Abstract
The COVID-19 pandemic drastically changed face-to-face interactions, as face masks cover facial zones and affect face perception. Preterm birth is associated with altered face perception, which is important in socio-cognitive development. Use of face masks in neonatal units could further impede face perception development. We assessed the impact of face masks on face perception, in preterm (23–30 weeks gestation at birth, n = 24) and term infants (n = 24) at 6 months’ post-term age, using functional near-infrared spectroscopy (fNIRS). The infants viewed alternating 5-s trials with images of full or masked happy faces, interspersed with 9-15 s baseline trials. Changes in oxy- and deoxy-haemoglobin concentration (ΔHbO and ΔHbR, µM), were measured using multichannel fNIRS covering inferior-frontal, temporo-parietal, and lateral occipital regions. Term infants showed higher ΔHbO than preterm infants for full faces in the right inferior-frontal region. The ΔHbO was higher for full than masked faces in the right temporo-parietal region for term infants, but not preterm infants. These findings reveal lower brain activation in preterm compared to term infants in the inferior-frontal region which is important for face and emotion processing. Preterm infants also show no differential brain response between full vs masked faces, reflecting altered face perception at 6 months’ post-term age.
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The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to ethical restrictions.
References
Ohuma, E. O. et al. National, regional, and global estimates of preterm birth in 2020, with trends from 2010: A systematic analysis. Lancet 402(10409), 1261–1271 (2023).
Zmyj, N., Witt, S., Weitkamper, A., Neumann, H. & Lucke, T. Social cognition in children born preterm: A perspective on future research directions. Front. Psychol. 8, 455 (2017).
Hornman, J., de Winter, A. F., Kerstjens, J. M., Bos, A. F. & Reijneveld, S. A. Emotional and behavioral problems of preterm and full-term children at school entry. Pediatrics https://doi.org/10.1542/peds.2015-2255 (2016).
Fischi-Gomez, E. et al. Structural brain connectivity in school-age preterm infants provides evidence for impaired networks relevant for higher order cognitive skills and social cognition. Cereb. Cortex. 25(9), 2793–2805 (2015).
Elsabbagh, M. et al. Infant neural sensitivity to dynamic eye gaze is associated with later emerging autism. Curr. Biol. 22(4), 338–342 (2012).
Telford, E. J. et al. Preterm birth is associated with atypical social orienting in infancy detected using eye tracking. J Child Psychol Psychiatry. 57(7), 861–868 (2016).
Bora, E. & Pantelis, C. Meta-analysis of social cognition in attention-deficit/hyperactivity disorder (ADHD): Comparison with healthy controls and autistic spectrum disorder. Psychol. Med. 46(4), 699–716 (2016).
Frith, C. Role of facial expressions in social interactions. Philos. Trans. R. Soc. Lond. B Biol. Sci. 364(1535), 3453–3458 (2009).
Carnevali, L., Gui, A., Jones, E. J. H. & Farroni, T. Face processing in early development: A systematic review of behavioral studies and considerations in times of COVID-19 pandemic. Front. Psychol. 13, 778247 (2022).
Sato, J. et al. Altered functional connectivity during face processing in children born with very low birth weight. Soc. Cogn. Affect Neurosci. 16(11), 1182–1190 (2021).
Reid, V. M. et al. The human fetus preferentially engages with face-like visual stimuli. Curr. Biol. 28(5), 824 (2018).
Johnson, M. H., Dziurawiec, S., Ellis, H. & Morton, J. Newborns’ preferential tracking of face-like stimuli and its subsequent decline. Cognition 40(1–2), 1–19 (1991).
Wang, Q. et al. A review of functional near-infrared spectroscopy studies of motor and cognitive function in preterm infants. Neurosci Bull. 36(3), 321–329 (2020).
Johnson, M. H. Subcortical face processing. Nat. Rev. Neurosci. 6(10), 766–774 (2005).
Nelson, C. A. The development and neural bases of face recognition. Infant Child Dev. 10(1‐2), 3–18 (2001).
Simion, F. & Giorgio, E. D. Face perception and processing in early infancy: Inborn predispositions and developmental changes. Front. Psychol. 6, 969 (2015).
