Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens)

This study explored whether the tendency of chimpanzees and children to use emulation or imitation to solve a tool-using task was a response to the availability of causal information. Young wild-born chimpanzees from an African sanctuary and 3- to 4-year-old children observed a human demonstrator use a tool to retrieve a reward from a puzzle-box. The demonstration involved both causally relevant and irrelevant actions, and the box was presented in each of two conditions: opaque and clear. In the opaque condition, causal information about the effect of the tool inside the box was not available, and hence it was impossible to differentiate between the relevant and irrelevant parts of the demonstration. However, in the clear condition causal information was available, and subjects could potentially determine which actions were necessary. When chimpanzees were presented with the opaque box, they reproduced both the relevant and irrelevant actions, thus imitating the overall structure of the task. When the box was presented in the clear condition they instead ignored the irrelevant actions in favour of a more efficient, emulative technique. These results suggest that emulation is the favoured strategy of chimpanzees when sufficient causal information is available. However, if such information is not available, chimpanzees are prone to employ a more comprehensive copy of an observed action. In contrast to the chimpanzees, children employed imitation to solve the task in both conditions, at the expense of efficiency. We suggest that the difference in performance of chimpanzees and children may be due to a greater susceptibility of children to cultural conventions, perhaps combined with a differential focus on the results, actions and goals of the demonstrator.     

Emulation and “overemulation” in the social learning of causally opaque versus causally transparent tool use by 23- and 30-month-olds

We explored whether a rising trend to blindly “overcopy” a model’s causally irrelevant actions between 3 and 5 years of age, found in previous studies, predicts a more circumspect disposition in much younger children. Children between 23 and 30 months of age observed a model use a tool to retrieve a reward from either a transparent or opaque puzzle box. Some of the tool actions were irrelevant to reward retrieval, whereas others were causally necessary. The causal relevance of the tool actions was highly visible in the transparent box condition, allowing the participants to potentially discriminate which actions were necessary. In contrast, the causal efficacy of the tool was hidden in the opaque box condition. When both the 23- and 30-month-olds were presented with either the transparent or opaque box, they were most commonly emulative rather than imitative, performing only the causally necessary actions. This strategy contrasts with the blanket imitation of both causally irrelevant and causally relevant actions witnessed at 3 and 5 years of age in our previous studies. The results challenge a current view of 1- and 2-year-olds as largely “blind imitators”; instead, they show that these young children have a variety of social learning processes available to them. More broadly the emerging patterns of results suggest, rather counterintuitively, that the human species becomes more imitative rather than less imitative with age, in some ways “mindlessly” so.     

Cultural transmission of irrelevant tool actions in diffusion chains of 3- and 5-year-old children

We used the diffusion chain method in order to investigate whether irrelevant actions would be transmitted along chains of 3- and 5-year-old children. Four chains of eight children witnessed a trained “expert” child perform a sequence of actions in order to retrieve a reward from either a transparent or an opaque puzzle box. The action sequence involved both goal relevant and goal irrelevant actions. In the transparent box chains the participants could potentially determine which of the actions were irrelevant as the causal effects were clearly visible. Results indicated that irrelevant actions transmitted down chains of 3-year-old children irrespective of box transparency. In contrast, irrelevant actions dropped out of the transparent box chain extremely quickly at 5 years, but were maintained within the opaque chain. These findings highlight the power of the diffusion chain method as a tool for exploring cultural learning.     

