Contingent parental investment: An evolutionary framework for understanding early interaction between mothers and children

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Contingent parental investment An evolutionary
framework for understanding early interaction
between mothers and children

• David Beaulieu, Daphne Bugental

Presented by Shelby Johanson, Michelle Cho
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Introduction

• Trivers (1974) theory of parental investment
• Zero-sum allocation of resources - any investment
  in one child means less investment in other
  current or future offspring.
• Factors affecting parental investment
• Low prospective reproductive potential of child
• Low maternal resources
• Supported by Daly and Wilson (1984, 1988),
  Garbarino (1985)

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Introduction
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Introduction

• Non human examples
• Birds (Gottlander,1987)
• Primates (Nakamichi, 1986)
• Human evidence
• Parents in high poverty vs. high wealth
  neighborhoods
• Past Experiment
• By Beaulieu and Bugental
• Matched pairs, limited measures of investment

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Introduction
Current Study

• Tested which model of PI (Additive or Contingent)
• Contingent predicted to be stronger.
• Looked at attentional resources
• Most other studies have looked at physical
  resources.
• Depressed mothers respond to infants with low
  levels of attention
• Depressed mothers have low levels of attentional
  resources.

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Introduction
Additional Tests

• Trivers-Willard model (1973)
• Mothers in good condition will
• invest more in sons, mothers in
• poor condition will invest more in daughters
• Depression and low education marked poor
  condition
• Hagen (2002) Age and parity
• Older mothers will invest more in singleton
  offspring (Even if high-risk)
• First born vs later born
• Greater investment expected in later born (Rohde
  et al.)

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Participants

• 60 mothers and children
• Within child abuse prevention program
• 56 Latino, 4 Anglo mothers (mean age27)
• Kids average age 8.56 weeks at intake, 20 months
  at follow up
• Half of children premature, half full term
• Groups were equivalent in other ways

Methods
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Measures

• Demographic variables
• Birth history
• Maternal depression
• Measure of attentional resources.
• Beck Depression Inventory (BDI)
• Parental Investment
• See next slide

Methods
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Measures of PI

• Motivational measure
• Mothers shown 12 pictures of items (approximately
  equal value) available on the internet.
• Half were mother directed, half child directed.
• Mothers chose the three they would prefer as
  gifts at a later time.
• Zero-Sum measure ranking of one to three
  according to number of items for mom vs child
• Computational/perceptual measure
• Mothers height estimation of child
• Underestimation suggests mother believes child is
  weaker and more in need of investment.

Methods
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• Potential confounds
• Maternal age, maternal education, maternal
  ethnicity, number of siblings, child gender, and
  presence of father.
• Shown to not have a relationship with the
  dependent variables.
• Procedure
• Demographic and BDI at intake
• PI at 18 month visit
• In-home

Methods
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Critiques

• Sample
• Limited in terms of ethnicity, education, etc.
  (Even if they found the variables to not be
  related)
• PI was tested considerable after BDI scores were
  taken

Methods
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Series of regression analyses

• Maternal education and presence of father in the
  home
• Maternal age and parity
• Child gender and maternal condition
• Childs birth order
• First-born vs. later-born

Results
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Hierarchical Regression Analysis

• Step 1
• Covariate
• Differential participation in one of two home
  visitation programs
• Step 2
• Independent variables
• Child gestational age and maternal scores on the
  BDI
• Step 3
• Predicted interaction

Results
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Motivational Investment
Results
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Computational Investment
Results
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Motivational Indicators of PI

• Benefits to the child vs. benefits to the self
• Depressed mothers
• Give benefits to full-term infants
• Non-depressed mothers
• Give benefits to preterm infants
• Similar findings to nonhuman research
• Mothers provide different resources based on
  characteristics of the young

Discussion
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Computational Indicators of PI

• Care giving responses
• Mothers with low resources (depressive) and has
  premature infant
• less protective care system
• Non-depressed mothers with premature infant
• more protective care system

Discussion
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Supported or not?

• Predictions for both Bugental and Beaulieu (2003)
  and Mann (1992) were supported

Discussion
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Evidence for the other hypotheses

• Differential investment
• Occurs in male vs. female offspring based on the
  mothers condition
• Not significant
• Combined effects of maternal age and parity
• It was not significant once follow-up analysis
  was applied
• genders
• No significance in birth order

Discussion
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Limitations

• Replication is needed
• For observed effects
• Useful to include other types of PI
• Financial or time investment
• Selective investment patterns was limited
• Fathers low involvement in child care
• Constraints
• Age limitations

Discussion
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Conclusion

• If Then decision-making model
• Good response from parents to
• their offspring
• Parental decisions are contingent on complex
  computations
• Similarity in the investment pattern by both
  nonhuman and humans
• Shared evolutionary influences

Discussion
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THE END