52.00

42.89

38.39

36.30

(8.07)

(8.46)

(8.32)

(7.99)

(8.67)

(9.08)

(7.74)

(7.06)

(7.66)

1977

Male

54.50

54.44

54.27

51.00

53.97

49.66

45.77

39.00

35.78

(7.89)

(6.70)

(9.04)

(7.88)

(11.13)

(9.38)

(8.01)

(8.42)

(6.70)

Female

54.75

56.82

54.64

50.00

49.08

48.26

46.84

40.27

36.42

(10.48)

(5.70)

(7.14)

(8.84)

(8.40)

(9.84)

(9.02)

(9.21)

(7.59)

Total

54.62

55.71

54.45

50.46

51.62

48.93

46.33

39.60

36.12

(9.19)

(6.25)

(8.10)

(8.36)

(10.15)

(9.58)

(8.51)

(8.76)

(7.14)

1984

Male

56.43

57.11

55.07

53.77

50.24

50.77

45.65

43.21

38.58

(9.72)

(7.43)

(6.84)

(6.71)

(9.00)

(8.11)

(9.71)

(6.95)

(6.96)

Female

54.61

53.71

54.05

56.08

52.64

48.23

47.12

43.83

35.89

(7.98)

(8.10)

(7.11)

(7.07)

(7.54)

(8.53)

(8.62)

(8.89)

(6.39)

Total

55.21

55.38

54.49

55.15

51.44

48.37

46.40

43.51

37.16

(8.59)

(7.89)

(6.97)

(6.96)

(8.33)

(8.39)

(9.14)

(7.89)

(6.74)

1991

Male

55.30

55.48

57.41

56.03

53.32

50.62

48.67

45.49

39.62

(7.41)

(6.62)

(8.72)

(7.89)

(9.06)

(6.81)

(7.53)

(9.36)

(7.31)

Female

57.09

53.63

55.35

54.90

53.15

49.73

48.58

46.30

40.82

(6.91)

(8.28)

(6.49)

(9.07)

(8.25)

(8.03)

(8.03)

(8.19)

(7.80)

Total

56.28

54.43

56.37

55.36

53.23

50.12

48.62

45.90

40.23

(7.14)

(7.61)

(7.69)

(8.57)

(8.60)

(7.49)

(7.77)

(8.74)

(7.53)

1998

Male

60.06

55.32

56.21

53.34

52.58

53.02

48.60

44.88

43.03

(8.54)

(7.15)

(7.00)

(6.98)

(8.88)

(7.55)

(7.90)

(7.76)

(6.38)

Female

56.08

55.03

54.00

53.03

52.90

49.79

47.71

46.03

40.60

(5.68)

(6.36)

(7.87)

(8.53)

(6.85)

(7.14)

(6.51)

(7.37)

(8.41)

Total

57.63

55.19

55.00

53.18

52.75

51.56

48.27

45.52

41.82

(7.11)

(6.75)

(7.53)

(7.77)

(7.81)

(7.50)

(7.39)

(7.50)

(7.50)

Index of Educational Aptitude

1956

Male

51.26

52.70

50.72

49.57

47.66

40.23

41.03

(8.77)

(9.59)

(9.39)

(9.68)

(10.09)

(9.01)

(7.92)

Female

53.50

55.49

50.69

55.03

47.46

44.24

40.08

(7.65)

(7.51)

(10.45)

(7.32)

(9.28)

(8.29)

(7.84)

Total

52.38

54.17

50.70

52.09

47.56

42.29

40.55

(8.25)

(8.61)

(9.86)

(9.04)

(9.62)

(8.82)

(7.84)

1963

Male

52.88

52.77

54.00

49.11

45.55

42.90

38.92

37.66

(8.25)

(8.37)

(7.78)

(9.12)

(9.85)

(8.99)

(8.88)

(8.90)

Female

54.50

54.63

52.70

51.53

47.41

46.53

41.52

37.50

(8.38)

(7.58)

(7.12)

(8.70)

(9.42)

(10.01)

(8.32)

(8.03)

Total

53.82

53.84

53.31

50.30

46.60

44.80

40.21

37.58

(8.32)

(7.95)

(7.44)

(8.97)

(9.62)

(9.68)

(8.67)

(8.41)

1970

Male

53.81

52.71

53.47

53.42

53.32

52.47

41.86

36.38

35.27

(7.93)

(8.81)

(7.46)

(8.14)

(7.36)

(9.38)

(7.50)

(7.06)

(8.54)

Female

55.20

55.16

53.06

54.19

52.22

49.00

43.86

39.24

36.21

(7.51)

(7.84)

(7.68)

(8.15)

(7.69)

(8.06)

(8.42)

(5.64)

(6.95)

Total

54.59

54.11

53.23

53.80

52.72

50.65

42.93

37.72

35.72

(7.67)

(8.29)

(7.55)

(8.11)

(7.52)

(8.83)

(8.03)

(6.56)

(7.75)

1977

Male

54.21

55.17

53.84

52.31

52.68

49.31

43.28

37.70

33.96

(7.95)

(7.11)

(9.81)

(8.86)

(9.71)

(9.74)

(8.17)

(8.51)

(6.60)

Female

56.18

56.85

55.58

51.00

50.46

48.63

45.84

40.24

34.29

(9.33)

(6.87)

(7.44)

(10.18)

(9.77)

(8.75)

(8.99)

(9.46)

(6.60)

Total

55.20

56.06

54.70

51.61

51.61

48.96

44.62

38.90

34.14

(8.65)

(6.98)

(8.71)

(9.54)

(9.74)

(9.18)

(8.65)

(9.00)

(6.55)

1984

Male

54.89

56.52

56.70

55.27

51.64

50.78

46.48

41.61

38.80

(8.05)

(6.27)

(6.03)

(6.16)

(8.19)

(8.11)

(8.71)

(5.92)

(8.71)

Female

56.55

54.51

58.00

57.33

57.18

51.56

52.07

47.30

40.85

(7.16)

(8.33)

(6.25)

(6.16)

(6.39)

(8.19)

(8.11)

(8.40)

(7.02)

Total

56.00

55.27

56.56

56.58

53.62

51.11

47.37

43.41

38.19

(7.46)

(7.42)

(6.11)

(6.21)

(7.56)

(8.10)

(8.40)

(7.41)

(7.82)

1991

Male

53.70

56.52

57.64

56.53

54.08

52.41

48.69

46.39

38.73

(8.04)

(6.02)

(6.51)

(6.36)

(7.56)

(7.87)

(8.32)

(8.70)

(6.82)

Female

55.36

55.41

54.34

56.49

55.58

52.67

50.97

48.48

43.60

(6.46)

(8.21)

(5.72)

(6.49)

(6.69)

(8.03)

(8.19)

(9.07)

(9.01)

Total

55.18

55.38

57.82

57.00

55.67

51.93

50.61

46.86

39.79

(7.28)

