In Experiment 2, we aimed to equate conditions with respect to the integrating theme or coherent narrative. What, however, should count as an ‘integrating theme’ or ‘coherent narrative?’ Mandler and Johnson (1977), Thorndyke (1977) and Rumelhart (1977) developed the idea, originally put forward by Bartlett (1932), that stories are particularly easy to remember because they form coherent narratives that can be represented by a hierarchical schema structure. It is unlikely, however, that a paragraph of approximately 60 words would have such a complex hierarchical structure, beyond a simple linear chain of events linked causally and temporally. For example, the pregnancy causes the professor to refuse to see Nancy, which then causes Nancy to threaten to tell his wife about the affair. In contrast, a chain that is linked temporally but not causally would simply be a list of unconnected events and lack coherence, while a chain that is linked causally but not temporally would not form a narrative. Each type of material used in Experiment 2 was therefore designed to constitute a comparable linear chain of events linked causally and temporally, so that superior recall of the gossip material can be more definitely attributed to its gossip-like content rather than its greater structural coherence, as was possible in Experiment 1.
Materials and Methods
The design of Experiment 2 was largely identical to that of Experiment 1, with 10 chains each comprising four participants again transmitting all types of material. There were three minor differences: first, there were four types of material (gossip, social, individual and physical) rather than three; second, the order in which this material was presented was now counterbalanced; and third, five of the chains were female, and five were male. None of the participants tested here took part in, or had any knowledge of, Experiment 1. All 40 participants were students, participated voluntarily, were unpaid and had normal reading and writing ability. Their mean age was 21.40 years (SD=3.83).
The original material given to the first participant in each chain is reproduced in Appendix B. The gossip information again featured an affair and pregnancy as its theme, although the information that Nancy is lying to her friends did not fit into the single linear chain, so was replaced with extra information at the end concerning the professor's wife leaving the professor. The social (non-gossip) information comprised a causal and temporal chain consisting of a series of social interactions and containing the same number of agents as the gossip, but without gossip-like content such as deception, infidelity and pregnancy. Individual information featured a chain consisting of interactions between a single character and the inanimate world. Finally, physical information contained no intentional agents in the chain, consisting entirely of interactions within a physical system.
To test whether each of the four types of material were comparable on dimensions other than the desired experimental manipulation of social content, 10 additional participants not involved in the experiment proper were given the four paragraphs (gossip, social, individual and physical) and asked to rate each of them on a 7-point scale for coherence, familiarity and realism. No significant differences were found between the paragraphs on any of these dimensions, suggesting that any differences found in Experiment 2 are unlikely to be due to differences in coherence, familiarity or realism, which had been a concern in Experiment 1.
The aim of the present study was to investigate whether there is a bias for social information in human cultural transmission, as predicted by evolutionary theories that posit a social origin for human intelligence. Experiment 1 found evidence that gossip-like social information is transmitted with significantly greater accuracy and in greater quantity than non-social information. Experiment 2 replicated this finding using material equivalent in narrative coherence, demonstrating that coherence was not responsible for the superior recall of the gossip. Experiment 2 also found that information concerning social interactions that would not be described as gossip was transmitted with an accuracy and in a quantity not significantly different from the gossip itself. That is, the gossip-like content of infidelity, deception and pregnancy was relatively unimportant; what mattered for superior transmission was that there were a number of third party social agents interacting with one another.
These results are therefore consistent with the Machiavellian intelligence (Byrne & Whiten, 1988; Whiten, 1999b; Whiten & Byrne, 1997) or the social brain (Dunbar, 1998, 2003) hypothesis that primate intelligence evolved primarily to deal with social, rather than ecological, information. Here, this is reflected in a social bias in cultural transmission. The results are also consistent with Dunbar's (1993, 1996) social gossip theory of language evolution that language evolved to exchange social information. A stronger form of the Machiavellian intelligence hypothesis, and theories that argue for a more negative, exploitative function of language (Enquist & Leimar, 1993; Wilson et al., 2000), were not supported, in that information commonly considered gossip-like in content was transmitted no better than equivalent non-gossip social information. Theories that argue that primate intelligence is the result of ecological selection pressures were also not supported, with information concerning the non-social environment transmitted poorly.
One possible objection to our interpretation of the results might be that the social material used in Experiment 2 (asking directions from strangers) was not ‘social’ in the sense of the Machiavellian intelligence hypothesis. That is, the relationships between the characters were not very meaningful and the characters were not exchanging information about themselves or other people. The broad Machiavellian intelligence hypothesis, however, predicts that any social interactions should be memorable, whatever their content or quality. There are still many potentially important social cues present, such as the personality of the character (e.g. their helpfulness) or the reliability of the information they give. This information can then be stored and used to negotiate future social interactions, which may be more complex. In any case, information which is intermediate between the social and the gossip material, featuring interactions more strongly Machiavellian than the social material (but not as strong or negative as the gossip material), would presumably be transmitted just as well as these two were in Experiment 2.
