Sandeep Prasada

Principled and statistical connections in common sense conception

Nominal concepts represent things as tokens of types. We report six experiments that investigate the nature of the relations we represent between the type of thing something is (e.g. DOG) and its other properties. The experiments provide evidence that we represent principled connections between the type of thing something is (e.g. DOG) and some of its properties (k-properties; e.g. having four legs for dogs), but not other properties (t-properties; e.g. being brown for dogs). Principled connections are different from logical, statistical, and causal connections. Principled connections, (i) license the expectation that tokens of the type will generally possess the k-property, (ii) license explanation of the presence of k-properties in tokens of a type by reference to the type of thing it is, and (iii) license normative expectations concerning the presence of the k-property in tokens of the type. The experiments provide evidence for all three of these aspects of principled connections. The experiments also demonstrate that principled connections must be distinguished from merely strong statistical connections. We suggest that principled connections are one of the fundamental types of relations (in addition to logical, statistical, and causal relations) in terms of which our conceptual knowledge is structured. We argue that principled connections reveal a formal mode of understanding and explanation. This mode of understanding complements other modes of understanding that have been studied within the theory-based approach to conceptual representation. Finally, we suggest that kind representations are distinguished from representations of mere types by the representation of principled connections to k-properties.

Acquiring generic knowledge

Generic knowledge is knowledge about kinds of things. The existence of generic knowledge poses a difficult acquisition problem: how do we acquire knowledge about kinds of things if we have experience with only a limited number of examples of the kinds in question? The problem is exacerbated by the fact that we sometimes acquire generic knowledge on the basis of experience with only a single instance of the kind. In this review, it is argued that there is a formal system for common-sense conception that underlies the acquisition of an important class of generic knowledge. Generic knowledge acquired through the use of the formal system represents the stable knowledge we have about kinds of things. It complements, rather than replaces, the statistical and causal (mechanistic) knowledge acquired through the use of other learning mechanisms.

Representation of principled connections: a window onto the formal aspect of common sense conception.

Nominal concepts represent things as tokens of types. Recent research suggests that we represent principled connections between the type of thing something is (e.g., DOG) and some of its properties (k-properties; e.g., having four legs for dogs) but not other properties (t-properties; e.g., being brown for dogs). Principled connections differ from logical, statistical, and causal connections. Principled connections license (i) the expectation that tokens of the type will generally possess their k-properties, (ii) formal explanations (i.e., explanation of the presence of k-properties in tokens of a type by reference to the type of thing it is), and (iii) normative expectations concerning the presence of k-properties in tokens of the type. The present paper investigates the hypothesis that representing principled connections requires representing properties as aspects of being the relevant kind of thing (Aspect Hypothesis). Experiment 1 provides a direct test of the Aspect Hypothesis. Experiments 2 and 3 provide indirect tests of the Aspect Hypothesis. All three experiments provide support for the Aspect Hypothesis. Experiment 4 investigates a prediction of the Aspect Hypothesis concerning the manner in which formal explanations are licensed by principled connections. Finally, Experiment 5 investigates a prediction of the Aspect Hypothesis concerning the nature of the normative expectations licensed by principled connections. Together these results provide strong evidence for the idea that representing principled connections involves representing a property as being an aspect of being a given kind of thing. The results also help clarify the manner in which formal explanation differs from other modes of explanation. Finally, the results of the experiments are used to motivate a proposal concerning the formal structure of the conceptual representations implicated by principled connections. This structure provides a domain-general way of structuring our concepts and embodies the perspective we take when we think and talk of things as being instances of a kind.

Conceiving of entities as objects and as stuff.

What is the difference between conceiving of an entity as an object of some kind and conceiving of it as an amount of solid stuff? We propose that the difference lies in how one thinks about the entitys structure. Object construals require thinking of the structure as being nonarbitrary, whereas substance construals require thinking of the structure as being arbitrary. We report six experiments that provide empirical support for this proposal. Regularity of structure, repetition of structure, and the existence of structure-dependent functions, all of which provide reasons to consider the structure of an entity to be nonarbitrary, were shown to bias participants towards object construals. We also discuss how the proposed account of what it means to construe an entity as an object or as some stuff can account for a range of findings in the literature on lexical development. These include the relation between cohesiveness and ontological category, shape and ontological category, and complexity of shape and ontological category. Finally, we discuss the nature of construals and the relation of object and substance construals to the physical, design, and intentional stances.

