Chapter 8: Child Development Research methods:    Longitudinal research: study same individuals over a period of time.       Advantages: can observe development directly.       Drawbacks: can take a long time and be expensive, attrition, practice effects.    Cross-sectional research: study individuals of different ages at one point in time.       Advantages: can be done relatively quickly, no practice effects, no attrition.       Drawbacks: cohort effects (people of different ages have had different life experiences)    Longitudinal-sequential design: study individuals of different ages over a period of time.       Advantages: can compare persons born in different years with one another when they are the same age to assess cohort effects; can compare longitudinal and cross-sectional results.       Drawbacks: can take a long time and be expensive, attrition, practice effects. Attachment: strong affectional bonds between the infant and the caregiver that may influence future relationships.     Primary drives theory: attachment results from associating the satisfaction of primary drives with the being that satisfies them. Proven wrong by Harlow’s research.     Interorganismic theory: attachment is a species-specific predisposition with survival value.        Stranger anxiety: begins around 6 months, peaks at 1 year and then declines; particularly strong in unfamiliar situation.        Separation anxiety: begins around 8 months, peaks around 15 months and then declines.     Securely attached kids use the caregiver as a secure base: they freely explore the environment and touch base with the caregiver periodically. Parental responsiveness to kids’ needs is high.     Avoidant kids are not very attached to the caregiver: they don’t cry when the caregiver leaves and are slow to seek comfort. Parental responsiveness is low.     Ambivalent kids first seek comfort but then avoid the caregiver. Parental responsiveness is inconsistent.