Cumulative culture and explicit metacognition: a review of theories, evidence and key predictions

A variety of different proposals have attempted to explain the apparent uniqueness of human cumulative culture as a consequence of underlying mechanisms that are also assumed to be uniquely well-developed in humans. Recently, Heyes and colleagues have proposed explicit (or Type 2) metacognition as a key feature of human cognition that might enable cumulative culture. In the current review we examine these arguments, and consider their plausibility. Firstly we consider whether distinctions between cognitive processes described as explicit/implicit, and Type 1/2 (or Systems 1/2), do indeed capture features that distinguish processes specific to human cognition, versus those that are shared with other species. In particular we consider whether this applies to distinctions relating to metacognitive processes. We also consider the ways in which explicit metacognitive processing might plausibly facilitate cumulative culture. We categorise the potential benefits as either optimising receiver behaviour, or optimising sender behaviour. Within both of these categories benefits could arise as a consequence of more effective representation of either one’s own knowledge state, or that of others. We evaluate the current state of evidence supporting each of these potential benefits. We conclude by proposing methodological approaches that could be used to directly test the theory, and also identify which (if any) of the possible causal mechanisms may be implicated

Human teaching and cumulative cultural evolution

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 648841 RATCHETCOG ERC-2014-CoG.Although evidence of teaching behaviour has been identified in some nonhuman species, human teaching appears to be unique in terms of both the breadth of contexts within which it is observed, and in its responsiveness to needs of the learner. Similarly, cultural evolution is observable in other species, but human cultural evolution appears strikingly distinct. This has led to speculation that the evolutionary origins of these capacities may be causally linked. Here we provide an overview of contrasting perspectives on the relationship between teaching and cultural evolution in humans, and briefly review previous research which suggests that cumulative culture (here meaning cultural evolution featuring a trend towards improving functionality) can occur without teaching. We then report the results of a novel experimental study in which we investigated how the benefits of teaching may depend on the complexity of the skill to be acquired. Participants were asked to tie knots of varying complexity. In our Teaching condition, opportunities to interact with an experienced partner aided transmission of the most complex knots, but not simpler equivalents, relative to exposure to completed products alone (End State Only condition), and also relative to information about the process of completion (Intermediate States condition). We conclude by considering the plausibility of various accounts of the evolutionary relationship between teaching and cultural evolution in humans.Publisher PDFPeer reviewe

Inferring behavior from partial social information plays little or no role in the cultural transmission of adaptive traits

This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No. 648841 RATCHETCOG ERC‐2014‐CoG.Many human cultural traits become increasingly beneficial as they are repeatedly transmitted, thanks to an accumulation of modifications made by successive generations. But how do later generations typically avoid modifications which revert traits to less beneficial forms already sampled and rejected by earlier generations? And how can later generations do so without direct exposure to their predecessors' behavior? One possibility is that learners are sensitive to cues of non‐random production in others' behavior, and that particular variants (e.g., those containing structural regularities unlikely to occur spontaneously) have been produced deliberately and with some effort. If this non‐random behavior is attributed to an informed strategy, then the learner may infer that apparent avoidance of certain possibilities indicates that these have already been sampled and rejected. This could potentially prevent performance plateaus resulting from learners modifying inherited behaviors randomly. We test this hypothesis in four experiments in which participants, either individually or in interacting dyads, attempt to locate rewards in a search grid, guided by partial information about another individual's experience of the task. We find that in some contexts, valid inferences about another's behavior can be made from partial information, and these inferences can be used in a way which facilitates trait adaptation. However, the benefit of these inferences appears to be limited, and in many contexts—including some which have the potential to make inferring the experience of another individual easier—there appears to be no benefit at all. We suggest that inferring previous behavior from partial social information plays a minimal role in the adaptation of cultural traits.Publisher PDFPeer reviewe

Action-matching biases in monkeys (Sapajus spp.) in a stimulus-response compatibility task: Evaluating experience-dependent malleability

Stimulus-response compatibility effects occur when observing certain stimuli facilitate the performance of a related response and interfere with performing an incompatible or different response. Using stimulus-response action pairings, this phenomenon has been used to study imitation effects in humans, and here we use a similar procedure to examine imitative biases in non-human primates. Eight capuchin monkeys (Sapajus spp.) were trained to perform hand and mouth actions in a stimulus-response compatibility task. Monkeys rewarded for performing a compatible action (i.e., using their hand or mouth to perform an action after observing an experimenter use the same effector) performed significantly better than those rewarded for incompatible actions (i.e., performing an action after observing an experimenter use the other effector), suggesting an initial bias for imitative action over an incompatible S-R pairing. After a predetermined number of trials, reward contingencies were reversed; i.e., monkeys initially rewarded for compatible responses were now rewarded for incompatible responses, and vice versa. In this second training stage no difference in performance was identified between monkeys rewarded for compatible or incompatible actions, suggesting any imitative biases were now absent. In a second experiment, two monkeys learned both compatible and incompatible reward contingencies in a series of learning reversals. Overall, no difference in performance ability could be attributed to the type of rule (compatible/incompatible) being rewarded. Together, these results suggest that monkeys exhibit a weak bias towards action copying, which (in line with findings from humans) can largely be eliminated through counter-imitative experience

APC mutations lead to cytokinetic failures in vitro and tetraploid genotypes in Min mice

