MATERNAL RESPONSIVENESS: A POTENTIAL MEDIATOR FOR ASSOCIATIONS AMONG MATERNAL DEPRESSION, LOW SOCIOECONOMIC STATUS, AND NEGATIVE INFANT LANGUAGE DEVELOPMENT

AND INTRODUCTION Infant language development is thought to be the product of myriad biological, environmental, and interpersonal influences, the exact nature of which is not yet fully understood. Although much remains to be learned about what these factors are and how they both individually and jointly affect infants’ communicative abilities, a considerable body of research has indicated that infant-caregiver relationships play a significant role in the language acquisition process. In particular, mothers’ verbal and nonverbal responses to their infants during everyday interactions seem to have a notable impact on expressive and receptive language development. Naturally, the content, frequency, and quality of these responses is not consistent across all mothers, and research has attributed this variation to several factors. Two of these potential contributing factors include maternal depression and socioeconomic status (SES), which have both been linked to differences in the ways mothers respond to and communicate with their infants. The association between infant language development and both maternal depression and low socioeconomic status may be the result of similar differences in maternal responsiveness to infants relative to nondepressed mothers and mothers of middle or high socioeconomic status. This potential connection has implications regarding the importance of the relational qualities of language and potential interventions aimed at improving the language abilities of infants whose mothers are depressed or who are members of a low SES household. THE EFFECT OF MATERNAL DEPRESSION ON INFANT LANGUAGE DEVELOPMENT A substantial body of research has established that maternal depression is associated with deficits in multiple facets of infant language development. Quevedo et al. (2012), for instance, evaluated 296 mothers for depression between 30 and 60 days postpartum and again when their children were one year old. The Bayley Scales of Infant Development III were then administered to the infants when they were 12 months old. Infants whose mothers were depressed at both times of evaluation scored the lowest on a composite score of the Bayley-III Receptive Communication and Expressive Communication subscales, followed by infants whose mothers had experienced depression at only one time point. These results were partially replicated by Kaplan et al. (2014) in a correlational study that established an association between 80 mothers’ scores on the Beck Depression Inventory and their 10 to 14-month-old infants’ scores on the revised Bayley Scales of Infant and Toddler Development, such that infants whose mothers had higher BDI-II scores, suggesting a greater degree of depression, scored lower on the Bayley Expressive Communication subscale. In contrast to the prior study, however, they did not find a significant association between mothers’ BDI-II scores and infants’ Receptive Communication subscale scores. Although these results are contradictory in that Kaplan et al. (2014) did not find an association between maternal depression and infant receptive communication, there are potential explanations that could account for this discrepancy. First, Quevedo et al. (2012) based their results on a total composite score of both expressive and receptive communication, whereas Kaplan et. al (2014) reported associations for each subscale separately. Consequently, the association between maternal depression and infant language scale scores may be accounted for primarily by Expressive Communication subscale scores. M. MILLER: MATERNAL RESPONSIVENESS AS A POTENTIAL MEDIATOR 2 Second, unlike Quevedo et al. (2012), Kaplan et al. (2014) did not measure maternal depression at multiple time points and thus were not able to assess the effects of depression duration. Considering that Quevedo et al. (2012) reported a significant effect of depression duration on infant language scale scores after adjusting for confounding variables, such that infants of mothers who were depressed for longer had lower scores than infants of mothers who were only depressed at one time point, it is possible that the difference in the results may be accounted for by depression duration. If this were indeed the reason for the discrepancy, it would suggest that receptive communication is particularly affected by the cumulative effects of depression over a long period of time compared to expressive communication. THE EFFECT OF LOW SOCIOECONOMIC STATUS ON INFANT LANGUAGE DEVELOPMENT Comparably, low socioeconomic status has also been associated with negative effects on infant language development. Betancourt, Brodsky, and Hurt (2015) examined the association between socioeconomic status and language skills in a sample of 54 seven-month-old African American females using the Preschool Language Scale-5 to assess expressive and receptive communication. Low SES infants had