Tag Archives: Nancy Snidman

Why is Temperament Important to Parents and Teachers?

Roughly 10-20% Caucasian children are shy and hesitant in unfamiliar situations. Another 10-20% are sociable and intrepid in response to novelty. The underlying features of these predispositions usually referred to as “temperament”, remain remarkably consistent over time. It has also been found that the caregiving environment in the early years can significantly influence the behaviors characteristic of these temperaments. That makes the study of temperament particularly relevant to this blog.

Nancy Snidman, a colleague of the pioneer researcher in temperament, defines temperament as a “predisposition to respond to the environment in certain ways” (lecture to UMB IPMHPCP, March 6, 2016). The baby comes into the world with certain temperamental qualities. These temperamental qualities may be due to genetics or epigenetics – influences from the environment in the womb. Children’s temperament influences the way they react to their environment – physical, social, and emotional. For example, a child’s temperament affects the way they react to novelty, sensory stimulation, or transitions. How does temperament at infancy translate to temperamental characteristics such as shyness in a preschool child? What does the “shy” infant look like as an older child or adult? Snidman and Kagan did a series of longitudinal studies to try to answer these questions.

Kagan and Snidman studied 400, 4-month old babies and classified them as high reactive (HR) and low reactive (LR) on the basis of their response to auditory, visual, and olfactory stimuli. They observed the babies’ responses in the form of heart rate increase, motor arousal (such as limb flexion and extension, motor tension, and back arch) and fretting or crying. They looked for the extremes of HR and LR babies and started to follow them.

They postulated that the HR children had inherited a low threshold of excitability in the amygdala; a part of the mid-brain called the limbic system, and the related limbic areas. The amygdala sends signals to the autonomic nervous system, communicating a sense of threat in the environment.

They studied the babies’ physiology and behavior in response to a number of laboratory procedures, from 9 months to 15 years. Some of these procedures were mild, such as puppets or tasting sweet and sour liquids, and some were more challenging, such as a toy robot and a stranger approaching wearing a lab coat and a gas mask. The two extreme styles of temperament, HR or LR, or behaviorally inhibited (BI) – shy, wary of novelty, slow to approach, or behaviorally uninhibited (BU) – sociable, comfortable with novelty, were remarkably consistent over the years.

Interestingly, the researchers found that as the kids got older the physiological markers were more important than the behavioral ones. This was because the children were taught to be polite. It was less the general behavior to strangers that distinguished the HR from the LR kids, and more the smiles and spontaneous comments. When children are presented with the same stimuli in repeated exposures, for example when they are shown invalid pictures (a horse head on a fish body), they usually habituate to the stimulus. That means their reaction becomes smaller with repeated exposures. In the case of HR kids, however, there is no habituation! That means that although they look more and more like their LR peers in terms of social behavior, their heart rate, pupillary dilatation, muscle tension, and stress hormones remain more reactive.

This is very interesting to me in my work with children and families. For more than two decades, Attachment Theory has dominated research in child psychology. This way of understanding child development minimizes the contribution of temperament. Yet, I have found temperament a very useful way of making sense of some of the problems that parents bring to me regarding their children’s behavior. It is also helpful to me when I consult to preschool teachers. In the next blog posting I will describe how I use ideas of temperament to help parents and teachers understand the children in their care.


Schwartz C, Snidman N, Kagan J (1999). Adolescent social anxiety as an outcome of inhibited temperament in childhood, JAACAP 38(8):1008-1015.

Kagan J (1997) Temperament and the reactions to unfamiliarity, Child Development 68(1):139-143.

Kagan J (1989). Temperamental contributions to social behavior, American Psychologist 44(4):668-674.

More About Orchids

IMG_6913 - Version 2

I am interrupting my blog progression again to talk about a recent infant parent mental health weekend, while it is still on my mind. We heard two terrific lectures last month about temperament and attachment, both subjects of particular interest to me.

The lecture on temperament was again given by Nancy Snidman, the temperament researcher. Nancy defines temperament as “predisposition to respond to the environment in certain ways”. There are many terms to describe temperamental characteristics – for example, introversion and extraversion, fearfulness, sociability, rhythmicity, thrill and adventure seeking, thoughtfulness or empathy, and many more.