(7.37)

(6.09)

(6.41)

(7.25)

(7.92)

(8.38)

(8.85)

(8.00)

1998

Male

56.25

55.63

56.46

54.60

54.86

55.38

50.92

46.92

44.77

(5.81)

(6.59)

(6.58)

(7.21)

(8.38)

(7.12)

(7.88)

(7.94)

(7.35)

Female

55.36

55.41

54.34

56.49

55.58

52.67

50.97

48.48

43.60

(5.86)

(7.12)

(7.49)

(7.33)

(6.42)

(7.80)

(6.72)

(8.14)

(7.82)

Total

55.71

55.53

55.30

55.55

55.25

54.15

50.94

47.79

44.18

(5.78)

(6.79)

(7.02)

(7.31)

(7.36)

(7.51)

(7.44)

(8.01)

(7.55)

Summed Over All Measurement Occasions

Verbal Meaning

Male

52.04

53.53

54.25

52.57

51.45

49.31

45.28

41.20

39.26

(8.29)

(7.94)

(8.13)

(8.76)

(9.57)

(10.32)

(9.60)

(9.24)

(8.87)

Female

53.72

53.95

53.62

54.38

52.02

49.53

46.72

43.56

39.37

(7.84)

(7.88)

(8.05)

(8.19)

(8.91)

(9.18)

(9.34)

(9.42)

(9.00)

Total

53.00

53.75

53.91

53.51

51.75

49.43

46.00

42.42

39.31

(8.07)

(7.91)

(8.09)

(8.51)

(9.22)

(9.73)

(9.49)

(9.39)

(8.92)

Spatial Orientation

Male

59.26

57.06

57.07

54.48

52.29

50.49

47.33

43.86

42.21

(9.39)

(8.17)

(8.11)

(8.40)

(8.46)

(8.76)

(7.89)

(7.78)

(6.85)

Female

55.06

53.95

51.47

50.67

48.31

45.91

43.11

40.67

38.33

(9.44)

(8.18)

(9.15)

(9.19)

(8.58)

(7.98)

(7.87)

(7.05)

(6.94)

Total

56.86

55.39

54.08

52.50

50.19

48.10

45.22

42.28

40.23

(9.64)

(8.31)

(9.11)

(9.01)

(8.75)

(8.66)

(8.15)

(7.59)

(7.15)

Inductive Reasoning

Male

57.29

55.90

54.67

51.59

49.41

47.22

43.19

41.12

39.27

(7.90)

(7.92)

(8.30)

(8.35)

(8.87)

(8.90)

(7.85)

(7.13)

(6.24)

Female

58.90

57.26

54.89

53.94

50.50

47.34

44.65

41.95

39.12

(7.55)

(7.43)

(7.61)

(8.59)

(8.95)

(8.44)

(8.48)

(7.49)

(6.28)

Total

58.21

56.63

54.79

52.81

49.99

47.29

43.92

41.54

39.19

(7.74)

(7.68)

(7.93)

(8.55)

(8.92)

(8.66)

(8.20)

(7.32)

(6.25)

Number

Male

50.19

52.85

53.02

52.94

52.42

51.44

48.89

46.81

45.00

(8.86)

(11.14)

(10.23)

(9.97)

(11.41)

(10.79)

(9.51)

(9.49)

(8.94)

Female

49.72

50.66

50.91

51.34

50.65

49.61

47.63

46.09

42.79

(8.64)

(8.60)

(8.93)

(9.66)

(9.79)

(10.17)

(9.11)

(9.09)

(9.18)

Total

49.92

51.67

51.89

52.11

51.49

50.48

48.26

46.46

43.87

(8.73)

(9.90)

(9.61)

(9.83)

(10.61)

(10.50)

(9.33)

(9.29)

(9.11)

Word Fluency

Male

53.81

52.23

52.79

51.13

50.03

48.36

45.56

43.04

40.70

(9.84)

(9.13)

(9.26)

(9.52)

(10.32)

(8.85)

(9.48)

(8.90)

(7.90)

Female

54.29

55.01

52.97

53.13

51.63

50.24

47.05

45.73

43.10

(9.42)

(9.59)

(8.89)

(9.52)

(9.05)

(9.47)

(8.88)

(9.11)

(8.28)

Total

54.08

53.73

52.89

52.17

50.87

49.34

46.30

44.37

41.93

(9.60)

(9.47)

(9.06)

(9.56)

(9.70)

(9.22)

(9.21)

(9.10)

(8.17)

Index of Intellectual Ability

Male

55.26

55.47

55.48

53.29

51.53

49.37

45.08

41.59

39.03

(8.42)

(8.10)

(8.20)

(8.21)

(9.68)

(9.37)

(8.79)

(8.45)

(7.58)

Female

55.15

55.05

53.43

53.34

50.84

48.18

44.76

41.96

37.96

(8.36)

(7.80)

(7.58)

(8.65)

(8.99)

(8.92)

(8.83)

(8.37)

(7.68)

Total

55.20

55.24

54.38

53.32

51.17

48.75

44.93

41.77

38.48

(8.37)

(7.93)

(7.94)

(8.44)

(9.32)

(9.15)

(8.80)

(8.40)

(7.64)

Index of Educational Aptitude

Male

53.53

54.42

54.67

52.51

51.03

48.70

44.42

40.67

38.59

(8.06)

(7.79)

(7.92)

(8.54)

(9.46)

(10.03)

(9.27)

(8.83)

(8.39)

Female

55.35

55.09

54.20

54.58

51.78

48.94

45.95

42.80

38.65

(7.60)

(7.61)

(7.71)

(8.22)

(8.96)

(8.96)

(9.16)

(9.12)

(8.22)

Total

54.57

54.78

54.42

53.58

51.43

48.82

45.19

41.73

38.62

(7.84)

(7.69)

(7.80)

(8.43)

(9.20)

(9.48)

(9.20)

(9.00)

(8.28)

(p.70) (p.71) (p.72) (p.73) (p.74) (p.75) (p.76) (p.77) (p.78)
                   Cross-Sectional Studies                   Cross-Sectional Studies

figure 4.4 Age Difference Patterns of the Five Primary Mental Abilities by Gender for the First (1956) and Last (1998) Cross-Sectional Comparisons.

study participants, much greater shifts can be observed. In young adulthood, females now show higher performance on Spatial Orientation than was the case some 42 years ago. For this ability, the peak age for women is now in midlife. For the women, age differences in Number ability have virtually disappeared, and the peak age for Verbal Meaning has moved to the early 50s.

Absolute age differences across the adult life span, observed at any given point, have been reduced over time, but remain substantial for most abilities. However, there has been a sharp reduction of age differences in performance observed until the late 60s are reached. For example, for Verbal Meaning the absolute difference between ages 25 and 81 currently amounts to 0.8 SD for both men and women. But the absolute difference between ages 25 and 67 has been reduced from 0.8 to 0.2 SD for men and from 1.2 to 0.1 SD (or virtually no difference) for women.

