Sabine Hunnius

The early development of object knowledge: A study of infants’ visual anticipations during action observation.

This study examined the developing object knowledge of infants through their visual anticipation of action targets during action observation. Infants (6, 8, 12, 14, and 16 months) and adults watched short movies of a person using 3 different everyday objects. Participants were presented with objects being brought either to a correct or to an incorrect target location (e.g., cup to mouth, phone to ear vs. cup to ear, brush to mouth). When observing the action sequences, infants as well as adults showed anticipatory fixations to the target areas of the displayed actions. For all infant age-groups, there were differences in anticipation frequency between functional and nonfunctional object-target combinations. Adults exhibited no effect of object-target combination, possibly because they quickly learned and flexibly anticipated the target area of observed actions, even when they watched objects being brought to incorrect target areas. Infants, however, had difficulties anticipating to incorrect target locations for familiar objects. Together, these findings suggest that by 6 months of age, infants have acquired solid knowledge about objects and the actions associated with them.

The role of frequency information and teleological reasoning in infants' and adults' action prediction

This study investigates the contribution of frequency learning and teleological reasoning to action prediction in 9-month-old infants and adults. Participants observed how an agent repeatedly walked to a goal while taking the longer of 2 possible paths, as the shorter and more efficient path was impassable. In the subsequent test phase, both paths were passable. In the 1st test trial, infants and adults anticipated the agent to take the longer path. Unlike adults, infants kept anticipating movements to the longer path even after observing that the agent now took the more efficient path, indicating that the frequency of previous observations dominates action prediction. These results provide evidence, contrary to existing claims in the developmental literature, that frequency learning underlies action prediction in infancy, whereas teleological reasoning might gain importance later on in life.

Prelinguistic Infants Are Sensitive to Space-Pitch Associations Found Across Cultures

People often talk about musical pitch using spatial metaphors. In English, for instance, pitches can be “high” or “low” (i.e., height-pitch association), whereas in other languages, pitches are described as “thin” or “thick” (i.e., thickness-pitch association). According to results from psychophysical studies, metaphors in language can shape people’s nonlinguistic space-pitch representations. But does language establish mappings between space and pitch in the first place, or does it only modify preexisting associations? To find out, we tested 4-month-old Dutch infants’ sensitivity to height-pitch and thickness-pitch mappings using a preferential-looking paradigm. The infants looked significantly longer at cross-modally congruent stimuli for both space-pitch mappings, which indicates that infants are sensitive to these associations before language acquisition. The early presence of space-pitch mappings means that these associations do not originate from language. Instead, language builds on preexisting mappings, changing them gradually via competitive associative learning. Space-pitch mappings that are language-specific in adults develop from mappings that may be universal in infants.

Joint action modulates motor system involvement during action observation in 3-year-olds

When we are engaged in a joint action, we need to integrate our partner’s actions with our own actions. Previous research has shown that in adults the involvement of one’s own motor system is enhanced during observation of an action partner as compared to during observation of an individual actor. The aim of this study was to investigate whether similar motor system involvement is present at early stages of joint action development and whether it is related to joint action performance. In an EEG experiment with 3-year-old children, we assessed the children’s brain activity and performance during a joint game with an adult experimenter. We used a simple button-pressing game in which the two players acted in turns. Power in the mu- and beta-frequency bands was compared when children were not actively moving but observing the experimenter’s actions when (1) they were engaged in the joint action game and (2) when they were not engaged. Enhanced motor involvement during action observation as indicated by attenuated sensorimotor mu- and beta-power was found when the 3-year-olds were engaged in the joint action. This enhanced motor activation during action observation was associated with better joint action performance. The findings suggest that already in early childhood the motor system is differentially activated during action observation depending on the involvement in a joint action. This motor system involvement might play an important role for children’s joint action performance.

Online prediction of others’ actions: the contribution of the target object, action context and movement kinematics

Previous research investigated the contributions of target objects, situational context and movement kinematics to action prediction separately. The current study addresses how these three factors combine in the prediction of observed actions. Participants observed an actor whose movements were constrained by the situational context or not, and object-directed or not. After several steps, participants had to indicate how the action would continue. Experiment 1 shows that predictions were most accurate when the action was constrained and object-directed. Experiments 2A and 2B investigated whether these predictions relied more on the presence of a target object or cues in the actor’s movement kinematics. The target object was artificially moved to another location or occluded. Results suggest a crucial role for kinematics. In sum, observers predict actions based on target objects and situational constraints, and they exploit subtle movement cues of the observed actor rather than the direct visual information about target objects and context.