The role of transmission biases in the cultural diffusion of irrelevant actions

This study used a diffusion chain paradigm to explore the cultural transmission of causally irrelevant tool actions in chains of adult participants. Each chain witnessed an "expert" adult retrieve a reward from inside a puzzle box using a combination of causally relevant actions and causally irrelevant actions. Which of the actions were causally relevant was evident in two of the chains where a transparent box was used. In the other two chains, the causal effectiveness of the tool was hidden inside an opaque version of the box. Results indicated that fewer of the irrelevant actions performed by the expert model were reproduced in the transparent box chains, than the opaque box chains. However, irrelevant actions, although not in their original form, were evident within each chain suggesting that causally irrelevant tool actions can survive within groups of adults. The current article places these results, alongside those from earlier overimitation studies, within a framework of cultural evolution. The proposal here is that the social learning of irrelevant actions is heavily influenced by the interaction between various transmission biases, including frequency-based biases, model-based biases, and content-based biases. It is further proposed that the transmission bias witnessed may differ according to the interplay between characteristics of the model, characteristics of the observer, and the contents of the task.     

From over-imitation to super-copying: adults imitate causally irrelevant aspects of tool use with higher fidelity than young children

Recent research has revealed a striking tendency in young children to imitate even causally irrelevant actions, a phenomenon dubbed 'over-imitation'. To investigate whether children develop beyond this, we allowed both adults and children to witness either a child or adult model performing goal-relevant and goal-irrelevant actions to extract a reward from a transparent puzzle box. Surprisingly, copying of irrelevant actions increased with age, with the adults performing the task with less efficiency than the children. Participants of all ages were more likely to perform the irrelevant actions performed by an adult model, than by a child model. These results suggest that people may become more imitative as they mature, whilst selectively copying particular models with a high level of fidelity. We suggest that this combination of faithful copying and selectivity underwrites the powerful social learning necessary for the level of cultural transmission on which our species depends.     

Guided by Intention: Preschoolers' Imitation Reflects Inferences of Causation

Object use is a ubiquitous characteristic of the human species, and learning how objects function is a fundamental part of development. In this article the authors examine the role that intentionality plays in children's understanding of causal relationships during observational learning of object use. Children observed demonstrations in which causally irrelevant and causally relevant actions were performed to achieve a desired goal. The intentionality of these actions was manipulated using verbal markers. Irrelevant actions were performed either intentionally (“There!”) or accidentally (“Whoops! I didn't mean to do that!”). Three-, 4-, and 5-year-olds, but not 2-year-olds, were less likely to imitate causally irrelevant actions performed accidentally than when they were performed intentionally. This suggests that older children used intentionality to guide causal inference and perceived intentional actions as causally effective and accidental actions as causally ineffective. Findings are discussed from an evolutionary perspective in relation to the cultural transmission of tool-use knowledge.     

Children over-imitate adults and peers more than puppets

Researchers commonly use puppets in development science. Amongst other things, puppets are employed to reduce social hierarchies between child participants and adult experimenters akin to peer interactions. However, it remains controversial whether children treat puppets like real-world social partners in these settings. This study investigated children's imitation of causally irrelevant actions (i.e., over-imitation) performed by puppet, adult, or child models. Seventy-two German children (Age_Range = 4.6–6.5 years; 36 girls) from urban, socioeconomically diverse backgrounds observed a model retrieving stickers from reward containers. The model performed causally irrelevant actions either in contact with the reward container or not. Children were more likely to over-imitate adults’ and peers’ actions as compared to puppets’ actions. Across models, they copied contact actions more than no-contact actions. While children imitate causally irrelevant actions from puppet models to some extent, their social learning from puppets does not necessarily match their social learning from real-world social agents, such as children or adults.

Research Highlights

• We examined children's over-imitation from adult, child, and puppet models to validate puppetry as an approach to simulate non-hierarchical interactions.
• Children imitated adults and child models at slightly higher rates than puppets.
• This effect was present regardless of whether the irrelevant actions involved physical contact to the reward container or not.
• In our study children's social learning from puppets does not match their social learning from human models.

