Microgenetic Designs Designed to answer questions about how

Microgenetic Designs • Designed to answer questions about how learning occurs

• Three “essential” characteristics: – Observations are made across a period of rapidly changing competence in a particular area – Within this period, the density of observations is high relative to the rate of change – Observations are analyzed intensively to infer underlying processes

• Microgenetic studies typically involve: – Relatively small numbers of participants (or single subject designs) – Trial-by-trial assessments of children’s strategies for solving particular types of problems – Behavioral observations of strategy use (often supplemented with self-reports in children 5 years and older)

Overlapping Waves Theory (R. S. Siegler) • Microgenetic studies across different areas consistently indicate that children’s thinking is highly variable • For example: – Different children use different strategies – Individual children use different strategies on different problems within a single test session – Individual children use different strategies to solve the same problem on two occasions close in time

• According to Overlapping Waves Theory: – Development is a process of variability, choice, and change – Children typically know and use varied strategies for solving a given problem at any one time – With age and experience: • Relative frequency of existing strategies changes • New strategies are discovered • Some older strategies are abandoned

– Children usually choose adaptively among strategies • Choose strategies that fit the demands of the problem given the strategies and available knowledge that children possess – Choices of strategies become even more adaptive with experience in a particular content area

• According to OWT, cognitive change can be analyzed along five dimensions – Source of change (causes that set the change in motion) – Path of change (sequence of knowledge states or predominant behaviors that children use while gaining competence) – Rate of change (how much time or experience separates initial use of a new strategy from consistent use of it) – Breadth of change (how widely the new strategy is generalized to other problems and contexts) – Variability of change (differences among children in the other dimensions of change; changing set of strategies used by individual children)

• Siegler (1995) – Examined effects of training on strategy use for number conservation problems (N=45; 54 -73 mos. , mean = 5. 17 years) – Could add more buttons and make one line a different length; could take away buttons and make one line a different length; or could change the length of the line and not add or take away any buttons – Random assignment to one of three training conditions • Feedback only (answer correct/incorrect) • Feedback plus explain-own-reasoning (“How did you know that? ” followed by feedback) • Feedback plus explain-experimenter’s reasoning (Feedback followed by “How do you think I knew that? ”)

Findings • Different Types of Strategies (Explanations) Used: – Relative Length: Compare lengths of two rows – Type of Transformation: Objects added/subtracted or just moved around – Counting – “Don’t know”

• Over the course of the experiment: – Frequency of length strategies decreased – Frequency of transformation strategies increased – Frequency of counting remained consistently low – “I don’t know” first increased and then decreased