Previous research has proposed that genomic instability contributes to cancer progression, with its initiation linked to tetraploid cell formation (Duesberg, P., and R. Li. 2003. Cell Cycle. 2:202–210; Ganem, N.J., Z. Storchova, and D. Pellman. 2007. Curr. Opin. Genet. Dev. 17:157–162). However, there is little direct evidence linking cancer-causing mutations with such events, and it remains controversial whether genomic instability is a cause or an effect of cancer. In this study, we show that adenomatous polyposis coli (APC) mutations found in human colorectal cancers dominantly inhibit cytokinesis by preventing mitotic spindle anchoring at the anaphase cortex and, thus, blocking initiation of the cytokinetic furrow. We find that dividing crypt cells in the small intestines of APCMin/+ mice exhibit similar mitotic defects, including misoriented spindles and misaligned chromosomes. These defects are observed in normal crypt cells with wild-type levels of β-catenin and, importantly, are associated with tetraploid genotypes. We provide direct evidence that the dominant activity of APC mutants induces aneuploidy in vivo. Our data support a model whereby tetraploid cells represent a first step in the onset of genomic instability and colorectal cancer

Persistence of contrasting traditions in cultural evolution: Unpredictable payoffs generate slower rates of cultural change

We report an experimental test of the hypothesis that contrasting traditions will persist for longer, maintaining cultural differences between otherwise similar groups, under conditions of uncertainty about payoffs from individual learning. We studied the persistence of two alternative, experimentally-introduced, task solutions in chains of human participants. In some chains, participants were led to believe that final payoffs would be difficult to predict for an innovative solution, and in others, participants were aware that their final payoff would be directly linked to their immediate solution. Although the difference between the conditions was illusory (only participants' impressions were manipulated, not actual payoffs) clear differences were found between the conditions. Consistent with predictions, in the chains that were less certain about final payoffs, the distinctive variants endured over several replacement "generations" of participants. In contrast, in the other chains, the influence of the experimentally-introduced solutions was rapidly diluted by participants' exploration of alternative approaches. The finding provides support for the notion that rates of cultural change are likely to be slower for behaviors for which the relationship between performance and payoff may be hard to predict

Increasing population size can inhibit cumulative cultural evolution

The extent to which larger populations enhance cumulative cultural evolution (CCE) is contentious. We report a large-scale experiment (n = 543) that investigates the CCE of technology (paper planes and their flight distances) using a transmission-chain design. Population size was manipulated such that participants could learn from the paper planes constructed by one, two, or four models from the prior generation. These social-learning conditions were compared with an asocial individual-learning condition in which individual participants made repeated attempts at constructing a paper plane, without having access to any planes produced by other participants. Larger populations generated greater variation in plane performance and gave participants access to better-adapted planes, but this did not enhance CCE. In fact, there was an inverse relationship between population size and CCE: plane flight distance did not improve over the experimental generations in the 2-Model and 4-Model conditions, but did improve over generations in the 1-Model social-learning condition. The incremental improvement in plane flight distance in the 1-Model social-learning condition was comparable to that in the Individual Learning condition, highlighting the importance of trial-and-error learning to artifact innovation and adaptation. An exploratory analysis indicated that the greater variation participants had access to in the larger populations may have overwhelmed their working memory and weakened their ability to selectively copy the best-adapted plane(s). We conclude that larger populations do not enhance artifact performance via CCE, and that it may be only under certain specific conditions that larger population sizes enhance CCE

Reply to Martens: Various factors may enable large populations to enhance cumulative cultural evolution, but more evidence is needed

Martens (1) suggests that including model-based bias (e.g., prestige) in our experiment would have enhanced cumulative cultural evolution (CCE) in the larger populations reported in our paper (2). This is a plausible hypothesis, but not one our experiment was designed to test. Given the controversy around the relationship between population size and CCE (3), our experiment was designed to isolate the basic effect of population size on CCE by excluding extraneous factors, including model-based bias. In our experiment increasing population size did not enhance CCE. We do not conclude that larger populations do not enhance CCE but that other factors may be necessary to see this benefit.Output Type: Lette

Automatic imitation effects are influenced by experience of synchronous action in children

By their fourth year children are expert imitators but it is unclear how this ability develops. One approach suggests that certain types of experience might forge associations between the sensory and motor representations of an action that might facilitate imitation at a later time. Sensorimotor experience of this sort may occur when an infant’s action is imitated by a caregiver or when socially synchronous action occurs. This learning approach therefore predicts that the strength of sensory-motor associations should depend on the frequency and quality of previous experience. Here, we tested this prediction by examining automatic imitation; i.e., the tendency of an action stimulus to facilitate the performance of that action and interfere with the performance of an incompatible action. We required children (aged between 3:8 and 7:11) to respond to actions performed by an experimenter (e.g., two hands clapping), with both compatible actions (i.e., two hands clapping) and incompatible actions (i.e., two hands waving) at different stages in the experimental procedure. As predicted by a learning account, actions thought to be performed in synchrony (i.e., clapping/waving) produced stronger automatic imitation effects when compared to actions where previous sensorimotor experience is likely to be more limited (e.g., pointing/hand closing). Furthermore, these automatic imitation effects were not found to vary with age, as both compatible and incompatible responses quickened with age. These findings suggest a role for sensorimotor experience in the development of imitative ability

Studying cumulative cultural evolution in the laboratory

Cumulative cultural evolution is the term given to a particular kind of social learning, which allows for the accumulation of modifications over time, involving a ratchet-like effect where successful modifications are maintained until they can be improved upon. There has been great interest in the topic of cumulative cultural evolution from researchers from a wide variety of disciplines, but until recently there were no experimental studies of this phenomenon. Here we describe our motivations for developing experimental methods for studying cumulative cultural evolution, and review results we have obtained using these techniques. The results that we describe have provided insights into understanding the outcomes of cultural processes at the population level. Our experiments show that cumulative cultural evolution can result in adaptive complexity in behaviour, and also can also produce convergence in behaviour. These findings lend support to ideas that some behaviours commonly attributed to natural selection and innate tendencies could in fact be shaped by cultural processes