One of the most important dialectics is the relationship between temperament and environment. In this case, temperament refers to inherited characteristics and the environment refers to experiences with family, friends, school, and life events. Nancy pointed out that there has been a long history of ways of thinking about temperament. In classical times, the Greeks and Romans thought of temperament in terms of the “humors”. In the 18th century, John Locke deemphasized temperament in favor of the influence of the environment, but then in the 19th century, Darwin focused on the importance of heritable factors in his evolutionary theory. The post World War II period again attributed the most powerful influence to the environment, for example in Freudian theory that gained widespread popularity. However, current research, such as in genetics and neuroimaging, has brought us back to a focus on temperament. Luckily, contemporary theories generally maintain a complex perspective by also including the important influence of the environment.

Some of the variables used by Nancy in studies of temperament deriving from Rothbart infant behavior questionnaire include approach, sadness, activity, perceptual sensitivity, fear, soothability. For example, does the baby get excited when given a new toy (approach), or how sad does the baby get when the caregiver goes away, is the baby easily soothed, does the baby enjoy cuddling?
Nancy reported on a longitudinal study of two styles of temperament – behaviorally inhibited (shy, wary of novelty, slow to approach), and behaviorally uninhibited (sociable, comfortable with novelty). They measured the time it took 31-month old children to accommodate to various novel situations, such as the time it took for them to enter a toy cloth tunnel, the time it took them to approach a robot. Some children behaved in relatively “inhibited” ways, and others were significantly less inhibited. The researchers wondered where this “shy” and “outgoing” behavior was coming from.
Starting with the hypothesis that people have different thresholds of excitability in the amygdala that create different sympathetic nervous system responses, resulting in different kinds of behavioral reaction to uncertainty, Nancy’s research team designed various kinds of auditory, visual, and olfactory stimuli to activate their amygdalas and test their hypothesis. In the lecture, Nancy showed films of 4-month old babies in the experimental situation. The babies were seated in a baby seat, and first one mobile figure was waved in front of him and then another, and then three at once. The first baby sat, attentively watching the moving figures, moving his fingers slightly, calm. The second baby started to fuss as the level of stimulation increased until he arched his back and began to scream. The experimenters studied the frequency and direction of every arm and leg movement, negative vocalization, arched back, etc. The babies sorted themselves out into high reactive babies with “high motor/high cry” and low reactive babies with “low motor/low cry”. Then they studied a group of children from 9-months to 15 years, to see what happened to them.
They were thinking of reactivity in terms of biology. If the amygdala fires, there is sympathetic nervous system activity – arousal, heart rate, respiratory rate. They believe that the biology of the children has a direct effect on their behaviors. If the amygdala is firing and the sympathetic nervous system is “Go!” it will produce behavioral responses. The hypothesis was that the babies who at 4 months were high reactive (high motor/high cry) by 2 ½ years became shy children, and that was because they had inherited a temperament associated with a low threshold of reactivity in the amygdala. These children were what I have referred to previously in the blog as “orchids”.
Across the years, they measured the children’s behavioral and physiological responses – at home at school, and in the lab – to situations that challenged them with different types of novelty or uncertainty. They found that the children moved from simple high reactivity in the youngest babies to a mixture of reactivity and shyness, or inhibition, in the older babies. This shift from high motor activity and high vocalization, to inhibition in the older infants reflects what we know about adults. In some high reactive older infants, when the experimenter changed the tone of her voice from pleasant to harsh as she invited the child to touch a toy, the child withdrew. Over the years, the researchers found remarkable consistency in the reactive style of the children. Some of the high reactive children became less shy, but the uninhibited children did not change. Interestingly, when the high reactive children became comfortable in their environments, they did OK. It was the transitions that are the problem. The high reactive children had more trouble with transitions.
The researchers concluded that there is “strong evidence that infant reactivity is related to a predisposition to have an excitable limbic system” and that this kind of reactivity is a “stable quality over time and situation” (Snidman, 2014). In addition, the research suggests that though these biological factors do not determine anything about the child’s future, and that environment can have an important influence on the child’s behavior and personality characteristics, these biological constraints remain as part of the child’s inherited predisposition.
From my point of view as a clinician, I would stress the value in helping parents understand their children, and teachers understand their pupils, so that they can take the children’s temperament into account when they make expectations of them. Children of all temperaments may be able to achieve the same accomplishments, but they may require different degrees and different types of support in order to achieve them. Earlier blog postings include information related to this subject.

photograph by Ginger Gregory

Snidman, Nancy, “Temperament: Importance, Influence, Impact”, Lecture given at Infant-Parent Mental Health Program, U Mass Boston, Sept. 19, 2014.


