Richerson et al.'s discussion rightly characterizes social learning as one of the key facilitators of cultural group selection (CGS). While we agree with the idea that social learning is essential for cultural inheritance, and serves as a source of cultural variation and selection, we believe that the authors' discussion has underspecified the significant role of the rational, critical, and selective social learner in these evolutionary processes.
We would first like to note that behavioral imitation, which the authors focus on, is not the only form of social learning that could reduce intergroup cultural variation. Cultural variation between groups is a starting point not only for the spread of group-beneficial behaviors but also for group-beneficial beliefs, ideas, or concepts. Contact with out-group scientific knowledge, for example, could result in the adoption of this cultural information by less successful groups. In such cases, learning would not be primarily imitative in nature – one could not describe cross-cultural learning about microbes, for example, as primarily imitative in nature, and yet this has reduced between-group variation in cultural beliefs about the unseen causes of disease.
That said, the selective social learner is influenced by factors beyond those cited by Richerson et al. (those being a penchant for conformity, the sway of prestige, affinity for cultural norms, or group membership biases). A growing body of developmental research characterizes even the youngest social learners as active participants in the learning process, whose selectivity can act to preserve or cull testimonial information on the basis of its accuracy, support, and coherence with other beliefs (Stephens et al. Reference Stephens, Suárez and Koenig2015). These belief-formation processes are supported by children's rapid assessments of others' competence, expertise and trustworthiness. Monitoring the content and coherence of messages protects learners against misinformation, alerting them to conflicts between incoming messages and their already established knowledge and beliefs (Mercier & Sperber Reference Mercier and Sperber2011). For example, infants detect overt labeling errors and anomalous referential actions (Gliga & Csibra Reference Gliga and Csibra2009). They expect humans with appropriate information to speak truthfully, and actively correct inaccurate labelers (Koenig & Echols Reference Koenig and Echols2003). In imitation research, children have been found to give priority to the approach taken by a successful individual over an unsuccessful group, showing that in learning actions, successful outcomes often trump conventional means (Scofield et al. Reference Scofield, Gilpin, Pierucci and Morgan2013; Seston & Kelemen Reference Seston and Kelemen2014; Wilks et al. Reference Wilks, Collier-Baker and Nielsen2015). Further research suggests that the detection of inaccuracy might lead to enhanced memory for incompetent sources and poor memory for the information they present (Corriveau & Harris Reference Corriveau and Harris2009; Koenig & Woodward Reference Koenig and Woodward2010; Sabbagh & Shafman Reference Sabbagh and Shafman2009).
Even more relevant to CGS, research in this field suggests that children make rational learning decisions on the basis of whether or not the messages they receive from informants violate their existing understanding of the world (Sobel & Kushnir Reference Sobel and Kushnir2013). Preschoolers, for example, have been known to preferentially learn from more expert (Koenig & Harris Reference Koenig and Harris2005; Koenig & Jaswal Reference Koenig and Jaswal2011), more grammatically proficient (Corriveau et al. Reference Corriveau, Pickard and Harris2011; Sobel & Macris Reference Sobel and Macris2013), and logically consistent informants (Doebel et al. Reference Doebel, Koenig and Rowell2011). They also flexibly adjust their trust in informants' testimony based on their understanding of what is improbable and impossible (Corriveau et al. Reference Corriveau, Chen and Harris2014; Shtulman & Carey Reference Shtulman and Carey2007; Woolley & Ghossainy Reference Woolley and E Ghossainy2013). Young learners' reliance on their own understanding of what is correct, true, or possible should not be underestimated: Their preferences for native-accented speakers (Corriveau et al. Reference Corriveau, Kinzler and Harris2013), adults (Jaswal & Neely Reference Jaswal and Neely2006), and familiar speakers (Corriveau & Harris Reference Corriveau and Harris2009) are reversed if they learn that such sources have proven inaccurate. This is not to say that children are always critical in the face of message conflicts: Preschoolers have been found to trust a deceptive adult who provides inaccurate information about an object's location (Jaswal Reference Jaswal2010; Jaswal et al. Reference Jaswal, Croft, Setia and Cole2010). Interestingly, this may be because preschoolers are more sensitive to violations of commonly held cultural knowledge (Stephens & Koenig Reference Stephens and Koenig2015; Koenig & Stephens Reference Koenig, Stephens, Robinson and Einav2014).
