Exploring in Silence: Hearing and Deaf Infants Explore Objects Differently Before Cochlear Implantation

Abstract

Infant development has rarely been informed by the behavior of infants with sensory differences despite increasing recognition that infant behavior itself creates sensory learning opportunities. The purpose of this study of object exploration was to compare the behavior of hearing and deaf infants, with and without cochlear implants, in order to identify the effects of profound sensorineural hearing loss on infant exploration before cochlear implantation, the behavioral effects of access to auditory feedback after cochlear implantation, and the sensory motivation for exploration behaviors performed by hearing infants as well. The results showed that 9‐month‐old deaf infants explored objects as often as hearing infants but they used systematically different approaches and less variation before compared to after cochlear implantation. Potential associations between these early experiences and later learning are discussed in the context of embodied developmental theory, comparative studies, and research with adults. The data call for increased recognition of the active sensorimotor nature of infant learning and future research that investigates differences in sensorimotor experience as potential mechanisms in later learning and sequential memory development.

Prelinguistic Consonant Production and the Influence of Mouthing Before and After Cochlear Implantation

“…However, the evidence shows that most did not. Instead, they showed a significant decline in the overall proportion of vocalizations with mouthing, consistent with reports of decreases in object mouthing alone between 9 and 15 mo in hearing infants and infants with profound hearing loss (McCall 1974;Belsky & Most 1981;Ruff 1984;Fagan 2019). The results of the present study extend this literature to additionally reveal a decline in vocalization-mouthing combinations in both groups from the first to the second year.…”

“…That is, the vocalization-mouthing episodes that may have benefited consonant acquisition in the pre-CI infants occurred before they received CIs, during a period in the first year when they were unlikely to perceive auditory feedback from SGC exploration in vocalization-mouthing combinations. Instead, the pre-CI infants likely explored tactile and proprioceptive object (and oral) properties (Fagan 2019), rather than auditory-motor variation in vocalization-mouthing behaviors.…”

“…In a recent study of object mouthing alone conducted with hearing infants and infants with profound hearing loss, object mouthing was even more frequent in infants with profound hearing loss in the first year than it was for hearing infants (Fagan 2019). Furthermore, in the study of infants with profound hearing loss and in other studies of hearing infants (McCall 1974; Belsky & Most 1981; Ruff 1984; Fagan & Iverson 2007; Fagan 2019), object mouthing was comparatively less frequent in the second year of life—the very period when many infants with hearing loss first begin to use CIs—than in the first year of life. Because vocalizations that occur during mouthing have not been examined in infants with profound hearing loss, their influence on consonant production and acquisition is unknown.…”

“…(3) Do prelinguistic vocalizations co-occur with mouthing in infants with hearing loss and, if so, are they more likely to contain supraglottal consonants than vocalizations that do not? Based on vocalization-mouthing research with 6- to 9-mo-old hearing infants and evidence of frequent object mouthing alone in infants with profound hearing loss in the first year (Fagan 2019), we hypothesize that pre-CI infants will produce vocalizations during mouthing and that they will be more likely to contain supraglottal consonants than vocalizations without mouthing. Because object mouthing alone declined in the second year for hearing infants and infants with CIs, investigation of vocalization-mouthing combinations in the second year will be exploratory for both groups.…”