Infant preference for specific phonetic cue relations in the contrast between voiced and voiceless stops

Acoustic variability in the speech input has been shown, in certain contexts, to be beneficial during infants' acquisition of sound contrasts. One approach attributes this result to the potential of variability to make the stability of individual cues visible. Another approach suggests that, instead of highlighting individual cues, variability uncovers stable relations between cues that signal a sound contrast. Here, we investigate the relation between Voice Onset Time and the onset of F1 formant frequency, two cues that subserve the voicing contrast in German. First, we verified that German-speaking adults' use of VOT to categorize voiced and voiceless stops is dependent on the value of the F1 onset frequency, in the specific form of a so-called trading relation. Next, we tested whether 6-month-old German learning infants exhibit differential sensitivity to stimulus continua in which the cues varied to an equal extent, but either adhered to the trading relation established in the adult experiment or adhered to a reversed relation. Our results present evidence that infants prefer listening to speech in which phonetic cues conform to certain cue trading relations over cue relations that are reversed.

Exploring the impact of parents' face-mask wearing on dyadic interactions in infants at higher likelihood for autism compared with general population

Since the COVID-19 pandemic, both the public and researchers have raised questions regarding the potential impact of protective face-mask wearing on infants' development. Nevertheless, limited research has tested infants' response to protective face-mask wearing adults in real-life interactions and in neurodiverse populations. In addition, scarce attention was given to changes in interactive behavior of adults wearing a protective face-mask. The aims of the current study were (1) to examine differences in 12-month-old infants' behavioral response to an interactive parent wearing a protective face-mask during face-to-face interaction, (2) to investigate potential differences in infants at higher likelihood for autism (HL-ASD) as compared with general population (GP) counterparts, and (3) to explore significant differences in parents' behaviors while wearing or not wearing a protective face-mask. A total of 50 mother-infant dyads, consisting of 20 HL-ASD infants (siblings of individuals with autism) and 30 GP infants, participated in a 6-min face-to-face interaction. The interaction was videotaped through teleconferencing and comprised three 2-min episodes: (a) no mask, (b) mask, and (c) post-mask. Infants' emotionality and gaze direction, as well as mothers' vocal production and touching behaviors, were coded micro-analytically. Globally, GP infants exhibited more positive emotionality compared with their HL-ASD counterparts. Infants' negative emotionality and gaze avoidance did not differ statistically across episodes. Both groups of infants displayed a significant increase in looking time toward the caregiver during the mask episode. No statistically significant differences emerged in mothers' behaviors. These findings suggest that the use of protective face-masks might not negatively affect core dimensions of caregiver-infant interactions in GP and HL-ASD 12-month-old infants.

The link between non-human primate vocalizations and cognition is not constrained by maturation alone: Evidence from healthy preterm infants

To acquire language, infants must not only identify the signals of their language(s), but also discover how these signals are connected to meaning. By 3 months of age, infants' native language, non-native languages, and vocalizations of non-human primates support infants' formation of object categories-a building block of cognition. But by 6 months, only the native language exerts this cognitive advantage. Prior work with preterm infants indicates that maturation constrains this developing link between the native language and cognition. Here, we assess whether maturation exerts similar constraints on the influence of non-human primate vocalizations on infant categorization. Cross-sectional growth curve analyses of new data from preterm infants and extant data from fullterm infants indicate that developmental tuning of this signal's influence on categorization is best predicted by infants' chronological age, and not gestational status. This evidence, together with prior work, suggests that as infants tune the initially broad set of signals that support early cognition, they are guided by two independent processes: maturation constrains the expression of a link between their native language and cognition, while the influence of non-linguistic signals are guided by other factors, such as postnatal age and experience.

Prosody outweighs statistics in 6-month-old German-learning infants' speech segmentation

It is well established that infants use various cues to find words within fluent speech from about 7 to 8 months of age. Research suggests that two main mechanisms support infants' speech segmentation: prosodic cues like the word stress patterns, and distributional cues like transitional probabilities (TPs). We tested 6-month-old German-learning infants' use of prosodic and statistical cues for speech segmentation in three experiments. In Experiment 1, infants were familiarized with an artificial language string where TPs signaled either word boundaries or iambic words-a stress pattern that is disfavored in German. Experiment 2 was a control and only the test phase was presented. In Experiment 3, prosodic cues were absent in the string and only TPs signaled word boundaries. All experiments included the same conditions at test: disyllabic words with high TPs in the string, words with low TPs and words with non-co-occurring syllables. Results showed that infants relied more strongly on prosodic cues than on TPs for word segmentation. Notably, no segmentation evidence emerged when prosodic cues were absent in the string. This finding underlines early impacts of language-specific structural properties on segmentation mechanisms.

Attentional blink in infants under 7 months

Attentional blink manifests in infants at 7 months of age, indicating that the working memory capacity of 7-month-olds is comparable to that of adults. However, attentional blink in infants under 7 months is not well understood. In this study, we conducted two experiments to investigate attentional blink in 5- and 6-month-old infants. The results of Experiment 1 demonstrated that attentional blinks were not observed with either a short lag (200 ms) or a long lag (800 ms). This suggests that 5- and 6-month-olds are unable to consolidate both targets regardless of the temporal distance between the two. We then split the infants into two groups by their age and conducted Experiment 2 with infants aged younger and older than 180 days to compare their consolidating ability to observe whether they could recognize a single item at 100-ms speed by presenting the same visual stream that was used in Experiment 1 except that one target was eliminated. The results showed that infants over 180 days of age could identify a single target in the visual stream at 100-ms presentation speed, whereas infants under 180 days could not. The findings of the current study indicate that the limitation of working memory capacity in infants under 7 months of age is a possible reason for the lack of attentional blink.

