Differential susceptibility hypothesis
Encyclopedia
According to the differential susceptibility hypothesis by Belsky individuals vary in the degree they are affected by experiences or qualities of the environment they are exposed to. Some individuals are more susceptible to such influences than others––not only to negative but also to positive ones.
or dual-risk terms. That is, some individuals, due to their biological, temperamental and/or behavioral characteristics (i.e., “diathesis” or “risk 1”), are more vulnerable to the adverse effects of negative experiences (i.e., “stress” or “risk 2”), whereas others are relatively resilient with respect to them (see
Figure 1, an adaptation of Bakermans-Kranenburg and van IJzendoorn’s (2007) Figure 1).
A fundamentally different, even if not competing view, of the very same phenomenon is central to Belsky’s differential susceptibility hypothesis and Boyce and Ellis’ (2005) related notion of biological sensitivity to context: Individuals do not simply vary in the degree to which they are vulnerable to the negative effects of adverse experience but, more generally, in their developmental plasticity. More “plastic” or malleable individuals are more susceptible than others to environmental influences in a for-better-and-for-worse manner, that is, to both the adverse developmental sequelae associated with negative environments and the positive developmental consequences of supportive ones. Less susceptible individuals, in contrast, are less affected by rearing conditions, be they presumptively supportive or undermining of well being (see Figure 2, an adaptation of Bakermans-Kranenburg and van IJzendoorn’s (2007) Figure 1).
optimizing strategy involving bet hedging, natural selection
would have shaped parents to bear children varying in plasticity
. This way, if an effect of parenting had proven counterproductive in fitness
terms, those children not affected by parenting would not have incurred the cost of developing in ways that ultimately proved “misguided”. Importantly, in light of inclusive-fitness
considerations, these less malleable children’s “resistance” to parental influence would not only have benefited themselves directly, but even their more malleable sibs—indirectly, given that sibs, like parents and children, have 50% of their genes in common. By the same token, had parenting influenced children in ways that enhanced fitness
, then not only would more plastic offspring have benefited directly by following parental leads, but so, too, would their parents and even their less malleable sibs who did not benefit from the parenting they received, again for inclusive-fitness reasons.
This line of evolutionary argument leads to the prediction that children should vary in their susceptibility to parental rearing and perhaps to environmental influences more generally. As it turns out, a long line of developmental inquiry, informed by a “transactional” perspective, has more or less been based on this unstated assumption.
.
A list of currently proposed susceptibility factors—which all emerged repeatedly in empirical studies—is provided in Table 1.
Differential susceptibility versus diathesis-stress
The idea that individuals vary in their responsivity to qualities of the environment is generally framed in diathesis-stressDiathesis-stress model
The diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
or dual-risk terms. That is, some individuals, due to their biological, temperamental and/or behavioral characteristics (i.e., “diathesis” or “risk 1”), are more vulnerable to the adverse effects of negative experiences (i.e., “stress” or “risk 2”), whereas others are relatively resilient with respect to them (see
Figure 1, an adaptation of Bakermans-Kranenburg and van IJzendoorn’s (2007) Figure 1).
A fundamentally different, even if not competing view, of the very same phenomenon is central to Belsky’s differential susceptibility hypothesis and Boyce and Ellis’ (2005) related notion of biological sensitivity to context: Individuals do not simply vary in the degree to which they are vulnerable to the negative effects of adverse experience but, more generally, in their developmental plasticity. More “plastic” or malleable individuals are more susceptible than others to environmental influences in a for-better-and-for-worse manner, that is, to both the adverse developmental sequelae associated with negative environments and the positive developmental consequences of supportive ones. Less susceptible individuals, in contrast, are less affected by rearing conditions, be they presumptively supportive or undermining of well being (see Figure 2, an adaptation of Bakermans-Kranenburg and van IJzendoorn’s (2007) Figure 1).
Theoretical background of the differential susceptibility hypothesis
Because the future is and always has been inherently uncertain, ancestral parents, just like parents today, could not have known (consciously or unconsciously) what childrearing practices would prove most successful in promoting the reproductive fitness of offspring—and thus their own inclusive fitness. As a result, and as a fitnessFitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
optimizing strategy involving bet hedging, natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
would have shaped parents to bear children varying in plasticity
Phenotypic plasticity
Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship...
. This way, if an effect of parenting had proven counterproductive in fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
terms, those children not affected by parenting would not have incurred the cost of developing in ways that ultimately proved “misguided”. Importantly, in light of inclusive-fitness
Inclusive fitness
In evolutionary biology and evolutionary psychology, the inclusive fitness of an organism is the sum of its classical fitness and the number of equivalents of its own offspring it can add to the population by supporting others...
considerations, these less malleable children’s “resistance” to parental influence would not only have benefited themselves directly, but even their more malleable sibs—indirectly, given that sibs, like parents and children, have 50% of their genes in common. By the same token, had parenting influenced children in ways that enhanced fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
, then not only would more plastic offspring have benefited directly by following parental leads, but so, too, would their parents and even their less malleable sibs who did not benefit from the parenting they received, again for inclusive-fitness reasons.
This line of evolutionary argument leads to the prediction that children should vary in their susceptibility to parental rearing and perhaps to environmental influences more generally. As it turns out, a long line of developmental inquiry, informed by a “transactional” perspective, has more or less been based on this unstated assumption.
Criteria for the testing of differential susceptibility
Belsky, Bakermans-Kranenburg, & van IJzendoorn, (2007) delineated a series of empirical requirements—or steps—for convincingly establishing evidence of differential susceptibility to environmental influences and distinguishing differential susceptibility from other interaction effects including diathesis-stress/dual-riskDiathesis-stress model
The diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
.
