Leonard, J. A., Lee, Y., & Schulz, L. E. (2017). Infants make more attempts to achieve a goal when they see adults persist. Science, 357(6357), 1290–1294. Retrieved from http://dx.doi.org/10.1126/science.aan2317.

Video exemplar

(tried to embed, but this only works sporadically.)



Methods info from supplementary materials

“Button presses were operationalized as a hand pushing down the button. Button presses were coded from videotape by two coders blind to hypotheses and condition (inter-rater reliability \(r = .99, p < .001\)). Data from a single coder was used for analyses but all results held with the second coder’s data. Coders agreed with the experimenter’s judgment on the termination of the experiment 100% of the time.”

(Supplement, p. 2)

“Additionally, a coder blind to condition and hypotheses coded the tapes for potential confounds. No difference was found across the conditions for whether the parent talked to the child (\(\chi^2 (2, N=102)=1.03\), \(p = .60\)), parents’ proximity to the infant (as distance in inches, \(H(2) = 4.32\), \(p = .12\)), and parents’ encouragement to the infant (\(\chi^2 (2, N = 102) = 5.56\), \(p = .06\)). Additionally, because the experimenter might have conveyed more enthusiasm in handing the toy to the child in the Effort than the No Effort condition, a second coder rated the experimenter’s enthusiasm at the start of the test trial on a Likert scale, blind to conditions (\(W = 525\), \(p = .50\)).”

(Supplement, p. 2)

Questions, cheers, & lamentations


  • Could ‘effort’ be based on personal qualities of child?
  • Differences in environment (noise, what parent did, etc.)?
  • What do parents & siblings do (for work, at home)?
  • Would parent as demonstrator elicit stronger responses from kid?
  • How does child’s attention span affect outcome?
  • Individual differences in child’s interest in the toy?