Formal theories clarify the complex: Generalizing a neural process account of the interaction of visual exploration and word learning in infancy

The interaction of visual exploration and auditory processing is central to early cognitive development, supporting object discrimination, categorization, and word learning. Research has shown visual-auditory interactions to be complex, created from multiple processes and changing over multiple timescales. To better understand these interactions, we generalize a formal neural process model of early word learning to two studies examining how words impact 9- to 22-month-olds' attention to novelty. These simulations clarify the origin and nature of previously demonstrated effects of labels on visual exploration and the basis of mutual exclusivity effects in word learning. We use our findings to discuss key questions for this special section: what makes a good theory and how should formal theories interface with empirical paradigms and findings?

The cascading development of visual attention in infancy: Learning to look and looking to learn

The development of visual attention in infancy is typically indexed by where and how long infants look, focusing on changes in alerting, orienting, or attentional control. However, visual attention and looking are both complex systems that are multiply determined. Moreover, infants' visual attention, looking, and learning are intimately connected. Infants learn to look, reflecting cascading effects of changes in attention, the visual system and motor control, as well as the information infants learn about the world around them. Furthermore infants' looking behavior provides the input infants use to perceive and learn about the world. Thus, infants look to learn about the world around them. A deeper understanding of development will be gained by appreciating the cascading effects of changes across these intertwined domains.

A principled link between object naming and representation is available to infants by seven months of age

By their first birthdays, infants represent objects flexibly as a function of not only whether but how the objects are named. Applying the same name to a set of different objects from the same category supports object categorization, with infants encoding commonalities among objects at the expense of individuating details. In contrast, applying a distinct name to each object supports individuation, with infants encoding distinct features at the expense of categorical information. Here, we consider the development of this nuanced link between naming and representation in infants' first year. Infants at 12 months (Study 1; N = 55) and 7 months (Study 2; N = 96) participated in an online recognition memory task. All infants saw the same objects, but their recognition of these objects at test varied as a function of how they had been named. At both ages, infants successfully recognized objects that had been named with distinct labels but failed to recognize these objects when they had all been named with the same, consistent label. This new evidence demonstrates that a principled link between object naming and representation is available by 7 months, early enough to support infants as they begin mapping words to meaning.

Intersensory redundancy impedes face recognition in 12-month-old infants

This study examined the role of intersensory redundancy on 12-month-old infants' attention to and processing of face stimuli. Two experiments were conducted. In Experiment 1, 72 12-month-olds were tested using an online platform called Lookit. Infants were familiarized with two videos of an actor reciting a children's story presented simultaneously. A soundtrack either matched one of the videos (experimental condition) or neither of the videos (control condition). Visual-paired comparison (VPC) trials were completed to measure looking preferences for the faces presented synchronously and asynchronously during familiarization and for novel faces. Neither group displayed looking preferences during the VPC trials. It is possible that the complexity of the familiarization phase made the modality-specific face properties (i.e., facial characteristics and configuration) difficult to process. In Experiment 2, 56 12-month-old infants were familiarized with the video of only one actor presented either synchronously or asynchronously with the soundtrack. Following familiarization, participants completed a VPC procedure including the familiar face and a novel face. Results from Experiment 2 showed that infants in the synchronous condition paid more attention during familiarization than infants in the asynchronous condition. Infants in the asynchronous condition demonstrated recognition of the familiar face. These findings suggest that the competing face stimuli in the Experiment 1 were too complex for the facial characteristics to be processed. The procedure in Experiment 2 led to increased processing of the face in the asynchronous presentation. These results indicate that intersensory redundancy in the presentation of synchronous audiovisual faces is very salient, discouraging the processing of modality-specific visual properties. This research contributes to the understanding of face processing in multimodal contexts, which have been understudied, although a great deal of naturalistic face exposure occurs multimodally.

Embedding Play to Enrich Physical Therapy

Play is an active process by which an individual is intrinsically motivated to explore the self, the environment, and/or interactions with another person. For infants and toddlers, engaging in play is essential to support development across multiple domains. Infants and toddlers with or at risk of motor delays may demonstrate differences in play or challenges with engaging in play activities compared to typically developing peers. Pediatric physical therapists often use play as a modality to engage children in therapeutic assessment and interventions. Careful consideration of the design and use of physical therapy that embeds play is needed. Following a 3-day consensus conference and review of the literature, we propose physical therapy that embeds play should consider three components; the child, the environment, and the family. First, engage the child by respecting the child's behavioral state and following the child's lead during play, respect the child's autonomous play initiatives and engagements, use activities across developmental domains, and adapt to the individual child's needs. Second, structure the environment including the toy selection to support using independent movements as a means to engage in play. Allow the child to initiate and sustain play activities. Third, engage families in play by respecting individual family cultures related to play, while also providing information on the value of play as a tool for learning. Partner with families to design an individualized physical therapy routine that scaffolds or advances play using newly emerging motor skills.

