An edge-simplicity bias in the visual input to young infants.

The development of sparse edge coding in the mammalian visual cortex depends on early visual experience. In humans, there are multiple indicators that the statistics of early visual experiences has unique properties that may support these developments. However, there are no direct measures of the edge statistics of infant daily-life experience. Using head-mounted cameras to capture egocentric images of young infants and adults in the home, we found infant images to have distinct edge statistics relative to adults. For infants, scenes with sparse edge patterns-few edges and few orientations-dominate. The findings implicate biased early input at the scale of daily life that is likely specific to the early months after birth and provide insights into the quality, amount, and timing of the visual experiences during the foundational developmental period for human vision.

Infant vocal productions coincide with body movements.

Producing recognizable words is a difficult motor task; a one-syllable word can require the coordination of over 80 muscles. Thus, it is not surprising that the development of word productions in infancy lags considerably behind receptive language and is a known limiting factor in language development. A large literature has focused on the vocal apparatus, its articulators, and language development. There has been limited study of the relations between non-speech motor skills and the quality of early speech productions. Here we present evidence that the spontaneous vocalizations of 9- to 24-month-old infants recruit extraneous, synergistic co-activations of hand and head movements and that the temporal precision of the co-activation of vocal and extraneous muscle groups tightens with age and improved recognizability of speech. These results implicate an interaction between the muscle groups that produce speech and other body movements and provide new empirical pathways for understanding the role of motor development in language acquisition. RESEARCH HIGHLIGHTS: The spontaneous vocalizations of 9- to 24-month-old infants recruit extraneous, synergistic co-activations of hand and head movements. The temporal precision of these hand and head movements during vocal production tighten with age and improved speech recognition. These results implicate an interaction between the muscle groups producing speech with other body movements. These results provide new empirical pathways for understanding the role of motor development in language acquisition.

Look before you reach: Fixation-reach latencies predict reaching kinematics in toddlers.

Research on infant and toddler reaching has shown evidence for motor planning after the initiation of the reaching action. However, the reach action sequence does not begin after the initiation of a reach but rather includes the initial visual fixations onto the target object occurring before the reach. We developed a paradigm that synchronizes head-mounted eye-tracking and motion capture to determine whether the latency between the first visual fixation on a target object and the first reaching movement toward the object predicts subsequent reaching behavior in toddlers. In a corpus of over one hundred reach sequences produced by 17 toddlers, we found that longer fixation-reach latencies during the pre-reach phase predicted slower reaches. If the slowness of an executed reach indicates reach difficulty, then the duration of pre-reach planning would be correlated with reach difficulty. However, no relation was found with pre-reach planning duration when reach difficulty was measured by usual factors and independent of reach duration. The findings raise important questions about the measurement of reach difficulty, models of motor control, and possible developmental changes in the relations between pre-planning and continuously unfolding motor plans throughout an action sequence.

Controlling the input: How one-year-old infants sustain visual attention.

Traditionally, the exogenous control of gaze by external saliencies and the endogenous control of gaze by knowledge and context have been viewed as competing systems, with late infancy seen as a period of strengthening top-down control over the vagaries of the input. Here we found that one-year-old infants control sustained attention through head movements that increase the visibility of the attended object. Freely moving one-year-old infants (n = 45) wore head-mounted eye trackers and head motion sensors while exploring sets of toys of the same physical size. The visual size of the objects, a well-documented salience, varied naturally with the infant's moment-to-moment posture and head movements. Sustained attention to an object was characterized by the tight control of head movements that created and then stabilized a visual size advantage for the attended object for sustained attention. The findings show collaboration between exogenous and endogenous attentional systems and suggest new hypotheses about the development of sustained visual attention.

Discourse with Few Words: Coherence Statistics, Parent-Infant Actions on Objects, and Object Names.

