Justin P. Halberda
Assistant Professor
Dept of Psychological & Brain Sciences
231 Ames Hall
3400 North Charles Street
Johns Hopkins University
Baltimore, MD 21218

halberda@jhu.edu

phone: 410-516-6289
fax: 410-516-4478


Lab Sites


johns hopkins univ

DEMOS

Nichols, S., Halberda, J. (in preparation). Modal reasoning in preschoolers.

Abstract

This study presents a scenario in which the child has to answer questions about both the outcome of a physical event (i.e., actual outcome) and some hypothetical alternatives (i.e., possible or impossible outcomes). We used a physical “probability machine” involving balls that go down ramps to investigate preschoolers understanding of the modal concepts of possibility and impossibility. Children’s answers fell into 4 consistent patterns progressing from failure to represent constraints on the possible (Category 2), to adult-like success, which included the ability to report one’s own previous false belief (Category 5).

Results

Category 2 (Affirmation Focused):

Children in this category responded “yes” to all possible and impossible outcomes maintaining, for instance, that the ball could even go down a ramp that was physically blocked. These tended to be the youngest children in the study (see video).

Category 3 (Outcome Focused):

The next stage occurs when the child reaches almost four years of age, where they believe that a ball seeks the path it previously went down. These children maintain, even in the face of evidence to the contrary, that each ball will travel the path it previously went down. Children in this category responded “no” to every possible and impossible scenario (see video).

Category 4 (Developing Theory of Mind):

The next stage comes at just over four years, where children understand possibility/impossibility in this task, but lack theory of mind. Children at this stage respond correctly to all possible and impossible scenarios until the final question; “Before I took this hat off, did you know that this ball would not go down the e.g., yellow ramp?” These children fail to report their own previous false belief and instead claim that they knew that the ball would not go down the e.g., yellow (i.e., blocked) ramp (see video).

Category 5 (Theory of Mind):

Theory of mind and full adult understanding of possibility/impossibility in our task seems to be attained at just over four and a half years of age. Children in this category have theory of mind and answer all questions as an adult would. These children also successfully report their own previous false-belief (where Category 4 children fail), and they also successfully pass a related TOM false-belief Crayons task (see video).