(p.79) Age Difference Patterns Across Abilities Age difference data are not directly relevant to testing propositions about ontogenetic change. Such data, however, when examined in the context of cross-sectional sequences, are quite appropriate for testing the proposition of invariance in age difference patterns over time. Given certain assumptions, they are also the data of choice to evaluate the magnitude of cohort differences and time-of-measurement (period) effects.

Throughout our study, we have questioned whether age difference patterns remain invariant over time and have concluded that statistically significant shifts in such patterns can be observed. This conclusion is based in part on finding Age × Time interactions in time-sequential analyses and Cohort × Time interactions in cross-sequential analyses (Schaie & Hertzog, 1983; Schaie, Labouvie, & Buech, 1973; Schaie & Strother, 1968c).

(p.80)

                   Cross-Sectional Studies                   Cross-Sectional Studies                   Cross-Sectional Studies

figure 4.5 Age Difference Patterns of the Primary Mental Abilities for the Total Sample by Test Occasion.

To examine shifts in age profiles as well as the peak ages across the seven cross-sectional studies, mean values for each study across age for the five PMAs and the composite indexes are graphed in figure 4.5. What seems most apparent is that means observed at the same ages tend to rise to progressively higher levels for successive cohorts attaining a given age. This is clearly the case for Verbal Meaning, Spatial Orientation, and Inductive Reasoning as well as for the composite indexes. Successively lower levels are attained for successive cohorts on Number; the cohort pattern for Word Fluency is less clearly defined.

For Verbal Meaning there has been a general increase in performance level at all ages. Most noteworthy, however, are performance increases at the older ages. For ages 60 to 74 years, these increases amount to a full standard deviation over (p.81) a 42-year period. Equally dramatic, at 81 years of age, performance has increased by approximately 1 SD over the 28 years monitored for this age group.

Somewhat smaller increases across time, averaging approximately 0.3 SD, were observed for Spatial Orientation until 53 years of age. At ages 60 and 67 years, there was a gain of 0.5 SD, with less improvement (0.2 SD) for the two oldest age groups. Inductive Reasoning also showed large rises in performance over time at comparable ages (averaging about 0.7 SD), whereas Number and Word Fluency showed complex changes involving curvilinear patterns of age differences.

The summary indexes of Intellectual Ability and Educational Aptitude also showed significant reductions in age differences at all comparable ages. Changes in performance level are discussed in greater detail in chapter 6, with explicit discussions of cohort and period effect. (p.82)

(p.83) Table 4.2 also contains means and standard deviations by age and gender summed across all observations. These values represent the averages for all seven replications over a 42-year period. Correlations among the five basic abilities by age group and for the total sample are reported in appendix A-4.1.

Expanded Cognitive Data

The expanded cognitive battery described in chapter 3 was administered in Cycles 5, 6, and 7, except for the Perceptual Speed measures of Finding A's and Identical Pictures, which were first introduced during the fourth cycle. Cross-sectional analyses for these cycles were consequently done both at the level of individual measures and at the latent construct level to determine within-ability and across-ability age difference patterns (see Schaie & Willis, 1993).

Most of the major longitudinal studies of adult development in the past collected only very limited data that speak to the issues of generalizability of findings within and across domains in the area of intellectual functioning (e.g., Busse, 1993; Costa & McCrae, 1993; Eichorn, Clausen, Haan, Honzik, & Mussen, 1981; Rott, 1990; Schaie, 1983b; Schmitz-Scherzer & Thomae, 1983; Shock et al., 1984; Siegler, 1983). Cross-sectional data may actually be quite instructive with respect to this issue because such data allow us to draw concurrent comparisons of age difference patterns within and across domains without requiring attention to the thorny methodological issues associated with comparisons across time (see chapter 2).

There are likely to be substantial life stage differences in adulthood in the degree to which levels of performance for different ability markers are equivalent both within and across ability domains. First I examine the extent to which patterns of age differences are congruent within a particular ability domain by describing age difference patterns for six psychometric abilities (see Schaie & Willis, 1993). These abilities broadly sample higher-order constructs, such as those espoused by Horn (1982). Thus, fluid intelligence is represented by the ability of Inductive Reasoning. Verbal Ability and Numeric Ability stand as representatives of crystallized intelligence, and mental rotation is represented by our Spatial Ability construct. Verbal Memory and Perceptual Speed are examined as ability samplers for the memory and speed domains, respectively. Next, consideration is therefore given to the age difference patterns across the various ability domains.

What is at issue is the question of whether patterns of age differences in ability remain invariant for multiple markers of the primary mental abilities. This issue is addressed again in chapter 8, in which several studies are reported that examine invariance across age and time by means of structural analyses (see Schaie et al., 1989, 1998), and it is shown that configural invariance (i.e., number of factors and factor pattern) is preserved across widely differing age groups. Here, we examine shifts of different marker variables at different life stages, an effect observed a long time ago in cross-sectional studies of the Wechsler Adult Intelligence Scale (Cohen, 1957).

The reasons for such shifts may be sought in such contextual variables as shifts in educational exposure to the skills embodied in a particular marker variable or latent construct and the impact of slowing in perceptual and/or motor speed that (p.84) may differentially affect various markers. For example, we know that conditions of instructions and speededness imposed by time limits differentially affect performance on the PMA and Educational Testing Service vocabulary tests (Hertzog, 1989). Likewise, it is known that there have been generational shifts in instruction in quantitative skills that should affect numerical performance for different cohorts. For other abilities, congruence would be expected across the entire life span until the 80s are reached. At that late stage, the differential memorization demands as well as the relative motor complexity of answer sheet as compared with disposable booklet formats might result in differential efficiency of a given marker.

Age-difference patterns appear generally invariant across sex within domains (albeit there is strong evidence for overall gender differences in level of performance), but it is not a foregone conclusion that such invariance holds for all abilities or for all markers of a given ability. Gender differences will therefore be examined, and results are reported separately by gender when warranted.

The issue of the generalizability of markers within domains is particularly important for age comparative studies. For valid cross-sectional comparisons, it must be shown that an observed variable provides a reasonable representation of the developmental trajectory of the latent construct to be marked. If this is the case, then a single marker may suffice. But if there is wide discrepancy in developmental trajectories for multiple markers, we would then be forced to multiply mark the construct, providing differential weights for the markers at different life stages. The data presented here provide some guidance on these matters.

All scores on the observed variables were rescaled into T-score form (M= 50; SD = 10) using parameters for the total sample at first test (N = 2,476). Factor scores for the six intellectual abilities were computed using factor regression weights based on a previously determined best-fitting factor model (Schaie et al., 1991).

