Although the evolutionary story that Henrich and Gil-White offer seems plausible on its face, particularly when brought to life with examples of modern-day prestigious individuals, when we dig deeper we see that in order for the prestige bias account to have explanatory force, it entails a set of particular commitments, for which the empirical evidence is mixed. Once we relax these commitments, it becomes difficult to make the case for the explanatory power of prestige bias accounts over, for example, a naive goal-directed agent explanation.
I will highlight issues that fall into two broad themes: firstly, that empirical evidence in support of prestige bias uses a concept of prestige that is pruned in deference to prestige bias theory, in a way which casts doubt upon the extent to which this work constitutes evidence in support of prestige bias, and secondly, that the prestige bias account entails particular commitments regarding the cognitive basis of prestige bias, and the extent to which it will be flexible and sensitive to context. Both these themes have a direct impact on the comparison between a prestige bias account and a goal-directed agent account. This comparison will be drawn explicitly in Sect. 4.
Characterising prestige
The first key problem with the prestige bias account concerns the vagueness regarding how the concept of prestige is understood. Precisely what prestige is comprised of is not fully characterised in Henrich and Gil-White’s account, or indeed in other accounts of prestige bias. This is important to note, particularly when considering the evidence from empirical studies which use various proxies for prestige. There appears to be a disconnect between how prestige is understood within the Henrich and Gil-White account, how prestige is understood in general usage, and how prestige is operationalised in empirical work on prestige bias. In particular, the definition of prestige used in empirical work is often pruned in deference to the prestige bias account itself, calling into question the extent to which these studies can be used as evidence of prestige bias.
Henrich and Gil-White give a tentative ‘ethology’ of prestige, where they describe prestigious individuals as in control of the time spent with ‘subordinates’, having a free posture without grandstanding or violent gestures, and appearing confident yet self-deprecating. This is drawn in explicit contrast to dominance, where individuals rely on aggression and threat of physical force to maintain their rank. However, this is not comprehensive in that many individuals in a society may display these kinds of behaviours, without being regarded as ‘prestigious’. By this I mean that there are many individuals, at least in modern societies, that do not display either dominant (aggressive) behaviours, or subordinate (threatened or submissive) behaviours. They may project confidence in their interactions with others, and be in control of who they spend their time with, and yet not enjoy the status benefits we typically associate with prestige (and will not be named as prestigious by others). In fact, the observed behaviours of prestigious people may not differ from less prestigious people in any systematic way, other than that the behaviour of others may be modulated in the presence of people they consider prestigious.
Additionally, it is unclear to what extent their use of the term ‘prestigious’ lines up with the common usage of the term. They use the example of Stephen Hawking as a prestigious individual in modern-day society (which would line up with our common sense notions of prestige). However, the common-sense notion of a prestigious individual does not require that many people are looking to copy their behaviours or ideas.
In Henrich and Gil-White’s evolutionary story, the most prestigious individuals are measured by the individuals that most learners are seeking to copy. Even if prestige bias in modern-day societies operates differently than in ancestral environments, we would still minimally expect prestige bias to drive individuals to seek contact or opportunities for observation with prestigious models, and to be driven to preferentially copy them. It is therefore unclear whether the key component of prestige is deference from others and conferring of status onto prestigious individuals, or the seeking of prolonged access to and opportunities to copy from prestigious individuals from learners. We may expect these to often come apart.
The lack of a consistent conception or definition of prestige becomes a pressing issue when assessing the empirical evidence for the existence of prestige bias. In some lab-based studies prestige is measured by the number of people observing a model. In a 2012 study by Chudek et al. the ‘prestigious’ model was the one which was observed by two other individuals, while the other was not. Their measure of prestige is simply that other individuals are observing the model. Presumably this measure is chosen because of its relationship to the operation of prestige as described in the evolutionary origins story of Henrich and Gil-White: the number of people observing a model (and therefore paying deference benefits for access) was the low-cost cue that new learners could use. However, this appears to significantly differ from both common-sense notions of prestige, the identification of prestigious individuals in studies based in real world networks, and several examples or potential applications given in theoretical work.
