Coregistration of EEG and eye-tracking in infants and developing populations

Infants cannot be instructed where to look; therefore, infant researchers rely on observation of their participant's gaze to make inferences about their cognitive processes. They therefore started studying infant attention in the real world from early on. Developmental researchers were early adopters of methods combining observations of gaze and behaviour with electroencephalography (EEG) to study attention and other cognitive functions. However, the direct combination of eye-tracking methods and EEG to test infants is still rare, as it includes specific challenges. The current article reviews the development of co-registration research in infancy. It points out specific challenges of co-registration in infant research and suggests ways to overcome them. It ends with recommendations for implementing the co-registration of EEG and eye-tracking in infant research to maximise the benefits of the two measures and their combination and to orient on Open Science principles while doing so. In summary, this work shows that the co-registration of EEG and eye-tracking in infant research can be beneficial to studying natural and real-world behaviour despite its challenges.

Visual competition attenuates emotion effects during overt attention shifts

Numerous different objects are simultaneously visible in a person's visual field, competing for attention. This competition has been shown to affect eye-movements and early neural responses toward stimuli, while the role of a stimulus' emotional meaning for mechanisms of overt attention shifts under competition is unclear. The current study combined EEG and eye-tracking to investigate effects of competition and emotional content on overt shifts of attention to human face stimuli. Competition prolonged the latency of the P1 component and of saccades, while faces showing emotional expressions elicited an early posterior negativity (EPN). Remarkably, the emotion-related modulation of the EPN was attenuated when two stimuli were competing for attention compared to non-competition. In contrast, no interaction effects of emotional expression and competition were observed on other event-related potentials. This finding indicates that competition can decelerate attention shifts in general and also diminish the emotion-driven attention capture, measured through the smaller effects of emotional expression on EPN amplitude. Reduction of the brain's responsiveness to emotional content in the presence of distractors contradicts models that postulate fully automatic processing of emotions.

Testing predictions of a neural process model of visual attention in infancy across competitive and non-competitive contexts

A key question in early development is how changes in neural systems give rise to changes in infants' behavior. We examine this question by testing predictions of a dynamic field (DF) model of infant spatial attention. We tested 5‐, 7‐, and 10‐month‐old infants in the Infant Orienting With Attention (IOWA) task containing the original non‐competitive cue conditions (when a central stimulus disappeared before a cue onset) and new competitive cue conditions (when a central stimulus remained visible throughout the trial). This allowed testing of five model predictions: (1) that orienting accuracy would be higher and (2) reaction times would be slower for all competitive conditions; (3) that all infants would be slower to orient in the competitive conditions, though (4) older infants would show the strongest competition costs; and (5) that reaction times would be particularly slow for un‐cued competitive conditions. Four of these five predictions were supported, and the remaining prediction was supported in part. We next examined fits of the model to the expanded task. New simulation results reveal close fits to the present findings after parameter modification. Critically, developmental parameters of the model were not altered, providing support for the DF model's account of neuro‐developmental change.

Emotional content influences eye-movements under natural but not under instructed conditions

ABSTRACTIn everyday life, people can freely decide if and where they would like to move their attention and gaze, often influenced by physical and emotional salience of stimuli. However, many laboratory paradigms explicitly instruct participants when and how to move their eyes, leading to unnatural instructed eye-movements. The current preregistered study compared eye-movements to peripherally appearing faces with happy, angry and neutral expressions under natural and instructed conditions. Participants reliably moved their eyes towards peripheral faces, even when they were not instructed to do so; however, eye-movements were significantly slower under natural than under instructed conditions. Competing central stimuli decelerated eye-movements independently of instructions. Unexpectedly, the emotional salience only affected eye-movements under natural conditions, with faster saccades towards emotional than towards neutral faces. No effects of emotional expression occurred when participants were instructed to move their eyes. The study shows that natural eye-movements significantly differ from instructed eye-movements and emotion-driven attention effects are reduced when participants are artificially instructed to move their eyes, suggesting that research should investigate eye-movements under natural conditions.

Overt and covert attention shifts to emotional faces: Combining EEG, eye tracking, and a go/no-go paradigm

In everyday life, faces with emotional expressions quickly attract attention and eye movements. To study the neural mechanisms of such emotion-driven attention by means of event-related brain potentials (ERPs), tasks that employ covert shifts of attention are commonly used, in which participants need to inhibit natural eye movements towards stimuli. It remains, however, unclear how shifts of attention to emotional faces with and without eye movements differ from each other. The current preregistered study aimed to investigate neural differences between covert and overt emotion-driven attention. We combined eye tracking with measurements of ERPs to compare shifts of attention to faces with happy, angry, or neutral expressions when eye movements were either executed (go conditions) or withheld (no-go conditions). Happy and angry faces led to larger EPN amplitudes, shorter latencies of the P1 component, and faster saccades, suggesting that emotional expressions significantly affected shifts of attention. Several ERPs (N170, EPN, LPC) were augmented in amplitude when attention was shifted with an eye movement, indicating an enhanced neural processing of faces if eye movements had to be executed together with a reallocation of attention. However, the modulation of ERPs by facial expressions did not differ between the go and no-go conditions, suggesting that emotional content enhances both covert and overt shifts of attention. In summary, our results indicate that overt and covert attention shifts differ but are comparably affected by emotional content.