6-, 10-, and 12-month-olds remember complex dynamic events across 2 weeks

Whereas infants' ability to remember simple static material (e.g., pictures) has been documented extensively, we know surprisingly little about infants' memory of dynamic events (i.e., events unfolding in time) in the first year after birth. Although there is evidence to suggest that infants show some kind of sensitivity toward complex dynamic events (i.e., events involving agents and a storyline) as indicated by visual engagement in the first year after birth, 16- to 18-month-olds are hitherto the youngest infants documented to remember such material. Using a visual paired-comparison (VPC) task, in Experiment 1 we examined 6-, 10-, and 12-month-olds' (N = 108) ability to encode and remember cartoons involving complex dynamic events across 2 weeks. Results showed that all age groups remembered these cartoons. To investigate further the role of a complex storyline, in Experiment 2 we assessed the memory of 107 infants of the same age groups for similar cartoons but without coherent storyline information by scrambling the temporal presentation of the information in the cartoons. The results showed that the two youngest age groups did not remember this version. To our knowledge, this is the first experiment to document memory for such complex material in young infants using VPC.

Seeing a talking face matters: Infants' segmentation of continuous auditory-visual speech

Visual speech cues from a speaker's talking face aid speech segmentation in adults, but despite the importance of speech segmentation in language acquisition, little is known about the possible influence of visual speech on infants' speech segmentation. Here, to investigate whether there is facilitation of speech segmentation by visual information, two groups of English-learning 7-month-old infants were presented with continuous speech passages, one group with auditory-only (AO) speech and the other with auditory-visual (AV) speech. Additionally, the possible relation between infants' relative attention to the speaker's mouth versus eye regions and their segmentation performance was examined. Both the AO and the AV groups of infants successfully segmented words from the continuous speech stream, but segmentation performance persisted for longer for infants in the AV group. Interestingly, while AV group infants showed no significant relation between the relative amount of time spent fixating the speaker's mouth versus eyes and word segmentation, their attention to the mouth was greater than that of AO group infants, especially early in test trials. The results are discussed in relation to the possible pathways through which visual speech cues aid speech perception.

Face processing in the infant brain after pandemic lockdown

The role of visual experience in the development of face processing has long been debated. We present a new angle on this question through a serendipitous study that cannot easily be repeated. Infants viewed short blocks of faces during fMRI in a repetition suppression task. The same identity was presented multiple times in half of the blocks (repeat condition) and different identities were presented once each in the other half (novel condition). In adults, the fusiform face area (FFA) tends to show greater neural activity for novel versus repeat blocks in such designs, suggesting that it can distinguish same versus different face identities. As part of an ongoing study, we collected data before the COVID-19 pandemic and after an initial local lockdown was lifted. The resulting sample of 12 infants (9-24 months) divided equally into pre- and post-lockdown groups with matching ages and data quantity/quality. The groups had strikingly different FFA responses: pre-lockdown infants showed repetition suppression (novel > repeat), whereas post-lockdown infants showed the opposite (repeat > novel), often referred to as repetition enhancement. These findings provide speculative evidence that altered visual experience during the lockdown, or other correlated environmental changes, may have affected face processing in the infant brain.

Learning with certainty in childhood

Learners use certainty to guide learning. They maintain existing beliefs when certain, but seek further information when they feel uninformed. Here, we review developmental evidence that this metacognitive strategy does not require reportable processing. Uncertainty prompts nonverbal human infants and nonhuman animals to engage in strategies like seeking help, searching for additional information, or opting out. Certainty directs children's attention and active learning strategies and provides a common metric for comparing and integrating conflicting beliefs across people. We conclude that certainty is a continuous, domain-general signal of belief quality even early in life.

Habituation and Dishabituation in Motor Behavior: Experiment and Neural Dynamic Model

Does motor behavior early in development have the same signatures of habituation, dishabituation, and Spencer-Thompson dishabituation known from infant perception and cognition? And do these signatures explain the choice preferences in A not B motor decision tasks? We provide new empirical evidence that gives an affirmative answer to the first question together with a unified neural dynamic model that gives an affirmative answer to the second question.In the perceptual and cognitive domains, habituation is the weakening of an orientation response to a stimulus over perceptual experience. Switching to a novel stimulus leads to dishabituation, the re-establishment of the orientation response. In Spencer-Thompson dishabituation, the renewed orientation response transfers to the original (familiar) stimulus. The change in orientation responses over perceptual experience explains infants' behavior in preferential looking tasks: Familiarity preference (looking longer at familiar than at novel stimuli) early during exposure and novelty preference (looking longer at novel than at familiar stimuli) late during exposure. In the motor domain, perseveration in the A not B task could be interpreted as a form of familiarity preference. There are hints that this preference reverses after enough experience with the familiar movement. We provide a unified account for habituation and patterns of preferential selection in which neural dynamic fields generate perceptual or motor representations. The build-up of activation in excitatory fields leads to familiarity preference, the build-up of activation in inhibitory fields leads to novelty preference. We show that the model accounts for the new experimental evidence for motor habituation, but is also compatible with earlier accounts for perceptual habituation and motor perseveration. We discuss how excitatory and inhibitory memory traces may regulate exploration and exploitation for both orientation to objects and motor behaviors.

Predicting explicit memory for meaningful cartoons from visual paired comparison in infants and toddlers

We tested the memory of 18-, 33-, and 39-month-olds (N = 120) for dynamic stimulus material (simple cartoons) after 6 months in a visual paired comparison (VPC) task. We also tested the explicit recognition memory (ERM) for the same material. Only the oldest age group (39-month-olds) showed a significant visual (familiarity) preference at the test. Similarly, only the oldest group reliably chose the correct cartoon in the ERM test. Data from the VPC and ERM tasks did not correlate in any age group. However, we suggested a novel score (coined ΔVPC) measuring how much visual preference changes during the test phase in the VPC task. We found that this ΔVPC score (and vocabulary) predicted children's performance in the ERM task, whereas other potential predictors such as age and conventional novelty preference did not. We discuss the impact of these findings in relation to the development of implicit and explicit memory. Furthermore, we propose that VPC measures are associated with explicit memory only when the participants processed the stimuli conceptually. In such cases, we suggest that the ΔVPC score is an approximation of how demanding it is to construct the mental representation of the familiar stimulus during the test phase.