- While diathesis-stress/dual-riskDiathesis-stress modelThe diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
arises when the most vulnerable are disproportionately affected in an adverse manner by a negative environment but do not also benefit disproportionately from positive environmental conditions, differential susceptibility is characterized by a cross-over interaction: the susceptible individuals are disproportionately affected by both negative and positive experiences. - A further criterion that needs to be fulfilled to distinguish differential susceptibility from diathesis-stress/dual-riskDiathesis-stress modelThe diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
is the independence of the outcome measure from the susceptibility factor: if the susceptibility factor and the outcome are related, diathesis-stress/dual-riskDiathesis-stress modelThe diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
is suggested rather than differential susceptibility. - Further, environment and susceptibility factor must also be unrelated to exclude the alternative explanation that susceptibility merely represents a function of the environmentGene-environment interactionGene–environment interaction is the phenotypic effect of interactions between genes and the environment....
. - The specificity of the differential-susceptibility effect is demonstrated if the model is not replicated when other susceptibility factors (i.e., moderators) and outcomes are used.
- Finally, the slope for the susceptible subgroup should be significantly different from zero and at the same time significantly steeper than the slope for the non- (or less-) susceptible subgroup.
Susceptibility markers and empirical evidence
Characteristics of individuals that have been shown to moderate environmental effects in a manner consistent with the differential susceptibility hypothesis can be subdivided into three categories:- Genetic FactorsGenotypeThe genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
E.g., Bakermans-Kranenburg and van IJzendoorn (2006) were the first to test the differential susceptibility hypothesis as a function of genes regarding the moderating effect of the dopamine receptor D4 7-repeat polymorphism (DRD4-7R) on the association between maternal sensitivity and externalizing behavior problems in 47 families. Children with the DRD4-7R allele and insensitive mothers displayed significantly more externalizing behaviors than children with the same allele but with sensitive mothers. Children with the DRD4-7R allele and sensitive mothers had the least externalizing behaviors of all whereas maternal sensitivity had no effect on children without the DRD4-7R allele. - Endophenotypic FactorsEndophenotypeEndophenotype is a psychiatric concept and a special kind of biomarker. The purpose of the concept is to divide behavioral symptoms into more stable phenotypes with a clear genetic connection...
E.g., Obradovic, Bush, Stamperdahl, Adler and Boyce’s (2010) investigated associations between childhood adversity and child adjustment in 338 5-year olds. Children with high cortisol reactivityHypothalamic-pituitary-adrenal axisThe hypothalamic-pituitary-adrenal axis , also known as thelimbic-hypothalamic-pituitary-adrenal axis and, occasionally, as the hypothalamic-pituitary-adrenal-gonadotropic axis, is a complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland ,...
were rated by teachers as least prosocial when living under adverse conditions, but most prosocial when living under more benign conditions (and in comparison to children scoring low on cortisol reactivity). - Phenotypic FactorsPhenotypeA phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
E.g., Pluess and Belsky (2009) reported that the effect of child care quality on teacher-rated socioemotional adjustment varied as a function of infant temperamentTemperamentIn psychology, temperament refers to those aspects of an individual's personality, such as introversion or extroversion, that are often regarded as innate rather than learned...
in the case of 761 4.5-year olds participating in the NICHD Study of Early Child Care and Youth Development (NICHD Early Child Care Research Network, 2005). Children with difficult temperaments as infants manifest the most and least behavior problems depending on whether they experienced, respectively, poor or good quality care (and in comparison to children with easier temperaments).
A list of currently proposed susceptibility factors—which all emerged repeatedly in empirical studies—is provided in Table 1.
See also
- Diathesis-stress modelDiathesis-stress modelThe diathesis–stress model is a psychological theory that explains behavior as a result of both biological and genetic vulnerability , and stress from life experiences....
- EndophenotypeEndophenotypeEndophenotype is a psychiatric concept and a special kind of biomarker. The purpose of the concept is to divide behavioral symptoms into more stable phenotypes with a clear genetic connection...
- Gene-environment interactionGene-environment interactionGene–environment interaction is the phenotypic effect of interactions between genes and the environment....
- Gene-environment correlationGene-environment correlationGene-environment correlation is said to occur when exposure to environmental conditions depends on an individual's genotype.-Definition:...
- GenotypeGenotypeThe genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
- Highly sensitive personHighly sensitive personA highly sensitive person is a person having the innate trait of high psychological sensitivity . According to Elaine N...
- Hypothalamic-pituitary-adrenal axisHypothalamic-pituitary-adrenal axisThe hypothalamic-pituitary-adrenal axis , also known as thelimbic-hypothalamic-pituitary-adrenal axis and, occasionally, as the hypothalamic-pituitary-adrenal-gonadotropic axis, is a complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland ,...
- Norms of reactionNorms of reactionIn ecology and genetics, a norm of reaction describes the pattern of phenotypic expression of a single genotype across a range of environments. One use of norms of reaction is in describing how different species—especially related species—respond to varying environments...
- PhenotypePhenotypeA phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
- ResiliencePsychological resilienceResilience in psychology refers to the idea of an individual's tendency to cope with stress and adversity. This coping may result in the individual “bouncing back” to a previous state of normal functioning, or using the experience of exposure to adversity to produce a “steeling effect” and function...
- TemperamentTemperamentIn psychology, temperament refers to those aspects of an individual's personality, such as introversion or extroversion, that are often regarded as innate rather than learned...