The data for early object name learning is often conceptualized as a problem of mapping heard names to referents. However, infants do not hear object names as discrete events but rather in extended interactions organized around goal-directed actions on objects. The present study examined the statistical structure of the nonlinguistic events that surround parent naming of objects. Parents and 12-month -old infants were left alone in a room for 10 minutes with 32 objects available for exploration. Parent and infant handling of objects and parent naming of objects were coded. The four measured statistics were from measures used in the study of coherent discourse: (1) a frequency distribution in which actions were frequently directed to a few objects and more rarely to other objects; (2) repeated returns to the high-frequency objects over the 10-minute play period; (3) clustered repetitions, continuity, of actions on objects; and (4) structured networks of transitions among objects in play that connected all the played-with objects. Parent naming was infrequent but related to the statistics of object-directed actions. The implications of the discourse-like stream of actions are discussed in terms of learning mechanisms that could support rapid learning of object names from relatively few name-object co-occurrences.

Sampling statistics are like story creation: a network analysis of parent-toddler exploratory play.

Actions in the world elicit data for learning and do so in a stream of interconnected events. Here, we provide evidence on how toddlers with their parent sample information by acting on toys during exploratory play. We observed 10 min of free-flowing and unconstrained object exploration of by toddlers (mean age 21 months) and parents in a room with many available objects (n = 32). Borrowing concepts and measures from the study of narratives, we found that the toy selections are not a string of unrelated events but exhibit a suite of what we call coherence statistics: Zipfian distributions, burstiness and a network structure. We discuss the transient memory processes that underlie the moment-to-moment toy selections that create this coherence and the role of these statistics in the development of abstract and generalizable systems of knowledge. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

The temporal structure of parent talk to toddlers about objects.

Toddlers learn words in the context of speech from adult social partners. The present studies quantitatively describe the temporal context of parent speech to toddlers about objects in individual real-world interactions. We show that at the temporal scale of a single play episode, parent talk to toddlers about individual objects is predominantly, but not always, clustered. Clustered speech is characterized by repeated references to the same object close in time, interspersed with lulls in speech about the object. Clustered temporal speech patterns mirror temporal patterns observed at longer timescales, and persisted regardless of play context. Moreover, clustered speech about individual novel objects predicted toddlers' learning of those objects' novel names. Clustered talk may be optimal for toddlers' word learning because it exploits domain-general principles of human memory and attention, principles that may have evolved precisely because of the clustered structure of natural events important to humans, including human behavior.

Episodes of experience and generative intelligence.

How do humans, including toddlers, take knowledge from past experiences and apply this knowledge in new ways? Current approaches to human and artificial intelligence (AI) fail to offer satisfactory explanations. We suggest the explanation will be found in the coherence statistics of the individual time-extended episodes of human experience and the cognitive processes those statistics engage.

Scene saliencies in egocentric vision and their creation by parents and infants.

Across the lifespan, humans are biased to look first at what is easy to see, with a handful of well-documented visual saliences shaping our attention (e.g., Itti & Koch, 2001). These attentional biases may emerge from the contexts in which moment-tomoment attention occurs, where perceivers and their social partners actively shape bottom-up saliences, moving their bodies and objects to make targets of interest more salient. The goal of the present study was to determine the bottom-up saliences present in infant egocentric images and to provide evidence on the role that infants and their mature social partners play in highlighting targets of interest via these saliences. We examined 968 unique scenes in which an object had purposefully been placed in the infant's egocentric view, drawn from videos created by one-year-old infants wearing a head camera during toy-play with a parent. To understand which saliences mattered in these scenes, we conducted a visual search task, asking participants (n = 156) to find objects in the egocentric images. To connect this to the behaviors of perceivers, we then characterized the saliences of objects placed by infants or parents compared to objects that were otherwise present in the scenes. Our results show that body-centric properties, such as increases in the centering and visual size of the object, as well as decreases in the number of competing objects immediately surrounding it, both predicted faster search time and distinguished placed and unplaced objects. The present results suggest that the bottom-up saliences that can be readily controlled by perceivers and their social partners may most strongly impact our attention. This finding has implications for the functional role of saliences in human vision, their origin, the social structure of perceptual environments, and how the relation between bottom-up and top-down control of attention in these environments may support infant learning.

