Can children learn verbs from events separated in time? Examining how variability and memory contribute to verb learning.

Children in everyday environments experience verbs separated by minutes or hours and linked to events that vary in their similarity. Prior studies have shown that seeing similar events can be beneficial for verb learning (e.g., complex events), but there is also evidence that varied events or seeing both similar and varied events is useful; more studies are needed. In addition, few prior verb studies have tested verb learning from spaced practice. In Study 1, 3½- and 4½-year-olds (N = 72) saw either three similar events, three varied events, or a single live event (control) while hearing a new verb; events were separated by 1-min delays. Results showed better performance in multiple-event conditions than in the single-event condition and showed more extensions with age. Specifically, children benefitted more from seeing varied events with age. In Study 2, 2½-, 3½-, and 4½-year-olds (N = 163) either saw similar and then varied events or saw all varied video events separated by 1-min delays or no delays. The youngest children performed significantly better in the similar first condition than in the all varied condition, showing the first evidence of this benefit following spaced practice. In addition, as in Study 1, performance after seeing varied events increased with age. Together, these studies show that children can compare events separated in time and that their ability to learn verbs from varied examples develops with age.

Preschool Children's Processing of Events during Verb Learning: Is the Focus on People (Faces) or Their Actions (Hands)?

Verbs are central to the syntactic structure of sentences, and, thus, important for learning one's native language. This study examined how children visually inspect events as they hear, and do not hear, a new verb. Specifically, there is evidence that children may focus on the agent of the action or may prioritize attention to the action being performed; to date, little evidence is available. This study used an eye tracker to track 2-, 3-, and 4-year-olds' looking to the agent (i.e., face) vs. action (i.e., hands) while viewing events linked to a new verb as well as distractor events. A Tobii X30 eye tracker recorded children's fixations to AOIs (head/face and hands) as they watched three target events and two distractor events in different orders during the learning phase, and pointed to one of two events in two test trials. This was repeated for a second novel verb. Pointing results show that children in all age groups were able to learn and extend the new verbs to new events at test. Additionally, across age groups, when viewing target events, children increased their looking to the hands (where the action is taking place) as those trials progressed and decreased their looking to the agents' face, which is less informative for learning a new verb's meaning. In contrast, when viewing distractor events, children decreased their looking to hands over trials and maintained their attention to the face. In summary, children's visual attention to agents' faces and hands differed depending on whether the events cooccurred with the new verb. These results are important as this is the first study to show this pattern of visual attention during verb learning, and, thus, these results help reveal underlying attentional strategies children may use when learning verbs.

Can Young Children Ignore Irrelevant Events, or Subevents, During Verb Learning?

Children learning a verb may benefit from hearing it across situations (e.g., Behrend, 1995; Childers, 2011; Fisher et al, 1994; Pinker, 1989). At the same time, in everyday contexts, situations in which a verb is heard will be interrupted by distracting events. Using Structural Alignment theory as a framework (e.g., Gentner & Namy, 2006), Study 1 asks whether children can learn a verb when irrelevant, interleaved events are present. Two½- and 3½-year-old children saw dynamic events and were randomly assigned to one of three experimental conditions (differing in orders of events), or one of two control conditions. They extended the verbs in the experimental conditions, and not the control conditions. Three ½-year-olds were more successful than 2½-year-olds, though the younger children could extend verbs. A more difficult task is segmenting dynamic action into subevents that could be relevant for a verb (e.g., finding "chopping" in a cooking scene). In Study 2, 2½-, 3½- and 4½-year-old children were assigned to experimental conditions in which relevant events flowed into irrelevant events (or vice versa), or to a control. Two½-year-olds failed to extend the verbs at test, differing from the older children; children in experimental conditions extended the verbs while children in the control condition did not. Altogether, these results show children can ignore irrelevant events (and subevents), and extend new verbs by 3½ years. Results are important to understand learning in everyday contexts in which verbs are heard in varied situations over time.

Does Variability Across Events Affect Verb Learning in English, Mandarin, and Korean?

Extending new verbs is important in becoming a productive speaker of a language. Prior results show children have difficulty extending verbs when they have seen events with varied agents. This study further examines the impact of variability on verb learning and asks whether variability interacts with event complexity or differs by language. Children (aged 2½ to 3 years) in the United States, China, Korea, and Singapore learned verbs linked to simple and complex events. Sets of events included one or three agents, and children were asked to extend the verb at test. Children learning verbs linked to simple movements performed similarly across conditions. However, children learning verbs linked to events with multiple objects were less successful if those events were enacted by multiple agents. A follow-up study rules out an influence of event order. Overall, similar patterns of results emerged across languages, suggesting common cognitive processes support children's verb learning.

Early Verb Learning: How Do Children Learn How to Compare Events?

An important problem verb learners must solve is how to extend verbs. Children could use cross-situational information to guide their extensions, however comparing events is difficult. Two studies test whether children benefit from initially seeing a pair of similar events ('progressive alignment') while learning new verbs, and whether this influence changes with age. In Study 1, 2 ½- and 3 ½-year-old children participated in an interactive task. Children who saw a pair of similar events and then varied events were able to extend verbs at test, differing from a control group; children who saw two pairs of varied events did not differ from the control group. In Study 2, events were presented on a monitor. Following the initial pair of events that varied by condition, a Tobii x120 eye tracker recorded 2 ½-, 3 ½- and 4 ½-year-olds' fixations to specific elements of events (AOIs) during the second pair of events, which were the same across conditions. After seeing the pair of events that were highly similar, 2 ½-year-olds showed significantly longer fixation durations to agents and to affected objects as compared to the all varied condition. At test, 3 ½-year-olds were able to extend the verb, but only in the progressive alignment condition. These results are important because they show children's visual attention to relevant elements in dynamic events is influenced by their prior comparison experience, and they show that young children benefit from seeing similar events as they learn to compare events to each other.