March IPMH Meeting: Epigenetics II


(Continuation of Barry Lester’s presentation with discussion)

What are some long-term prenatal stressors that affect placental genes? These risk factors may play a role in future problems but do not predict the future. What they can do is alter the HPA system set points and affect the way the newborn responds to stress. This in turn could influence the baby’s regulation.  One could hypothesize that potentially this could lead to dis-inhibition, psychopathology, cognitive problems, and adolescent substance abuse. Of course, there are many steps along the way and many forks in the road. We are only talking about risk factors in a very complex set of processes. We don’t know what these pathways are that lead to problems down the road. We only see correlations. 

Let’s look at cocaine using mothers. It becomes difficult to isolate a particular risk factor in the lives of these women. But the cocaine exposed babies showed higher reactivity to stress. What are the other stressors in the picture? In addition to cocaine use, there is also a relationship of the babies’ high reactivity to the number of caregiver changes. The important point is that you are looking at how the drug interacts with adversity in the postnatal environment, not just the effect of the drug itself.

Which epigenetic changes will be passed on?  Ed (Tonick) says that nutritional studies show that it takes two more generations after the parent generation to clear out some of the nutritional effects in the generation of the grandparents. Do these pass through the mother’s line only? (There are also those who dispute the intergenerational transmission.) If the changes that are passed on represent a guess about the environment, then that is important. How stable are these epigenetic changes anyway? It is possible that they are short lived but that the environment reinstates them. Suppose you are a 2-yo and you are neglected and so you methylate your GR receptors (stress regulatory system). Then you get neglected again, so you methylate them again. There then may be changes in your hippocampus that in effect become a damaged part of your stress regulatory system. Is it causality or association? It seems unlikely that methylation of one gene is going to cause the changes we are talking about. 

It is essential to keep in mind that the connections we are talking about do not represent the actual events of the real world. Ed says that “simple” and “sovereign” is always wrong. We tend to find a new paradigm, and the situation always becomes more complicated the more you look at it. We always find a new paradigm and it gets more complicated the more you look at it. If you look at the Dutch famine study, think about the mothers who were pregnant during a war in which the whole country was starving. The famine ends, but people have died, fetuses have been aborted, the babies who are born are smaller and more irritable. The women who mother them are traumatized. We talk about the famine but do not seriously take into consideration all the other horrible factors that were involved. These amplifying and reinforcing factors were still going on even after the war.

The magnitude of effects – the effect size of all these factors – is small.  It is interesting that you get this variability in the relationship between methylation and behavior in healthy babies, and it makes you wonder what would happen if you look at “at risk” populations; in that case, do you magnify the effects? Within the normal range you can find the same relationship between birth rate and behavior in a study done by Ed Tronick and Barry Lester. You need to consider the whole range – babies who weigh 8 pounds and those who weigh 6 pounds – will the bigger babies have a little better organized behavior? 

There is a new NICU at Brown with single rooms. The changes taking place include more breast feeding, more kangaroo care, etc. An Italian colleague of Ed’s, Rosario, did a study in which he looked at the quality of care in 24 different NICU’s in Italy. He categorized them and gave them assessments, and the babies in the better NICU’s had better scores than those in the least good ones. You are then discharging a baby who is medically in better shape and also neurobehaviorally in better shape. Also, the higher the level of neurodevelopmental care, the lower the incidence of depression in the mothers. All of these NICU’s ascribe to a particular care policy, but in fact they vary. Some of the things that are done in developmental care are thought of as “neuro-protective”. Ideas of developmental care have shifted. 

Schizophrenia – what is the epigenetic issue? There are people who are studying epigenetic changes related to schizophrenia and autism. There is not a lot published yet, but it seems there are prenatal effects that are related to schizophrenia. We also need to look at the relationship between epigenetic changes and genotype. 

Steve Suomi  has done cross fostering studies of rhesus monkeys. He took inhibited and uninhibited babies and cross fostered them, and found that there was evidence of temperament coming through in addition to the environment. Barry Lester thinks of temperament as a protective factor. Nancy Snidman asked about individual differences in the pups – not all the pups get licked, do they? Everyone agreed that there are probably individual differences among the pups that influence how much they get licked. Ed pointed out that just because these models have to do with stress, it doesn’t mean that stress is all bad. We don’t know what appropriate levels of stress are. What about the stress and temperament interaction – is it possible that stress for a highly reactive kid can lead to a blow out, whereas stress for a low reactor can be facilitating? Yes, but it also depends on what you mean by stress. These kids have different thresholds for reactivity. Some people get a rush that is positive, and others feel a negative reaction immediately.

