Infants’ attention is biased by emotional expressions and eye gaze direction Stefanie Hoehl a , Letizia Palumbo c , Christine Heinisch b and Tricia Striano d a Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, b Ruhr-University Bochum, Bochum, Germany, c University of Rome La Sapienza, Rome, Italy and d Hunter College, CUNY, New York City, USA Correspondence toTricia Striano, Department of Psychology, Hunter College, CUNY, 695 Park Avenue, New York, NY 10065 -5024 Tel: + 1 212 772 5678; e-mail: tstriano@hunter.cuny.edu Received 21 January 2008; accepted 22 January 2008 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 e¡ect 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. NeuroReport 19:579^582 c 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins. Keywords: emotional expressions, event-related potentials, eye gaze, infants, threat detection Introduction The communication of threat is crucial and fast processing of this information is adaptive already in infancy. Two of the most important social cues that can be used to communicate threat are facial expressions and eye gaze direction. Detection of eye gaze is a phylogenetically ancient mechan- ism [1], and primates use eye gaze, for instance to express emotional states or to attract others’ attention toward objects in the environment [2]. Human infants are sensitive to others’ eye gaze direction from birth [3]. By 3 months of age, infants use eye gaze to guide their own attention and to facilitate encoding of novel objects [4,5]. Despite growing evidence that infants use eye gaze to learn about their environment, little is known about how young infants use social cues to detect potential threat. In addition to their sensitivity for eye gaze direction, infants are also sensitive to emotional expressions in face and voice [6,7], especially in ambiguous or disturbing situations [8]. By the end of the first year, infants show social referencing, that is, they actively seek and use emotional expressions provided by others to disambiguate potentially dangerous situations and to guide their own behavior [9]. It is, however, not yet clear at what age social referencing emerges, as almost all studies in this field investigated infants’ behavioral responses from the age of 10–12 months onwards [8,9]. As infants constantly encoun- ter situations they perceive as ‘novel’, it is likely that infants’ attention system is affected by eye gaze and emotional expressions much earlier. Event-related potentials (ERPs) may be the more sensitive measure to explore this question in young infants compared with overt behavioral responses that require a sophisticated motor system. Fearful facial expressions are particularly interesting in the context of threat detection [10]. In adults, processing of fearful faces is facilitated when eye gaze is averted to the side compared with direct gaze [11]. This indicates that fearful faces with averted gaze are an indicator of threat, because the eyes might be directed at something dangerous in the environment [12]. In a recent study with infants, however, no difference in neural processing of fearful faces with direct or averted gaze was found in 7-month-olds [13]. This might be owing to the fact that faces in this study were presented in a dyadic face-to-face context, without an external referent of the adult’s eye gaze. Possibly, infants need a concrete referent of the adult’s gaze to be sensitive to the threat-related signal value of a fearful expression. We reasoned that fearful faces with gaze averted to the side and looking toward an object next to the face would elicit enhanced neural processing in 7-month-old infants relative to fearful faces with gaze directed at the infant and neutral faces. To test for this hypothesis, we conducted two experiments in which infants’ processing of fearful (experimental condition) and neutral (control condition) faces was assessed in different social contexts. In experiment 1, infants saw fearful or neutral faces gazing toward novel objects (triadic context). We hypothesized that infants’ allocation of attention would be enhanced in the fearful face condition compared with the neutral face condition, as indicated by an enhanced Nc (negative central) component. The Nc is a well-documented component in infant ERP research and its amplitude has consistently been related to attention [14]. In experiment 2, fearful and neutral faces directed eye gaze at the infant and thus averted gaze from the object (dyadic DEVELOPMENTAL NEUROSCIENCE NEUROREPORT 0959-4965 c Wolters Kluwer Health | Lippincott Williams & Wilkins Vol 19 No 5 26 March 2008 579