Di Lorenzo, R. et al. Brain responses to faces and facial expressions in 5-month-olds: An fNIRS study. Front. Psychol. 10, 1240 (2019).
Abutalebi, J. et al. On the brain struggles to recognize basic facial emotions with face masks: an fMRI study. Front. Psychol. 15, 1339592 (2024).
Lloyd-Fox, S. et al. Cortical responses before 6 months of life associate with later autism. Eur. J. Neurosci. 47(6), 736–749 (2018).
Braukmann, R. et al. Diminished socially selective neural processing in 5-month-old infants at high familial risk of autism. Eur. J. Neurosci. 47(6), 720–728 (2018).
Blanco, B. et al. Cortical responses to social stimuli in infants at elevated likelihood of ASD and/or ADHD: A prospective cross-condition fNIRS study. Cortex 169, 18–34 (2023).
Lloyd-Fox, S. et al. Reduced neural sensitivity to social stimuli in infants at risk for autism. Proc. Biol. Sci. 280(1758), 20123026 (2013).
Pereira, S. A. et al. A comparison between preterm and full-term infants’ preference for faces. J Pediatr (Rio J.). 93(1), 35–39 (2017).
Frie, J., Padilla, N., Aden, U., Lagercrantz, H. & Bartocci, M. Extremely preterm-born infants demonstrate different facial recognition processes at 6-10 months of corrected age. J. Pediatr. 172, 96-102 e1 (2016).
Dean, B. et al. Eye-tracking for longitudinal assessment of social cognition in children born preterm. J Child Psychol Psychiatry. 62(4), 470–480 (2021).
Yamanaka, N., Kanazawa, S. & Yamaguchi, M. K. Infants’ brain activity to cartoon face using functional near-infrared spectroscopy. PLoS ONE 17(2), e0262679 (2022).
Capelli, E. et al. Exploring the impact of parents’ face-mask wearing on dyadic interactions in infants at higher likelihood for autism compared with general population. J. Exp. Child Psychol. 247, 106037 (2024).
Pezzotti, E. et al. Masked or not, I smile to you: Exploring full-term and preterm infants’ social smiles to adults wearing a protective facemask. Infant Behav. Dev. 75, 101947 (2024).
Kammermeier, M. & Paulus, M. Infants’ responses to masked and unmasked smiling faces: A longitudinal investigation of social interaction during Covid-19. Infant Behav. Dev. 73, 101873 (2023).
DeBolt, M. C. & Oakes, L. M. The impact of face masks on infants’ learning of faces: An eye tracking study. Infancy 28(1), 71–91 (2023).
Lloyd-Fox, S. et al. Cortical specialisation to social stimuli from the first days to the second year of life: A rural Gambian cohort. Dev. Cogn. Neurosci. 25, 92–104 (2017).
Carbajal-Valenzuela, C. C., Santiago-Rodriguez, E., Quirarte, G. L. & Harmony, T. Development of emotional face processing in premature and full-term infants. Clin. EEG Neurosci. 48(2), 88–95 (2017).
Moor, B. G. et al. Neurodevelopmental changes of reading the mind in the eyes. Soc. Cogn. Affect. Neurosci. 7(1), 44–52 (2012).
Safyer, P. et al. More than meets the eye: The neural development of emotion face processing during infancy. Infant Behav Dev. 59, 101430 (2020).
Ravicz, M. M., Perdue, K. L., Westerlund, A., Vanderwert, R. E. & Nelson, C. A. Infants’ neural responses to facial emotion in the prefrontal cortex are correlated with temperament: A functional near-infrared spectroscopy study. Front. Psychol. 6, 922 (2015).
Blakemore, S. J. The social brain in adolescence. Nat. Rev. Neurosci. 9(4), 267–277 (2008).
Johnson, M. H., Grossmann, T. & Cohen Kadosh, K. Mapping functional brain development: Building a social brain through interactive specialization. Dev. Psychol. 45(1), 151–159 (2009).
Pitcher, D., Dilks, D. D., Saxe, R. R., Triantafyllou, C. & Kanwisher, N. Differential selectivity for dynamic versus static information in face-selective cortical regions. Neuroimage 56(4), 2356–2363 (2011).
Downing, P. E., Chan, A. W., Peelen, M. V., Dodds, C. M. & Kanwisher, N. Domain specificity in visual cortex. Cereb. Cortex 16(10), 1453–1461 (2006).