     

Children's reasoning about the causal significance of the temporal order of events

Four experiments examined children's ability to reason about the causal significance of the order in which 2 events occurred (the pressing of buttons on a mechanically operated box). In Study 1, 4-year-olds were unable to make the relevant inferences, whereas 5-year-olds were successful on one version of the task. In Study 2, 3-year-olds were successful on a simplified version of the task in which they were able to observe the events although not their consequences. Study 3 found that older children had difficulties with the original task even when provided with cues to attend to order information. However, 5-year-olds performed successfully in Study 4, in which the causally relevant event was made more salient.     

Development of young children's understanding that the recent past is causally bound to the present

The results of 6 studies (involving 304 children) suggested that 4- and 5-year-olds, but not 3-year-olds, understand that very recent past events determine the present. In Studies 1-3, 3- and 4-year-old children were introduced to 2 empty hiding locations. With children's backs to these locations, a camera recorded an experimenter secretly hiding a puppet in one of them. Children then viewed the videotape of what had just happened, along with another tape that depicted identical events except with a different child and with the puppet hidden in the other location. Only 4-year-olds were subsequently able to locate the puppet, even though 3-year-olds remembered the contents of the tapes and understood the equivalence between the video events and the real world. In Study 4, similar effects were obtained when a verbal analog of the test was presented to 3-5-year-olds. Studies 5 and 6 showed that when children observed 2 events in which they had just participated, only 5-year-olds understood that the most recent events were relevant.     

Irrelevant‐action imitation is short‐term and contextual: Evidence from two under‐studied populations

Across the lifespan and across populations, humans ‘overimitate’ causally unnecessary behaviors. Such irrelevant‐action imitation facilitates faithful cultural transmission, but its immediate benefits to the imitator are controversial. Over short time scales, irrelevant‐action imitation may bootstrap artifact exploration or interpersonal affiliation, and over longer time scales it may facilitate acquisition of either causal models or social conventions. To investigate these putative functions, we recruited community samples from two under‐studied populations: Yasawa, Fiji, and Huatasani, Peru. We use a two‐action puzzle box: first after a video demonstration, and again one month later. Treating age as a continuous variable, we reveal divergent developmental trajectories across sites. Yasawans (44 adults, M = 39.9 years, 23 women; 42 children, M = 9.8 years, 26 girls) resemble documented patterns, with irrelevant‐action imitation increasing across childhood and plateauing in adulthood. In contrast, Huatasaneños (48 adults, M = 37.6 years, 33 women; 47 children, M = 9.3 years, 13 girls) evince a parabolic trajectory: adults at the site show the lowest irrelevant‐action imitation of any demographic set in our sample. In addition, all age sets in both populations reduce their irrelevant actions at Time 2, but do not reduce their relevant‐action imitation or goal attainment. Taken together, and considering the local cultural contexts, our results suggest that irrelevant‐action imitation serves a short‐term function and is sensitive to the social context of the demonstration.     

Contexts of a person's prior intentions facilitate observational learning in 2.5-year-old children

We examined whether contexts suggesting an actor's prior intentions facilitate observational learning in 2.5-year-olds. In Experiment 1, children observed an experimenter handle one box before proceeding to open a second box. In two prior intention conditions, children either watched the experimenter extract a toy from the first box or saw that the box had already been opened. In two no prior intention conditions, children watched the demonstration with only the second box or paired with irrelevant actions upon the first box. Children successfully opened the second box more often in the two prior intention conditions than in the two no prior intention conditions. Experiment 2 investigated stimulus generalization as another explanation for these results. A functionally different trap-tube task served as the pre-demonstration apparatus. Before watching the experimenter open the box, children either saw her extract a toy from the tube with a stick or observed the toy accidentally fall from the opening. In both cases, children opened the box at similar high rates. We discuss children's use of others’ prior intentions or observable outcomes in observational learning.     

Delayed self-recognition in 2.5-year-old children: Evidence of a restricted sense of self?

