A meta-analysis of 50 studies was conducted to investigate whether juvenile delinquents use lower levels of moral judgment than their nondelinquent age-mates and, if so, what factors may influence or moderate the developmental delay. The results show a lower stage of moral judgment for juvenile delinquents (d=.76). Effect sizes were large for comparisons involving male offenders, late adolescents, delinquents with low intelligence, and incarcerated delinquents. The largest effect sizes were found for period of incarceration and comparisons involving juvenile delinquents with psychopathic disorder. Production instead of recognition measures, dilemma-free assessment methods, and non-blind scoring procedures yielded relatively large effect sizes, whereas effect sizes were medium for comparisons involving delinquents with average intelligence, non-incarcerated delinquents, female offenders, as well as early and middle adolescents. Psychopathic disorder and institutionalization were identified as unique moderators of the link between moral judgment and juvenile delinquency. It is concluded that developmentally delayed moral judgment is strongly associated with juvenile delinquency, even after controlling for socioeconomic status, gender, age and intelligence.

John Bowlby is generally regarded as the founder of attachment theory, with the help of Mary Ainsworth. Through her Uganda and Baltimore studies Ainsworth provided empirical evidence for attachment theory, and she contributed the notion of the secure base and exploratory behavior, the Strange Situation Procedure and its classification system, and the notion of maternal sensitivity. On closer scrutiny, many of these contributions appear to be heavily influenced by William Blatz and his security theory. Even though Blatz's influence on Ainsworth has been generally acknowledged, this article, partly based on understudied correspondence from several personal archives, is the first to show which specific parts of attachment theory can be traced back directly to Blatz and his security theory. When Ainsworth started working with Bowlby in the 1950s, around the time he turned to evolutionary theory for an explanation of his findings, she integrated much of Blatzian security theory into Bowlby's theory in the making and used her theoretical and practical experience to enrich attachment theory. Even though Blatz is hardly mentioned nowadays, several of his ideas live on in attachment theory.

The American-Canadian psychologist Mary Ainsworth (1913-1999) developed the Strange Situation Procedure (SSP) to measure mother-child attachment and attachment theorists have used it ever since. When Ainsworth published the first results of the SSP in 1969, it seemed a completely novel and unique instrument. However, in this paper we will show that the SSP had many precursors and that the road to such an instrument was long and winding. Our analysis of hitherto little-known studies on children in strange situations allowed us to compare these earlier attempts with the SSP. We argue that it was the combination of Ainsworth's working experience with William Blatz and John Bowlby, her own research in Uganda and Baltimore, and the strong connection of the SSP with attachment theory, that made the SSP differ enough from the other strange situation studies to become one of the most widely used instruments in developmental psychology today.

In this contribution the reciprocal influence of Harlow and Spitz concerning the consequences of maternal deprivation of monkeys and men, respectively, is described. On the basis of recently disclosed correspondence between Harlow and Spitz, it is argued that not only was Spitz's work on hospitalism an inspiration for Harlow to start his cloth and wire surrogate work with rhesus monkeys but, at the same time, Harlow's work was a new impetus for Spitz's work on the sexual development of (deprived) infants. It is described how the two men first established personal contact in the early 1960s, after Harlow had published his first surrogate papers, how they became close friends subsequently, and inspired each other mutually.

Harry Harlow, famous for his experiments with rhesus monkeys and cloth and wire mothers, was visited by psychiatrist and psychoanalyst John Bowlby and by child psychologist Bruno Bettelheim in 1958. They made similar observations of Harlow’s monkeys, yet their interpretations were strikingly different. Bettelheim saw Harlow’s wire mother as a perfect example of the ‘refrigerator mother’, causing autism in her child, while Bowlby saw Harlow’s results as an explanation of how socio-emotional development was dependent on responsiveness of the mother to the child’s biological needs. Bettelheim’s solution was to remove the mother, while Bowlby specifically wanted to involve her in treatment. Harlow was very critical of Bettelheim, but evaluated Bowlby’s work positively.