Infant and parent factors associated with early maternal sensitivity: A caregiver-
attachment systems approach
By W. Roger Mills-Koonce, Jean-Louis Gari´epy, Cathi Propper, Kelly Suttona, Susan Calkins,
Ginger Moore, Martha Cox
Mills-Koonce, W. R., Gariépy, J.-L., Propper, C. B., Sutton, K., Calkins, S., Moore, G., & Cox,
M. J. (2007). Infant and parent factors associated with early maternal sensitivity: A
caregiver-attachment systems approach. Infant Behavior and Development, 30, 114-126.
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Abstract:
We examined variations in maternal sensitivity at 6 months of child age as a function of child
negativity and maternal physiology. We expected maternal vagal withdrawal in response to
infant negative affect to facilitate the maintenance of sensitivity, but only for mothers of securely
attached children. One hundred and forty-eight infant-mother dyads were observed in multiple
contexts at 6 months of child age, and associations among maternal and child variables were
examined with respect to 12-month attachment quality. Mothers of later securely attached
children were more sensitive than mothers of avoidant children. However, sensitivity decreased
for all mothers at high levels of infant negative affect. Furthermore, for mothers of avoidant
children, vagal withdrawal was associated with sensitivity to child distress. No association was
found between vagal withdrawal and sensitivity for mothers of securely attached children. This
suggests that mothers of avoidant children may be uniquely challenged by the affective demands
of their infants. © 2007 Published by Elsevier Inc. Keywords: Infant; Parent; Caregiver
Article:
The conception of parental sensitivity as a stable personality attribute that directly benefits
attachment security has been challenged by meta-analyses (De Wolff & van IJzendoorn,1997)
identifying child factors as important contributors to attachment formation (Goldsmith &
Alansky, 1987) and showing that the relation between maternal sensitivity and attachment
security is not as strong as initially proposed by Ainsworth, Blehar, Waters, and Wall (1978).
Two reports by Crockenberg (1981) and van den Boom (1994) that highly irritable infants tend
to receive less sensitive care and are at greater risk for developing insecure relationships to their
caregiver were especially compelling in this regard. Their findings suggest that sensitive
parenting might be challenged and reduced by infant negativity, but enhanced when the child
positively stimulates the mother and responds to her bids for interaction (see also Atkinson et al.,
1999; Cox, Owen, Henderson, & Margand, 1992; Kochanska, 2001; Thompson, 1997; van den
Boom, 1997).
In this light, both van den Boom (1997) and Thompson (1997) have pressed for amore
dyadic/contingent concept of caregiver sensitivity that takes into account the infant’s changing
affective state. Additionally, the notion that there may be caregiver regulatory qualities that, via
their effects on sensitivity, promote or compromise security of attachment (van IJzendoorn,
1995) has also gained visibility in attachment research (Adam, Gunnar, & Tanaka, 2004;
Kochanska, Murray, & Harlan, 2000; Pederson, Gleason, Moran, & Bento, 1998; Pedersen &
Moran, 1995). In this study, we examine how maternal sensitivity at 6 months of child age varies
as a function of child distress and the mother’s ability to physiologically self-regulate in response
to this distress.
1. CHILD FACTORS, MATERNAL SENSITIVITY, AND ATTACHMENT SECURITY
Bowlby’s (1969) attachment theory highlighted the importance of shifts between positive and
negative affect as the primary mechanism of communication for infants. Accordingly, while
positive affect promotes affiliation and the acquisition of competence through play and
exploration, shifts to negative affect serve as potent signals of distress and the need for comfort
from the caregiver. The caregiving system must adequately detect and attend to these shifts in
order to support the development of a secure attachment relationship. The coordination of
caregiving behaviors with the infant attachment system is a benchmark of sensitive parenting,
which is exemplified by child-centered responses to the physical and emotional needs of the
infant (Ainsworth et al., 1978; Bowlby, 1969). Repeated experience with this type of caregiving
allows the child to develop a sense of efficacy and agency and to use the full repertoire of
emotional communication in a well-regulated manner (Tronick,1989). The fact that the
caregiving system must respond appropriately to a variety of emotional needs from the child
highlights the relevance of examining parenting across a spectrum of interactive contexts.
