Tasks and Results

Previous studies found that infants' brain response differs when they see familiar vs unfamiliar faces on a screen and that this difference is changing over the course of the first year of life. Here we present a whole range of faces resembling more mum's or a stranger's face to the child, to find out which of the faces elicits the strongest attention in the infant brain, whether this differs between younger and older infants, and how this relates to how they approach other tasks, how they engage in play and to their behaviour in daily life. This study uses EEG.

The study. Previous group studies found that infants' brain response differs when they look at a person engaging with them compared to a spinning toy. Here, we use EEG to study how the brain response is mapped onto a range of behaviours varying in the communicative cues they carry, which of these behaviours elicit the strongest response in the infant's social brain networks, and how this relates to how they approach other tasks, how they engage in play and to their behaviour in daily life. During the experiment, we computed a target brain signal that previously was indicated to signal infant attention, and the software aimed to predict the stimulus that maximally triggers this target brain signal. This study included infants aged 6-12 months.

The results. We expected infants to show the strongest target signal towards behaviours that we considered highly infant-directed (direct gaze combined with infant-directed speech). We found that infants did not have a group-level overall preference towards any specific kind of our stimuli. We also found that this is not due to a lack of preference, but due to heterogeneous individual preferences. Finally, which kind of stimulus maximised the target brain signal seemed to systematically vary between infants: it showed to be related to parent-reported behaviour in social situations and parental affect. In specific, infants with already more advanced skills in social relationships were more likely to show strongest attention during non-speech behaviours with averted gaze. Possibly, this kind of behaviour could have been interpreted by the infant as representing a joint attention (JA) situation, i.e. a situation in which they interpret that they are attending to the same object together with an interaction partner, a skill typically evolving around the 9th month of age. Possibly infants who already started acquiring this skill were more attentive to the those behaviours than the other infants. Further, infants of parents who experienced lower positive affect were more likely to show strongest attention during behaviours combining speech and averted gaze as well as behaviours combining non-speech and direct gaze compared to behaviours combining speech and direct gaze. This finding might be in line with the idea of a mutually reinforcing mechanism in early parent-child interaction. Our main take-home message is that individual differences seem to play a role in which aspect of live social interaction infants experience as most attention-capturing. Last but not least, this study showed that the novel experimental approach (which requires clean and robust data) can be successfully used even in a naturalistic context in which infants typically move around more freely (and thus produce more artefacts in the data).

The full article can be found here.

Previous group studies found that infants' brain response differs when they look at faces with contrary facial expressions and gaze directions. Here we use EEG to investigate which facial expressions and gaze direction in mum's face shown on the screen elicits the strongest attentional response in the infant brain, and to see how that varies across the different expressions and gaze directions in relation to how they engage during play and how they approach other tasks.