In two experiments, we explored whether 2.5-year-olds can use delayed video information to locate objects placed somewhere covertly after first being given pre-test video experience. Our findings revealed that children had little difficulty passing a surprise-object task, that is, a teddy bear hidden in a box that was placed behind the child and hence only visible in the delayed video. In contrast, the children did not pass the surprise-mark task or delayed self-recognition (DSR) task, even with pre-test video training. Similarly, delayed self-image experience and pre-test video training did not facilitate DSR performance in 2.5-year-olds. Children were also just as likely to fail a live video self-recognition task, suggesting that object-retrieval tasks pertaining to self using video information are difficult for children at this age. The findings are discussed in light of possible changes in representational capabilities; the implications for the development of a temporally extended self are also noted.     

Young Children's Imitative and Innovative Behaviour on the Floating Object Task

Past research has shown that children will copy the actions of adults with high fidelity, even actions that are obviously causally irrelevant to the modelled outcome. However, this phenomenon has always been documented in cases where a clear functional outcome has been brought about (e.g. getting a box open to retrieve a toy). Here, we demonstrate how young children will continue to adopt the precise actions shown to them by an adult even if the goal of the actions is not realized during modelling. A group of 4‐year‐old participants were presented with a toy lying at the bottom of a Perspex tube. Despite the availability of a bottle of water, and unlike the responses of a group of adults, few children spontaneously identified the solution of pouring the water into the tube to raise the toy up the tube where it could be reached. The majority did so, however, after seeing an adult demonstrate this approach. Critically, children copied the specific method of the adult, even when this involved the unnecessary steps of pouring from the bottle into a cup before pouring from the cup into the tube. These results highlight the value of overimitation to children growing up in a world filled with objects whose operating mechanisms are often hidden or unclear. Copyright © 2012 John Wiley & Sons, Ltd.     

Selective copying of the majority suggests children are broadly “optimal‐” rather than “over‐” imitators

Human children, in contrast to other species, are frequently cast as prolific “over‐imitators”. However, previous studies of “over‐imitation” have overlooked many important real‐world social dynamics, and may thus provide an inaccurate account of this seemingly puzzling and potentially maladaptive phenomenon. Here we investigate this topic using a cultural evolutionary approach, focusing particularly on the key adaptive learning strategy of majority‐biased copying. Most “over‐imitation” research has been conducted using consistent demonstrations to the observer, but we systematically varied the frequency of demonstrators that 4‐ to 6‐year‐old children observed performing a causally irrelevant action. Children who “over‐imitate” inflexibly should copy the majority regardless of whether the majority solution omits or includes a causally irrelevant action. However, we found that children calibrated their tendency to acquire the majority behavior, such that copying did not extend to majorities that performed irrelevant actions. These results are consistent with a highly functional, adaptive integration of social and causal information, rather than explanations implying unselective copying or causal misunderstanding. This suggests that our species might be better characterized as broadly “optimal‐” rather than “over‐” imitators.     

遵守规范的动机对儿童过度模仿的影响

模仿非任务相关动作的行为被称为过度模仿。研究以94名4-6岁儿童为被试,通过操纵无关动作与结果之间的关系,考察了儿童遵守规范的动机对过度模仿的影响。结果发现,当遵守规范导致不能得到想要的结果时,儿童没有表现出明显的过度模仿;而当遵守规范与得到结果不冲突时,儿童过度模仿的比例显著增加。这些结果说明遵守规范的动机影响儿童的过度模行为,当遵守规范的动机降低时,过度模仿行为减少。     

Imitation of hierarchical structure versus component details of complex actions by 3- and 5-year-olds

We investigated developmental changes in the level of information children incorporate into their imitation when a model executes complex, hierarchically organized actions. A total of 57 3-year-olds and 60 5-year-olds participated, watching video demonstrations of an “artificial fruit” box being opened through a complex series of nine different steps. Half of each sample observed the same nine steps performed through either of two different, hierarchically organized procedures, whereas half witnessed differing component action details. Children were found to imitate at both levels but were more likely to copy at the higher hierarchical level than at the level of specific action details. Fidelity to hierarchical organization, but not to the imitation of specific detail, increased with age. However, variation in imitativeness across children at one of these levels did not predict imitativeness at the other level.     