If you have an acute stressful event and it finishes and is done, and yet you ruminate about it, that self-amplifies the stress.  This is where a psychodynamic factor plays an important role. In the case that the individual makes a harmful, self-critical meaning of the stress, then when stress happens, things deteriorate. Stress reactivity by itself, the cortisol effect, is a nonspecific model that could go many different ways. The Kagan model is more specific – it is reaction to novelty – across the lifespan. Stress reactivity and care is a different model. There are many paths that fussiness in a baby can take. Nancy and Kagan were looking at reaction to novelty, and they wanted to get the system aroused to see the physiological systems respond. There were a lot of things they could not include that have to do with caretaking. The amygdala approach-withdrawal reaction – is specific in its relation to novelty. They started with older children. How could they bring that reaction down to infancy and what was going on in the brain? They do see SES differences. Nancy reminds us that most kids are a mix of the temperamental features they are talking about. They were studying mainly the extremes. 

This kind of research is also constrained by the use of checklists. Remember that it is not only parental translation to what these words like “seldom” and “often” mean; it is also what we mean. In the checklist we have to interpret the answers, and what was “trouble” when the checklist was developed and what it is now sometimes has changed. The reason you use CBCL is that the parent has a thick relationship with the child and you may not see all these things for 15 min in the lab. It is also true that the more extreme anything is, the greater effect you will see from it. So that you will see a greater effect the more abnormal the caretaking is. In the case of the relationship between temperament and training in dogs, it is harder to train certain breeds to be aggressive than others, but you can do it. You could probably override most traits. 

In the discussion, one fellow talked about a home placement program in which a child who has not been able to develop certain skills is put into a supportive foster home. Then, when he is better, he is sent back into the home, and they cannot manage. It is typical for kids to do well in structured environments but do poorly at home, and the school says. There is a tendency to dismiss the fact that the child does better in one context because of the regulatory support context.

In the next blog, I will report on the presentation about Attachment Theory. 

Read this blog in Spanish.


March Infant Parent Mental Health Weekend: Temperament


 We began the weekend with Dr.Nancy Snidman, a colleague of Dr. Jerome Kagan who talked to us about temperament. She defined temperament as “what a child brings to the interaction with the environment to create personality”, pointing out that nowadays we tend to talk about “individual differences” instead of temperament, but that individual differences tends to be a “blend of temperament and environment”.  Nancy talked to us about the differences in reactivity of children related to different thresholds of reactivity in the amydala. In their study of the amydala output effects, such as sympathetic responses, output to the larynx (crying), and output to the skeletal motor system, the research group identified a group of “timid” children who had inherited a low threshold of reactivity of the amydala.

It turns out that if you look at the sensory integration scale and the temperament scale, you find a lot of overlap, and some people think they are not so different. Nancy said that if part of your definition of sensory integration disorder is that there is an overwhelming response to sensory information that the child is born with, you could call it temperament. 

Nancy showed us videos of two 4-month old infants responding to a mobile. One baby was highly reactive to the stimulus, and the other was not. The research group chose babies who were high reactive and low reactive in terms of motor behavior and crying modes of reactivity and they followed them over time. Starting at 21 months the researchers saw a lot of consistency. 

The high reactive girls at 21 months started to look shy, a trait that diminished later on. As the children grew older, the best behavioral indicator of their status was spontaneous smiles and comments. The cognitive style related to high reactivity is associated with high levels of response inhibition and over control. The most cohesive group was low reactive boys. 

Socialization differences did have an impact. Interestingly, the low reactive boys tended to seek out risky behavior, whereas the (more “timid”) high reactive boys were often encouraged by their parents to get into sports, against their initial inclination. When these high reactive boys were older they would often end up in individual sports such as swimming, which is a team sport but may avoid some of the rough and tumble aggression characterizing the others.  As the kids got older, it was novelty that would trigger the threat. In preschool, when they became familiar with the school, they were fine. There were some high reactive boys who were doing very well in high school but couldn’t manage the transition (the novelty) to college. 

Nancy sees temperament as underlying all that gets created in the interaction between the individual and the environment. What is the environment that the child finds him or herself in?  If you were counseling parents, you might think – in the case of a high reactive child – to suggest that the parent take more time with transitions. In the case of a low reactive boy, you might try to protect the child against a tendency towards risky behavior. 

Read this blog in Spanish.