Age Difference Patterns Within Ability Domains

The age difference patterns for the observed markers of the six primary ability domains (in standardized form) are reported in table 4.3. Means and standard deviations are given separately by gender and for the total age/cohort groupings. This table also reports averages over the three data points. Correlations among the variables in the extended battery by age group and for the total sample can be found in appendix A-4.2.

The age difference gradients graphed in figure 4.6, comparing the markers for each latent construct, represent averages over three cohorts assessed at the same age. Results with respect to congruence among the patterns for the different operations measuring the ability constructs are described in the following paragraphs.

The new markers of the Inductive Reasoning factor have very similar age profiles, with an overall age difference of about 2 SD from the youngest to the oldest age cohort. Significant age differences from the youngest (peak) age appear by age 46 for all three tests. Gender differences were not significant for Letter Series, but favored women for Word Series and men for Number Series. A significant overall increase in performance level across the three assessment times was found only for Letter Series.

(p.85)

table 4.3 Means and Standard Deviations for the Expanded Ability Battery by Sample and Gender

Age

25

32

39

46

53

60

67

74

81

Inductive Reasoning

Letter Series

1984

Male

60.22

57.66

55.60

53.73

49.17

48.21

44.11

39.64

36.20

(6.53)

(8.31)

(8.60)

(7.54)

(8.20)

(8.70)

(8.30)

(6.00)

(7.39)

Female

54.92

55.96

55.81

51.80

49.97

49.66

44.94

42.19

38.06

(9.31)

(8.98)

(8.07)

(8.06)

(8.00)

(8.76)

(7.63)

(6.58)

(7.48)

Total

57.57

56.81

55.70

52.77

49.57

47.43

44.53

40.91

37.13

(8.54)

(8.57)

(8.27)

(7.88)

(8.08)

(8.75)

(7.92)

(6.42)

(7.35)

1991

Male

56.56

58.69

57.92

55.26

50.74

47.47

45.15

41.34

37.34

(9.76)

(6.91)

(7.77)

(7.40)

(8.75)

(6.00)

(8.72)

(8.97)

(6.26)

Female

60.06

57.30

56.56

55.55

53.30

47.82

47.32

42.67

36.00

(9.10)

(8.10)

(6.07)

(9.93)

(7.67)

(8.06)

(9.16)

(7.24)

(7.31)

Total

58.31

57.99

57.24

55.41

52.02

47.65

46.23

42.01

36.67

(9.48)

(7.60)

(6.96)

(8.93)

(8.26)

(7.17)

(8.99)

(8.11)

(6.80)

1998

Male

64.67

58.14

57.25

53.84

51.10

51.08

45.07

42.54

39.70

(6.62)

(7.65)

(7.62)

(7.27)

(8.07)

(7.45)

(8.24)

(7.34)

(4.79)

Female

59.80

59.25

55.96

54.66

52.27

47.58

44.60

41.77

38.30

(5.71)

(6.72)

(7.83)

(7.82)

(8.00)

(6.43)

(8.01)

(9.16)

(5.05)

Total

62.23

58.70

56.61

54.25

51.68

49.33

44.83

42.16

38.99

(6.44)

(7.19)

(7.73)

(7.53)

(8.01)

(7.17)

(8.11)

(8.35)

(4.92)

Word Series

1984

Male

59.00

56.68

54.57

53.31

48.72

48.07

43.23

39.26

32.27

(6.20)

(8.18)

(7.84)

(7.12)

(8.33)

(7.98)

(9.16)

(7.64)

(6.34)

Female

55.77

56.40

57.04

53.29

51.46

48.45

45.65

43.84

36.62

(9.13)

(8.32)

(8.02)

(7.19)

(6.70)

(8.15)

(8.68)

(8.29)

(7.46)

Total

57.38

56.54

55.80

53.30

50.09

48.26

44.44

41.55

34.45

(8.06)

(8.17)

(8.01)

(7.13)

(7.65)

(8.05)

(8.95)

(8.29)

(7.23)

1991

Male

55.41

56.41

54.41

55.00

50.47

47.84

44.51

40.00

33.47

(8.60)

(7.23)

(8.51)

(6.33)

(8.64)

(6.79)

(8.27)

(9.02)

(5.59)

Female

59.24

57.88

57.00

55.55

54.45

47.15

47.34

44.14

36.68

(7.31)

(8.94)

(6.53)

(8.05)

(9.06)

(7.71)

(7.90)

(9.12)

(8.57)

Total

57.32

57.14

55.71

55.28

52.46

47.50

45.93

42.07

35.07

(8.07)

(8.24)

(7.65)

(7.36)

(9.02)

(7.27)

(8.14)

(9.25)

(7.40)

1998

Male

60.93

57.23

56.94

52.05

51.60

50.18

44.95

43.21

36.97

(4.45)

(7.23)

(7.49)

(8.32)

(7.82)

(8.44)

(8.01)

(9.22)

(6.46)

Female

58.80

56.91

56.98

53.03

52.76

50.48

47.11

43.39

39.37

(9.61)

(9.48)

(7.54)

(7.89)

(7.74)

(7.03)

(7.65)

(8.99)

(7.91)

Total

59.87

57.07

56.96

52.54

52.18

50.33

46.03

43.30

38.17

(8.06)

(8.32)

(7.48)

(8.09)

(7.75)

(7.76)

(7.91)

(9.01)

(7.23)

Number Series

1984

Male

61.67

57.33

55.41

56.14

51.58

50.76

47.71

42.60

37.09

(4.61)

(11.01)

(8.52)

(7.85)

(8.88)

(7.69)

(9.50)

(8.55)

(4.46)

Female

53.48

51.90

52.58

49.94

48.04

46.02

44.78

41.00

39.75

(10.09)

(7.66)

(8.35)

(10.07)

(8.59)

(10.16)

(9.06)

(7.16)

(6.99)

Total

57.55

54.61

54.00

53.04

49.81

48.39

46.25

41.80

38.42

(9.32)

(9.90)

(8.51)

(9.68)

(8.88)

(9.39)

(9.34)

(7.81)

(6.13)

1991

Male

57.89

56.84

58.10

55.88

54.84

49.12

48.35

44.46

39.03

(9.20)

(8.41)

(9.79)

(8.14)

(9.79)

(6.74)

(8.70)

(9.88)

(6.35)

Female

56.21

54.08

52.40

50.37

51.30

45.78

46.41

42.12

38.28

(8.81)

(7.89)

(6.66)

(8.54)

(8.43)

(8.04)

(10.56)

(7.08)

(5.99)

Total

57.05

55.46

55.25

53.12

53.07

47.45

47.38

43.29

38.66

(8.95)

(8.18)

(8.78)

(8.76)

(9.23)

(7.63)

(9.83)

(8.56)

(6.13)

1998

Male

62.94

57.79

57.48

53.29

52.77

52.50

48.83

46.24

45.59

(6.70)