Preschool children's learning proclivities: When the ritual stance trumps the instrumental stance

Previous research has demonstrated an efficiency bias in social learning whereby young children preferentially imitate the functional actions of a successful individual over an unsuccessful group member. Our aim in the current research was to examine whether this bias remains when actions are presented as conventional rather than instrumental. Preschool children watched videos of an individual and a group member. The individual always demonstrated a successful instrumental action and the group member an unsuccessful action that was either causally transparent or opaque. Highlighting the selective nature of social learning, children copied the group at higher rates when the demonstrated actions were causally opaque than when they were causally transparent. This research draws attention to the influence of conventional/ritual‐like actions on young children's learning choices and emphasizes the role of this orientation in the development of human‐specific cumulative culture.     

The susceptibility of young preschoolers to source similarity effects: Confusing story or video events with reality

This study examined children’s tendency to confuse events that varied in source similarity, which was manipulated using different media of event presentation. In Experiment 1, children in two age groups (3- and 4-year-olds and 5- and 6-year-olds) experienced a live presentation of an event, and another event was either heard from a story (low similarity group) or seen on a video (high similarity group). Immediately afterward, the children were asked to monitor the source of the events. The children in the low similarity group produced higher source discrimination scores than did the children in the high similarity group. Overall, the older children were better at source monitoring than were the younger children. In Experiment 2, the procedure was replicated except that the children’s source monitoring was tested after a 4-day delay. When attributing the source of the story or video events, both 3- and 4-year-olds and 5- and 6-year-olds in the low similarity group produced more accurate story or video attributions than did their age mates in the high similarity group. However, when attributing the source of the live events, only the 3- and 4-year-olds evidenced this effect of source similarity. The 5- and 6-year-olds in both the low and high similarity groups performed at ceiling levels for live discriminations.     

Controlling for causally relevant third variables

In 3 experiments, the authors tested the conditions under which 3rd variables are controlled for in making causal judgments. The authors hypothesized that 3rd variables are controlled for when the 3rd variables are themselves perceived as causal. In Experiment 1, the participants predicted test performance after seeing information about wearing a lucky garment, taking a test-preparation course, and staying up late. The course (perceived as more causally relevant) was controlled for more than was the garment (perceived as less causally relevant) in assessing the effectiveness of staying up late. In Experiments 2 and 3, to obviate the many alternative accounts that arise from the realistic cover story of Experiment 1, participants predicted flowers' blooming after the presentation or nonpresentation of liquids. When one liquid was trained as causal, it was controlled for more in judging another liquid than when it was trained as neutral. Overall, stimuli perceived as causal were controlled for more when judging other stimuli. The authors concluded that the effect of perceived causal relevance on causal conditionalizing is real and normatively reasonable.     

Cause or effect: What matters? How 12‐month‐old infants learn to categorize artifacts

This paper investigates the role of cause and effect relations for infants' learning about artifacts. Two experiments tested whether 12‐month‐olds categorized a given set of unfamiliar artifacts according to overall similarity and/or according to part similarity, depending on what kind of video demonstration was presented before the start of the categorization task. In both experiments, the actions performed with objects were accompanied by interesting effects but the causal relation between object‐structure and effects was teased apart. In one video demonstration (Expt 1), the experimenter used the object part to produce some kind of effect in a causally plausible way. In another video demonstration (Expt 2), the experimenter performed similar actions with the same objects as in Expt 1, followed by the same effects as before. Importantly, however, no plausible cause–effect relation was provided this time. Only infants participating in Expt 1 categorized the set of unfamiliar objects according to part similarity. This finding suggests that 12‐month‐olds attend to the causal relation between specific object parts and their functional use when categorizing artifacts, rather than merely associating form‐characteristics with an interesting effect.