A similar definition of prestige is used in a study by Atkisson et al. (2012), where participants were tasked to ‘design’ an arrowhead on a computer, with the opportunity to modify their design based on arrowheads which were presented alongside information regarding the ‘prestige’ of the individuals that designed them. Here prestige was represented by the time that four individuals spent examining the given arrowhead (generated randomly by the computer), where arrowheads designed by more prestigious individuals were examined by others for longer periods of time. In both the Chudek et al. and Atkisson et al. study, prestige is defined in a way that presupposes the concept of prestige given in Henrich and Gil-White’s account. To make use of an analogy, this is as if we are seeking to test the connection between depression and lower serotonin levels, and in our test we define depression as lower serotonin levels. We can therefore question the extent to which studies which define prestige in this way are in fact evidential support for prestige bias.
A study by Acerbi and Tehrani (2018) did use a definition of prestige which is congruent with our general notion of prestige, in their test of the relative role of content versus context biases in the selection of quotations. Quotations varied in their content, and also in their context (either by being associated with a popularity score, measuring conformist bias, or in the prestige of the individual they were attributed to, measuring prestige bias). Individuals were then asked to choose their preferred quote. They measured prestige by attributing quotes to either a famous individual (i.e., one we would generally consider prestigious), or to an unknown author. However, they did not find a statistically significant preference for quotes by more prestigious individuals.
Therefore, there appear to be, broadly, two definitions of prestige operating in the literature. There is the one found in much of the theoretical work, and in studies in small-scale societies, where prestige typically involves acknowledged success or skill in a given domain or domains, the payment of deference and of status-related goods. This may or may not coincide with other individuals seeking to observe and spend time with prestigious individuals, and seeking to copy their behaviours. Alternatively, there is the operative definition of prestige used in lab-based studies, which focuses around the number of individuals that observe a model. This can occur without any of the characteristics associated with prestige in the first sense.
The cognitive basis of prestige bias
In addition to the tension between definitions of prestige which affect our assessment of the empirical evidence for prestige bias, I will argue that prestige bias as understood by Henrich and Gil-White is dependent upon a particular understanding of social learning biases as unconscious or not amenable to reflective consideration.
There are broadly two ways to understand what ‘prestige bias’ refers to. The first is on a purely populational level, where we see a pattern towards copying the behaviours of more prestigious people, with no commitment to how this bias is realised on a cognitive level. The bias could be the product of intelligent reasoning and conscious thought, it could be implicit and automatic, it could have an affective dimension, or not. The second way is to place constraints on what this bias entails: for example, understanding it as a subpersonal, automatic, implicit process (which has implications for how it operates). Here, I will argue that, while it is tempting to take a populational view that avoids specific cognitive commitments, the explanatory value of prestige bias explanations is in part determined by what kind of cognitive processes the bias is constituted by.
Cecilia Heyes, in her 2018 book Cognitive Gadgets: the Cultural Evolution of Thinking, outlines two ways to conceptualise the mechanisms that make social learning selective (i.e. that give rise to biases such as prestige bias): the ‘strategic’ approach and the ‘attentional’ approach. The strategic approach implies that the selectivity occurs at the output stage: in the case of prestige bias, if an observer is exposed to two models performing different actions (one more prestigious than the other), she will encode both inputs, and then when confronted with a situation where she has to make a decision about which action to choose, she is more likely to choose the action performed by the prestigious individual. In this approach, the agent “uses” a strategy, which Heyes believes implies that this depends on reportable, high-level processes, rather than low-level, automatic processes. In contrast, the attentional approach asserts that selection occurs at the point of information reception: if an observer is exposed to two models performing different actions (one more prestigious than the other), she will attend more closely to the more prestigious model, and therefore will learn more about this action than the other. In this case the bias is due to the modulation of learning by low-level or automatic attentional processes, rather than the application of an explicit rule.
