Environmental sensitivity describes the ability of an individual to perceive and process information about their environment. It is a basic trait found in many organisms that enables an individual to adapt to different environmental conditions. Levels of Environmental Sensitivity often vary considerably from individual to individual, with some being more and others less sensitive to the same conditions. Such differences have been observed across many species such as pumpkinseed fish, zebra finches, mice, non-human primates and humans, indicating that there is a biological basis to differences in sensitivity.
Theoretical background
The concept of Environmental Sensitivity integrates multiple theories on how people respond to negative and positive experiences. These include the frameworks of Diathesis-stress model and Vantage Sensitivity, as well as the three leading theories on more general sensitivity: Differential Susceptibility, Biological Sensitivity to Context, and Sensory processing sensitivity (see Figure 1 for an illustration of the different models). These will be described briefly in turn, before presenting the integrative theory of Environmental Sensitivity in more detail.
Diathesis-stress
According to the long-standing Diathesis-stress model, people differ in their response to adverse experiences and environments, with some individuals more negatively affected by environmental stressors than others. The model proposes that such differences in response result from the presence of "vulnerability" factors, which include psychological (e.g., impulsive personality), physiological (e.g., high physiological reactivity) and genetic factors (e.g., genetic variation in the serotonin transporter [5-HTTLPR short allele]). In other words, the model suggests that individuals carrying certain vulnerability factors are at greater risk of developing problems when exposed to adverse environments. While the Diathesis-stress model is helpful in understanding differences in response to negative stressors, it does not consider or describe differences in response to positive experiences.
Vantage sensitivity
The vantage sensitivity framework was developed in 2013 by Michael Pluess and Jay Belsky to describe individual differences in response to positive experiences and environments. While some people appear to benefit particularly strongly from positive experiences (e.g., positive parenting, supportive relationships, psychological interventions), others appear to benefit less. Although a relatively new concept, a growing number of studies provides evidence to support the framework. While the Vantage Sensitivity framework considers individual differences in response to positive experiences, it does not make predictions about the response to negative experiences.
Differential susceptibility
Differential susceptibility, proposed by Jay Belsky, brings the differential responses to both positive and negative experiences together in one single model. Grounded in evolutionary theory, Belsky and colleagues sought to understand why and how children differ so fundamentally in their developmental response to external influences, with some being more and others less susceptible. Importantly, the theory finds that more susceptible individuals are not only more negatively affected by adverse experiences (as described in the Diathesis-stress model) but also particularly positively affected by the presence of favourable conditions (as described in the Vantage Sensitivity model). According to empirical studies, Differential Susceptibility is associated with various genetic, physiological and psychological factors, some of which are described below (see Empirical Evidence). Although early research suggested that differences in individuals' susceptibility are rooted in genetic factors, more recent research has shown that susceptibility is also influenced by prenatal and early postnatal environmental factors.
Biological Sensitivity to Context
The theory of Biological Sensitivity to Context by Tom Boyce and Bruce Ellis is based on evolutionary thinking and proposes that an individual's sensitivity to the environment is shaped by the quality of early life experiences. For example, particularly negative or especially positive childhood environments are understood to predict greater physiological reactivity later in life. In contrast, sensitivity is expected to be lowest for individuals with childhood environments that were neither extremely beneficial nor extremely adverse.