Eighteen-month-old infants represent nonlocal syntactic dependencies

As mature speakers of a language, we are able to produce and understand an indefinite number of sentences. This ability comes from a powerful cognitive system—syntax—whose properties reveal the types of computations that human minds can engage in. One core property is the capacity to encode abstract grammatical dependencies that can hold at a distance. When does this property emerge in development? We identify a nonlocal dependency that 18-mo-old infants, but not younger infants, represent syntactically. These findings suggest that the second year of life is a period of active syntactic development and that even before they regularly produce full sentences of their own, infants demonstrate some of the core computational capacities that syntax relies on.

The human ability to produce and understand an indefinite number of sentences is driven by syntax, a cognitive system that can combine a finite number of primitive linguistic elements to build arbitrarily complex expressions. The expressive power of syntax comes in part from its ability to encode potentially unbounded dependencies over abstract structural configurations. How does such a system develop in human minds? We show that 18-mo-old infants are capable of representing abstract nonlocal dependencies, suggesting that a core property of syntax emerges early in development. Our test case is English wh-questions, in which a fronted wh-phrase can act as the argument of a verb at a distance (e.g., What did the chef burn?). Whereas prior work has focused on infants’ interpretations of these questions, we introduce a test to probe their underlying syntactic representations, independent of meaning. We ask when infants know that an object wh-phrase and a local object of a verb cannot co-occur because they both express the same argument relation (e.g., *What did the chef burn the pizza). We find that 1) 18 mo olds demonstrate awareness of this complementary distribution pattern and thus represent the nonlocal grammatical dependency between the wh-phrase and the verb, but 2) younger infants do not. These results suggest that the second year of life is a period of active syntactic development, during which the computational capacities for representing nonlocal syntactic dependencies become evident.

Visual exploration in adults: Habituation, mere exposure, or optimal level of arousal?

Exploration is one of the most powerful behaviours that drive learning from infancy to adulthood. The aim of the current study was to examine the role of novelty and subjective preference in visual exploration. To do this, we combined a visual exploration task with a subjective evaluation task, presenting novel and familiar pictures. The first goal was to ascertain whether, as demonstrated in babies, short habituation favors visual exploration of familiarity, whereas longer habituation leads to an exploration of novelty. The second goal was to evaluate the influence of familiarization on participants’ subjective evaluation of the stimuli. When presented with novel and very familiar stimuli, participants explored the novel stimuli more. In line with the optimal-level of arousal model, participants showed more positive evaluations of the semi-familiar stimuli compared with very familiar or very novel ones.

Labels and object categorization in six- and nine-month-olds: tracking labels across varying carrier phrases

Language shapes object categorization in infants. This starts as a general enhanced attentional effect of language, which narrows to a specific link between labels and categories by twelve months. The current experiments examined this narrowing effect by investigating when infants track a consistent label across varied input. Six-month-old infants (N = 48) were familiarized to category exemplars, each presented with the exact same labeling phrase or the same label in different phrases. Evidence of object categorization at test was only found with the same phrase, suggesting that infants were not tracking the label's consistency, but rather that of the entire input. Nine-month-olds (N = 24) did show evidence of categorization across the varied phrases, suggesting that they were tracking the consistent label across the varied input.

Additive and multiplicative probabilistic models of infant looking times

Additive and multiplicative regression models of habituation were compared regarding the fit to looking times from a habituation experiment with infants aged between 3 and 11 months. In contrast to earlier studies, the current study considered multiple probability distributions, namely Weibull, gamma, lognormal and normal distribution. In the habituation experiment the type of contrast between the habituation and the test trial was varied (luminance, color or orientation contrast), crossed with the number of habituation trials (1, 3, 5, or 7 habituation trials) and crossed with three age cohorts (4, 7, 10 months). The initial mean LT to dark stimuli (around 3.7 s) was considerably shorter than the mean LT to green and gray stimuli (around 5 s). Infants showed the strongest dishabituation to changes from dark to bright (luminance contrast) and weak-to-no dishabituation to a 90-degrees rotation of the gray stimuli (orientation contrast). The dishabituation was stronger after five and seven habituation trials, but the result was not statistically robust. The gamma distribution showed the best fit in terms of log-likelihood and mean absolute error and the best predictive performance. Furthermore, the gamma distribution showed small correlations between parameters relative to other models. The normal additive model showed an inferior fit and medium correlations between the parameters. In particular, the positive correlation between the initial looking time (LT) and the habituation rate was likely responsible for a different interpretation relative to the multiplicative models of the main effect of age on the habituation rate. Otherwise, the additive and multiplicative models provided similar statistical conclusions. The performance of the model versions without pooling and with partial pooling across participants (also called random-effects, multi-level or hierarchical models) were compared. The latter type of models showed worse data fit but more precise predictions and reduced correlations between the parameters. The performance of model variants with auto-regressive time structures were explored but showed considerably worse fit. The performance of quadratic models that allowed non-monotonic changes in LTs were investigated as well. However, when fitted with LT data, these models did not produce non-monotonic change in LTs. The study underscores the utility of partial-pooling models in terms of providing more accurate predictions. Further, it agrees with previous research in that a multiplicative LT model is preferable. Nevertheless, the current results suggest that the impact of the choice of an additive model on the statistical inference is less dramatic then previously assumed.