As children develop, they incorporate their growing knowledge and experience about speakers and the world to evaluate new information. Considerations about message coherence and plausibility are taken into account along with other factors – including, as Richerson et al. mention, informant prestige, cultural conventions, conformity, normativity, group membership, and so on. We suspect that children appraise social learning situations based on their recognition of both cultural and epistemic norms, with priority afforded to each based on the situation (Hodges Reference Hodges2014), type of testimony or information being exchanged (Stephens & Koenig Reference Stephens and Koenig2015), and the values endorsed in their environment (Reifen Tagar et al. Reference Reifen Tagar, Federico, Lyons, Ludeke and Koenig2014).
How exactly does this selective learner play a role in CGS? Richerson et al. describe three forms of social learning that help maintain or reduce group-level cultural variation: (1) accurate, rapid social learning; (2) conformist social learning, described as mechanisms that maintain intergroup variation of cultural norms and behaviors; and (3) selective imitation of cultural behaviors, described as a process by which intergroup variation is reduced. Along these lines, we would argue that the selective learner's ability to critically evaluate cultural information on the basis of its accuracy, support, and coherence contributes to CGS in two main ways. First, as previously described, the social learner can reduce intergroup cultural variation by rationally evaluating out-group cultural information and adopting that which is deemed to be not only useful, but reliable. Second, the selective social learner is able to ensure accurate cultural transmission not only through imitative or conformist strategies, but also by evaluating various forms of cultural information on the bases of accuracy, logic, and internal coherence. Thus, when a 16-month-old corrects an informant who labels a shoe as a ball, upholding culturally specific labels, what may appear to be an early tendency toward conformity may involve critical appraisals of messages, along with epistemic inferences about the informant.
In sum, we suggest that Richerson and colleagues take into further consideration the role of the rational and selective social learner, who can critically evaluate cultural information and adjust their own learning accordingly.
Richerson et al.'s discussion rightly characterizes social learning as one of the key facilitators of cultural group selection (CGS). While we agree with the idea that social learning is essential for cultural inheritance, and serves as a source of cultural variation and selection, we believe that the authors' discussion has underspecified the significant role of the rational, critical, and selective social learner in these evolutionary processes.
We would first like to note that behavioral imitation, which the authors focus on, is not the only form of social learning that could reduce intergroup cultural variation. Cultural variation between groups is a starting point not only for the spread of group-beneficial behaviors but also for group-beneficial beliefs, ideas, or concepts. Contact with out-group scientific knowledge, for example, could result in the adoption of this cultural information by less successful groups. In such cases, learning would not be primarily imitative in nature – one could not describe cross-cultural learning about microbes, for example, as primarily imitative in nature, and yet this has reduced between-group variation in cultural beliefs about the unseen causes of disease.
That said, the selective social learner is influenced by factors beyond those cited by Richerson et al. (those being a penchant for conformity, the sway of prestige, affinity for cultural norms, or group membership biases). A growing body of developmental research characterizes even the youngest social learners as active participants in the learning process, whose selectivity can act to preserve or cull testimonial information on the basis of its accuracy, support, and coherence with other beliefs (Stephens et al. Reference Stephens, Suárez and Koenig2015). These belief-formation processes are supported by children's rapid assessments of others' competence, expertise and trustworthiness. Monitoring the content and coherence of messages protects learners against misinformation, alerting them to conflicts between incoming messages and their already established knowledge and beliefs (Mercier & Sperber Reference Mercier and Sperber2011). For example, infants detect overt labeling errors and anomalous referential actions (Gliga & Csibra Reference Gliga and Csibra2009). They expect humans with appropriate information to speak truthfully, and actively correct inaccurate labelers (Koenig & Echols Reference Koenig and Echols2003). In imitation research, children have been found to give priority to the approach taken by a successful individual over an unsuccessful group, showing that in learning actions, successful outcomes often trump conventional means (Scofield et al. Reference Scofield, Gilpin, Pierucci and Morgan2013; Seston & Kelemen Reference Seston and Kelemen2014; Wilks et al. Reference Wilks, Collier-Baker and Nielsen2015). Further research suggests that the detection of inaccuracy might lead to enhanced memory for incompetent sources and poor memory for the information they present (Corriveau & Harris Reference Corriveau and Harris2009; Koenig & Woodward Reference Koenig and Woodward2010; Sabbagh & Shafman Reference Sabbagh and Shafman2009).