(9.20)

(9.29)

(7.75)

(9.53)

(8.41)

(7.86)

(8.49)

(7.94)

Female

54.60

54.31

52.90

51.38

48.92

48.70

43.51

43.93

37.93

(6.81)

(8.20)

(9.43)

(.36)

(7.56)

(9.19)

(7.11)

(8.22)

(7.45)

Total

58.77

56.05

55.19

52.34

50.84

50.60

46.17

45.09

41.76

(7.85)

(8.87)

(.60)

(8.62)

(8.69)

(8.91)

(7.98)

(8.34)

(8.56)

Spatial Orientation

Object Rotation

1984

Male

57.89

56.39

56.21

55.41

52.20

53.16

47.86

42.65

41.23

(5.58)

(6.78)

(7.76)

(6.91)

(7.52)

(6.86)

(8.88)

(9.63)

(8.49)

Female

53.00

53.83

52.87

52.72

48.95

48.16

44.71

39.84

37.88

(11.20)

(7.42)

(8.55)

(8.37)

(9.23)

(8.23)

(8.71)

(8.25)

(9.44)

Total

55.44

55.11

54.54

54.07

50.58

50.66

46.28

41.24

39.55

(9.73)

(7.14)

(8.36)

(7.89)

(8.58)

(8.00)

(8.90)

(8.96)

(9.03)

1991

Male

56.56

56.25

57.08

55.00

53.68

53.25

47.59

43.44

37.79

(7.59)

(6.70)

(8.05)

(6.26)

(7.82)

(6.48)

(9.94)

(9.73)

(8.94)

Female

56.21

53.68

49.62

52.43

50.20

47.37

42.80

38.72

35.59

(7.10)

(9.21)

(9.66)

(8.47)

(9.99)

(8.84)

(7.72)

(9.33)

(7.37)

Total

56.38

54.97

53.35

53.71

51.94

50.31

45.19

41.08

36.69

(7.26)

(8.25)

(9.60)

(7.71)

(9.11)

(8.37)

(9.00)

(9.76)

(8.19)

1998

Male

58.69

58.63

56.71

54.39

52.72

53.38

50.75

46.64

41.63

(7.26)

(5.85)

(6.23)

(7.71)

(7.04)

(7.84)

(7.89)

(11.38)

(7.78)

Female

56.92

54.97

55.24

50.89

49.04

48.24

45.29

37.00

36.72

(6.20)

(7.76)

(8.22)

(11.47)

(9.78)

(9.92)

(8.53)

(9.93)

(7.61)

Total

57.80

56.80

55.97

52.64

50.88

50.76

48.02

41.82

39.18

(6.60)

(6.99)

(7.39)

(9.90)

(8.77)

(9.13)

(8.51)

(11.56)

(8.02)

Alphanumeric Rotation

1984

Male

57.56

56.59

55.31

54.12

51.87

50.24

46.94

42.13

38.08

(3.75)

(5.05)

(7.81)

(7.24)

(8.09)

(8.41)

(9.60)

(9.32)

(8.60)

Female

51.31

56.84

54.19

52.59

49.08

47.77

45.91

41.47

37.81

(12.04)

(4.64)

(7.65)

(7.84)

(10.15)

(8.89)

(8.77)

(9.11)

(7.93)

Total

54.43

56.72

54.75

53.36

50.47

49.01

46.42

41.80

37.95

(9.91)

(4.84)

(7.71)

(7.61)

(9.26)

(8.74)

(9.13)

(9.16)

(8.06)

1991

Male

56.70

55.90

56.67

56.68

53.55

50.03

45.56

42.54

37.15

(6.01)

(7.42)

(5.20)

(5.43)

(7.96)

(8.37)

(9.18)

(9.76)

(10.06)

Female

57.56

55.28

54.79

54.16

53.10

46.70

45.32

41.77

35.18

(6.16)

(7.67)

(7.32)

(7.84)

(8.69)

(9.44)

(8.87)

(8.70)

(9.57)

Total

57.13

55.59

55.73

55.42

53.33

48.37

45.44

42.15

36.16

(6.05)

(7.52)

(6.38)

(7.03)

(8.29)

(9.07)

(8.96)

(9.19)

(9.79)

1998

Male

56.87

59.37

57.90

53.93

52.95

50.95

49.18

44.42

38.52

(7.18)

(3.53)

(5.02)

(7.71)

(7.01)

(10.24)

(9.47)

(11.41)

(7.36)

Female

53.68

56.38

55.79

53.05

50.02

48.70

45.46

40.32

37.41

(9.97)

(6.34)

(7.09)

(8.40)

(9.69)

(11.64)

(9.00)

(10.82)

(8.50)

Total

55.27

57.87

56.84

53.49

51.49

49.82

47.32

42.37

37.96

(9.06)

(5.25)

(6.28)

(8.05)

(8.64)

(10.89)

(9.42)

(11.17)

(7.88)

Cube Comparison

1984

Male

58.44

57.06

58.47

55.81

51.81

51.00

45.26

41.87

38.27

(8.63)

(10.26)

(8.81)

(8.45)

(7.58)

(8.46)

(7.07)

(7.91)

(7.10)

Female

56.00

51.92

51.26

49.00

46.34

45.05

43.33

41.88

39.06

(11.50)

(7.40)

(8.47)

(7.03)

(6.99)

(7.34)

(7.27)

(5.78)

(5.46)

Total

57.22

54.49

54.86

52.41

49.07

48.02

44.29

41.87

38.67

(10.27)

(9.40)

(9.30)

(8.32)

(7.76)

(8.39)

(7.23)

(6.76)

(6.06)

1991

Male

59.59

58.55

61.36

56.71

53.95

50.44

45.63

44.71

38.28

(11.19)

(9.39)

(9.38)

(7.57)

(10.44)

(7.33)

(7.36)

(7.61)

(6.01)

Female

56.32

53.78

54.21

52.20

49.70

44.95

45.59

40.74

40.48

(9.24)

(8.23)

(8.15)

(8.17)

(8.19)

(7.31)

(7.45)

(6.08)

(5.98)

Total

57.96

56.16

57.78

54.45

51.82

47.69

45.61

42.73

39.38

(10.19)

(8.99)

(9.45)

(8.19)

(9.53)

(7.77)

(7.37)

(7.11)

(6.05)

1998

Male

66.67

61.43

61.43

55.11

55.83

50.84

48.07

45.38

43.28

(9.84)

(8.17)

(8.77)

(9.47)

(8.51)

(8.80)

(7.49)

(8.56)

(5.47)

Female

56.32

57.72

54.34

52.48

49.29

47.21

45.69

42.65

42.11

(8.04)

(8.75)

(9.18)

(9.74)

(9.03)

(8.51)

(5.17)

(4.98)

(7.49)

Total

61.49

59.57

57.88

53.80

52.56

49.03

45.88

44.01

42.19

(10.01)