Heyes argues that those who adopt the strategic approach tend to assume that these domain-specific, high-order selective social learning bias are genetically inherited, and see prestige bias as a “cognitive instinct” (Heyes 2018, p. 87). She argues that it is in fact preferable to understand these kinds of social learning biases as what she terms ‘cognitive gadgets’, or metacognitive rules or strategies. These metacognitive strategies are likely to be culturally rather than genetically inherited, transmitted with fidelity and accuracy through training and socialisation, and may take highly domain-specific forms (such as the role ‘copy the boat builder with the largest fleet’). She claims that, while the attentional approach is plausible for a lot of social learning, especially in non-human species, the kind of social learning biases that make humans uniquely capable of cumulative culture involve this kind of metacognition.
If we understand prestige bias as implicit and automatic (or as a domain-general, attentional process), then the value of a ‘prestige bias’ explanation over a general ‘goal-directed agent’ explanation is evident. Not only do they differ in the cognitive details (prestige bias is subpersonal, not available to conscious deliberation and rational reflection), but they would also clearly differ in their predictions. For example, an individual with general prestige bias would show a tendency to copy the behaviours of a prestigious individual even in situations where skill did not correlate with prestige, and where copying the behaviour would not be an effective way of harnessing expertise. We would expect less flexibility, and less ability for individuals to reflect on and report on these biases. The differences in the explanatory capacity of these accounts will be elaborated on in the following section.
However, if we understand prestige bias using the strategic, or metacognitive approach, things become less clear. To take Heyes’ example of a metacognitive rule, ‘copy the boat builder with the largest fleet’, it is unclear how we would distinguish cognition and behaviour based on such a ‘rule’, compared to the intervention of general intelligence. For example, an individual may, upon conscious deliberation, decide that the copying the boat builder with the largest fleet is what is most likely to enable them to build the best boat. This may not be the same strategy they follow when building something else, and this strategy may change depending on circumstances. If this is the case, then it is not clear what the advantage is of conceptualising these behaviours as ‘rule’ or ‘strategy’-following. Heyes’ examples include the boat-builder, and ‘copy digital natives’ (i.e., copy those that we judge to have digital expertise) (2018, p. 82). We could think of similar rules for any kind of human decision-making, such as ‘copy the writing style of successful academics’. However, it is unclear that this constitutes a plausible reflection of human cognition. Heyes gives us no reason to identify certain behaviours as rule-following, and as examples of culturally evolved ‘cognitive gadgets’, over others.
Precisely what kinds of cognition underlie these biases matters. It matters because it will change the predictions of prestige bias explanations, which will either lie in contrast to or bear more similarities to goal-directed agent type explanations. An approach that remains agnostic to the cognitive underpinnings loses explanatory value. Imagine it were the case that we could understand individual behaviours just as well using a goal-directed agent type approach, understanding decisions through the goals and limitations of individual agents, but when seen from a populational level, a prestige bias pattern emerges (we find it is often effective to copy the most prestigious people). We could term this a prestige bias, but we would then lose what is distinctive from the existing accounts. We would lose the adaptive explanation for the emergence of prestige hierarchies, and an explanation for prestige that does not rely on general intelligence. It would be unclear why we should see prestige bias as an interesting explanation for behaviour, even if a pattern emerges at the populational level.
The context-sensitivity of prestige bias
Following from this, understanding prestige bias as an unconscious or implicit social learning rule results in certain predictions about how prestige bias operates. These predictions are crucial to the explanatory value of prestige bias. If prestige bias is highly context-sensitive and reliant on complex and shifting calculations carried out by individuals regarding who best to learn from, it becomes increasingly difficult to separate out its predictions from a goal-directed agent account. Lewens (2015), in his assessment of conformist bias, highlights the need for conformist bias to not simply be a tendency to copy the most common traits, but be a tendency for individuals to disproportionately copy the most common traits in a group. In the case of prestige bias, learners should be biased towards copying prestigious people over and above what we would expect from a general account of individuals as goal-directed agents. In an extreme case, if learners reason that in certain contexts prestige would be a useful cue, deploy it only when they believe it to be beneficial, and are able to articulate why they are relying on it in these cases, a prestige bias account would not offer anything distinctive over a goal-directed account. This would not support Henrich and Gil-White’s particular evolutionary story, and would call into question why we should understand population-level patterns of prestige-biased learning, if they exist, in terms of individuals holding this specific social learning bias, rather than the result of rational, reflective, goal-directed action.
