Eyes or mouth? Exploring eye gaze patterns and their relation with early stress perception in European Portuguese

Abstract

Previous research has shown that eye gaze patterns relate to language development, with more attention to the mouth signaling ongoing acquisition. We examined infants' eye gaze in a stress perception experiment, in which European Portuguese (EP) learning infants showed a preference for the iambic stress pattern. Specifically, we asked whether there was a relation between eye gaze patterns and the preferred stress pattern. Eye gaze patterns of 25 monolingual typically developing infants aged 5-6 months old were examined using eye-tracking. Our results show that, although an interaction between looks to the area of interest (face, eyes, mouth, and arm) and stress preference was not found, eye gaze to the mouth region (and to the face) was modulated by the stress pattern, with more attention to the mouth in infants that do not show an iambic preference. These findings add further support for infants' use of eye gaze in early language development. They also highlight the need for multimodal approaches for a better understanding of language development. In the particular case of the challenging topic of the acquisition of stress in European Portuguese, they provide converging evidence for an advantage of iambic stress in early development. (195 words).

Early Visual Attention Abilities and Audiovisual Speech Processing in 5–7 Month-Old Down Syndrome and Typically Developing Infants

“…We observed that the two groups demonstrated certain similarities in their looking pattern: both groups do attend less to the waving arm at this age than the face and the background, suggesting that at this age the waiving gesture is not a particular salient communicative cue. Further, when attending to the face, both groups look more at the eyes than the mouth, in line with many recent studies done at similar ages (e.g., [ 41 , 42 , 43 ]). However, we observed a striking difference between the groups: TD infants attend more to the face than to the background, whereas DS infants attend similarly (~40 percent of their looking time to the screen) to the background and the face.…”

“…In particular, the richness of the interplay between the acoustic signal, articulatory movements and facial expressions is reduced in animated characters, in comparison to a human face. Interestingly, even with the animated character, DS and TD infants attend more to the eyes than the mouth, similar to previous studies assessing attention to a human face (e.g., [ 41 , 42 , 43 ]). Moreover, we also found that DS infants differ from TD infants in how they attend to communicative cues in an animated character talking face.…”

Early Word Segmentation Behind the Mask

“…We observed that, depending on mask condition, the infants' looking patterns changed. In response to the face mask, the infants dominantly spent more time looking at the eyes, whereas, without the mask, the infants alternated between the eyes and the mouth (in line with Cruz et al, 2020 ; Pejovic et al, 2021 ; Sekiyama et al, 2021 ). This suggests that, when articulatory cues are occluded, infants do not attend to the occluded area but redirect their attention to the available visual cues, namely, those provided by the eyes.…”

“…During the 1st year of life, infants are dominantly exposed to human faces in comparison to other stimuli in their environment (Fausey et al, 2016 ; Jayaraman and Smith, 2018 ), and research has demonstrated infants' early sensitivity to visual speech (e.g., Kuhl and Meltzoff, 1984 ; Patterson and Werker, 1999 ; Lewkowicz and Hansen-Tift, 2012 ; Tomalski et al, 2013 ; Morin-Lessard et al, 2019 ; Pejovic et al, 2019 ). Such early sensitivity to visual speech has been proved important in infants' language development, namely, in language discrimination abilities (Weikum et al, 2007 ; Sebastián-Gallés et al, 2012 ), learning of phonemic contrasts (Teinonen et al, 2008 ), processing of stress (Cruz et al, 2020 ), and processing of familiar words (Weatherhead and White, 2017 ). When processing faces, infants dominantly attend to the eyes and the mouth of a speaker (e.g., Hunnius and Geuze, 2004 ).…”

“…Specifically, the authors found that infants already at 4 months of age demonstrate segmentation for words at edge position, i.e., attend more to words they previously heard at utterance edges than to unfamiliar words, whereas words previously heard at utterance-medial position were still not clearly differentiated from unfamiliar words by 10 months of age. The second reason for focusing on 7–9-month-olds was that infants at that age tend to increase their attention to the mouth (e.g., Hunnius and Geuze, 2004 ; Lewkowicz and Hansen-Tift, 2012 ; Cruz et al, 2020 ; Pejovic et al, 2021 ), the region that is occluded by a face mask. In line with earlier work, segmentation abilities will be signaled by a consistent difference between looking times to previously heard (familiar) target words and unfamiliar target words, independently of the direction of preference.…”