Proceso de trabajo con las huellas en el lugar del hecho

Should retrospective exemplars generally be considered as a first step in the word learning process? We argue that, under the right conditions, children can indeed benefit from unlabeled exposures to word referents in subsequent word learning con- texts. We showed this for verb learning in the current study, but our findings could also explain the putative finding from Clerkin et al. (2017) that the objects children see frequently are possible referents for the first nouns they learn, although it was unclear whether parents labeled the objects in their child’s view or not. Children could explore two possible routes for word learning, which are not mutually exclu- sive. First, children could form concepts of referents through exposures (that do not involve labeling) before they learn linguistic labels for those referents. Second, children could form concepts of referents and semantic representations of words in parallel. Indeed, the act of labeling itself promotes creation of object categories in infants (A. Booth & Waxman, 2002; Fulkerson & Haaf, 2003; Waxman & Markow, 1995). It could be interesting to investigate whether seeing iconic gestures with un- labeled exemplars of word referents also leads to categorical knowledge about these referents, and future referents that belong to the same category. Furthermore, when adults provided further conceptual knowledge (e.g., animate vs. artifacts) about objects after these objects were labeled with novel nouns, the type of conceptual knowledge they provided shaped infants’ semantic representations, leading to dif- ferent patterns in noun generalization (A. Booth, Waxman, & Huang, 2005). It may be the case that for words that children acquire early, children form concepts and semantic representations simultaneously, but for words that children acquire later, children form concepts before they form semantic representations. The route children explore may also depend on type of referents (i.e., are they referents for verbs or nouns). This is because exposures to noun referents and verb referents are fundamentally different. Children often see one object exemplar repeatedly, which makes it easy to form an object concept, but action exemplars naturally always look different, which makes it hard to form an action concept. Children may be more

likely to form concepts of referents before learning the linguistic labels for these referents if the conditions allow them to link exemplars of the same referents. How- ever, it is unclear whether the same conditions help children to link exemplars of word referents from different word classes (e.g., verbs, nouns, prepositions). Thus, more research is needed to investigate the conditions under which children make us of prior (nonlinguistic) knowledge for word learning.

5.5.4 The Saliency of Actors Prevents Verb Learning

Our finding from Experiment 6 that children who saw retrospective exemplars with interactive gestures did not outperform children who saw irrelevant exemplars with interactive gestures in a novel verb learning task did not support our prediction. One possible explanation for this outcome is that children were not able to extract the invariance of action between exemplars in the retrospective exemplar condition, because they only heard a novel verb with one of the exemplars so there was no “cue” to compare exemplars of the same action (Childers, 2011). However, this is unlikely because children who saw retrospective exemplars with iconic gestures could compare unlabeled and labeled exemplars of the same action without such a cue. Another possible explanation is that children were not able to extract the invariance of action between exemplars, because the saliency of seeing a novel actor in each exemplar prevented children from individuating action and mapping a novel verb to action alone. This interpretation is consistent with findings from a study by Maguire et al. (2008), who showed in a novel verb learning task that 3-year-old children were better at extracting the action component from multiple exemplars in which the same actor performed the same action than from multiple exemplars in which different, novel actors performed the same action. This interpretation may also explain why children who saw two different retrospective exemplars in Experiment 7 barely performed above chance level in the novel verb learning task. Even when exemplars are shown side by side, which is a structural cue for children to compare exemplars, it is difficult for them to extract the action component when those exemplars show novel actors.

5.5.5 Conclusion

We conclude that multiple sources of information about verb referents can be pro- vided to children before these referents are labeled, and children use these sources of information to learn the linguistic labels for these referents, but only if they are structured in a particular way. Helping children to individuate actions is key to verb

learning; pre-exposing children to action exemplars while the actions are highlighted in iconic gestures is the best way to do so, but pre-exposing them to two exemplars side by side without gesture helps too. Importantly, iconic gestures helped children to form action concepts with schematic representations of actions, which led to more adult-like semantic representations of individual verb meanings in a subsequent verb learning task than side by side presentation of exemplars. The way children interpret verbs (i.e., what is included in their semantic representations) is a product of how they form action concepts. Under the right circumstances, children can form action concepts before linguistic labels for these actions are introduced, which facilitates mapping those labels to their referents. Thus, prior nonlinguistic action knowledge may be an important first step of the verb learning process.