Overview of Indicator Variables

The life history-based model tested in this study (see Figure 1) included a number of higher-order, unobserved variables. Each of these latent variables was measured by several observed items (i.e., manifest/indicator variables). The indicator variables were selected based on a consideration of exactly how each latent construct is defined within the various life history theories of attachment and reproduction. In what follows, a brief summary of the indicators associated with each latent variable in the integrated-LHT model will be presented. Please refer to Appendix D for a full and more detailed description of each indicator variable, its associated computation and/or coding, reliabilities of the indicators, and rationale for inclusion.

Early Family Environment. Ten manifest variables were initially used to

measure the latent construct of Early Family Environment (see Figure 3 for a schematic representation of the latent variable and associated indicators). Variables listed included those that were explicitly outlined within the life history theories described in Section 1.2 and/or have been empirically related to attachment patterns in childhood, the timing of somatic development, or reproductive strategy choice. All indicators indexed the quality of the early family environment. The 10 indicators were: (1) a “Family affection” index and (2) a “Family abuse” index, derived from items from Part I of the RAQ (Parkes, 2006), (3) Mother’s psychiatric health and (4) Father’s psychiatric health, also derived from items from the RAQ Part I, (5) SES of the family household (either Total SES, computed from information about parental occupation and education, or Financial SES, computed only from information about parental occupation. The decision about which of the two SES indicators to include, given the overlapping computational information, was made at the level of the measurement model analyses, based on an empirical

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Figure 3. Indicators of Early Family Environment latent construct. Indicator (observed) variables initially used to index the Early Family Environment latent construct.

revisited in Section 3.2.5), (6) “Family structure” index for ages 0-4 years, (7) “Family structure” index for ages 5-9 years, and (8) “Family structure” index for ages 10 years and up, each of which quantified the effects of family structure (e.g., two-parent household vs. single parent living alone, etc.) during development on the quality of participants’ early family environmental experience. Finally, indicators of (9) the presence or absence of a non-biological stepparent during the first 16 years of life and (10) the death of a parent during the first 16 years of life were included. Each indicator was coded such that a higher score was reflective of a poorer quality environment.

Because the latent variable of Early Family Environment is a weighted composite, where each indicator variable represents an index of the quality of the early family

environment, the direction of causality runs from the indicators to the latent composite. This differs from the other latent constructs included in the model, which are assumed to cause the indicator variables.

Retrospective Childhood Attachment. Following Parkes’ (2006) computational

procedures, a total insecure attachment score was calculated from Part I and Part II of the RAQ. Higher scores on this continuous measure corresponded to a more insecure

childhood attachment pattern. Scores reflected attachment to parents in general, which is consistent with the life history-based theories reviewed here that do not differentiate between the unique developmental consequences of maternal vs. paternal attachment configurations (for review see Del Giudice, 2009). Although individual scores for the 3 insecure attachment patterns (anxious/ambivalent, avoidant, disorganized) can be separately computed from the RAQ, because Belsky et al. (1991) and Chisholm (1999) speculate only about the causes and consequences of overall attachment insecurity (vs.

security) without differentiating among the specific varieties of insecure attachment in their theoretical models, the decision was made to only compute the total insecure attachment score as a single indicator of the childhood attachment style.

Non-Sexual Reproductive Strategy. The indicator variables thought to be caused

by the Non-Sexual Reproductive Strategy latent construct (see Figure 4) included the personality traits usually associated with the Young Male Syndrome (Wilson & Daly,

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Figure 4. Indicators of Non-Sexual Reproductive Strategy latent construct. Indicator (observed) variables presumed to be caused by the Non-Sexual Reproductive Strategy latent construct.