When novelty prevails on familiarity: Visual biases for child versus infant faces in 3.5- to 12-month-olds

The current study examined the influence of everyday perceptual experience with infant and child faces on the shaping of visual biases for faces in 3.5-, 6-, 9-, and 12-month-old infants. In Experiment 1, infants were presented with pairs of photographs of unfamiliar child and infant faces. Four groups with differential experience with infant and child faces were composed from parents' reports of daily exposure with infants and children (no experience, infant face experience, child face experience, and both infant and child face experience) to assess influence of experience on face preferences. Results showed that infants from all age groups displayed a bias for the novel category of faces in relation to their previous exposure to infant and child faces. In Experiment 2, this pattern of visual attention was reversed in infants presented with pictures of personally familiar child faces (i.e., older siblings) compared with unfamiliar infant faces, especially in older infants. These results suggest that allocation of attention for novelty can supersede familiarity biases for faces depending on experience and highlight that multiple factors drive infant visual behavior in responding to the social world.

Linking disambiguation and retention in a developmental eye-tracking study with monolingual and multilingual children

The disambiguation effect, also referred to as process of elimination, occurs during word learning, whereby novel words are mapped onto new referents, precluding the application of a novel label to a familiar object. Prior studies showed that the emergence and use of disambiguation can be affected by children's vocabulary growth and linguistic experience, such as growing up with more than one language. To test this, we investigated (a) whether monolingual and multilingual children disambiguated a novel word-object mapping, (b) whether they retained a trained, previously seen word-object mapping, (c) whether they retained the novel fast-mapped word-object mapping, and (d) whether and how age, English vocabulary size, and language background modulated disambiguation and retention. Lastly, we tested (e) whether children who disambiguated also retained better. Eye-tracking data from 18- to 30-month-old monolingual children (n = 43) and multilingual children (n = 40) were collected. A looking-while-listening paradigm with two objects included two familiar items, one novel item, and one trained item. Mixed-effect models reported that vocabulary size predicted the outcome of mapping and retention better than age. Monolingual children's accuracy on disambiguation trials was high from the start, whereas multilingual children started to disambiguate later as their vocabulary grew. Only monolingual children performed above chance level on retaining the novel label. Lastly, the use of disambiguation improved retention for monolingual children but not for multilingual children. This research corroborates that disambiguation should be regarded as a mechanism facilitating default fast mapping rather than fully fledged learning. Vocabulary growth leading to an increase in disambiguation supports the notion that the disambiguation effect stems from prior episodes of learning.

Experience with research paradigms relates to infants' direction of preference

Interpreting and predicting direction of preference in infant research has been a thorny issue for decades. Several factors have been proposed to account for familiarity versus novelty preferences, including age, length of exposure, and task complexity. The current study explores an additional dimension: experience with the experimental paradigm. We reanalyzed the data from 4 experiments on artificial grammar learning in 12-month-old infants run using the head-turn preference procedure (HPP). Participants in these studies varied substantially in their number of laboratory visits. Results show that the number of HPP studies is related to direction of preference: Infants with limited experience with the HPP setting were more likely to show familiarity preferences than infants who had amassed more experience with this paradigm. This evidence has important implications for the interpretation of experimental results: Experience with a given method or, more broadly, with the laboratory environment may affect infants' patterns of preferences.

Learning in Infancy Is Active, Endogenously Motivated, and Depends on the Prefrontal Cortices

A common view of learning in infancy emphasizes the role of incidental sensory experiences from which increasingly abstract statistical regularities are extracted. In this view, infant brains initially support basic sensory and motor functions, followed by maturation of higher-level association cortex. Here, we critique this view and posit that, by contrast and more like adults, infants are active, endogenously motivated learners who structure their own learning through flexible selection of attentional targets and active interventions on their environment. We further argue that the infant brain, and particularly the prefrontal cortex (PFC), is well equipped to support these learning behaviors. We review recent progress in characterizing the function of the infant PFC, which suggests that, as in adults, the PFC is functionally specialized and highly connected. Together, we present an integrative account of infant minds and brains, in which the infant PFC represents multiple intrinsic motivations, which are leveraged for active learning.

Determining the Function of Social Referencing: The Role of Familiarity and Situational Threat

In ambiguous situations, infants have the tendency to gather information from a social interaction partner to regulate their behavior [social referencing (SR)]. There are two main competing theories concerning SR’s function. According to social-cognitive information-seeking accounts, infants look at social interaction partners to gain information about the ambiguous situation. According to co-regulation accounts, infants look at social interaction partners to receive emotional support. This review provides an overview of the central developments in SR literature in the past years. We focus on the role of situational aspects such as familiarity of SR partners and situational threat, not only for SR (looking), but also for subsequent behavioral regulation (exploration, affect). As the competing accounts make different predictions concerning both contextual factors, this approach may reveal novel insights into the function of SR. Findings showed that a higher familiarity of SR partners consistently resulted in decreased looking (cf. social-cognitive accounts) and that higher threat remains largely understudied, but seemed to increase looking in the first few studies (cf. co-regulation accounts). Concerning behavioral regulation (exploration, affect) findings are mixed. We point out that moving toward a more complex situatedness may help to disentangle the heterogeneous results by considering the interaction between familiarity and threat rather than investigating the factors in isolation. From a general perspective, this review underlines the importance of situational factors and their interaction in eliciting a phenomenon, such as SR, but also in determining the nature of the phenomenon itself.

