Increased Focus on the Mouth Among Infants in the First Year of Life: A Longitudinal Eye‐Tracking Study

Abstract

The present study examines face-scanning behaviors of infants at 6, 9, and 12 months as they watched videos of a woman describing an object in front of her. The videos were created to vary information in the mouth (speaking vs. smiling) and the eyes (gazing into the camera vs. cueing the infant with head turn or gaze direction to an object being described). Infants tended to divide their attention between the eyes and the mouth, looking less at the eyes with age and more at the mouth than the eyes at 9 and 12 months. Attention to the mouth was greater on speaking trials than on smiling trials at all three ages, and this difference increased between 6 and 9 months. Despite consistent results within subjects, there was considerable variation between subjects. This raises the question of whether a developmental “norm” of face scanning in infancy ought to be pursued. Rather, these data add to emerging evidence suggesting that individual differences in face scanning might reliably predict aspects of later development.

Asymmetry in infants' selective attention to facial features during visual processing of infant-directed speech

“…In an effort to explore potential early identifiers of autism, Merin et al (2007) found that 6-month-old infants at-risk for autism fixated more on their mothers' mouths than did infants in the low-risk control group. However, contrary to expectations, a follow up study of these same infants found that, while not predictive of autism symptoms, infants who fixated more on their mothers' mouths at 6 months showed increased expressive language scores and growth over the next 18 months (Young et al, 2009)—a result that aligns with other studies arguing that increased mouth fixations play a role in speech and language development in infancy (Lewkowicz and Hansen-Tift, 2012; Tenenbaum et al, 2013). …”

“…Although this finding corresponds to other studies showing increased interest in eyes in still images (Maurer and Salapatek, 1976) and moving faces (Haith et al, 1977), it is somewhat in contrast to more recent eye tracking studies that have found a shift in infants' visual attention from the talker's eyes to the mouth starting at 6 months of age, peaking at 10 months, with a return to the talker's eye in adults (Lewkowicz and Hansen-Tift, 2012; Tenenbaum et al, 2013). Similarly, Hunnius and Geuze (2004) found increased fixation to the mouth between 6 and 26 weeks of age, using silent video stimuli.…”

“…A number of studies have shown that over the following months, infants' attention shifts to the mouth (Hunnius and Geuze, 2004). In a variety of speech perception tasks, older infants spent more time fixated on the talker's mouth, which may reflect the increased importance of phonetic information from the talker's mouth at this period of the infant's language development (Lewkowicz and Hansen-Tift, 2012; venbruck, Gervain and Schwarzer, Kubicek et al, 2013; Tenenbaum et al, 2013). In contrast, other work has shown that infants continue to distribute fixations more to talkers' eyes and upper part of the face (Liu et al, 2011).…”

Assessing individual differences in the speed and accuracy of intersensory processing in young children: The intersensory processing efficiency protocol.

“…However, they have not yet been developed as an individual difference measure and typically rely on only a single dependent measure (duration of looking to a region of interest). Group-level studies reveal that infants look longer to the mouth (the source of audiovisual redundancy) compared to other parts of the face while a woman is speaking (Tenenbaum, Shah, Sobel, Malle, & Morgan, 2012), when infants are first learning their native language (Lewkowicz & Hansen-Tift, 2012), and when there is a mismatch between visually- and acoustically-specified syllables (Tomalski et al, 2013). This methodology holds promise for future development as an index of individual differences in intersensory processing.…”

Developmental Trajectory of Audiovisual Speech Integration in Early Infancy. A Review of Studies Using the McGurk Paradigm

“…Between the ages of 6 and 10 months, monolingual infants spend progressively more time looking at the mouth and less at the eyes of dynamic articulating faces (Hunnius & Geuze, 2004;Lewkowicz & Hansen-Tift , 2012;Tenenbaum, Shah, Sobel, Malle, & Morgan, 2013;Tomalski et al, 2013), but no such developmental patt ern was found for static faces (Wilcox, Stubbs, Wheeler, & Alexander, 2013). Th is trend then reverses around 12 months of age with a gradual increase in looking to the eyes and a decrease in looking to the mouth, but only for native AV speech (Lewkowicz & Hansen-Tift , 2012), while for non-native speech 12-month-olds continue to exhibit a preference for the mouth (Pons, Bosch, & Lewkowicz, 2015).…”