Attention to Explicit and Implicit Contrast in Verb Learning.

Contrast information could be useful for verb learning, but few studies have examined children's ability to use this type of information. Contrast may be useful when children are told explicitly that different verbs apply, or when they hear two different verbs in a single context. Three studies examine children's attention to different types of contrast as they learn new verbs. Study 1 shows that 3 ½-year-olds can use both implicit contrast ("I'm meeking it. I'm koobing it.") and explicit contrast ("I'm meeking it. I'm not meeking it.") when learning a new verb, while a control group's responses did not differ from chance. Study 2 shows that even though children at this age who hear explicit contrast statements differ from a control group, they do not reliably extend a newly learned verb to events with new objects. In Study 3, children in three age groups were given both comparison and contrast information, not in blocks of trials as in past studies, but in a procedure that interleaved both cues. Results show that while 2 ½-year-olds were unable to use these cues when asked to compare and contrast, by 3 ½, children are beginning to be able to process these cues and use them to influence their verb extensions, and by 4 ½ years, children are proficient at integrating multiple cues when learning and extending new verbs. Together these studies examine children's use of contrast in verb learning, a potentially important source of information that has been rarely studied.

Children Use Different Cues to Guide Noun and Verb Extensions.

Learning new words involves decoding both how a word fits the current situation and how it could be used in new situations. Three studies explore how two types of cues- sentence structure and the availability of multiple instances-- affect children's extensions of nouns and verbs. In each study, 2½-year-olds heard nouns, verbs or no new word while seeing the experimenter use a novel object to perform an action; at test, they were asked to extend the word. In Study 1, children hearing nouns in simple sentences used object shape as the basis for extension even though, during the learning phase, they saw multiple objects in motion; children in the other conditions responded randomly. Study 2 shows that by changing in the type of sentences used in the noun and verb conditions, not only is the shape bias disrupted but children are successful in extending new verbs. In a final study, access to multiple examples was replaced by a direct teaching context, and produced findings similar to those in Study 2. An implication of this result is that seeing multiple examples can be as effective as receiving direct instruction from an adult. Overall, the set of results suggests the mix of cues available during learning influences noun and verb extensions differently. The findings are important for understanding how the ability to extend words emerges in complex contexts.

Attention to Multiple Events Helps 2 1/2-Year-Olds Extend New Verbs.

An important question in verb learning is how children extend new verbs to new situational contexts. In Study 1, 2 1/2-year-old children were shown a complex event followed by new events that preserved only the action from the initial event, only the result, or no new events. Children seeing events that preserved either the action or the result produced appropriate verb extensions at test while children without this information did not. In a follow-up study, children hearing new verbs produced more extensions than did children hearing nonlabeling speech. These studies suggest that attention to related events is helpful to young verb learners, perhaps because they structurally align these events (e.g., Gentner, 1983; 1989) during verb learning.

Korean- and English-speaking children use cross-situational information to learn novel predicate terms.

This paper examines children's attention to cross-situational information during word learning. Korean-speaking children in Korea and English-speaking children in the US were taught four nonce words that referred to novel actions. For each word, children saw four related events: half were shown events that were very similar (Close comparisons), half were shown events that were not as similar (Far comparisons). The prediction was that children would compare events to each other and thus be influenced by the events shown. In addition, children in these language groups could be influenced differently as their verb systems differ. Although some differences were found across language, children in both languages were influenced by the type of events shown, suggesting that they are using a comparison process. Thus, this study provides evidence for comparison, a new mechanism to describe how children learn new action words, and demonstrates that this process could apply across languages.

Joint attention and word learning in Ngas-speaking toddlers in Nigeria.

This study examines infants' joint attention behavior and language development in a rural village in Nigeria. Participants included eight younger (1 ;0 to 1 ;5, M age = 1 ;2) and eight older toddlers (1 ;7 to 2;7, M age= 2;1). Joint attention behaviors in social interaction contexts were recorded and coded at two time points six months apart. Analyses revealed that these toddlers were producing more high-level joint attention behaviors than less complex behaviors. In addition, the quality and quantity of behaviors produced by these Nigerian children was similar to those found in other cultures. In analyses of children's noun and verb comprehension and production (in relation to the number of nouns or verbs on a parental checklist), parents reported proportionally more verbs than nouns, perhaps because Ngas has some linguistic characteristics that are similar to languages in which a noun bias is not seen (e.g. Mandarin Chinese). An examination of the interrelations of joint attention and language development revealed that joint attention behaviors were related to both noun and verb development at different times. The set of results is important for understanding the emergence of joint attention in traditional cultures, the comprehension and production of nouns and verbs given the specific linguistic properties of a language, and the importance that early social contexts may have for language development.

Two-year-olds learn novel nouns, verbs, and conventional actions from massed or distributed exposures.

Two-year-old children were taught either 6 novel nouns, 6 novel verbs, or 6 novel actions over 1 month. In each condition, children were exposed to some items in massed presentations (on a single day) and some in distributed presentations (over the 2 weeks). Children's comprehension and production was tested at 3 intervals after training. In comprehension, children learned all types of items in all training conditions at all retention intervals. For production, the main findings were that (a) production was better for nonverbal actions than for either word type, (b) children produced more new nouns than verbs, (c) production of words was better following distributed than massed exposure, and (d) time to testing (immediate, 1 day, 1 week) did not affect retention. A follow-up study showed that the most important timing variable was the number of different days of exposure, with more days facilitating production. Results are discussed in terms of 2 key issues: (a) the domain-generality versus domain-specificity of processes of word learning and (b) the relative ease with which children learn nouns versus verbs.