Melissa M. Kibbe

The ability to consider multiple, incompatible possibilities supports human decision-making, but there is considerable variability in estimates of the age of emergence and development of this ability in young children. What accounts for this variability? We suggest that one major source is task-specific demands on developing cognitive processes that are not solely dedicated to possibility reasoning. In this paper, we outline a set of ancillary cognitive demands in a variety of common tasks that are currently used to study young children’s possibility reasoning (cups, gumball, slides, branching tube, and playground tasks). We identify five key cognitive demand dimensions – physical reasoning, action planning, working memory, language, and temporal context – and show that these demands can and do impact children’s behaviors in tasks designed to examine possibility reasoning. We discuss implications for understanding the cognitive mechanisms driving possibility reasoning and challenges for identifying developmental trajectories.

Infants can represent the quantity of a set of hidden objects, but if the number of objects hidden in a location exceeds three, infants experience “catastrophic forgetting”, failing to represent even a subset of the objects. Infants’ representations of an object also are impacted by other agents’ visual access to an object; infants represent what an agent observed about an object instead of what they themselves observed. Here, we asked whether an agent’s partial visual access to a set of objects would impact infants’ representations of the set’s quantity, and if so, whether this impact would apply when infants’ own representational limits are exceeded. Ten-14-month-olds (n = 85) completed an ordinal choice task in which they watched an experimenter distribute different quantities of crackers across two containers, and were allowed to crawl to one of the containers to obtain its contents. We manipulated whether the quantities hidden were within or outside of infants’ capacity limits (1 vs. 2 or 1 vs. 4) and whether a second experimenter, who infants saw had also observed the crackers being distributed, had partial knowledge of the arrays (observing 1 vs. 1 or 1 vs. 2, respectively) or no knowledge. Infants’ container choices suggested that they used the observing agent’s perspective to represent quantity whenever she had partial knowledge of the arrays. Our results suggest that an agent’s quantity representations may mandatorily supplant infants’ own, and this may allow infants to represent a subset of objects in situations in which they would normally experience catastrophic representational failure.

Young children struggle in situations involving mere possibility, such as when a target object could be in one of two possible locations. This difficulty is often interpreted as a general limitation on children’s ability to reason about possibility. We tested the hypothesis that a source of children’s difficulty may be their early-emerging object representational architecture, which necessarily represents where an object is, but only optionally represents what an object is. Two- to 4-year-old US children (n = 138) were tasked with finding a target object in one of several possible containers, and we manipulated whether the location or the identity of the target was uncertain. At all ages, children were better able to find the target when there was uncertainty about “what” versus uncertainty about “where”. We suggest that children’s object representational architecture can support uncertainty about identity but not location, and discuss implications for the development of possibility reasoning.

What is the minimum amount of information needed to represent in the mind an object's existence? We describe studies with prelinguistic infants that support a basic format for object representations. We show that, while infants can represent an object's' identity, doing so is not a requirement for representing that object's existence. We argue that the evidence suggests that a minimal representation of an object – the index - is sufficient for this purpose. It is minimal in that it can contain no descriptive information about an object whatsoever. We suggest that richer content, including physical properties characteristic of a “Spelke object” such as solidity or cohesion, are not necessarily contained in an object representation. Instead, the minimal object representation, together with the operational characteristics of the indexing mechanism, form an inceptual kernel within a language of thought from which such richer object representations will develop.

Young children with limited knowledge of formal mathematics can intuitively perform basic arithmetic‐like operations over nonsymbolic, approximate representations of quantity. However, the algorithmic rules that guide such nonsymbolic operations are not entirely clear. We asked whether nonsymbolic arithmetic operations have a function‐like structure, like symbolic arithmetic. Children (n = 74 4‐ to ‐8‐year‐olds in Experiment 1; n = 52 7‐ to 8‐year‐olds in Experiment 2) first solved two nonsymbolic arithmetic problems. We then showed children two unequal sets of objects, and asked children which of the two derived solutions should be added to the smaller of the two sets to make them “about the same.” We hypothesized that, if nonsymbolic arithmetic follows similar function rules to symbolic arithmetic, then children should be able to use the solutions of nonsymbolic computations as inputs into another nonsymbolic problem. Contrary to this hypothesis, we found that children were unable to reliably do so, suggesting that these solutions may not operate as independent representations that can be used inputs into other nonsymbolic computations. These results suggest that nonsymbolic and symbolic arithmetic computations are algorithmically distinct, which may limit the extent to which children can leverage nonsymbolic arithmetic intuitions to acquire formal mathematics knowledge.

“What is the structure of thought?” is as central a question as any in cognitive science. A classic answer to this question has appealed to a Language of Thought (LoT). We point to emerging research from disparate branches of the field that supports the LoT hypothesis, but also uncovers diversity in LoTs across cognitive systems, stages of development, and species. Our letter formulates open research questions for cognitive science concerning the varieties of rules and representations that underwrite various LoT-based systems and how these variations can help researchers taxonomize cognitive systems