Chan, A. W. & Downing, P. E. Faces and eyes in human lateral prefrontal cortex. Front. Hum. Neurosci. 5, 51 (2011).
Dal Monte, O. et al. The left inferior frontal gyrus is crucial for reading the mind in the eyes: brain lesion evidence. Cortex 58, 9–17 (2014).
Lordier, L. et al. Music in premature infants enhances high-level cognitive brain networks. Proc. Natl. Acad. Sci. U. S. A. 116(24), 12103–12108 (2019).
Kozberg, M. & Hillman, E. Neurovascular coupling and energy metabolism in the developing brain. Prog. Brain Res. 225, 213–242 (2016).
Erberich, S. G. et al. Somatosensory lateralization in the newborn brain. Neuroimage 29(1), 155–161 (2006).
Heep, A. et al. Functional magnetic resonance imaging of the sensorimotor system in preterm infants. Pediatrics 123(1), 294–300 (2009).
Zimmermann, B. B. et al. The confounding effect of systemic physiology on the hemodynamic response in newborns. Adv. Exp. Med. Biol. 737, 103–109 (2012).
Kusaka, T. et al. Noninvasive optical imaging in the visual cortex in young infants. Hum. Brain Mapp. 22(2), 122–132 (2004).
Bartocci, M. et al. Cerebral hemodynamic response to unpleasant odors in the preterm newborn measured by near-infrared spectroscopy. Pediatr. Res. 50(3), 324–330 (2001).
Hintz, S. R. et al. Bedside functional imaging of the premature infant brain during passive motor activation. J. Perinat. Med. 29(4), 335–343 (2001).
Arichi, T. et al. Development of BOLD signal hemodynamic responses in the human brain. Neuroimage 63(2), 663–673 (2012).
Lloyd-Fox, S. et al. Coregistering functional near-infrared spectroscopy with underlying cortical areas in infants. Neurophotonics 1(2), 025006 (2014).
Pelphrey, K. A., Morris, J. P. & McCarthy, G. Grasping the intentions of others: The perceived intentionality of an action influences activity in the superior temporal sulcus during social perception. J. Cogn. Neurosci. 16(10), 1706–1716 (2004).
Duchaine, B. & Yovel, G. A revised neural framework for face processing. Annu. Rev. Vis. Sci. 1, 393–416 (2015).
Mosconi, M. W., Mack, P. B., McCarthy, G. & Pelphrey, K. A. Taking an “intentional stance” on eye-gaze shifts: A functional neuroimaging study of social perception in children. Neuroimage 27(1), 247–252 (2005).
Moriguchi, Y., Ohnishi, T., Mori, T., Matsuda, H. & Komaki, G. Changes of brain activity in the neural substrates for theory of mind during childhood and adolescence. Psychiatry Clin. Neurosci. 61(4), 355–363 (2007).
Tang, T. et al. Face processing in prematurely born individuals-a systematic review. Brain Sci. https://doi.org/10.3390/brainsci14121168 (2024).
Yamamoto, M. et al. Do low birth weight infants not see eyes? Face recognition in infancy. Brain Dev. 43(2), 186–191 (2021).
Green, J., Staff, L., Bromley, P., Jones, L. & Petty, J. The implications of face masks for babies and families during the COVID-19 pandemic: A discussion paper. J. Neonatal Nurs. 27(1), 21–25 (2021).
Arcaro, M. J., Schade, P. F., Vincent, J. L., Ponce, C. R. & Livingstone, M. S. Seeing faces is necessary for face-domain formation. Nat. Neurosci. 20(10), 1404–1412 (2017).
Prete, G., D’Anselmo, A. & Tommasi, L. A neural signature of exposure to masked faces after 18 months of COVID-19. Neuropsychologia 174, 108334 (2022).
Galusca, C. I. et al. The effect of masks on the visual preference for faces in the first year of life. Infancy 28(1), 92–105 (2023).
Romeo, D. M. et al. Hammersmith infant neurological examination for infants born preterm: predicting outcomes other than cerebral palsy. Dev. Med. Child Neurol. 63(8), 939–946 (2021).