(8.59)

(9.63)

(9.66)

(9.34)

(8.79)

(6.79)

(6.84)

(6.55)

Numeric Ability

Addition

1984

Male

49.56

52.42

50.87

54.03

50.69

52.71

50.71

51.98

41.85

(5.50)

(10.06)

(9.70)

(10.52)

(10.44)

(10.68)

(10.98)

(7.13)

(7.31)

Female

47.50

51.00

52.69

52.65

52.01

50.57

51.83

49.47

46.38

(9.23)

(10.45)

(10.45)

(10.21)

(10.06)

(9.78)

(10.08)

(9.57)

(8.16)

Total

48.53

51.71

51.78

53.34

51.35

51.64

51.27

50.72

44.11

(8.02)

(10.19)

(10.14)

(10.33)

(10.24)

(10.18)

(10.47)

(8.60)

(7.99)

1991

Male

45.63

48.26

51.95

52.44

49.00

47.53

48.76

47.73

44.27

(8.36)

(7.94)

(11.02)

(8.39)

(11.64)

(7.65)

(8.48)

(10.85)

(12.76)

Female

48.94

48.78

51.20

51.96

50.72

48.49

48.84

50.58

46.68

(9.36)

(8.37)

(8.67)

(10.82)

(8.88)

(10.40)

(10.09)

(9.45)

(11.24)

Total

47.29

48.52

51.57

52.20

49.86

48.01

48.80

49.16

45.47

(9.01)

(8.13)

(9.84)

(9.85)

(10.28)

(9.24)

(9.40)

(10.20)

(11.98)

1998

Male

50.75

47.79

49.23

49.21

50.91

51.10

47.58

46.24

45.90

(12.33)

(10.17)

(9.35)

(8.54)

(11.73)

(8.98)

(10.05)

(9.66)

(9.43)

Female

46.84

49.22

49.77

48.70

49.64

47.61

49.09

47.29

45.97

(8.32)

(7.44)

(8.68)

(11.32)

(8.45)

(8.71)

(10.78)

(9.06)

(9.11)

Total

48.80

48.50

49.50

48.95

50.27

49.35

48.33

46.77

45.93

(10.12)

(8.99)

(8.95)

(10.00)

(10.06)

(8.97)

(10.20)

(9.26)

(9.19)

Subtraction and Multiplication

1984

Male

48.89

53.66

53.07

54.88

50.72

52.21

49.89

48.38

40.33

(6.13)

(11.70)

(8.44)

(9.59)

(10.00)

(9.22)

(10.63)

(7.16)

(5.96)

Female

44.54

50.20

53.84

52.02

51.23

50.48

49.91

47.06

43.00

(8.24)

(10.11)

(9.33)

(9.92)

(9.47)

(9.49)

(9.72)

(7.79)

(9.06)

Total

46.71

51.93

53.46

53.45

50.97

51.34

49.90

47.72

41.67

(7.61)

(11.07)

(8.94)

(9.86)

(9.71)

(9.38)

(10.10)

(7.50)

(7.87)

1991

Male

47.19

49.41

53.38

54.44

49.68

48.28

48.80

46.77

42.73

(10.08)

(9.57)

(10.52)

(8.07)

(12.53)

(9.46)

(7.67)

(8.14)

(9.50)

Female

50.44

49.30

52.28

54.16

51.72

46.98

48.40

48.81

45.97

(10.93)

(9.88)

(8.57)

(9.65)

(10.61)

(10.08)

(9.55)

(9.96)

(8.81)

Total

48.81

49.36

52.83

54.30

50.70

47.63

48.60

47.79

44.35

(10.60)

(9.68)

(9.55)

(8.99)

(11.56)

(9.76)

(8.75)

(9.12)

(9.23)

1998

Male

49.80

48.77

51.27

50.92

51.48

51.43

48.73

44.67

46.52

(12.85)

(11.62)

(10.64)

(9.71)

(11.04)

(9.89)

(8.76)

(10.49)

(9.45)

Female

48.08

49.69

50.05

49.77

49.86

46.88

47.31

47.58

44.15

(10.11)

(10.85)

(10.11)

(10.80)

(9.59)

(10.00)

(10.32)

(9.96)

(10.46)

Total

48.94

49.22

50.66

50.35

50.67

49.15

48.02

46.12

45.33

(11.08)

(11.18)

(10.33)

(10.25)

(10.26)

(10.13)

(9.34)

(10.20)

(9.93)

Verbal Ability

ETS Vocabulary

1984

Male

50.44

48.91

50.93

51.02

51.31

52.87

51.18

49.41

41.75

(6.54)

(7.66)

(9.94)

(9.20)

(9.20)

(8.76)

(11.25)

(11.60)

(18.40)

Female

44.92

51.72

50.71

51.83

52.52

51.09

52.54

49.78

49.94

(13.10)

(6.54)

(8.90)

(8.43)

(8.49)

(10.25)

(9.67)

(10.07)

(10.07)

Total

47.68

50.31

50.82

51.42

51.91

51.98

51.86

49.59

45.84

(11.05)

(7.27)

(9.33)

(8.73)

(8.84)

(9.62)

(10.44)

(10.71)

(14.53)

1991

Male

43.67

48.00

49.03

49.08

50.24

50.50

51.07

47.59

50.85

(8.49)

(8.12)

(8.95)

(9.24)

(9.67)

(9.18)

(9.78)

(12.13)

(11.99)

Female

41.91

43.95

52.23

52.27

53.58

49.72

52.57

49.74

49.59

(9.35)

(12.19)

(6.32)

(8.24)

(6.65)

(9.91)

(8.07)

(10.52)

(9.96)

Total

42.79

45.98

50.63

50.68

51.91

50.11

51.82

48.66

50.22

(8.95)

(10.79)

(7.86)

(8.75)

(8.37)

(9.53)

(8.82)

(11.32)

(10.94)

1998

Male

44.67

48.60

47.96

48.64

48.64

51.08

49.32

48.88

50.86

(10.20)

(9.51)

(8.99)

(10.18)

(11.39)

(10.29)

(10.00)

(11.07)

(7.83)

Female

42.72

44.53

45.18

48.98

51.53

48.63

47.31

50.45

52.48

(9.38)

(12.19)

(10.55)

(10.23)

(7.57)

(10.45)

(10.08)

(8.79)

(7.58)

Total

43.69

46.57

46.57

48.80

50.09

49.86

48.32

49.66

51.67

(9.61)

(10.98)

(9.92)

(10.17)

(9.58)

(10.36)

(10.02)

(9.79)

(7.68)

ETS Advanced Vocabulary

1984

Male

49.89

49.44

50.93

52.78

51.27

53.16

51.89

49.97

43.17

(8.94)

(9.25)

(10.41)

(8.90)

(9.27)

(8.68)