A Network Analysis of Children's Emerging Place-Value Concepts.

Examining how informal knowledge systems change after formal instruction is imperative to understanding learning processes and conceptual development and to implementing effective educational practices. We used network analyses to determine how the organization of informal knowledge about multidigit numbers in kindergartners (N = 279; mean age = 5.76 years, SD = 0.55; 135 females) supports and is transformed by a year of in-school formal instruction. The results show that in kindergarten, piecemeal knowledge about the surface properties of reading and writing multidigit numbers and the use of base-10 units to determine large quantities are strongly associated with each other and connected in a stringlike manner to other emerging skills. After a year of instruction, each skill becomes connected to the "hub" abilities of reading and writing multidigit numbers, which also become strongly connected to more advanced knowledge of base-10 principles. These findings provide new insights into how partial knowledge provides the backbone on which explicit principles are learned.

Real-world statistics at two timescales and a mechanism for infant learning of object names.

Infants begin learning the visual referents of nouns before their first birthday. Despite considerable empirical and theoretical effort, little is known about the statistics of the experiences that enable infants to break into object­name learning. We used wearable sensors to collect infant experiences of visual objects and their heard names for 40 early-learned categories. The analyzed data were from one context that occurs multiple times a day and includes objects with early-learned names: mealtime. The statistics reveal two distinct timescales of experience. At the timescale of many mealtime episodes (n = 87), the visual categories were pervasively present, but naming of the objects in each of those categories was very rare. At the timescale of single mealtime episodes, names and referents did cooccur, but each name­referent pair appeared in very few of the mealtime episodes. The statistics are consistent with incremental learning of visual categories across many episodes and the rapid learning of name­object mappings within individual episodes. The two timescales are also consistent with a known cortical learning mechanism for one-episode learning of associations: new information, the heard name, is incorporated into well-established memories, the seen object category, when the new information cooccurs with the reactivation of that slowly established memory.

The development of place value concepts: Approximation before principles.

Place value concepts were measured longitudinally from kindergarten (2017) to first grade (2018) in a diverse sample (n = 279; Mage  = 5.76 years, SD = 0.55; 135 females; 41% Black, 38% White, 8% Asian, 12% Latino). Children completed three syntactic tasks that required an explicit understanding of base-10 symbols and three approximate tasks that could be completed without this explicit understanding. Approximate performance was significantly better in both age groups. A factor analysis confirmed that syntactic and approximate tasks tapped separate latent variables in kindergarten, but not in first grade. Path analyses indicated that only kindergarten approximate performance predicted overall first-grade place value understanding. These findings suggest that explicit understanding of base-10 principles develops from implicit, partial knowledge of multidigit numbers.

The infant's view redefines the problem of referential uncertainty in early word learning.

The learning of first object names is deemed a hard problem due to the uncertainty inherent in mapping a heard name to the intended referent in a cluttered and variable world. However, human infants readily solve this problem. Despite considerable theoretical discussion, relatively little is known about the uncertainty infants face in the real world. We used head-mounted eye tracking during parent-infant toy play and quantified the uncertainty by measuring the distribution of infant attention to the potential referents when a parent named both familiar and unfamiliar toy objects. The results show that infant gaze upon hearing an object name is often directed to a single referent which is equally likely to be a wrong competitor or the intended target. This bimodal gaze distribution clarifies and redefines the uncertainty problem and constrains possible solutions.

Head and eyes: Looking behavior in 12- to 24-month-old infants.

This study demonstrates evidence for a foundational process underlying active vision in older infants during object play. Using head-mounted eye-tracking and motion capture, looks to an object are shown to be tightly linked to and synchronous with a stilled head, regardless of the duration of gaze, for infants 12 to 24 months of age. Despite being a developmental period of rapid and marked changes in motor abilities, the dynamic coordination of head stabilization and sustained gaze to a visual target is developmentally invariant during the examined age range. The findings indicate that looking with an aligned head and eyes is a fundamental property of human vision and highlights the importance of studying looking behavior in freely moving perceivers in everyday contexts, opening new questions about the role of body movement in both typical and atypical development of visual attention.

