Weighing the Evidence: Children's Naïve Theories of Balance Affect Their Exploratory Play

Weighing the Evidence: Children’s Naive Theories of Balance Affect Their Exploratory Play Elizabeth Baraff Bonawitz, Suejean Lim, & Laura E. Schulz {liz_b, slim13, lschulz}@mit.edu Department of Brain and Cognitive Sciences Massachusetts Institute of Technology Cambridge, MA 02139 USA & Piaget, 1958; Koslowski, 1996; Kuhn, 1989). These results pose a problem for the Piagetian account: if children’s exploratory play is largely unsystematic, how might they generate the type of evidence that could support learning? One possibility is that although the particular actions children take in the course of play might not be systematic, children’s exploratory play might nonetheless be sensitive to the ambiguity of the evidence they observe. In a recent study for instance, children were introduced to a toy and shown either confounded or unconfounded evidence about the causal structure of the toy. The toy was removed and then returned, along with a novel toy and children were allowed to play freely for 60 seconds. Children who observed unconfounded evidence showed the standard novelty preference and played primarily with the novel toy. However, children who observed confounded evidence did not show the novelty preference: they spent more time playing with the familiar toy (Schulz & Bonawitz, in press). This research was a first step in understanding how different types of evidence might lead to differential exploration. In that study, children were shown different patterns of evidence (confounded v. unconfounded) under the assumption that all children had similar prior beliefs about how the toy might work. However, research suggests that children’s theories affect their interpretation of evidence (Bonawitz, Griffiths, & Schulz, 2006; Schulz, Bonawitz, & Griffiths, in press). If theories play an important role in how children construct knowledge, then children who have different initial theories but observe identical evidence might also show different patterns of exploratory play. The current study tests this hypothesis. Abstract In this paper we show that, given identical evidence, children with different naive theories exhibit different patterns of exploratory play. Karmiloff-Smith & Inhelder (1974) demonstrated that before children develop an adult Mass Theory of balance, they entertain a Center Theory , believing that all objects should be balanced at their geometric center. Younger, No Theory children balance blocks by trial and error. In Experiment 1 we let Mass Theorists and Center Theorists play with a block that was weighted off to one side. We then “balanced” the block on a post either at the block's geometric center or at its center of mass. (Thus evidence that was theory- consistent for a Center Theorist was theory-violating for a Mass Theorist and vice versa.) We also introduced a novel toy (a peg and rings). Children were allowed to play freely for 60 seconds. When the evidence about the balancing block was consistent with the children's theories, they showed a standard novelty preference and played mostly with the novel toy. When the evidence violated children's theories, they preferentially played with the balancing blocks. In Experiment 2, we replicated the design with younger, No-Theory children; they showed a novelty preference regardless of whether the block was balanced in its geometric center or center of mass. These results suggest that children's spontaneous exploratory play is systematically affected by the interaction of their naive theories and the evidence they observe. We discuss these results in terms of the optimality of children's play. Keywords: Exploratory play, theories, evidence, balance task, cognitive development, learning Play and Learning Since Piaget (1951), researchers have believed that children’s own actions on the environment play a central role in how they learn about the world. At the heart of the Piagetian account is the idea that children “construct” knowledge (and particularly causal knowledge) by active exploration. Although this “constructivist account” is widely accepted, there is in fact little evidence for a systematic relationship between children’s play and their naive theories. In general, the only systematic finding about children’s exploratory play is that children (and many other creatures) preferentially explore novel over familiar stimuli (e.g. Berlyne, 1960; Hutt & Bhavnani, 1972; Pavlov, 1927). Moreover, considerable research suggests that even older children have difficulty designing informative experiments (Chen & Klahr, 1999; Inhelder Getting ahead with a theory of balance Because the development of children’s theories has been well established in the domain of balancing blocks, this domain is particularly conducive for investigating the relationship between children’s folk theories and their exploratory play. In a seminal study, Karmiloff-Smith & Inhelder (1974) looked at children’s understanding of balance between the ages of 4 and 9 years of age. They demonstrated that between 6 and 8 years, children first entertain a “Center Theory”, believing that regardless of the center of mass, an object should be balanced at its geometric center. Center Theorists repeatedly attempt to balance unevenly weighted blocks at their geometric center.