Which method did Lawrence Kohlberg use to study moral development in children?

Concept: Kohlberg's method for studying moral development centred on presenting children with hypothetical moral dilemmas -- short story situations built around a moral conflict with no single 'correct' choice -- and then, through an in-depth interview, analysing the REASONING a child gave to justify a response. The stage of moral development assigned was based primarily on the content and structure of that reasoning, rather than on the choice itself or on a statistical count of how many children picked a given option.

Application: Kohlberg used this technique in his research, most famously the Heinz dilemma, in which a man must decide whether to steal an unaffordable drug to save his dying wife. By analysing how each child justified the decision, Kohlberg classified the reasoning into his three levels and six stages of moral development (pre-conventional, conventional, and post-conventional).

• Posing moral dilemmas to children and analysing responses -- this matches the dilemma-interview technique described above.

• Quantitative research approach -- this technique is characterised by numerical/statistical measurement, such as tallying how many children picked a certain option; Kohlberg's stage classification was based on the structure of individual reasoning rather than such counts, so this label does not fit.

• Conducting observations of children during play -- this technique is characterised by naturalistic observation of behaviour as the primary data source, which is a different research technique from the one described above.

• Experimental method -- this technique is characterised by manipulating an independent variable under controlled conditions, which is not what the dilemma-interview technique involves.

Cross-check: The three levels and six stages Kohlberg is known for (e.g., punishment-obedience, individualism, good-boy/good-girl, law-and-order, social contract, universal ethical principles) are all classifications of REASONING patterns given in response to dilemmas -- confirming that the dilemma-and-analysis technique, not a quantitative, observational, or experimental method, is how the data was gathered.