Corrigendum: Reduced Mu Power in Response to Unusual Actions Is Context-Dependent in 1-Year-Olds.

[This corrects the article DOI: 10.3389/fpsyg.2018.00036.].

Reduced Mu Power in Response to Unusual Actions Is Context-Dependent in 1-Year-Olds.

During social interactions infants predict and evaluate other people's actions. Previous behavioral research found that infants' imitation of others' actions depends on these evaluations and is context-dependent: 1-year-olds predominantly imitated an unusual action (turning on a lamp with one's forehead) when the model's hands were free compared to when the model's hands were occupied or restrained. In the present study, we adapted this behavioral paradigm to a neurophysiological study measuring infants' brain activity while observing usual and unusual actions via electroencephalography. In particular, we measured differences in mu power (6 - 8 Hz) associated with motor activation. In a between-subjects design, 12- to 14-month-old infants watched videos of adult models demonstrating that their hands were either free or restrained. Subsequent test frames showed the models turning on a lamp or a soundbox by using their head or their hand. Results in the hands-free condition revealed that 12- to 14-month-olds displayed a reduction of mu power in frontal regions in response to unusual and thus unexpected actions (head touch) compared to usual and expected actions (hand touch). This may be explained by increased motor activation required for updating prior action predictions in response to unusual actions though alternative explanations in terms of general attention or cognitive control processes may also be considered. In the hands-restrained condition, responses in mu frequency band did not differ between action outcomes. This implies that unusual head-touch actions compared to hand-touch actions do not necessarily evoke a reduction of mu power. Thus, we conclude that reduction of mu frequency power is context-dependent during infants' action perception. Our results are interpreted in terms of motor system activity measured via changes in mu frequency band as being one important neural mechanism involved in action prediction and evaluation from early on.

Metaphors as Second Labels: Difficult for Preschool Children?

This study investigates the development of two cognitive abilities that are involved in metaphor comprehension: implicit analogical reasoning and assigning an unconventional label to a familiar entity (as in Romeo's 'Juliet is the sun'). We presented 3- and 4-year-old children with literal object-requests in a pretense setting (e.g., 'Give me the train with the hat'). Both age-groups succeeded in a baseline condition that used building blocks as props (e.g., placed either on the front or the rear of a train engine) and only required spatial analogical reasoning to interpret the referential expression. Both age-groups performed significantly worse in the critical condition, which used familiar objects as props (e.g., small dogs as pretend hats) and required both implicit analogical reasoning and assigning second labels. Only the 4-year olds succeeded in this condition. These results offer a new perspective on young children's difficulties with metaphor comprehension in the preschool years.

Children's level of word knowledge predicts their exclusion of familiar objects as referents of novel words.

When children are learning a novel object label, they tend to exclude as possible referents familiar objects for which they already have a name. In the current study, we wanted to know if children would behave in this same way regardless of how well they knew the name of potential referent objects, specifically, whether they could only comprehend it or they could both comprehend and produce it. Sixty-six monolingual German-speaking 2-, 3-, and 4-year-old children participated in two experimental sessions. In one session the familiar objects were chosen such that their labels were in the children's productive vocabularies, and in the other session the familiar objects were chosen such that their labels were only in the children's receptive vocabularies. Results indicated that children at all three ages were more likely to exclude a familiar object as the potential referent of the novel word if they could comprehend and produce its name rather than comprehend its name only. Indeed, level of word knowledge as operationalized in this way was a better predictor than was age. These results are discussed in the context of current theories of word learning by exclusion.

3-year-old children make relevance inferences in indirect verbal communication.

Three studies investigated 3-year-old children's ability to determine a speaker's communicative intent when the speaker's overt utterance related to that intent only indirectly. Studies 1 and 2 examined children's comprehension of indirectly stated requests (e.g., "I find Xs good" can imply, in context, a request for X; N = 32). Study 3 investigated 3- and 4-year-old children's and adults' (N = 52) comprehension of the implications of a speaker responding to an offer by mentioning an action's fulfilled or unfulfilled precondition (e.g., responding to an offer of cereal by stating that we have no milk implies rejection of the cereal). In all studies, 3-year-old children were able to make the relevance inference necessary to integrate utterances meaningfully into the ongoing context.

How two word-trained dogs integrate pointing and naming.