Although experiencing sensitive caregiving is important for children in all contexts, experiencing
effective soothing and comfort when distressed may be particularly important for the
development of self-regulation. In contrast, the inability to rely on the caregiver for comfort
when distressed may lead the child to develop coping strategies, such as avoidance, that in the
long term are maladaptive. Several researchers, such as Thompson (1997), have proposed that
―sensitivity expressed when the child is fearful, anxious or distressed might be more prognostic
of a secure attachment than sensitivity displayed during nonstressful episodes . . . ‖ (p. 596).
Although several studies have examined the relationships between infant affect, maternal
sensitivity, and attachment security (Braungart & Stifter, 1991; Frodi & Thompson, 1985;
Mangelsdorf, Gunnar, Kestenbaum, Lang, & Andreas, 1990; Thompson & Lamb, 1984), to date
only a few longitudinal studies explicitly considered early child influences on maternal
sensitivity and later attachment classification (Braungart-Reiker, Garwood, Powers, & Wang,
2001; Posada et al., 1999). Although these studies identify independent effects of early maternal
sensitivity and infant affective displays on later attachment classification, they also highlight the
difficulty of establishing clear causal links between maternal and infant behaviors. In spite of
these limitations, there is much to be gained by examining how these behaviors are coordinated,
especially with respect to the dyad’s emerging attachment relationship.
For the purpose of the present research, we measured maternal sensitivity at 6 months of child
age under three different conditions of increasing stress for the dyad. We expected that these
conditions would differ in terms of the probability of observing child negative affect. These
conditions included a free play session, a book reading session, and the recovery period that
followed two challenge procedures known to elicit infant distress. Based on previous findings
that mothers of insecurely attached children (especially of avoidant children; Cassidy, 1999)
have more difficulties with their own emotion regulation and parental function under conditions
of infant distress than mothers of secure children, we hypothesized that mothers of children later
categorized as secure would be better able to maintain sensitivity under conditions of infant
distress than mothers from insecure dyads.
2. MOTHER’S SELF-REGULATION IN RESPONSE TO INFANT DISTRESS
Bowlby (1969) posited that negative affect is the most potent tool of communication available to
the infant because of its distinctness and saliency for the mother in almost any situation.
Although being aroused by a crying infant is certainly an adaptive feature of the caregiving
system, infant distress can also be quite dysregulating for mothers, especially when persistent
and intense. Consider the current definitions of parental sensitivity, including attentiveness and
awareness of child signaling, emotional availability, consistency, appropriate emotional tone, and
lack of irritation and anger (Ainsworth et al., 1978; NICHD Early Child Care Research Network,
1999; Posada et al., 1999; van den Boom, 1997). Each of these descriptive aspects requires some
degree of behavioral self-regulatory capabilities on the part of the mother. Given this, our second
goal was to determine whether physiological measures of maternal self-regulation were
associated with sensitive caregiving in response to changes in the infant’s affective state.
In measuring maternal emotion regulation it was important to consider that differential maternal
responding to infant distress signals may be associated with and supported by differences in
maternal reactivity and self-regulation, both of which have known biological bases in the
autonomic and central nervous systems (Rothbath & Derryberry,1981). Thus, the quality of a
mother’s response to her child’s needs may depend in part on the degree to which her
physiological stress regulation supports active attention and engagement with the needs of the
child. There is ample evidence from the animal literature that such physiological support for
organized parenting behavior is necessary (e.g., Boccia & Pederson, 2001; Porges, 1998;
Winslow et al., 2000; Wotjak et al., 1996). Of special relevance to this topic is the demonstration
by Porges (1998) that mammalian pair-bonding is supported by the vagal system, which
physiologically mediates social engagement, facial expressivity, and vocalization. Thus, as part
of the broader caregiving system, maternal vagal regulation in response to infant distress signals
may provide a psychophysiological support system for the organization of effective parenting
behaviors.