Out of the blue: understanding abrupt and wayward transitions in thought using probability and predictive processing

Thoughts that appear to come to us ‘out of the blue’ or ‘out of nowhere’ are a familiar aspect of mental experience. Such thoughts tend to elicit feelings of surprise and spontaneity. Although we are beginning to understand the neural processes that underlie the arising of such thoughts, little is known about what accounts for their peculiar phenomenology. Here, we focus on one central aspect of this phenomenology—the experience of surprise at their occurrence, as it relates to internal probabilistic predictions regarding mental states. We introduce a distinction between two phenomenologically different types of transitions in thought content: (i) abrupt transitions, which occur at surprising times but lead to unsurprising thought content, and (ii) wayward transitions, which occur at surprising times and also lead to surprising thought content. We examine these two types of transitions using a novel approach that combines probabilistic and predictive processing concepts and principles. We employ two different probability metrics—transition and occurrence probability—to characterize and differentiate between abrupt and wayward transitions. We close by discussing some potentially beneficial ways in which these two kinds of transitions in thought content may contribute to mental function, and how they may be implemented at the neural level.

This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.

Infant categorization as a dynamic process linked to memory

Recency effects are well documented in the adult and infant literature: recognition and recall memory are better for recently occurring events. We explore recency effects in infant categorization, which does not merely involve memory for individual items, but the formation of abstract category representations. We present a computational model of infant categorization that simulates category learning in 10-month-olds. The model predicts that recency effects outweigh previously reported order effects for the same stimuli. According to the model, infant behaviour at test should depend mainly on the identity of the most recent training item. We evaluate these predictions in a series of experiments with 10-month-old infants. Our results show that infant behaviour confirms the model's prediction. In particular, at test infants exhibited a preference for a category outlier over the category average only if the final training item had been close to the average, rather than distant from it. Our results are consistent with a view of categorization as a highly dynamic process where the end result of category learning is not the overall average of all stimuli encountered, but rather a fluid representation that moves depending on moment-to-moment novelty. We argue that this is a desirable property of a flexible cognitive system that adapts rapidly to different contexts.

Sensitivity to Visual-Tactile Colocation on the Body Prior to Skilled Reaching in Early Infancy

Two experiments examined perceptual colocation of visual and tactile stimuli in young infants. Experiment 1 compared 4- (n = 15) and 6-month-old (n = 12) infants' visual preferences for visual-tactile stimulus pairs presented across the same or different feet. The 4- and 6-month-olds showed, respectively, preferences for colocated and noncolocated conditions, demonstrating sensitivity to visual-tactile colocation on their feet. This extends previous findings of visual-tactile perceptual colocation on the hands in older infants. Control conditions excluded the possibility that both 6- (Experiment 1), and 4-month-olds (Experiment 2, n = 12) perceived colocation on the basis of an undifferentiated supramodal coding of spatial distance between stimuli. Bimodal perception of visual-tactile colocation is available by 4 months of age, that is, prior to the development of skilled reaching.

Explaining individual differences in infant visual sensory seeking

Individual differences in infants’ engagement with their environment manifest early in development and are noticed by parents. Three views have been advanced to explain differences in seeking novel stimulation. The optimal stimulation hypothesis suggests that individuals seek further stimulation when they are under‐responsive to current sensory input. The processing speed hypothesis proposes that those capable of processing information faster are driven to seek stimulation more frequently. The information prioritization hypothesis suggests the differences in stimulation seeking index variation in the prioritization of incoming relative to ongoing information processing. Ten‐month‐old infants saw 10 repetitions of a video clip and changes in frontal theta oscillatory amplitude were measured as an index of information processing speed. Stimulus‐locked P1 peak amplitude in response to checkerboards briefly overlaid on the video at random points during its presentation indexed processing of incoming stimulation. Parental report of higher visual seeking did not relate to reduced P1 peak amplitude or to a stronger decrease in frontal theta amplitude with repetition, thus not supporting either the optimal stimulation or the processing speed hypotheses. Higher visual seeking occurred in those infants whose P1 peak amplitude was greater than expected based on their theta amplitude. These findings indicate that visual sensory seeking in infancy is explained by a bias toward novel stimulation, thus supporting the information prioritization hypothesis.

Visual short-term memory for overtly attended objects during infancy

We investigated limitations in young infants' visual short-term memory (VSTM). We used a one-shot change detection task to ask whether 4- and 8.5-month-old infants (N = 59) automatically encode fixated items in VSTM. Our task included trials that consisted of the following sequence: first a brief (500 ms) presentation with a sample array of two items, next a brief (300 ms) delay period with a blank screen, and finally a test array (2,000 ms) identical to the sample array except that the color of one of the two items is changed. In Experiment 1, we induced infants to fixate one item by rotating it during the sample (the other item remained stationary). In Experiment 2, none of the items rotated. In both experiments, 4-month-old infants looked equally at the fixated item when it did and did not change color, providing no evidence that they encoded in VSTM the fixated item. In contrast, 8.5-month-old infants in Experiment 1 preferred the fixated item when it changed color from sample to test. Thus, 4-month-old infants do not appear to automatically encode fixated items in VSTM.

The role of prior knowledge and curiosity in learning

Recent work has argued that curiosity can improve learning. However, these studies also leave open the possibility that being on the verge of knowing can itself induce curiosity. We investigate how prior knowledge relates to curiosity and subsequent learning using a trivia question task. Curiosity in our task is best predicted by a learner's estimate of their current knowledge, more so than an objective measure of what they actually know. Learning is best predicted by both curiosity and an objective measure of knowledge. These results suggest that while curiosity is correlated with knowledge, there is only a small boost in learning from being curious. The implication is that the mechanisms that drive curiosity are not identical to those that drive learning outcomes.