Therefore, the explanatory value of prestige bias accounts is dependent upon the extent to which the tendency for learners to copy prestigious individuals is the result of reflective deliberation or goal-directed intent. One indication of this is the extent to which prestige bias is cross-domain. By this I mean that when learners copy the behaviour of prestigious individuals, they copy their behaviour in many respects, not just a very limited subset of behaviours that are directly responsible for adaptive outcomes.
The evolution of prestige bias is based on prestige as a low-cost cue for who is best to copy. In this scenario, it would be too costly (in terms of time, material resources, or potential for error), or difficult, to directly discern which behaviours are adaptive and copy these, rather than gaining prolonged access to a model in order to copy many behaviours. If individuals were able to hone in on the behaviours of successful models that are responsible for their success, then presumably cooperation of the model in providing proximity and interaction would play a far smaller role. Additionally, if learners are copying the adaptive behaviours prestigious individuals only in cases when it would be adaptive to do so, this behaviour could be explained by a goal-directed agent account. It would therefore be difficult to see the explanatory gains from positing prestige bias in particular to explain these phenomena.
At least in modern-day societies, it does not seem to be the case that individuals copy suites of behaviours and practices from the most prestigious individuals. We can see this more clearly by looking at some of the examples used. In the prestige bias literature, we find a mix of informal and formal examples. One often invoked example is the existence of celebrities. Authors frequently gesture at the ability for prestige bias to explain why people in modern-day societies have a tendency to copy the clothing choices of celebrities, amongst other things (e.g., Henrich 2001; Mesoudi 2009; Jiménez and Mesoudi 2019). However, prestige bias seems to be an ill-fitting explanation for this phenomenon in two ways. Firstly, many prestigious individuals are deferred to and given prestige by others who do not wish to copy them. As previously outlined, Henrich and Gil-White offer the example of Stephen Hawking as a prestigious individual. However, Stephen Hawking was regarded as ‘prestigious’ by a large number of people (who may well have paid him deference and other benefits of prestige), whilst we might imagine that only a very small number of people would be looking to copy his behaviours or ideas (most broadly, physicists). Secondly, celebrities who are copied are often strikingly not copied in domains that are responsible for their success. For example, many individuals might copy the style choices of Odell Beckham Jr., with no intention of trying to copy his American football skills, or the make-up of Kylie Jenner, without copying her business practices. If prestige bias is an unconscious or implicit bias towards copying prestigious people where learners cannot discern which behaviours are responsible for success, we would expect learners to copy all (or a large set of) the behaviours of a prestigious individual. In our evolutionary history, if prestige-biased learners selectively copied the non-adaptive traits of prestigious individuals whilst not copying the adaptive traits, prestige bias would not have been adaptive and would not have been culturally selected for.
Although it is outside the scope of this paper to defend a particular alternative explanation here, one possible explanation of the existence of prestigious individuals who are not generally copied from (such as Stephen Hawking) might be through a process of rational reflection. For example, individuals might value traits such as intelligence, and afford respect to those who they perceive as exemplifying these traits. Additionally, individuals may copy the style of someone like Kylie Jenner due to (in part) biologically and socially shaped aesthetic preferences. It is difficult to see how positing prestige bias explains features of the influence of celebrities in a way that intention-centred explanations cannot.
Additionally, empirical studies have found mixed evidence for the cross-domain action of prestige bias. Chudek et al. (2012) carried out studies where they claimed to find evidence of prestige-biased learning in children. In these studies they showed groups of children (around 4 years old) two adult female ‘models’ performing a series of actions. Firstly, they were shown the models making a choice between two objects. One model was being observed by two other individuals, who were not interacting with the model or each other, only gazing at the model (the ‘prestigious’ model). The other model was not being observed. Then, they were shown the same two models making a series of preferences: for example, picking toy A over toy B, or biscuit A over biscuit B. They were then given the opportunity to make choices between the two options themselves. They found that children were more likely to copy the choice of the ‘prestigious’ model, although this was significant for some domains and not others (in one study, for artifacts, but not for food or drink preferences, and in another, only for the domain that prestige was cued in).
