Publications of Hoehl, Stefanie

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.

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.

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.