The Unknown Importance of the Mouth in Visually Impaired Children’s Learning of Objects

Child Mouthing an Object

Project Overview

A pencil and a Lego are more than objects that can be felt and seen, they are tools for cultural goals; a pencil is a means of communication; a Lego is a building block to represent real objects in the world. Blind or visually impaired children lag behind sighted peers in this critical developmental milestone: using objects in conventional ways. This research investigates two risk factors that limit blind and visually impaired children’s cultural use of objects: a. Whether/when these children’s mouthing of objects needs to be discouraged in favor of hand skills development; b. What is the typical development of these children’s ability to pay attention to how social partners use objects? Results will inform practices for assessing blind and visually impaired children’s development, determining when intervention is needed, and designing strategies for promoting these children’s healthy development.

If you open a book on child development, you will read that infants’ earliest primary means of exploration is touching objects with their mouths. The initial reflexive sucking on objects is influenced by experience; infants learn which objects are suitable for mouthing and to bring them to the mouth. As the main mechanism for object exploration, mouthing decreases toward the end of the first year, and is eventually replaced by manual exploration.

Observational research and care providers’ anecdotal accounts indicate that visually impaired children show mouthing behavior more extensively and/or until later ages than sighted peers. It is known that age related changes in hand exploration maximize hand perception of object properties, and accommodate greater learning about culturally appropriate use of objects. Thus, when visually impaired infants show mouthing behavior beyond what is thought to be normal in sighted peers, clinicians deliberately discourage mouthing in favor of more hand use.

The mouth is very sensitive for detecting spatial relationships between parts of objects, and other object properties. It is possible that mouthing serves an important stimulus for brain development that supports the perception of objects, and of spatial relationships in general. The lips and tongue provide the highest sensitivity to detailed tactile information, and are over-represented in brain areas that process information from the skin. Our preliminary results from semi-structured interviews indicate that visually impaired adults use the mouth to determine properties of objects, for example, to estimate fine differences in the texture of materials. This challenges the assumption that mouthing must be discontinued to support hand use.

This research is investigating the hypothesis that in visually impaired infants, mouthing continues to provide critical information about objects. Visually impaired and sighted infants are video recorded exploring objects that vary in their properties. Videos will be coded to determine whether amount of mouthing varies depending on objects’ amount of spatial information. Visually impaired infants’ visual levels are assessed with the Preferential Looking Technique to determine the relationship between amount of mouthing and decreases in visual processing function. Additionally, interviews in which visually impaired adults were asked about their use of mouthing for object perception are being analyzed to infer properties that visually impaired infants may perceive through mouthing.

The outcome of this study will be a better understanding of the function of mouthing for visually impaired infants’ object understanding. Results will inform early-intervention practices by aiding to differentiate between “atypical” behaviors that are indeed normative and instrumental for these infants, and those that signal developmental difficulties that warrant special intervention.

More information on this study can be found here (PDF file, opens in new window).


Join This Study

INCLUSION: Children aged 6 months through 6 years who have any degree of visual impairment, children aged 6 months through 6 years who have normal vision. EXCLUSION: N/A

Andrea Urqueta Alfaro, PhD
LC Industries Postdoctoral Research Fellow
Parent Consent Form (PDF File, opens in new window)

Team Members

Laura Walker, PhD
Executive Director

References & Publications

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Bakeman, R., & Adamson, L. B. (1984). Coordinating attention to people and objects in mother-infant and peer-infant interactions. Child Development, 55(4), 1278-1289.

Bigelow, A. (2003). The development of joint attention in blind infants. Development and Psychopathology, 15, 259-275.

Cholewiak, R., & Collins, A. (1991). Sensory and physiological bases of touch. In M.A. Heller and W. Schiff (Eds.) The Psychology of touch. Hillsdale, NJ: Lawrence Erlbaum Associates.

Dale, N. J., Tadić V., & Sonksen P. (2013). Social communicative variation in 1–3-year-olds with severe visual impairment. Child: Care Health Development, 40(2), 158-164.

Van Boven, R. W., & Johnson, K. O. (1994). The limit of tactile resolution in humans: grating orientation discrimination at the lip, tongue, and finger. Neurology, 44, 2361-2366.

Urqueta, A. (2015). Visual Impairments. In The Cambridge Encyclopedia of Child Development (2nd Ed.). Cambridge, England: Cambridge University Press. Accepted for publication.

Urqueta, A. (2015). Joint engagement and attachment patterns in infants with visual impairments (Doctoral dissertation).

Urqueta, A. (2014). So called autistic-like behaviors in children with visual impairments: Is it the right label?. Terra Haptica, 4, 137-146.

Morash, V., Connell. A., Urqueta, A., McKerracher, A. (2011). A review of spatial abilities in the blind.  Cognition and Computation: An Interdisciplinary Journal,12:2-3, 83-95.