Dynamic effects of habituation and novelty detection on newborn event-related potentials

Newborns habituate to repeated auditory stimuli, and discriminate syllables, generating opportunities for early language learning. This study investigated trial-by-trial changes in newborn electrophysiological responses to auditory speech syllables as an index of habituation and novelty detection. Auditory event-related potentials (ERPs) were recorded from 16 term newborn infants, aged 1-3 days, in response to monosyllabic speech syllables presented during habituation and novelty detection tasks. Multilevel models demonstrated that newborns habituated to repeated auditory syllables, as ERP amplitude attenuated for a late-latency component over successive trials. Subsequently, during the novelty detection task, early- and late-latency component amplitudes decreased over successive trials for novel syllables only, indicating encoding of the novel speech syllable. We conclude that newborns dynamically encoded novel syllables over relatively short time periods, as indicated by a systematic change in response patterns with increased exposure. These results have important implications for understanding early precursors of learning and memory in newborns.

Infant Visual Attention and Stimulus Repetition Effects on Object Recognition

This study examined behavioral, heart rate (HR), and event-related potential (ERP) correlates of attention and recognition memory for 4.5-, 6-, and 7.5-month-old infants (N = 45) during stimulus encoding. Attention was utilized as an independent variable using HR measures. The Nc ERP component associated with attention and the late slow wave (LSW) associated with recognition memory were analyzed. The 7.5-month-olds demonstrated a significant reduction in Nc amplitude with stimulus repetition. This reduction in Nc was not found for younger infants. Additionally, infants only demonstrated differential LSW amplitude based on stimulus type on attentive trials as defined by HR changes. These findings indicate that from 4.5 to 7.5 months, infants' attentional engagement is influenced by an increasingly broader range of stimulus characteristics.

Fixations and Fixation Shifts in Own-Race and Other-Race Face Pairs at Three, Six and Nine Months

Caucasian infants were presented 15 pairs of Caucasian own-race faces and 15 pairs of African other-race faces. The infants were assessed longitudinally at ages three, six and nine months. Two measures were obtained from the infants' eye-movements: (1) the length of fixations on either stimulus of a pair presented for 5.5 s (fixation duration) and (2) the amount of fixation shifts between the two stimuli (shift frequency). The study analyzes the changes in both measures with age and across the within-race face pair presentations. Despite general age-related improvements reflected in shorter fixation durations and a higher shift frequency, the results reveal differences between African face pairs and Caucasian face pairs at six and nine months. During the first trials (spontaneous looking behavior) the infants shift more often between the Caucasian own-race faces than between the African other-race faces. The fixation durations, however, which are typically of focus in Visual Pair Preference Tasks, do not differ significantly between the face races. The results are interpreted in terms of processing differences for own-race faces and the emerging Other-Race-Effect by six months of age. Furthermore, the usability of fixation duration as the only measure in the pair comparison setting is discussed.

Neural signatures of recognition memory in 10- to 12-month-old infants

Understanding memory mechanisms is crucial in the study of infant social and cognitive development. Here, we show that the Nc ERP component, known to reflect frequency-related attentional and/or memory processes, is a good candidate to investigate infant recognition memory. Previous paradigms have only investigated the effect of frequency during on-line stimulus presentation, but not during stimulus encoding. In this paper, we present a novel method for measuring the neural correlates of recognition memory and the 'degree' of familiarity in 10- to 12-month-old infants. During a familiarization phase, two images were presented frequently, while another two images were presented infrequently to the infants. In the test phase, the infrequent familiar, the frequent familiar, and the novel stimuli, were all presented with equal probability. We found larger Nc amplitudes following the familiar stimuli compared to the novel ones. The 'degree' of familiarity, on the other hand, did not modulate the Nc amplitude. These results can only be explained with memory-related processes, since in our paradigm the on-line presentation frequency did not vary. Furthermore, the lack of familiarization frequency effect suggests that the Nc might be a neural correlate of declarative memory.

Infants' advances in speech perception shape their earliest links between language and cognition

The power of human language derives not only from the precision of its signal or the complexity of its grammar, but also from its links to cognition. Infants as young as 3 months have begun to link language and core cognitive capacities. At 3 and 4 months, this link is not exclusive to human language: listening to vocalizations of nonhuman primates also supports infant cognition. By 6 months, infants have tuned this link to human speech alone. Here we provide evidence that infants' increasing precision in speech perception shapes which signals they will link to cognition. Infants listening to German, a nonnative language that shares key rhythmic and prosodic properties with their own native language (English), successfully formed object categories. In contrast, those listening to Cantonese, a language that differs considerably in these suprasegmental properties, failed. This provides the first evidence that infants' increasingly precise perceptual tuning to the sounds of their native language sets constraints on the range of human languages they will link to cognition: infants begin to specify which human languages they will link to core cognitive capacities even before they sever the link between nonhuman primate vocalizations and cognition.

Split-Brain Babies? Differences in Representation of Bilaterally and Unilaterally Presented Visual Stimuli in Infancy

Information needed for perception and action is often distributed across the two hemispheres of the human brain. During development, representations lateralized due to topographic sensory maps may be available independently before they can be integrated across hemispheres. These studies (total N = 211) investigate visual interhemispheric integration in two domains in infancy. In Experiment 1, infants (8-14 months) showed stronger evidence of representing the equality of two shapes when the shapes were presented in the same visual hemifield. In Experiments 2-4, infants (10-19 months) showed evidence of greater familiarization when shown 16 dots in one hemifield than when shown 8 dots in each hemifield. The possibility that interhemispheric integration poses an unusually late-resolved challenge in infant vision is discussed.