Einspieler, C. et al. The general movement optimality score: a detailed assessment of general movements during preterm and term age. Dev. Med. Child Neurol. 58(4), 361–368 (2016).
Liu, T. Y. et al. Predictive validity of the Bayley-III cognitive scores at 6 months for cognitive outcomes at 24 months in very-low-birth-weight infants. Front Pediatr. 9, 638449 (2021).
Baek, S. et al. Attrition rate in infant fNIRS research: A meta-analysis. Infancy 28(3), 507–531 (2023).
Mathot, S., Schreij, D. & Theeuwes, J. OpenSesame: an open-source, graphical experiment builder for the social sciences. Behav. Res. Methods. 44(2), 314–324 (2012).
Tottenham, N. et al. The NimStim set of facial expressions: judgments from untrained research participants. Psychiatry Res. 168(3), 242–249 (2009).
Huppert, T. J., Diamond, S. G., Franceschini, M. A. & Boas, D. A. HomER: a review of time-series analysis methods for near-infrared spectroscopy of the brain. Appl Opt. 48(10), D280–D298 (2009).
Di Lorenzo, R. et al. Recommendations for motion correction of infant fNIRS data applicable to multiple data sets and acquisition systems. Neuroimage 200, 511–527 (2019).
Delpy, D. T. et al. Estimation of optical pathlength through tissue from direct time of flight measurement. Phys Med Biol. 33(12), 1433–1442 (1988).
Duncan, A. et al. Optical pathlength measurements on adult head, calf and forearm and the head of the newborn infant using phase resolved optical spectroscopy. Phys Med Biol. 40(2), 295–304 (1995).
Otsuka, Y. et al. Neural activation to upright and inverted faces in infants measured by near infrared spectroscopy. Neuroimage 34(1), 399–406 (2007).
Nakato, E., Otsuka, Y., Kanazawa, S., Yamaguchi, M. K. & Kakigi, R. Distinct differences in the pattern of hemodynamic response to happy and angry facial expressions in infants--A near-infrared spectroscopic study. Neuroimage 54(2), 1600–1606 (2011).
Nakato, E. et al. When do infants differentiate profile face from frontal face? A near-infrared spectroscopic study. Hum. Brain Mapp. 30(2), 462–472 (2009).
Benjamini Y, Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple hypothesis testing. J R Stat Soc B. 1995;57.
Lloyd-Fox, S., Blasi, A. & Elwell, C. E. Illuminating the developing brain: The past, present and future of functional near infrared spectroscopy. Neurosci. Biobehav. Rev. 34(3), 269–284 (2010).
Issard, C. & Gervain, J. Variability of the hemodynamic response in infants: Influence of experimental design and stimulus complexity. Dev. Cogn. Neurosci. 33, 182–193 (2018).
Funding
This work was supported by the NHMRC Investigator Grant [grant number 2034520] and the Victorian Government’s Operational Infrastructure Support Program. FYW has been supported by the Victor Yu Clinical Research Fellowship, the RACP Career Development Fellowship and the NHMRC Investigator Grant [grant number 2034520]. CB was supported by the KNAW Ter Meulen grant [grant number TMB23442] and the dr. Catharine van Tussenbroek grant [grant number A-2023–40]. The sponsors had no role in relation to the study design, collection, analysis and interpretation of data, writing of the report or decision to submit the article for publication.
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FW, DW and RL conceptualized and supervised the work, with funding acquisition by FW and resources provided by both RL and FW. The methodology was developed by CB, RL and FW. Project administration was carried out by CB, EN, RL and FW. Data curation, formal analysis and investigation were jointly performed by CB, EN, SV, NK, KvL, AS, RL and FW. Visualization of the data was done by CB. The main manuscript was drafted by FW and CB and reviewed and edited by EN, SV, NK, KvL, AS, DW and RL. All authors have approved the manuscript and have agreed both to be personally accountable for their own contributions and to ensure that questions related to the accuracy or integrity of the work are appropriately investigated and resolved.
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Brunsch, C., Nanizawa, E., Vallabhapurapu, S. et al. Face perception and impact of face masks at 6 months post-term age in preterm and term infants (The BabyFace Study). Sci Rep (2026). https://doi.org/10.1038/s41598-026-48027-y
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DOI: https://doi.org/10.1038/s41598-026-48027-y