Variability in eating behavior throughout the weaning period.

During the introduction of solid food (usually indicated as the weaning period), infant and caregiver have to adjust their feeding interactions to a completely changed feeding context. In this paper, we argue that these adjustments can be seen as a complex process in which many factors are involved. As a result of these complex interactions, eating behavior can be highly variable between infants and from feed to feed. The aim of this study is to describe these patterns of variability across this critical transition in feeding. The study is based on naturalistic observations of 20 infant-caregiver dyads (15 repeated observations of each dyad), from the first attempt to spoon-feed till 12 weeks after the introduction of solid food. The results show that there is considerable short-term variability in eating behavior (food intake, meal duration, feeding efficiency, and food refusal), especially immediately after the introduction of solid food. The largest intra-individual variability was found in the earliest feeding sessions, which is consistent with the proposition that systems that undergo rapid development are most sensitive to context variables and thus most variable.

The early development of visual attention and its implications for social and cognitive development

Looking behavior plays a crucial role in the daily life of an infant and forms the basis for cognitive and social development. The infants visual attentional systems undergo rapid development during the first few months of life. During the last decennia, the study of visual attentional development in infants has received increasing interest. Several reliable measures to investigate the early development of attentional processes have been developed, and currently a number of new methods are giving fresh impetus to the field. Research on overt and covert as well as exogenously and endogenously controlled attention shifts is presented. The development of gaze shifts to peripheral targets, covert attention, and visual scanning behavior is treated. Whereas most attentional mechanisms in very young infants are thought to be mediated mainly by subcortical structures, cortical mechanisms become increasingly more functional throughout the first months. Different accounts of the neurophysiological underpinnings of attentional processes and their developmental changes are discussed. Finally, a number of studies investigating the implications of attentional development for early cognitive and social development are presented.

Higher-order action planning for individual and joint object manipulations

Many actions involve multiple action steps, which raises the question how far ahead people plan when they perform such actions. Here, we examined higher-order planning for action sequences and whether people planned similarly or differently when acting individually or together with an action partner. For individual performances, participants picked up an object with one hand and passed it to their other hand before placing it onto a target location. For joint performances, they picked up the object and handed it to their action partner, who placed it onto the target location. Each object could be grasped at only two possible grasping positions, implying that the first selected grasp on the object determined the postures for the rest of the action sequence. By varying the height of the target shelf, we tested whether people planned ahead and modulated their grasp choices to avoid uncomfortable end postures. Our results indicated that participants engaged in higher-order planning, but needed task experience before demonstrating such planning during both individual and joint performances. The rate of learning was similar in the two conditions, and participants transferred experience from individual to joint performance. Our results indicate similarity in mechanisms underlying individual and joint action sequence planning.

Joint action coordination in 2½- and 3-year-old children.

When acting jointly with others, adults can be as proficient as when acting individually. However, how young children coordinate their actions with another person and how their action coordination develops during early childhood is not well understood. By means of a sequential button-pressing game, which could be played jointly or individually, the action coordination of 2½- and 3-year-old children was examined. Performance accuracy and variability of response timing were taken as indicators of coordination ability. Results showed substantial improvement in joint action coordination between the age of 2½ and 3, but both age groups performed equally well when acting individually. Interestingly, 3-year-olds performed equally well in the joint and the individual condition, whereas 2½-year-olds did not yet show this adult-like pattern as indicated by less accurate performance in the joint action. The findings suggest that in contrast to 3-year-olds, 2½-year-olds still have difficulties in establishing well-coordinated joint action with an adult partner. Possible underlying cognitive abilities such as action planning and action control are discussed.

The dynamics of feeding during the introduction to solid food

In the first year of life, infants go through a crucial transition in feeding when they are introduced to solid food. However, the literature is lacking a good description of the changes in feeding behaviors during this transition. The current paper addresses this by means of a multiple case study focusing on how caretaker and infant build a new and effective feeding dialogue after the transition to solid food. It describes the development of stable interaction patterns, as they emerge during this transition. Feeding interactions are studied directly through repeated naturalistic observations. The results show that while the interaction behavior of some caretaker-infant dyads remains variable, others stabilize quickly. However, ultimately most dyads self-organize their behaviors towards a stable feeding dialogue, which is both sensitive and effective. Evidence for the existence of four characteristic patterns was found. We argue that this finding can be interpreted as the result of a co-regulation process of consensual frames. The study also offers a framework for analyzing other processes of co-regulation that occur throughout human development.