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Click to increase image sizeClick to decrease image size Additional informationNotes on contributorsWillard W. HartupWillard Hartup is Director of the Institute of Child Development at the University of Minnesota.Michael D. LougeeMichael D. Lougee is a pre-doctoral trainee at the Institute of Child Development. This paper was completed with the aid of financial assistance from Grant No. 5-P01-05027, National Institute of Child Health and Human Development, and a traineeship award to the second author from Grant No. 2-T01-MH06668, National Institute of Mental Health.
Hartup et al. (Mon,) studied this question.