Stefanie Hoehl

The perception of biological motion by infants: An event-related potential study

The current study investigates how human infants process and interpret human movement. Neural correlates to the perception of biological motion by 8-month-old infants were assessed. Analysis of event-related potentials (ERPs) resulting from the passive viewing of upright and inverted point-light displays (PLDs) depicting human movement indicated a larger positive amplitude in right parietal regions between 200 and 300 ms for observing upright PLDs when compared with observing inverted PLDs. These results show that infants at 8 months of age process upright and inverted PLDs differently from each other. The implications for our understanding of infant visual perception are discussed.

Looking at Eye Gaze Processing and Its Neural Correlates in Infancy--Implications for Social Development and Autism Spectrum Disorder.

The importance of eye gaze as a means of communication is indisputable. However, there is debate about whether there is a dedicated neural module, which functions as an eye gaze detector and when infants are able to use eye gaze cues in a referential way. The application of neuroscience methodologies to developmental psychology has provided new insights into early social cognitive development. This review integrates findings on the development of eye gaze processing with research on the neural mechanisms underlying infant and adult social cognition. This research shows how a cognitive neuroscience approach can improve our understanding of social development and autism spectrum disorder.

What are you looking at? Infants’ neural processing of an adult's object‐directed eye gaze

Previous research suggests that by 4 months of age infants use the eye gaze of adults to guide their attention and facilitate processing of environmental information. Here we address the question of how infants process the relation between another person and an external object. We applied an ERP paradigm to investigate the neural processes underlying the perception of the direction of an adults eye gaze in 4-month-old infants. Infants showed differential processing of an adults eye gaze, which was directed at a simultaneously presented object compared to non-object-directed eye gaze. This distinction was evident in two ERP components: The Negative component, reflecting attentional processes, and the positive slow wave, which is involved in memory encoding. The implications of these findings for the development of joint attention and related social cognitive functions are discussed.

The neural correlates of infant and adult goal prediction: evidence for semantic processing systems.

The sequential nature of action ensures that an individual can anticipate the conclusion of an observed action via the use of semantic rules. The semantic processing of language and action has been linked to the N400 component of the event-related potential (ERP). The authors developed an ERP paradigm in which infants and adults observed simple sequences of actions. In one condition the conclusion of the sequence was anticipated, whereas in the other condition the conclusion was not anticipated. Adults and infants at 9 months and 7 months were assessed via the same neural mechanisms-the N400 component and analysis of the theta frequency. Results indicated that adults and infants at 9 months produced N400-like responses when anticipating action conclusions. The infants at 7 months displayed no N400 component. Analysis of the theta frequency provided support for the relation between the N400 and semantic processing. This study suggests that infants at 9 months anticipate goals and use similar cognitive mechanisms to adults in this task. In addition, this result suggests that language processing may derive from understanding action in early development.

Recording Infant ERP Data for Cognitive Research

Researchers from different backgrounds have an increasing interest in investigating infant cognitive development using electroencephalogram (EEG) recordings. Although EEG measurements are suitable for infants, the method poses several challenges including setting up an infant-friendly, but interference-free lab environment and designing age-appropriate stimuli and paradigms. Certain specifics of infant EEG data have to be considered when deriving event-related potentials (ERPs) to investigate cognitive processes in the developing brain. The present article summarizes the practical aspects of conducting ERP research with infants and describes how researchers typically deal with the specific challenges entailed in this work.

The early development of face processing — What makes faces special?

In the present article we review behavioral and neurophysiological studies on face processing in adults and in early development. From the existing empirical and theoretical literature we derive three aspects that distinguish face processing from the processing of other visual object categories. Each of these aspects is discussed from a developmental perspective. First, faces are recognized and represented at the individual level rather than at the basic level. Second, humans typically acquire extensive expertise in individuating faces from early on in development. And third, more than other objects, faces are processed holistically. There is a quantitative difference in the amount of visual experience for faces and other object categories in that the amount of expertise typically acquired for faces is greater than that for other object categories. In addition, we discuss possible qualitative differences in experience for faces and objects. For instance, there is evidence for a sensitive period in infancy for building up a holistic face representation and for perceptual narrowing for faces of one’s own species and race. We conclude our literature review with questions for future research, for instance, regarding the exact relationship between behavioral and neuronal markers of face processing across development.

Children's processing of emotions expressed by peers and adults: An fMRI study

The recognition of emotional expressions is an important skill and relates to social functioning and adjustment in childhood. The current functional MRI study investigated the neural processing of angry and happy facial expressions in 5- to 6-year-old children and in adults. Participants were presented happy and angry faces of adults and children while they performed a non-emotion-related task with low cognitive load. Very similar neural networks were involved in the processing of angry and happy faces in adults and children, including the amygdala and prefrontal areas. In general, children showed heightened amygdala activation in response to emotional faces relative to adults. While children showed stronger amygdala activation in response to angry adult compared to angry child faces, adults showed stronger amygdala activation for angry child faces. In both age groups enhanced amygdala involvement was found for happy peer faces relative to happy non-peer faces, though this effect was only a tendency in adults. The findings are discussed in the context of the development of the social brain network.

The role of social interaction and pedagogical cues for eliciting and reducing overimitation in preschoolers

The tendency to imitate causally irrelevant actions is termed overimitation. Here we investigated (a) whether communication of a model performing irrelevant actions is necessary to elicit overimitation in preschoolers and (b) whether communication of another model performing an efficient action modulates the subsequent reduction of overimitation. In the study, 5-year-olds imitated irrelevant actions both when they were modeled by a communicative and pedagogical experimenter and when they were modeled by a non-communicative and non-pedagogical experimenter. However, children stopped using the previously learned irrelevant actions only when they were subsequently shown the more efficient way to achieve the goal by a pedagogical experimenter. Thus, communication leads preschoolers to adapt their imitative behavior but does not seem to affect overimitation in the first place. Results are discussed with regard to the importance of communication for the transmission of cultural knowledge during development.

Three-month-olds' brain responses to upright and inverted faces and cars.

We examined the processing of upright and inverted faces and cars in 3-month-old infants applying an event-related-potentials paradigm. The current study is the first to contrast human faces with an object category, cars, in a within-subjects design with infants. N290 amplitude was larger for inverted than upright faces, whereas no inversion effect was observed for cars. Moreover, N290 latency was enhanced for inverted faces and cars. This indicates that neural processing may already be partly face-specific in young infants.

Eye contact and emotional face processing in 6-month-old infants: Advanced statistical methods applied to event-related potentials

Event-related potential (ERP) studies with infants are often limited by a small number of measurements. We introduce a weighted general linear mixed model analysis with a time-varying covariate, which allows for the efficient analysis of all available event-related potential data of infants. This method allows controlling the signal to noise ratio effect on averaged ERP estimates due to small and varying numbers of trials. The method enables analyzing ERP data sets of infants, which would often not be possible otherwise. We illustrate this method by analyzing an experimental study and discuss the advantages in comparison to currently used methods as well as its potential limitations. In this study, 6-month-old infants saw a face showing a neutral or an angry expression in combination with direct or averted eye gaze. We examined how the infant brain processes facial expressions and whether the direction of eye gaze has an influence on it. We focused on the infant Negative Central ERP component (Nc). The neutral expression elicited larger amplitude and peaked earlier than the angry expression. An interaction between emotion and gaze was found for Nc latency, suggesting that emotions are processed in combination with eye gaze in infancy.