Two word-trained dogs were presented with acts of reference in which a human pointed, named objects, or simultaneously did both. The question was whether these dogs would assume co-reference of pointing and naming and thus pick the pointed-to object. Results show that the dogs did indeed assume co-reference of pointing and naming in order to determine the reference of a spoken word, but they did so only when pointing was not in conflict with their previous word knowledge. When pointing and a spoken word conflicted, the dogs preferentially fetched the object by name. This is not surprising since they are trained to fetch objects by name. However, interestingly, in these conflict conditions, the dogs fetched the named objects only after they had initially approached the pointed-to object. We suggest that this shows that the word-trained dogs interpret pointing as a spatial directive, which they integrate into the fetching game, presumably assuming that pointing is relevant to finding the requested object.

Domestic dogs use contextual information and tone of voice when following a human pointing gesture.

Domestic dogs are skillful at using the human pointing gesture. In this study we investigated whether dogs take contextual information into account when following pointing gestures, specifically, whether they follow human pointing gestures more readily in the context in which food has been found previously. Also varied was the human's tone of voice as either imperative or informative. Dogs were more sustained in their searching behavior in the 'context' condition as opposed to the 'no context' condition, suggesting that they do not simply follow a pointing gesture blindly but use previously acquired contextual information to inform their interpretation of that pointing gesture. Dogs also showed more sustained searching behavior when there was pointing than when there was not, suggesting that they expect to find a referent when they see a human point. Finally, dogs searched more in high-pitched informative trials as opposed to the low-pitched imperative trials, whereas in the latter dogs seemed more inclined to respond by sitting. These findings suggest that a dog's response to a pointing gesture is flexible and depends on the context as well as the human's tone of voice.

Young children follow pointing over words in interpreting acts of reference.

Adults refer young children's attention to things in two basic ways: through the use of pointing (and other deictic gestures) and words (and other linguistic conventions). In the current studies, we referred young children (2- and 4-year-olds) to things in conflicting ways, that is, by pointing to one object while indicating linguistically (in some way) a different object. In Study 1, a novel word was put into competition with a pointing gesture in a mutual exclusivity paradigm; that is, with a known and a novel object in front of the child, the adult pointed to the known object (e.g. a cup) while simultaneously requesting 'the modi'. In contrast to the findings of Jaswal and Hansen (2006), children followed almost exclusively the pointing gesture. In Study 2, when a known word was put into competition with a pointing gesture - the adult pointed to the novel object but requested 'the car'- children still followed the pointing gesture. In Study 3, the referent of the pointing gesture was doubly contradicted by the lexical information - the adult pointed to a known object (e.g. a cup) but requested 'the car'- in which case children considered pointing and lexical information equally strong. Together, these findings suggest that in disambiguating acts of reference, young children at both 2 and 4 years of age rely most heavily on pragmatic information (e.g. in a pointing gesture), and only secondarily on lexical conventions and principles.

Two-year-olds exclude novel objects as potential referents of novel words based on pragmatics.

Many studies have established that children tend to exclude objects for which they already have a name as potential referents of novel words. In the current study we asked whether this exclusion can be triggered by social-pragmatic context alone without pre-existing words as blockers. Two-year-old children watched an adult looking at a novel object while saying a novel word with excitement. In one condition the adult had not seen the object beforehand, and so the children interpreted the adult's utterance as referring to the gazed-at object. In another condition the adult and child had previously played jointly with the gazed-at object. In this case, children less often assumed that the adult was referring to the object but rather they searched for an alternative referent--presumably because they inferred that the gazed-at object was old news in their common ground with the adult and so not worthy of excited labeling. Since this inference based on exclusion is highly similar to that underlying the Principle of Contrast/Mutual Exclusivity, we propose that this principle is not purely lexical but rather is based on children's understanding of how and why people direct one another's attention to things either with or without language.

Two-year-olds use primary sentence accent to learn new words.

German children aged 2;1 heard a sentence containing a nonce noun and a nonce verb (Der Feks miekt). Either the noun or the verb was prosodically highlighted by increased pitch, duration and loudness. Independently, either the object or the action in the ongoing referential scene was the new element in the situation. Children learned the nonce noun only when it was both highlighted prosodically and the object in the scene was referentially new. They did not learn the nonce verb in any condition. These results suggest that from early in linguistic development, young children understand that prosodic salience in a sentence indicates referential newness.