1985), which Chisholm (1999) argues is the optimal reproductive strategy for males reared in environments of high uncertainty. Indicators of this personality cluster included total scores on the modified Buss and Perry (1992) Aggression Questionnaire, the Risk Taking Scale of the JPI-R (Jackson, 2004) and the Impulsivity subscale from the PRF-E (Jackson, 2003). Because dominance is a closely related concept to aggression (Archer, 1991), the total score on the Dominance subscale of the PRF-E was also included. In addition, measures of autonomy, self-esteem, and trait anxiety (reverse coded) were included. Total scores on the Autonomy subscale of the PRF-E, the RSE, and the

Anxiety subscale of the POMS were the observed variables, respectively. Each indicator variable was coded such that a higher score reflected a higher level of the construct.

Sexual Reproductive Strategy. Both Belsky et al. (1991) and Del Giudice (2009)

argue that the reproductive strategies predicted by insecure vs. secure attachment fall along a continuum of shorter-term to longer-term mating, earlier to later sexual activity, and unstable to enduring pair bonds. Consequently, the latent factor Sexual Reproductive Strategy (see Figure 5) was assumed to causally influence participants’ age at first

intercourse, their typical relationship length, as well as their total number of lifetime partners (both romantic and sexual). A current partner status observed variable was also included, which reflected whether or not participants were currently in a relationship, and if so, what type (see Appendix D), coded in a graded fashion according to how closely their current partnering status fit with a shorter-term vs. longer-term mating strategy.

Several components of the SOI (Simpson & Gangestad, 1991) were core indicators of the latent Sexual Reproductive Strategy construct and were individually included as separate items. Item 2 (“How many different partners do you foresee yourself having sex with during the next five years?”) and Item 3 (“With how many partners have you had sex on one and only one occasion, in your lifetime?”) were included as independent indicators. The standardized factor scores for the four items comprising the attitudinal facet of the SOI (items 4-8, excluding item 7) were used as an additional latent variable.

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Figure 5. Indicators of Sexual Reproductive Strategy latent construct. Indicator (observed) variables presumed to be caused by the Sexual Reproductive Strategy latent construct.

As noted during the model presentation in Section 1.9, because life history theorists are not in agreement as to whether romantic attachment itself is part of one’s sexual reproductive strategy (Belsky, 1997; Kirkpatrick, 1998; Del Giudice et al., 2009), or whether it is a correlated trait that predicts one’s sexual strategy (e.g., Hill et al., 1994a; Del Giudice, 2009), the various romantic attachment subscale scores from the RQ and ECR were tentatively included as separate indicator variables of the Sexual

Reproductive Strategy latent factor. Indicators were therefore: the ECR avoidance subscale score, the ECR anxiety subscale score, the RQ dismissing score, and the RQ preoccupied score, the latter as continuous variables. Because a person's overall level of romantic attachment security might also be a characteristic of his reproductive strategy choice, the RQ continuous security score (reverse-coded such that a higher score indicated less attachment security) was included as an indicator. Finally, there is a lack of clarity in LHT-based models about the role of adult fearful attachment (e.g., Del Giudice, 2009). Consequently, participants’ RQ continuous fearful score was also included as a possible indicator variable (see Appendix D for further discussion). Each indicator variable of the Sexual Reproductive Strategy was coded (or reverse coded if necessary) such that a higher score was consistent with a shorter-term reproductive strategy.

Biological Variables. For Adult T (Range: 30.53 to 302.98 pg/mL), the internal

consistency between first and second measurements was very high (α = .95), thus it was deemed appropriate to average the two measurements and use this as a single-indicator variable in the model. Similarly, the Cronbach’s alpha between the right and left hand digit ratio was in an excellent range for biological measures (α = .84) and it was also deemed appropriate to average the right and left hand measurements as a single-indicator of individual differences in prenatal T exposure (2D:4D; Range: .90 to 1.04). The CAG repeat length for each participant was measured in duplicate, however, within our sample none of the duplicates were found to differ. Thus the CAG repeat data displayed perfect correspondence, and as such was represented as a single-indicator in the model (CAG RL Range: 13 to 30 repeats).