significantly worse scores on the PLS-5 Total Language Composite, Expressive Communication Composite, and Auditory Comprehension Composite (which measures receptive communication skills) relative to infants in the high SES group. Likewise, Fernald, Marchman, and Weisleder (2013) evaluated the language skills of 48 infants when they were both 18 and 24 months old and discovered that infants in the low SES group had less advanced vocabularies and were slower and less accurate in recognizing spoken words than their high SES counterparts at both time points. Strikingly, infants in the high SES group made significantly greater improvements in expressive vocabulary at both 18 and 24 months and had the same accuracy on average in the looking-while-listening task at 18 months as the low SES group had at 24 months. Taken together, these results suggest that infants in low SES households experience delays in language development compared to infants in high SES households, which seem to accumulate and lead to a wide gap in language achievement as time progresses. Relatedly, Hoff (2003) examined the association between socioeconomic status and infant language development in 63 infants between the ages of f16 and 31 months in middle and high SES households. Vocabulary growth was estimated using the transcripts of two naturalistic observations of infant-mother interactions ten weeks apart. Despite similar vocabulary sizes at the time of the first observation, the high SES infants had a significantly larger increase in vocabulary over the course of ten weeks than the middle SES infants, and this association between SES and vocabulary growth was fully mediated by maternal responsiveness. Although this study observed the differences between infants of middle and high socioeconomic status and did not include infants of low socioeconomic status, its findings suggest that the effects of socioeconomic status on language development are not limited to those of low socioeconomic status. Instead, these linguistic differences between socioeconomic classes may operate on a spectrum, such that infants of low SES tend to struggle most and infants of high SES tend to struggle least. A multitude of factors may be responsible for the apparent differential language abilities of infants across social classes, given the broad effects of socioeconomic status on a person’s access to resources, values, personality, environment, parenting styles, goals, health, and education, among other things. It is quite probable that a confluence of several of these socioeconomic status-related differences, rather than one individual factor, is responsible for the variation in infant language development across social classes, though some factors may be more salient or influential than others. THE EFFECT OF MATERNAL RESPONSIVENESS ON INFANT LANGUAGE DEVELOPMENT One such factor that may at least partially explain the negative effects on language development that appear to be associated with maternal depression and low socioeconomic status is maternal responsiveness. Maternal responsiveness refers to the reactions that mothers and other caretakers have to their infants’ communicative efforts, behaviors, and experiences. Mothers often adjust their responses according to the infant’s current state and focus of attention. Responses that account for the infant’s experiences in this way, and which occur in quick succession to infant communicative bids are often referred to as “contingent responses. ” Appropriate maternal responses nourish infant language TCNJ JOURNAL OF STUDENT SCHOLARSHIP VOLUME XXV APRIL 2023 3 development by facilitating infants’ engagement with their environment, encouraging further thought and exploration, and providing them with words to understand their experiences as they occur. It is unsurprising, then, that maternal responsiveness has been directly associated with infant language development. In a longitudinal study of 12 mothers and their infants when the infants were 8 to 14 months old, Gros-Louis, West, and King (2014) found that increased maternal responses to infant mother-directed vocalizations were related to an increase in developmentally-advanced consonant-vowel vocalizations – an aspect of expressive communication – such that infants whose mothers responded more to mother-directed vocalizations had a larger increase in these advanced vocalizations from 8 to 14 months of age. Further, among the nine infants in the sample whose parents were given the MacArthur Communicative Development Inventory: Words and Gestures (MCDI) when infants were 15 months, infants whose mothers provided increased sensitive responses overall to their vocalizations had higher vocabulary production and gesture scores. Sensitive responses were classified as verbal or non-verbal responses that occurred within two seconds of infants’ vocalizations. Interestingly, mothers’ sensitive responses to prior infant vocalizations predicted increased infant mother-directed vocalizations in the following months. These results suggest that maternal sens