Studies in small-scale societies have also found differences in the relevance of prestige in different domains, as well as the connection between prestige and age. Reyes-Garcia et al. (2008) studied connections between ethnomedicinal plant knowledge and prestige within an Amazonian group called the Tsimane’, and did not find a clear association between such plant knowledge and level of prestige, and no association between prestige and age. Another study in Fijian villages examined success, knowledge, and model selection for three socially valued domains: fishing, yam-growing, and ethnomedicinal plant use (Henrich and Broesch 2011). Success in fishing and yam-growing were far better predictors of prestige than ethnomedicinal plant knowledge. Additionally, they only found age to be a predictor of model selection for some domains in some samples, and individuals were more likely to select models of the opposite gender to their own. Prestige bias models predict that older individuals are more likely to be copied and to have prestige, due to an average increase in skill and knowledge, and that same-gender individuals are more likely to copied (in a society where what constitutes adaptive behaviours differs between genders).
Brand and Mesoudi (2019) found similar indications that prestige may be domain-specific. They investigated prestige and dominance hierarchies in groups of adults who had pre-existing relationships (they were members of established community groups, rather than participants placed into a new group for the purpose of a study). In their study, the prestige ratings of an individual given by their group members did not predict that individual’s performance on the group task they were set, or who was selected to represent the group for a bonus task. The selection of the group representative was based not on perceived prestige or dominance, but correlated with the individual’s actual performance in the group task.Footnote 1 The potential domain-specificity of prestige-biased learning, or who is accorded prestige, matters for the assessment of prestige bias as an explanation. If prestige-biased learning is highly domain-specific, this becomes easier to explain in terms of the goal-directedness of agents: individuals may be evaluating when it is appropriate to rely on prestige cues, and when it is not.
Jiménez and Mesoudi (2019), in their review of the prestige bias literature, note the mixed evidence for the specific predictions of the Henrich and Gil-White model. Given this, they suggest modifications to these predictions. These modifications include restricting the presence of prestige bias to cases where the domain of prestige is currently valued for a social group, where individuals carry out tasks which are domain-relevant and difficult, when the variation in knowledge and skill is large, and when prestige is highly correlated with success. Although these modifications bring the prestige bias account further into agreement with the empirical evidence, they do so at the expense of explanatory power. If prestige bias is no longer a general ‘rule-of-thumb’, deployed implicitly and unconsciously, biasing social learning in clear and systematic ways, but rather a highly context-dependent phenomenon that relies on individuals having access to large amounts of social information, it becomes more difficult to make the case that prestige bias offers explanatory benefits that a goal-directed agent account does not.
However, there is empirical work which does appear to suggest a prestige bias account over a goal-directed account. Firstly, evidence of overimitation, where people have a tendency to copy irrelevant actions carried out by prestigious individuals, is suggestive of a systematic bias that is not easily explained through intentional behaviour. McGuigan (2013) carried out a study in children that showed that they were more likely to overimitate when copying high social rank models than low social rank models. However, a study by Chudek et al. (2016) found no difference in the propensity to overimitate high versus low status models. Secondly, cases where individuals were not consciously aware of the effect of prestige in deciding who to learn from would speak in favour of prestige bias, as an unconscious or implicit bias, over a simple goal-directed account. Priestley and Mesoudi (2015) found that users of the social media website Reddit ranked ‘social influence’ low on the factors that drove them to ‘upvote’ or ‘downvote’ content. However, as they note, previous work has suggested that artificially adding ‘upvotes’ (which could be construed as a measure of social influence) significantly increased the chance of further ‘upvotes’ (Muchnik et al. 2013). If this is indicative of a broader pattern whereby individuals are not aware they are acting in a prestige-biased manner, this would support the prestige bias account over a goal-directed or intention-based explanation. Further work is needed to determine the extent to which prestige-biased patterns of learning are flexible and context-sensitive, and individuals are aware of the drivers of their decision-making.