(10.12)

(10.93)

(14.19)

Female

43.92

45.82

51.33

52.84

52.70

47.78

52.02

49.51

49.24

(10.59)

(9.02)

(9.03)

(9.41)

(9.84)

(10.60)

(10.14)

(9.51)

(9.70)

Total

46.91

48.78

50.34

51.98

51.30

51.27

51.84

49.75

45.65

(10.18)

(9.09)

(9.63)

(9.21)

(9.53)

(9.91)

(10.10)

(10.11)

(11.85)

1991

Male

43.67

48.12

49.75

51.18

51.32

49.57

51.79

49.53

48.12

(8.50)

(9.18)

(9.11)

(9.52)

(9.53)

(9.63)

(9.64)

(12.47)

(12.00)

Female

43.44

45.82

51.33

52.84

52.70

47.78

52.02

49.51

49.24

(8.59)

(9.95)

(8.63)

(10.50)

(9.17)

(9.26)

(9.17)

(12.14)

(10.99)

Total

43.55

47.38

51.82

51.90

51.52

49.17

51.31

49.40

49.54

(8.48)

(9.69)

(8.83)

(10.09)

(9.36)

(9.46)

(9.35)

(12.23)

(11.41)

1998

Male

48.27

48.80

49.15

50.10

50.02

52.97

48.73

49.79

50.17

(9.44)

(10.09)

(8.87)

(9.86)

(11.06)

(9.83)

(9.86)

(10.14)

(9.76)

Female

42.32

46.59

46.00

50.37

50.98

48.39

46.46

48.58

53.33

(8.88)

(8.14)

(10.97)

(10.68)

(9.59)

(10.96)

(9.65)

(9.59)

(9.60)

Total

45.29

47.70

47.57

50.23

50.50

50.68

47.59

49.19

51.75

(9.44)

(9.21)

(10.13)

(10.24)

(10.25)

(10.55)

(9.80)

(9.76)

(9.73)

Verbal Memory

Immediate Recall

1984

Male

59.56

53.00

52.53

49.16

47.10

46.57

44.10

38.54

34.00

(5.25)

(7.94)

(8.72)

(8.25)

(9.21)

(8.16)

(9.69)

(8.48)

(6.18)

Female

57.38

56.32

54.87

52.46

50.11

48.61

47.86

44.18

46.00

(8.11)

(7.53)

(7.98)

(8.45)

(8.75)

(9.44)

(9.57)

(7.34)

(7.75)

Total

58.47

54.66

53.70

50.81

48.61

47.59

45.98

41.36

40.00

(7.02)

(7.87)

(8.36)

(8.50)

(9.08)

(8.92)

(9.78)

(8.31)

(9.24)

1991

Male

57.33

54.72

54.08

53.41

49.05

47.94

44.59

42.08

39.12

(6.18)

(8.82)

(8.82)

(8.86)

(10.42)

(8.13)

(8.71)

(10.47)

(7.84)

Female

59.26

57.40

57.16

57.76

55.30

49.35

50.16

44.67

41.65

(6.19)

(5.84)

(7.07)

(5.76)

(7.69)

(9.97)

(7.72)

(8.35)

(8.45)

Total

58.30

56.06

55.92

55.29

52.18

48.64

47.37

43.37

40.39

(6.21)

(7.31)

(8.15)

(7.38)

(9.59)

(9.16)

(8.57)

(9.46)

(8.20)

1998

Male

57.33

56.37

51.66

52.87

49.57

49.71

44.34

40.96

38.38

(7.42)

(7.90)

(8.70)

(8.57)

(7.78)

(8.35)

(8.52)

(9.54)

(8.81)

Female

59.96

58.47

54.77

55.58

54.26

50.70

47.65

45.10

41.37

(5.09)

(6.58)

(8.79)

(7.96)

(7.47)

(8.67)

(9.73)

(9.88)

(8.25)

Total

58.64

57.42

53.21

54.22

51.92

50.20

46.00

43.03

39.87

(6.12)

(7.28)

(8.85)

(8.35)

(7.93)

(8.45)

(9.08)

(8.87)

(8.60)

Delayed Recall

1984

Male

61.33

53.94

52.45

49.69

46.85

46.53

42.89

39.54

35.75

(5.29)

(7.56)

(8.49)

(7.81)

(9.12)

(7.44)

(8.58)

(7.29)

(6.85)

Female

57.69

58.00

55.74

52.71

49.92

49.16

48.06

43.14

43.53

(7.78)

(7.70)

(8.24)

(8.38)

(9.21)

(8.70)

(8.72)

(6.25)

(6.24)

Total

59.51

55.97

54.09

51.20

48.39

47.85

45.47

41.34

39.64

(6.97)

(7.82)

(8.48)

(8.27)

(9.26)

(8.23)

(9.01)

(6.93)

(7.51)

1991

Male

57.04

54.83

53.08

51.38

46.55

45.72

43.37

42.05

38.28

(6.21)

(9.24)

(8.05)

(9.12)

(9.93)

(7.78)

(7.06)

(9.36)

(7.88)

Female

60.88

57.20

58.51

57.00

54.80

48.88

50.77

44.14

42.03

(6.17)

(6.04)

(6.83)

(8.12)

(8.65)

(9.23)

(7.95)

(7.66)

(6.79)

Total

58.96

56.01

55.79

54.19

50.68

47.30

47.07

43.09

40.16

(6.43)

(7.58)

(7.91)

(8.93)

(10.08)

(8.70)

(8.40)

(8.54)

(7.52)

1998

Male

56.93

56.29

51.64

53.34

49.95

49.47

43.42

39.54

39.86

(8.58)

(8.16)

(9.49)

(7.82)

(8.07)

(8.42)

(7.56)

(7.55)

(6.95)

Female

61.52

59.34

56.61

56.42

54.45

51.36

48.77

45.00

42.69

(5.36)

(7.14)

(7.60)

(7.61)

(7.92)

(9.28)

(8.84)

(9.03)

(8.83)

Total

59.23

57.83

54.12

54.88

52.20

50.42

46.10

42.27

41.28

(7.01)

(7.79)

(8.81)

(7.84)

(8.26)

(8.82)

(8.43)

(8.77)

(7.95)

Perceptual Speed

Identical Pictures

1984

Male

60.65

56.76

56.19

52.44

50.71

45.89

42.65

37.70

35.00

(7.63)

(6.55)

(6.89)

(6.99)

(7.58)

(5.62)

(7.82)

(6.63)

(8.06)

Female

59.67

57.38

56.06

52.19

50.53

46.98

42.66

40.39

38.62

(5.36)

(7.33)

(8.16)

(8.01)

(6.98)

(8.37)

(7.11)

(7.44)

(7.13)

Total

60.16

57.07

56.12

52.32

50.62

46.43

42.65

39.04

36.81

(6.16)

(6.87)

