Measuring the comprehension of negation in 2- to 4-year-old children

Measuring the comprehension of negation in 2- to 4-year-old children Ann E. Nordmeyer Michael C. Frank anordmey@stanford.edu Department of Psychology Stanford University mcfrank@stanford.edu Department of Psychology Stanford University Abstract Negation is one of the most important concepts in human lan- guage, and yet little is known about children’s ability to com- prehend negative sentences. In this experiment, we explore how children’s comprehension of negative sentences changes between 2- to 4-year-old children, as well as how comprehen- sion is influenced by how negative sentences are used. Chil- dren between the ages of 2 and 4 years watched a video in which they heard positive and negative sentences. Negative sentences, such as “look at the boy with no apples”, referred either to an absence of a characteristic or an alternative char- acteristic. Older children showed significant improvements in speed and accuracy of looks to target. Children showed more difficulty when the negative sentence referred to nothing, com- pared to when it referred to an alternative. In addition, children showed an early tendency to look towards the named noun, even when that noun was negated. This study contributes to our understanding of children’s comprehension of negative sen- tences, as well as our understanding of the conceptual structure of negation. Keywords: Negation; language development Introduction “No” is among the first words that children learn, as well as one of the most important. Negation is a fundamental element of human language — it is essential to logical systems, allows us to evaluate whether a statement is true or false, and it gives us a way to express concepts such as nonexistence. Negation is also challenging for language users; adults take longer to process negative sentences than positive ones (Clark & Chase, 1972; Just & Carpenter, 1971, 1976; Carpenter & Just, 1975). These findings lead us to an apparent paradox — how is that negation is difficult for adults, yet acquired at such a young age? By examining children’s acquisition of negation, we can explore the origins and development of logical concepts. Not all uses of negation are the same; words like “no” and “not” allow us to express multiple concepts. Three primary categories have been identified in children’s early negative ut- terances: nonexistence, rejection, and denial/truth-functional (Bloom, 1970, 1993; Pea, 1980). A child expressing rejec- tion might say “no go outside” when they want to stay inside, while a child who says “no more juice” to describe an empty cup is expressing nonexistence (Bloom, 1970). Denial in- volves making a statement about falsehood; a child might say “that not lollipop” if they believe a candy has been falsely identified as a lollipop. Additional types of negation have been identified as well. Pea (1980) identified two additional categories — self-prohibition, used when the child is about to engage in a forbidden action, and unfulfilled expectations, used when an expected action/object is not present. Choi (1988) identified a full 9 categories of negation, including failure, inability, epistemic negation (e.g. “I don’t know”), and inferential negation (i.e. negation of inferred beliefs of others). Regardless of taxonomy, negation is used in a variety of contexts to express a range of different thoughts. The relationship between different types of negation is un- known. One possibility is that distinct categories of negation belong to a single cohesive concept. Even pre-linguistically, nonexistence, rejection, and denial could all fall under a su- perordinate conceptual category of negation. It is also pos- sible, however, that these types of negation represent fun- damentally different concepts. For example, the situation in which a child expresses a dislike for going outside (rejection) is very different from a child commenting on an empty juice cup (nonexistence). Perhaps it is only the common language used to describe these events that unites these concepts. One way of untangling these possibilities is by examining chil- dren’s understanding of different negative concepts, and ex- ploring how their conceptual structure changes as they de- velop the language to express these thoughts. The acquisition of linguistic negation follows a long de- velopmental trajectory. As early as 12 months, children pro- duce negation in the form of the word “no”, typically to ex- press nonexistence and rejection (Bloom, 1970, 1993; Pea, 1980). Denial doesn’t emerge until almost a year later, be- tween 19 and 23 months (Pea, 1980). Cross-linguistic studies suggest that this stratification by type, with certain negative categories produced earlier than others, can be seen across languages (McNeill & McNeill, 1968). Even after age 2, children continue to learn about negation, showing improve- ments in syntactic form (Klima & Bellugi, 1966; Cameron- Faulkner, Lieven, & Theakston, 2007) as well as increases in the frequency with which they produce spontaneous neg- atives (Pea, 1982). Furthermore, children as old as 4 years continue to have difficulty with implicitly negative terms such as marked adjectives (e.g. less) (Donaldson & Balfour, 1968; Klatzky, Clark, & Macken, 1973). Thus, although “no” is among the first words that children produce, they continue to grapple with the nuances of negation for several more years. Nearly all prior research on the acquisition of negation has focused on production. Very little work has examined chil- dren’s comprehension of negative sentences (cf. de Villiers & Tager-Flusberg, 1975). While production can tell us about the contexts in which children use negation, it does not reveal the extent to which children understand concepts underlying neg- ative sentences. Children may already have a sophisticated understanding of different types of negation before they start producing negative utterances. Alternatively, children’s con- ceptual understanding may change as they develop linguistic negation. By examining the development of children’s com-