Shifting Preferences for Primate Faces in Neurotypical Infants and Infants Later Diagnosed With ASD

Infants look at others' faces to gather social information. Newborns look equally at human and monkey faces but prefer human faces by 1 month, helping them learn to communicate and interact with others. Infants later diagnosed with autism spectrum disorder (ASD) look at human faces less than neurotypical infants, which may underlie some deficits in social-communication later in life. Here, we asked whether infants later diagnosed with ASD differ in their preferences for both human and nonhuman primate faces compared to neurotypical infants over their first 2 years of life. We compare infants' relative looking times to human or monkey faces paired with nonface controls (Experiment 1) and infants' total looking times to pairs of human and monkey faces (Experiment 2). Across two experiments, we find that between 6 and 18 months, infants later diagnosed with ASD show a greater downturn (decrease after an initial increase) in looking at both primate faces than neurotypical infants. A decrease in attention to primate faces may partly underlie the social-communicative difficulties in children with ASD and could reveal how early perceptual experiences with faces affect development. Autism Res 2019, 12: 249-262 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Looking at faces helps infants learn to interact with others. Infants look equally at human and monkey faces at birth but prefer human faces by 1 month. Infants later diagnosed with ASD who show deficits in social-communication look at human faces less than neurotypical infants. We find that a downturn (decline after an initial increase) in attention to both human and monkey faces between 6 and 18 months may partly underlie the social-communicative difficulties in children with ASD.

Two mechanisms underlying auditory dominance: Overshadowing and response competition

There are occasions when infants and children have difficulty in processing arbitrary auditory-visual pairings, with auditory input sometimes attenuating visual processing (i.e., auditory dominance). The current research examined possible mechanisms underlying these auditory dominance effects in infants and 4-year-olds. Do auditory dominance effects stem from auditory input attenuating encoding of visual input, from the difficulty of inhibiting auditory-based responses, or from a combination of these factors? In five reported experiments, 4-year-olds (Experiments 1A, 1B, 2A, and 2B) and 14- and 22-month-olds (Experiment 3) were presented with a variety of tasks that required simultaneous processing of auditory and visual input, and then we assessed memory for the visual items at test. Auditory dominance in young children resulted from response competition that children could not resolve. Infants' results were not as robust, but they provided some evidence that nonlinguistic sounds and possibly spoken words may attenuate encoding of visual input. The current findings shed light on mechanisms underlying cross-modal processing and auditory dominance and have implications for many tasks that hinge on the processing of arbitrary auditory-visual pairings.

Eye vergence responses to novel and familiar stimuli in young children

Eye vergence is the slow movement of both eyes in opposite directions enabling binocular vision. Recently, it was suggested that vergence could be involved in orienting visual attention and memory having a role in cognitive processing of sensory information. In the present study, we assessed whether such vergence responses are observed in early childhood. We measured eye vergence responses in 43 children (12-37 months of age) while looking at novel and repeated object images. Based on previous research, we hypothesized that visual attention and Visual Short-Term Memory (VSMT) would be evidenced by differential vergence responses for both experimental conditions, i.e. repeated (familiar) vs. novel items. The results show that attention related vergence is present in early childhood and that responses to repeated images differ from the ones to novel items. Our current findings suggest that vergence mechanisms could be linking visual attention with short-term memory recognition.

Meaningful Memory? Eighteen-Month-Olds Only Remember Cartoons With a Meaningful Storyline

In two studies we investigated the importance of a storyline for remembering cartoons across a delay of 2 weeks in 18-month-old infants by means of the visual paired-comparison (VPC) paradigm. In Study 1 seventy-one 18-month-olds were tested using similar cartoons as in a recent study from our lab while varying the richness of the storyline information. In a VPC task half of the infants watched uncompromised versions of the cartoons used in the recent study (Storyline Condition), whereas the other half watched Pixelized versions of the cartoons (number of pixels reduced by 98% covering up the narrative, but leaving perceptual details, e.g., colors, movements, the same, and Pixelized Condition). Two weeks later they were presented with the familiar cartoon and a novel cartoon from the same version (Storyline or Pixelized) simultaneously, while being eye-tracked. Results showed that only the infants in the Storyline Condition remembered the target cartoon, thus suggesting that the storyline is important for memory. However, an alternative interpretation of the results could be that what made the infants in the Storyline Condition remember the target cartoon was not the storyline, but the static conceptual information of the objects and agents present in the cartoon (which was not visible in the Pixelized version). To test this possibility, a control study was created. In Study 2 thirty-six infants were therefore presented with a version of the cartoon in which we broke down the temporal presentation into 1 s segments and presented these out of order. This was done to preserve the static conceptual information (e.g., objects and agents) while still disturbing the storyline. Results showed that the infants in this condition still did not remember the target cartoon, suggesting that the meaningfulness of the storyline - and not only static conceptual information - is important for later memory.

Lexical stress constrains English-learning infants' segmentation in a non-native language

Infants' ability to segment words in fluent speech is affected by their language experience. In this study we investigated the conditions under which infants can segment words in a non-native language. Using the Head-turn Preference Procedure, we found that monolingual English-learning 8-month-olds can segment bisyllabic words in Spanish (trochees and iambs) but not French (iambs). Our results are incompatible with accounts that rely on distributional learning, language rhythm similarity, or target word prosodic shape alone. Instead, we show that monolingual English-learning infants are able to segment words in a non-native language as long as words have stress, as is the case in English. More specifically, we show that even in a rhythmically different non-native language, English-learning infants can find words by detecting stressed syllables and treating them as word onsets or offsets.