A Statistical Physics Perspective to Understand Social Visual Attention in Autism Spectrum Disorder.

This study investigated social visual attention in children with Autism Spectrum Disorder (ASD) and with typical development (TD) in the light of Brockmann and Geisel's model of visual attention. The probability distribution of gaze movements and clustering of gaze points, registered with eye-tracking technology, was studied during a free visual exploration of a gaze stimulus. A data-driven analysis of the distribution of eye movements was chosen to overcome any possible methodological problems related to the subjective expectations of the experimenters about the informative contents of the image in addition to a computational model to simulate group differences. Analysis of the eye-tracking data indicated that the scanpaths of children with TD and ASD were characterized by eye movements geometrically equivalent to Lévy flights. Children with ASD showed a higher frequency of long saccadic amplitudes compared with controls. A clustering analysis revealed a greater dispersion of eye movements for these children. Modeling of the results indicated higher values of the model parameter modulating the dispersion of eye movements for children with ASD. Together, the experimental results and the model point to a greater dispersion of gaze points in ASD.

Theta- and alpha-band EEG activity in response to eye gaze cues in early infancy.

In order to elucidate the development of how infants use eye gaze as a referential cue, we investigated theta and alpha oscillations in response to object-directed and object-averted eye gaze in infants aged 2, 4, 5, and 9months. At 2months of age, no difference between conditions was found. In 4- and 9-month-olds, alpha-band activity desynchronized more in response to faces looking at objects compared to faces looking away from objects. Theta activity in 5-month-old infants differed between conditions with more theta synchronization for object-averted eye gaze. Whereas alpha desynchronization might reflect mechanisms of early social object learning, theta is proposed to imply activity in the executive attention network. The interplay between alpha and theta activity represents developmental changes in both kinds of processes during early infancy.

Infant and maternal sensitivity to interpersonal timing.

A perturbation paradigm was employed to assess 3- and 6-month-old infants' and their mothers' sensitivity to a 3-s temporal delay implemented in an ongoing televised interaction. At both ages, the temporal delay affected infant but not maternal behavior and only when implementing the temporal delay in maternal (Experiment 1, N=64) but not infant (Experiment 2, N=60) behavior. In addition, the experimental manipulation influenced promptness of maternal smiling responses reliably more than promptness of infant smiling responses. The findings suggest that the timing of maternal behavior plays an important role in infants' perception of maternal responsiveness, whereas mothers seem to monitor general aspects of infant behavior such as overall level of engagement.

The development of emotional face and eye gaze processing.

Recent research has demonstrated that infants' attention towards novel objects is affected by an adult's emotional expression and eye gaze toward the object. The current event-related potential (ERP) study investigated how infants at 3, 6, and 9 months of age process fearful compared to neutral faces looking toward objects or averting gaze away from objects. Furthermore, we examined how the processing of novel objects is affected by gaze direction and emotional expression. We hypothesized that an adult's fearful expression should be particularly salient when it is directed toward a referent in the environment. Furthermore, responses to objects should be increased if the face previously expressed fear toward the object. Three-month-olds did not show differential neural responses to fearful vs. neutral faces regardless of gaze direction. Six-month-olds showed an enhanced negative central (Nc) component for fearful relative to neutral faces looking toward objects, but not when eye gaze was averted away from the objects. Furthermore, 6-month-olds showed an enhanced Nc for objects that had been gaze-cued by a fearful compared to a neutral face. Nine-month-olds showed an enhanced Nc for fearful relative to neutral faces in both eye gaze conditions and showed an enhanced Nc for objects that had been gaze-cued by a neutral face. The findings are discussed in the context of social cognitive and brain 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.

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.

Infants' attention is biased by emotional expressions and eye gaze direction.

This study investigates infants' processing of emotional expressions in combination with referential eye gaze cues. In experiment 1, 7-month-old infants' neural responses to fearful and neutral faces, which were looking at a novel object, were assessed. Infants' attention, as indexed by the negative central component of the event-related potential, was enhanced when the adult gazed at the object with a fearful expression compared with a neutral expression. In experiment 2, no effect of emotion on amplitude of the negative central was found when the face directed eye gaze at the infant and away from the object. We conclude that by 7 months, infants use emotional expressions in triadic person-object-person contexts to detect threat in the environment.

N400 involvement in the processing of action sequences.

Understanding others' sequences of action is a fundamental aspect of human movement and is the key to detecting goal directed behavior and intentional actions. Human action contains semantic information whereby logical chains of events are entirely dependent on the sequence in which they are performed. The sequential nature of action ensures that an observing individual anticipates the conclusion of a viewed action. This experiment reports on the results of 15 participants who viewed videos of an actress performing actions. Half the stimuli contained an anticipated conclusion to the action whereas half did not. Results from the passive viewing of stimuli depicting eating actions indicated an increased N400 response over frontal, central and parietal regions when viewing the unanticipated conclusions of the actions as compared with the amplitude for the anticipated condition. These results show that (1) neural systems exist to rapidly discern semantic information in actions, and (2) the N400 component, which predicts semantic information in language, also anticipates information within goal directed action.

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 adult's eye gaze in 4-month-old infants. Infants showed differential processing of an adult's 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.

Neural processing of eye gaze and threat-related emotional facial expressions in infancy.

Combined with emotional expressions, eye gaze can provide essential information to indicate threat in the environment. The current study assessed the effects of eye gaze direction on infants' neural processing of fearful and angry faces. Event-related potentials were recorded from thirteen 7-month-old infants. Two face-sensitive posterior components, the N290 and P400, as well as a frontocentral negative component (Nc), indicating attentional arousal, were sensitive to eye gaze direction and emotion. A larger Nc was observed for angry faces with direct compared to averted eye gaze. Fearful faces elicited a larger N290 than angry faces, whereas angry faces elicited a more prominent P400 regardless of eye gaze direction. The findings are discussed in terms of early social cognitive and neural development.