Focus on One or More? Cultural Similarities and Differences in How Parents Talk About Social Events to Preschool Children.

How parents talk about social events shapes their children's understanding of the social world and themselves. In this study, we show that parents in a society that more strongly values individualism (the United States) and one that more strongly values collectivism (Japan) differ in how they talk about negative social events, but not positive ones. An animal puppet show presented positive social events (e.g., giving a gift) and negative social events (e.g., knocking over another puppet's block tower). All shows contained two puppets, an actor and a recipient of the event. We asked parents to talk to their 3- and 4-years old children about these events. A total of 26 parent-child dyads from the United States (M = 41.92 months) and Japan (M = 42.77 months) participated. The principal dependent measure was how much parent talk referred to the actor of each type of social event. There were no cultural differences observed in positive events - both the United States and Japanese parents discussed actors more than recipients. However, there were cultural differences observed in negative events - the United States parents talked mostly about the actor but Japanese parents talked equally about the actor and the recipient of the event. The potential influences of these differences on early cognitive and social development are discussed.

What are the building blocks of parent-infant coordinated attention in free-flowing interaction?

The present article investigated the composition of different joint gaze components used to operationalize various types of coordinated attention between parents and infants and which types of coordinated attention were associated with future vocabulary size. Twenty-five 9-month-old infants and their parents wore head-mounted eye trackers as they played with objects together. With high-density gaze data, a variety of coordinated attention bout types were quantitatively measured by combining different gaze components, such as mutual gaze, joint object looks, face looks, and triadic gaze patterns. The key components of coordinated attention that were associated with vocabulary size at 12 and 15 months included the simultaneous combination of parent triadic gaze and infant object looking. The results from this article are discussed in terms of the importance of parent attentional monitoring and infant sustained attention for language development.

An open-source, wireless vest for measuring autonomic function in infants.

Infant behavior, like all behavior, is the aggregate product of many nested processes operating and interacting over multiple time scales; the result of a tangle of inter-related causes and effects. Efforts in identifying the mechanisms supporting infant behavior require the development and advancement of new technologies that can accurately and densely capture behavior's multiple branches. The present study describes an open-source, wireless autonomic vest specifically designed for use in infants 8-24 months of age in order to measure cardiac activity, respiration, and movement. The schematics of the vest, instructions for its construction, and a suite of software designed for its use are made freely available. While the use of such autonomic measures has many applications across the field of developmental psychology, the present article will present evidence for the validity of the vest in three ways: (1) by demonstrating known clinical landmarks of a heartbeat, (2) by demonstrating an infant in a period of sustained attention, a well-documented behavior in the developmental psychology literature, and (3) relating changes in accelerometer output to infant behavior.

Parents Influence the Visual Learning Environment Through Children's Manual Actions.

The present research studied children in the second year of life (N = 29, Mage  = 21.14 months, SD = 2.64 months) using experimental manipulations within and between subjects to show that responsive parental influence helps children have more frequent sustained object holds with fewer switches between objects compared to when parents are either not involved or over-involved. Regardless of parental involvement, sustained holds were visually rich, based on the size, centeredness, and dominance of the held object relative to other objects. These findings are important because they suggest not only that the child's body creates visually rich scenes across play contexts but also that a responsive parent can increase the frequency of these visually rich and informative moments.

Number Representations Drive Number-Line Estimates.

The number-line task has been extensively used to study the mental representation of numbers in children. However, studies suggest that proportional reasoning provides a better account of children's performance. Ninety 4- to 6-year-olds were given a number-line task with symbolic numbers, with clustered dot arrays that resembled a perceptual scaling task, or with spread-out dot arrays that involved numerical estimation. Children performed well with clustered dot arrays, but poorly with symbolic numbers and spread-out dot arrays. Performances with symbolic numbers and spread-out dot arrays were highly correlated and were related to counting skill; neither was true for clustered dot arrays. Overall, results provide evidence for the role of mental representation of numbers in the symbolic number-line task.