Singular or plural? Children's knowledge of the factors that determine the appropriate form of count nouns

Two experiments investigated the factors that govern childrens use of singular and plural forms of count nouns. Experiment 1 used an elicited production task to investigate whether children use referential and/or syntactic information to determine the form of the count nouns when the two sources of information conflict (e.g. each x, one of the xs), as well as when the linguistic context does not provide any constraint on the form of the noun, but the referential context does (e.g. the dog(s)). 48 children, aged 1;9 to 5;6, participated in Experiment 1. The results suggest that even the youngest children can use referential information when relevant, and can ignore referential information when necessary. Children did, however, show a tendency to make errors with the quantifier each in non-partitive contexts, and a developmental trend was found in the use and avoidance of each in non-partitive contexts. Experiment 2, an act out task, provided a second test of the role of referential information in childrens use of singular and plural forms. Experiment 2 also investigated childrens appreciation of the semantic distinction between each and all. 48 children, aged 1;8 to 5;6, participated in Experiment 2. A weak sensitivity to the semantic distinction between the two quantifiers as well as the syntactic context in which they were used was found. The results of the two experiments suggest that, from the beginning, children approach the task of learning when to use singular and plural forms of count nouns on the basis of morphosyntactic, semantic, and referential properties of utterances, rather than initially using only one of these types of information.

Conceptual and Linguistic Representations of Kinds and Classes

We investigate the hypothesis that our conceptual systems provide two formally distinct ways of representing categories by investigating the manner in which lexical nominals (e.g., tree, picnic table) and phrasal nominals (e.g., black bird, birds that like rice) are interpreted. Four experiments found that lexical nominals may be mapped onto kind representations, whereas phrasal nominals map onto class representations but not kind representations. Experiment 1 found that phrasal nominals, unlike lexical nominals, are mapped onto categories whose members need not be of a single kind. Experiments 2 and 3 found that categories named by lexical nominals enter into both class inclusion and kind hierarchies and thus support both class inclusion (is a) and kind specification (kind of) relations, whereas phrasal nominals map onto class representations which support only class inclusion relations. Experiment 4 showed that the two types of nominals represent hierarchical relations in different ways. Phrasal nominals (e.g., white bear) are mapped onto classes that have criteria of membership in addition to those specified by the class picked out by the head noun of the phrase (e.g., bear). In contrast, lexical nominals (e.g., polar bear) specify one way to meet the criteria specified by the more general kind concept (e.g., bear). Implications for the language-conceptual system interface, representation of hierarchical relations, lexicalization, and theories of conceptual combination are discussed.

Characterising kinds and instances of kinds: ERP reflections

Syntactic and semantic information are computed online in a manner such that electrophysiological methods can detect distinct processes within a few hundred milliseconds of a word. The amplitude of the N400 response has been shown to reflect semantic integration of a word in the context of a preceding word, sentence, and discourse. We show, in a combined behavioural and ERP study, that the N400 amplitude to the same word, in nearly identical sentential contexts, is modulated as a function of subtly different morphosyntactic environments that condition either a generic (grass is green) or nongeneric (the grass is green) reading. The results suggest that N400 amplitude reflects not only the existence of a semantic computation but can reflect processes relevant to the type of semantic relation being computed. Specifically, it is sensitive to whether a word is interpreted as characterising a kind/type or an instance of a kind/token of a type.

The development of principled connections and kind representations

Kind representations draw an important distinction between properties that are understood as existing in instances of a kind by virtue of their being the kind of thing they are and properties that are not understood in this manner. For example, the property of barking for the kind dog is understood as being had by dogs by virtue of the fact that they are dogs. These properties are said to have a principled connection to the kind. In contrast, the property of wearing a collar is not understood as existing in instances by virtue of their being dogs, despite the fact that a large percentage of dogs wear collars. Such properties are said to have a statistical connection to the kind. Two experiments tested two signatures of principled connections in 4-7 year olds and adults: (i) that principled connections license normative expectations (e.g., we judge there to be something wrong with a dog that does not bark), and (ii) that principled connections license formal explanations which explain the existence of a property by reference to the kind (e.g., that barks because it is a dog). Experiment 1 showed that both the children and adults have normative expectations for properties that have a principled connection to a kind, but not those that have a mere statistical connection to a kind. Experiment 2 showed that both children and adults are more likely to provide a formal explanation when explaining the existence of properties with a principled connection to a kind than properties with statistical connections to their kinds. Both experiments showed no effect of age (over ages 4, 7, and adulthood) on the extent to which participants differentiated principled and statistical connections. We discuss the implications of the results for theories of conceptual representation and for the structure of explanation.

The representation of inherent properties.

Research on the representation of generic knowledge suggests that inherent properties can have either a principled or a causal connection to a kind. The type of connection determines whether the outcome of the storytelling process will include intuitions of inevitability and a normative dimension and whether it will ground causal explanations.