One commonly used index of vagal regulation and autonomic functioning is heart-rate
variability, a measure of parasympathetic activity. Heart-rate variability, or vagal tone, has been
linked to several measures of cognitive and emotional processes involving attention and stimulus
appraisal (Lacey & Lacey, 1958; Porges, Arnold, & Forbes, 1973; Richards, 1987; Wenger,
1941). Similarly, a decrease of vagal tone during periods of environmental challenge has been
linked to self-regulation and the ability to engage the source of stimulation or take distance from
it (Calkins, 1997; Kagan, 1994; Porges, 1996, 1998; Stifter & Fox, 1990; Stifter & Jain, 1996).
Interestingly, polyvagal theory (Porges, 1995) suggests that somatomotor and visceromotor
nerve fibers that innervate organs such as the larynx, pharynx, bronchi, and heart act
synergistically to promote social interaction. Porges explains that under most conditions, heart
rate is kept low and heart-rate variability high via the nucleus ambiguous serving as a vagal
―brake‖ in order to curb the use of psychophysiological resources. However, under challenging
conditions, this ―brake‖ is released and the resulting decrease in heart-rate variability and
increase in cardiac output facilitates active engagement and monitoring with respect to a set goal.
Although there are multiple methods for measuring this change, Porges (1985, 1991, 1996) has
developed a commonly used method that indexes heart-rate variability at the frequency of
breathing, known as respiratory sinus arrhythmia (RSA). A decrease in RSA from baseline levels
(i.e., vagal withdrawal) is believed to reflect the parasympathetic influence of vagal regulation,
whereby the withdrawal of parasympathetic control of the heart allows for sympathetic activity
and thus increases in heart rate and cardiac output. As such, effective vagal withdrawal has been
examined as an index of self-regulation and may underlie the behavioral attention strategies
necessary for regulation of arousal (Huffman et al., 1998; Posner & Rothbart, 2000). Although
most studies of vagal withdrawal and behavior focus on children, there is both theoretical and
empirical evidence to suggest that similar patterns of vagal-behavior associations exist among
adults (Beauchaine, 2001). As vagal withdrawal facilitates the flexible shift of resources from a
stable state to one that can meet environmental demands, we expected elevated withdrawal to be
associated with the maintenance of sensitive care even under conditions of high child distress.
Furthermore, we hypothesized this relationship to be particularly characteristic of mothers whose
infants would later show secure attachments.
3. HYPOTHESES
The goals of the current research were (1) to determine whether associations between child
negative affect and maternal sensitivity at 6 months of child age were constant across later
attachment classifications, and (2) to determine whether mother’s physiological regulation, as
indexed by vagal withdrawal, mediates or moderates associations between infant negativity and
maternal sensitivity. Specifically, the first hypothesis predicted that infant negative affect would
be more strongly associated with maternal sensitivity among mothers of insecurely attached
children. In contrast, we expected little to no measurable effects of infant negativity on maternal
sensitivity among securely attached dyads. For our second hypothesis, we predicted that for
mothers of secure children, high maternal vagal withdrawal would be associated with the
maintenance of sensitivity when mothers were faced with high levels of infant negative affect. In
contrast, low levels of vagal withdrawal in response to elevated infant negativity were expected
to be associated with less sensitive care among mothers of insecurely attached children.
