the process of neoteny. We speculate that the delaying of brain maturity, particularly in the frontal brain regions, may be a neotenous feature present in some shy individuals, which serves as a putative mechanism linking shyness and adaptive behavior.
Although it is difficult to empirically test ultimate and evolutionary explanations of behavior, as reviewed in the series of EEG studies above, we have begun to explore the proximate explanation using EEG measures to index brain maturation and emotion regulatory processes underlying adaptive shyness. We have also recently begun to explore more proximate hypotheses of the adaptive nature of shyness by examining adaptive processes in the shy brain using perceptual tasks. Here we adapt shy individuals to affective faces varying in emotional expressions and examine their corresponding afterimages to that particular emotion. For example, after adapting to a positive facial expression (e.g., happy faces), the typical visual afterimage that follows is to perceive a negative facial expression (e.g., angry face), while after adapting to a negative facial expression (e.g., angry face), the typical visual afterimage that follows is to perceive a positive facial expression (e.g., happy face). However, there appear to be individual differences in the experience of these afterimages. We found that young adults who had high levels of both shyness and sociability were more likely to perceive a negative face emotion afterimage after adapting to happy faces and a positive face emotion afterimage after adapting to angry faces than young adults classified by other combinations of high and low shyness and sociability (Poole et al., 2020). These findings suggest that the experiences of these afterimages appear to be linked to personality and may be a window into understanding individual differences in how well the brain adapts to social stimuli, with some shy subtypes possibly showing an advantage in adapting to these social stimuli.
Future research could test the proposed shyness‐neoteny hypothesis in several ways (see Schmidt & Poole, 2019). First, if there are indeed maturational delays associated with some types of shyness, then perhaps these delays would be evidenced on epigenetic markers of aging, which could be examined. Second, to the extent that neoteny may have allowed for prolonged learning to take place, then there may be differences in learning and memory among some types of shyness in different social contexts that could be examined. Lastly, the shyness‐neoteny hypothesis could be tested between the sexes for preferences across a range of stimuli, for example, people expressing neotenous features (e.g., coyness, youthful smiles) and characteristics of some types of shyness could be judged for attraction and interpersonal likeability.
Conclusion
In this chapter, we considered the evolutionary and neuroscientific basis for shyness. More specifically, we discussed the adaptive aspects of different subtypes of shyness, the putative function of these subtypes, some of the regulatory mechanisms of shyness subtypes, and how these mechanisms maybe instantiated in the brain. We put forth a speculate hypothesis that some types of shyness may be adaptive and linked to a delaying of brain maturation (i.e., neoteny). This delaying of maturation may have served an important function in our evolutionary past as humans began to evolve, our neocortex grew larger, and social interactions became more complex in that it may have allowed some individuals more time for additional learning to take place about the intentions and motives of conspecifics. To that end, in some sense, the shy brain has remained forever young.
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