Even more relevant to CGS, research in this field suggests that children make rational learning decisions on the basis of whether or not the messages they receive from informants violate their existing understanding of the world (Sobel & Kushnir Reference Sobel and Kushnir2013). Preschoolers, for example, have been known to preferentially learn from more expert (Koenig & Harris Reference Koenig and Harris2005; Koenig & Jaswal Reference Koenig and Jaswal2011), more grammatically proficient (Corriveau et al. Reference Corriveau, Pickard and Harris2011; Sobel & Macris Reference Sobel and Macris2013), and logically consistent informants (Doebel et al. Reference Doebel, Koenig and Rowell2011). They also flexibly adjust their trust in informants' testimony based on their understanding of what is improbable and impossible (Corriveau et al. Reference Corriveau, Chen and Harris2014; Shtulman & Carey Reference Shtulman and Carey2007; Woolley & Ghossainy Reference Woolley and E Ghossainy2013). Young learners' reliance on their own understanding of what is correct, true, or possible should not be underestimated: Their preferences for native-accented speakers (Corriveau et al. Reference Corriveau, Kinzler and Harris2013), adults (Jaswal & Neely Reference Jaswal and Neely2006), and familiar speakers (Corriveau & Harris Reference Corriveau and Harris2009) are reversed if they learn that such sources have proven inaccurate. This is not to say that children are always critical in the face of message conflicts: Preschoolers have been found to trust a deceptive adult who provides inaccurate information about an object's location (Jaswal Reference Jaswal2010; Jaswal et al. Reference Jaswal, Croft, Setia and Cole2010). Interestingly, this may be because preschoolers are more sensitive to violations of commonly held cultural knowledge (Stephens & Koenig Reference Stephens and Koenig2015; Koenig & Stephens Reference Koenig, Stephens, Robinson and Einav2014).
As children develop, they incorporate their growing knowledge and experience about speakers and the world to evaluate new information. Considerations about message coherence and plausibility are taken into account along with other factors – including, as Richerson et al. mention, informant prestige, cultural conventions, conformity, normativity, group membership, and so on. We suspect that children appraise social learning situations based on their recognition of both cultural and epistemic norms, with priority afforded to each based on the situation (Hodges Reference Hodges2014), type of testimony or information being exchanged (Stephens & Koenig Reference Stephens and Koenig2015), and the values endorsed in their environment (Reifen Tagar et al. Reference Reifen Tagar, Federico, Lyons, Ludeke and Koenig2014).
How exactly does this selective learner play a role in CGS? Richerson et al. describe three forms of social learning that help maintain or reduce group-level cultural variation: (1) accurate, rapid social learning; (2) conformist social learning, described as mechanisms that maintain intergroup variation of cultural norms and behaviors; and (3) selective imitation of cultural behaviors, described as a process by which intergroup variation is reduced. Along these lines, we would argue that the selective learner's ability to critically evaluate cultural information on the basis of its accuracy, support, and coherence contributes to CGS in two main ways. First, as previously described, the social learner can reduce intergroup cultural variation by rationally evaluating out-group cultural information and adopting that which is deemed to be not only useful, but reliable. Second, the selective social learner is able to ensure accurate cultural transmission not only through imitative or conformist strategies, but also by evaluating various forms of cultural information on the bases of accuracy, logic, and internal coherence. Thus, when a 16-month-old corrects an informant who labels a shoe as a ball, upholding culturally specific labels, what may appear to be an early tendency toward conformity may involve critical appraisals of messages, along with epistemic inferences about the informant.
In sum, we suggest that Richerson and colleagues take into further consideration the role of the rational and selective social learner, who can critically evaluate cultural information and adjust their own learning accordingly.