The current analyses are limited to dyads with organized attachment relationships at 12 months
of age. Although mothers of children with a disorganized primary classification are an interesting
subgroup, there is no conceptual basis for including them in the present analyses. Specifically,
several studies have shown that these mothers are as sensitive as mothers with children in other
attachment classifications, secure or otherwise (van IJzendoorn, Schuengel,
& Bakermans-Kranenburg, 1999). Rather, disorganized attachments have been linked to
maternal behaviors such as disruptive affective communication (Lyons-Ruth, Bronfman, &
Parsons, 1999), overt familial risks such as maltreatment (Carlson, Cicchetti, Barnett, &
Braunwald, 1989), or other broad environmental factors such as the death of a caregiver (van
IJzendoorn,1995). In fact, within disorganized samples the forced ABC classification of children
is often differentiated by maternal sensitivity, with forced secure children receiving sensitive
care to a similar degree as primarily secure children (Mills-Koonce, Gariepy, Sutton, & Cox,
under review). Given these findings, the current research focuses on mothers of children with
secure, insecure-avoidant, and insecure-resistant attachment classifications.
4. METHOD
4.1. Participants
The participants in the current study were 173 families recruited by the Durham Child Health
and Development Study. For this study, recruitment procedures specified an approximately equal
number of European- and African- American families sampled from both lower- and higher-
income groups. The family’s race was determined by the race of the mother (or primary
caregiver), while income status was determined by whether families were above or below 200
percent of the federally established poverty threshold. Birth order or family structures were not
used as inclusion criteria. Families were drawn from a largely urban community via fliers and
postings at birth and parenting classes, as well as through phone contact via birth records. There
was a 10 percent rate of attrition from the first to the second time point, resulting in a total
sample of 155 families that completed all assessment protocols. Of those, 7 families were
excluded due to audio-visual difficulties that made their videotaped assessments impossible to
code. The final sample of 148 families used for the current analyses was 56 percent African-
American and 44 percent European-American. Approximately 53 percent was low income
(below 200 percent of the poverty level). A total of 13 percent of mothers had no high school
degree, 43 percent had either a high school diploma or a G.E.D., 11 percent had some college or
vocational school, and 33 percent had a 4-year bachelors degree or higher. The ages of mothers
in this sample ranged from 18 to 40 (M= 28.3, SD = 5.6). In addition to the focal child, 69
families in this sample had additional children in the household. When present, the number of
additional children in the household ranged from 1 to 10 (M=1.6, SD = 2.7). All siblings were
older than the focal child, ranging from 1.5 to 13 years of age (M= 5.0, SD = 2.7). The sample
was almost evenly split based on the sex of the child, with 51 percent male. The distribution of
12-month attachment classifications in the present sample consisted of 96 children classified as
secure, 37 children classified as insecure-avoidant, and 15 classified as insecure-resistant.
4.2. Assessment Procedures
4.2.1. 6-Month free play observations
Mothers and children were observed in the home for the free play session, during which time
mothers were asked to interact with their children as they normally would during a typical day. A
standard set of toys was provided for the mother and child to use, and the pair was asked to sit on
a blanket that was laid out across the floor. This session was videotaped for later coding, with
researchers monitoring the camera discreetly to minimize interference with the ongoing
interaction.
4.2.2. 6-Month book reading observations
Within 2 weeks of the home visit, mothers and children participated in a 6-month laboratory
visit. During this time mothers were asked to try to involve their child with a picture book
provided by the researchers. The book involved pictures without words to control for any effect
of illiteracy among the parents. Mothers were responsible for creating a storyline that followed
the illustrations in the book. Like the free play session in the home visit, this procedure took
place on the floor with the child positioned between the mother and a single camera. Mothers
were allowed up to 10 min for this activity.
4.2.3. 6-Month challenge tasks observations
The challenge tasks administered in the laboratory visit were the Still Face Paradigm (Tronick,
Als, Adamson, Wise, & Brazelton, 1979) and the arms restraint procedure (Goldsmith &
Rothbarth, 1994). For these purposes the mother was asked to secure her child in a car seat
situated on top of a large, sturdy table. Prior to the still face episode, the mother was instructed to