(7.62)

(7.58)

(7.25)

(7.24)

(7.41)

(7.18)

(7.64)

1991

Male

58.67

57.42

58.26

57.53

52.71

47.62

43.56

40.32

34.27

(6.97)

(6.48)

(6.35)

(6.74)

(8.15)

(5.93)

(7.91)

(7.74)

(7.56)

Female

61.26

59.00

58.42

56.08

54.32

47.68

45.96

41.65

36.00

(4.19)

(6.10)

(5.30)

(7.19)

(7.58)

(6.21)

(6.08)

(6.40)

(8.19)

Total

59.97

58.21

58.34

56.81

53.52

47.65

44.76

40.98

35.14

(5.69)

(6.73)

(5.80)

(7.01)

(7.85)

(6.05)

(6.97)

(7.07)

(7.88)

1998

Male

60.31

58.05

56.46

52.76

52.09

48.95

45.53

41.68

37.23

(5.21)

(6.73)

(7.48)

(8.09)

(6.80)

(7.50)

(6.55)

(8.03)

(6.46)

Female

59.64

58.91

56.52

54.08

52.96

49.55

46.26

42.48

37.31

(4.98)

(6.65)

(6.29)

(7.89)

(9.00)

(8.18)

(7.04)

(7.11)

(6.90)

Total

59.98

58.48

56.49

53.42

52.53

49.25

45.90

42.08

37.27

(5.02)

(6.66)

(6.82)

(7.99)

(8.03)

(7.77)

(6.71)

(7.48)

(6.63)

Number Comparisons

1984

Male

49.44

52.37

51.01

49.23

47.85

46.49

44.52

40.85

36.23

(10.57)

(8.58)

(9.22)

(8.20)

(7.18)

(7.71)

(7.87)

(6.06)

(5.86)

Female

55.38

55.38

55.06

52.31

40.90

49.30

46.41

44.51

41.25

(8.14)

(8.70)

(8.85)

(9.97)

(7.64)

(9.12)

(8.01)

(8.28)

(6.77)

Total

52.41

53.83

53.04

50.77

49.37

47.90

45.47

42.68

38.74

(9.33)

(8.70)

(9.20)

(9.38)

(7.56)

(8.59)

(7.98)

(7.55)

(6.76)

1991

Male

51.93

53.97

53.23

52.12

47.55

46.31

44.29

41.68

38.19

(8.78)

(9.00)

(10.59)

(7.53)

(9.53)

(6.22)

(7.46)

(6.31)

(7.92)

Female

62.38

56.82

58.80

55.06

53.48

50.39

47.88

45.49

41.18

(8.29)

(8.17)

(8.46)

(9.26)

(10.09)

(9.70)

(7.51)

(8.03)

(7.49)

Total

57.15

55.40

56.02

53.59

50.51

48.35

46.08

43.59

39.68

(9.93)

(8.60)

(9.91)

(8.66)

(10.20)

(8.55)

(7.66)

(7.45)

(7.78)

1998

Male

59.75

58.11

53.52

50.73

49.23

50.60

45.50

43.28

40.40

(13.95)

(11.30)

(8.98)

(8.64)

(8.87)

(9.11)

(7.75)

(7.06)

(6.56)

Female

63.80

59.97

56.50

55.06

52.74

51.18

50.29

45.45

41.33

(9.52)

(9.94)

(8.88)

(8.89)

(8.38)

(10.77)

(7.28)

(8.37)

(6.80)

Total

61.78

59.04

55.01

52.89

50.98

50.89

47.89

44.37

40.87

(11.46)

(10.66)

(9.55)

(9.00)

(8.74)

(9.82)

(7.89)

(7.82)

(6.64)

Finding A's

1984

Male

53.47

51.97

50.52

49.30

47.04

47.18

47.70

42.10

40.83

(14.27)

(10.46)

(8.80)

(9.08)

(9.61)

(8.69)

(10.37)

(6.33)

(6.85)

Female

51.83

56.24

53.38

52.19

50.56

48.81

48.73

46.04

45.56

(11.58)

(10.14)

(10.77)

(10.57)

(8.45)

(9.79)

(8.94)

(7.56)

(9.16)

Total

52.65

54.10

51.95

50.74

48.80

48.00

48.22

44.07

43.20

(12.49)

(10.45)

(10.04)

(10.07)

(9.19)

(9.32)

(9.59)

(7.27)

(8.45)

1991

Male

52.52

49.86

53.36

50.18

46.66

46.09

43.46

44.95

41.48

(9.70)

(11.01)

(9.14)

(8.34)

(9.46)

(7.20)

(8.11)

(6.77)

(6.88)

Female

58.23

54.82

54.77

53.41

53.88

50.22

48.62

47.42

45.24

(10.82)

(10.45)

(9.54)

(9.41)

(8.98)

(7.98)

(9.48)

(8.66)

(8.80)

Total

55.38

52.34

54.06

51.79

50.27

48.16

46.04

46.18

43.36

(10.65)

(10.89)

(9.31)

(9.08)

(9.85)

(7.86)

(9.24)

(7.85)

(8.08)

1998

Male

57.07

52.00

53.12

50.46

50.12

49.18

46.90

46.92

47.31

(13.63)

(9.74)

(10.45)

(9.28)

(9.32)

(8.08)

(7.99)

(7.13)

(9.98)

Female

57.80

59.62

55.84

54.11

51.84

51.15

49.89

49.77

46.44

(10.87)

(13.54)

(9.54)

(10.33)

(8.84)

(9.25)

(8.40)

(9.09)

(7.55)

Total

57.43

55.81

54.48

52.29

50.98

50.17

48.39

48.35

46.88

(11.81)

(12.24)

(10.01)

(9.95)

(9.05)

(8.64)

(8.23)

(8.34)

(8.82)

Across All Measurement Occasions

Letter Series

Male

59.58

58.15

56.77

54.10

50.06

48.95

44.85

41.20

39.08

(9.02)

(7.60)

(8.07)

(7.38)

(8.30)

(7.85)

(8.16)

(7.52)

(5.25)

Female

59.04

57.60

56.08

53.56

51.50

47.14

45.60

42.37

37.57

(8.25)

(7.93)

(7.54)

(8.59)

(7.99)

(8.20)

(8.22)

(7.40)

(6.51)

Total

59.31

57.87

56.42

53.83

50.78

48.04

45.22

41.78

38.33

(8.54)

(7.76)

(7.78)

(8.08)

(8.16)

(8.08)

(8.19)

(7.46)

(5.97)

Word Series

Male

57.67

56.80

55.31

53.19

49.91

48.74

44.42

40.75

35.29

(7.51)

(7.49)

(7.94)

(7.49)

(8.32)

(7.70)

(8.30)

(8.47)

(6.18)

Female

58.46

57.18

57.11

53.75

52.56

48.60

46.45

44.11

37.70