Social cognition in the first year.

Although the study of infancy has answered many important questions about the human capacity for social cognition, the relatively young field of developmental social cognition is far from reaching its adulthood. With the merging of developmental, behavioral and neurocognitive sciences, some growing pains are in store. New work demonstrates that research into early social cognitive development must integrate various research fields and methods in order to achieve a more robust understanding of the nature and parameters of human social cognition.

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.

Impaired representational gaze following in children with autism spectrum disorder.

Using eye-tracking methodology, we compared spontaneous gaze following in young children with Autism Spectrum Disorder (mean age 5.8 years) to that of typically developing children (mean age 5.7 years). Participants saw videos in which the position of a hidden object was either perceptually visible or was only represented in another person's mind. The findings indicate that children with Autism Spectrum Disorder were significantly less accurate in gaze following and observed the attended object for less time than typically developing children only in the Representational Condition. These results show that children with Autism Spectrum Disorder are responsive to gaze as a perceptual cue although they ignore its representational meaning.

Infants' electric brain responses to emotional prosody.

In the current study, we examined 7-month-old infants' processing of emotional prosody using event-related brain potentials. Infants heard semantically neutral words that were spoken with either a happy, angry, or neutral voice. The event-related brain potential data revealed that angry prosody elicited a more negative response in infants' event-related potentials than did happy or neutral prosody, suggesting greater allocation of attention to angry prosody. A positive slow wave was elicited by angry and happy prosody over temporal electrode sites. This indicates an enhanced sensory processing of the emotionally loaded stimuli (happy and angry). The current findings demonstrate that very early in development, the human brain detects emotionally loaded words and shows differential attentional responses depending on their emotional valence.

Sex differences in the preattentive processing of vocal emotional expressions.

Emotional tone of voice indicates the significance of a spoken utterance. We asked whether listeners recognize this significance even when attending to something else and whether men and women differ in this regard. To answer these questions, we presented emotionally or neutrally spoken syllables as standards and deviants in a mismatch negativity paradigm. Independent of the listeners' sex, deviants elicited a mismatch negativity in the scalp-recorded event-related potential as an indicator of preattentive acoustic change detection. Only women, however, showed a larger mismatch negativity to emotional than to neutral deviants. Thus, even though both sexes detect change in voice preattentively, only women recruit additional processing resources when the change in voice is one of emotional valence.

Social-cognitive skills between 5 and 10 months of age.

Joint attention skills are an important part of human cultural learning. However, little is known about the emergence and meaning of these skills in early ontogeny. The development of, and relation among, various joint attention skills was assessed. Seventy-two 5 to 10-month-old infants were tested on a variety of joint attention tasks. Intercorrelations among these tasks were sparse, which puts into question the meaning of these various skills. In addition, the majority of infants exhibited some joint attention skill before 9 months of age, which points to a more gradual development of joint attention skills than suggested by previous research.

Eye gaze cueing facilitates neural processing of objects in 4-month-old infants.

A major issue in developmental science is how infants use the direction of other's eye gaze to facilitate the processing of information. Four-month-old infants passively viewed images of an adult face gazing toward or away from objects. When presented with the objects a second time, infants showed differences in a slow wave event-related potential, indicating that uncued objects were perceived as less familiar than objects previously cued by the direction of gaze of another person. This result shows that the direction of eye gaze of another cannot only bias infant attention, but also lead to enhanced information processing of the objects concerned.

Young children know that trying is not pretending: a test of the "behaving-as-if" construal of children's early concept of pretense.

In 3 studies, young children were tested for their understanding of pretend actions. In Studies 1 and 2, pairs of superficially similar behaviors were presented to 26- and 36-month-old children in an imitation game. In one case the behavior was marked as trying (signs of effort), and in the other case as pretending (signs of playfulness). Three-year-olds, and to some degree 2-year-olds, performed the real action themselves (or tried to really perform it) after the trying model, whereas after the pretense model, they only pretended. Study 3 ruled out a simple mimicking explanation by showing that children not only imitated differentially but responded differentially with appropriate productive pretending to pretense models and with appropriate productive tool use to trying models. The findings of the 3 studies demonstrate that by 2 to 3 years of age, children have a concept of pretense as a specific type of intentional activity.

Emergence of Selective Social Referencing in Infancy.

Seven and 10-month-old infants were presented with a remote-controlled toy dog that intermittently barked at 30-sec intervals as they faced an experimenter who either attended to them (look toward condition) or looked away (look away condition). Seven-month-old infants' looking toward the experimenter was significantly greater after the dog barking events compared to before regardless of experimental condition. In contrast, 10-month-old infants' looks were significantly greater after the barking events compared to before only when the experimenter was attending to them. These results suggest that by 10 months infants monitor and refer to people in an ambiguous situation depending on their attention toward them. This development is viewed as indexing the emergence of an intentional stance in social referencing by 10 months of age.

Eye contact during live social interaction modulates infants' oscillatory brain activity.

We examined infants' oscillatory brain activity during a live interaction with an adult who showed them novel objects. Activation in the alpha frequency range was assessed. Nine-month-old infants responded with desynchronization of alpha-band activity when looking at an object together with an adult during a social interaction involving eye contact. When infant and experimenter only looked at the object without engaging in eye contact, no such effect was observed. Results are interpreted in terms of activation of a generic semantic knowledge system induced by eye contact during a social interaction.