It might be argued that rather than being the result of a biologically evolved predisposition, the social bias seen here is the result of some related property of the material, such as its emotional impact or attentional salience. Various findings from the social psychological literature concerning memory might be used to account for some of our findings, such as that people have better recall for descriptions of behaviour that violates social norms (Wyer, Budesheim, Lambert, & Swan, 1994) for information that is incongruent with social expectations (Stangor & McMillan, 1992) and for negative self-discrepant in-group behaviour (Gramzow, Gaertner, & Sedikides, 2001). We do not, however, see these two types of explanation as in opposition. Properties such as arousing, salient or memorable represent the proximate mechanisms by which an evolved bias may operate. The two levels of explanation, ultimate and proximate, should be seen as separate and complementary (Tinbergen, 1963). Indeed, a full account of human cognition and behaviour requires empirical evidence from all explanatory levels.
It might also be argued that information about social relationships becomes particularly salient during development, causing such a bias to be learned. Again, however, this does not contradict an ultimate evolutionary argument for a biologically evolved predisposition or bias to learn and transmit certain types of information. To the contrary, the comparative evidence for the social brain hypothesis (Dunbar, 1995; Joffe, 1997) makes it likely that such a bias does indeed have an evolutionary basis at some stage of development. Nevertheless, developmental investigations would be useful in further clarifying the nature and origin of the social bias observed here.
A final objection might be that the transmission aspect of our study adds little to the findings of Owens et al. (1979) concerning recall at the individual level. Such an effect was already apparent in our first generation recall, where single participants recalled social information better than non-social information. However, a bias in memory or recall and a bias in transmission are not alternative or opposing phenomena. The long-term transmission bias does of course reflect a memory bias, but its significance is that it uniquely documents the cumulative operation of that memory bias in successive participants, providing an experimental microcosm for the study of cultural, as opposed to merely cognitive (memory) processes. Furthermore, the assumption that a consistent effect will be observed along an extended chain is just that — an assumption — which should be empirically tested. Indeed, previous transmission chain studies (e.g. Kashima, 2000a; Mesoudi & Whiten, 2004) have demonstrated crossover effects in which later generations reverse a trend exhibited by earlier generations.
Data on persistence consequently allow us to draw conclusions regarding the wider effect of a social bias on human culture in general. As noted by Kashima (2000b), Bartlett (1932) was interested not only in cultural transmission, but also large-scale cultural change, and Kashima suggests that the transmission chain method ‘provides one way of examining how micro-processes contribute to a macro-phenomenon such as the maintenance of culture’ (p. 394). We may speculate that the bias for social information found here can be extrapolated to the population level, to explain the popularity of socially oriented mass media such as gossip magazines and television soap operas over non-social or factual journals and television documentaries. There are a number of theoretical frameworks that might be used to make this link more formally, such as Moscovici's (1984) social representation theory, Sperber's (1996) epidemiological model of cultural change and theories of cultural evolution (Boyd & Richerson, 1985; Cavalli-Sforza & Feldman, 1981; Mesoudi, Whiten, & Laland, 2004, in press). Space does not permit us to examine these in any detail here.
As noted by Emler (2001), there has been very little experimental work on gossip in the past. Hence, this study was intended to be an initial investigation of the phenomenon under very simplified conditions. There are undoubtedly a number of factors not examined here that probably play an important role in the transmission of social information in the real world, and we hope that future work will systematically examine such factors. For example, our participants were not instructed that the experiment was a memory test, that the material had come from another participant, or that their recall would be passed on to another participant. The third parties described in the material were also not known to the participants. Given that it is well established that people often tailor their messages to suit the intended receiver (Sperber & Wilson, 1986), providing such information may well affect the content or accuracy of recall. Similarly, transmitting the material face-to-face rather than via anonymous written text would allow the investigation of interpersonal factors such as intonation of voice or non-verbal cues.
The conclusions drawn here are dependent on the specific material used, and there is a need to replicate the study with alternative examples of the different types of information. In Experiment 2, we strove to ensure that the four material types contained equivalent underlying causal and temporal chains so that differences in transmission could be more confidently attributed to differences in content. However, this underlying structure was still somewhat informal, and future studies might use more advanced models of causal links in narratives (e.g. Trabasso & Sperry's 1985 causal network representation model) to more precisely equate the underlying structure of the different material. There may also be an effect of varying the number of social agents or interactions. The gossip and social material in Experiment 2 featured three people, which is within the typical upper bound of four found in natural conversational groups (Dunbar, Duncan, & Nettle, 1995). Perhaps material featuring interactions between more than four people would be transmitted less well.
Finally, there is a need to replicate the study cross-culturally. Although condition-dependent biases might modulate outcomes according to ecological variations, the evolutionary theories outlined above would predict that people in many different societies would show the social bias found here. However, the sample used in the present study is particularly useful in one respect in challenging the stereotypical and historical view of ‘a gossip’ as poorly educated, of low intelligence and female (Emler, 2001, pp. 318–319). Here, we found that highly educated and intelligent young people of both sexes exhibit a bias for gossip over non-social (‘factual’) information.