Ildikó Király

Rational imitation in preverbal infants

Here we show that if an adult demonstrates a new way to execute a task to a group of infants aged 14 months, the children will use this action to achieve the same goal only if they consider it to be the most rational alternative. Our results indicate that imitation of goal-directed action by preverbal infants is a selective, interpretative process, rather than a simple re-enactment of the means used by a demonstrator, as was previously thought.

The early origins of goal attribution in infancy

We contrast two positions concerning the initial domain of actions that infants interpret as goal-directed. The narrow scope view holds that goal-attribution in 6- and 9-month-olds is restricted to highly familiar actions (such as grasping). The cue-based approach of the infants teleological stance, however, predicts that if the cues of equifinal variation of action and a salient action effect are present, young infants can attribute goals to a wide scope of entities including unfamiliar human actions and actions of novel objects lacking human features. It is argued that previous failures to show goal-attribution to unfamiliar actions were due to the absence of these cues. We report a modified replication of Woodward (1999) showing that when a salient action-effect is presented, even young infants can attribute a goal to an unfamiliar manual action. This study together with other recent experiments reviewed support the wide scope approach indicating that if the cues of goal-directedness are present even 6-month-olds attribute goals to unfamiliar actions.

The effect of light conditions on herbs, bryophytes and seedlings of temperate mixed forests in Őrség, Western Hungary

The effect of light on different understory plant groups (herbs, ground floor bryophytes, trunk-dwelling bryophytes and seedlings) was studied in a deciduous–coniferous mixed woodland in Western Hungary. The correlation of cover and species richness in each group and the cover of individual species to relative diffuse light were analyzed at different spatial scales. The study was carried out in 34 forest stands with different tree species composition. The importance of light in determining species composition was investigated by redundancy analysis. Species within each plant group were classified based on their light response. Light was positively correlated with species richness of herbs, cover of ground floor and trunk-dwelling bryophytes, and species richness and cover of seedlings. In redundancy analysis, the variance explained by light was 13.0% for herbs, 15.0% for bryophytes and 8.6% for seedlings. Within the group of herbs, species preferring open conditions and light-flexible (gap) species were separated on the basis of the spatial scale of the analysis, while shade-tolerant species were not correlated positively with light. Among bryophytes mainly terricolous, opportunistic and mineral soil-inhabiting species showed significant positive correlations with light, while epiphytic and epixylic species did not respond to light. Seedlings of Quercus petraea and Pinus sylvestris were positively related to light, while most other seedling species were shade-tolerant. In case of vascular plants, the species’ correlations with light were in agreement with their light indicator values; however, they were independent in the case of bryophytes. This study proved that the extent and spatial pattern of light influenced strongly the understory plant groups. Species within each group respond to light conditions differently, concerning the strength, direction and spatial scale of the relationships.

Beyond rational imitation: Learning arbitrary means actions from communicative demonstrations

The principle of rationality has been invoked to explain that infants expect agents to perform the most efficient means action to attain a goal. It has also been demonstrated that infants take into account the efficiency of observed actions to achieve a goal outcome when deciding whether to reenact a specific behavior or not. It is puzzling, however, that they also tend to imitate an apparently suboptimal unfamiliar action even when they can bring about the same outcome more efficiently by applying a more rational action alternative available to them. We propose that this apparently paradoxical behavior is explained by infants interpretation of action demonstrations as communicative manifestations of novel and culturally relevant means actions to be acquired, and we present empirical evidence supporting this proposal. In Experiment 1, we found that 14-month-olds reenacted novel arbitrary means actions only following a communicative demonstration. Experiment 2 showed that infants inclination to reproduce communicatively manifested novel actions is restricted to behaviors they can construe as goal-directed instrumental acts. The study also provides evidence that infants reenactment of the demonstrated novel actions reflects epistemic motives rather than purely social motives. We argue that ostensive communication enables infants to represent the teleological structure of novel actions even when the causal relations between means and end are cognitively opaque and apparently violate the efficiency expectation derived from the principle of rationality. This new account of imitative learning of novel means shows how the teleological stance and natural pedagogy--two separate cognitive adaptations to interpret instrumental versus communicative actions--are integrated as a system for learning socially constituted instrumental knowledge in humans.

Factors influencing epiphytic bryophyte and lichen species richness at different spatial scales in managed temperate forests

The effect of management related factors on species richness of epiphytic bryophytes and lichens was studied in managed deciduous-coniferous mixed forests in Western-Hungary. At the stand level, the potential explanatory variables were tree species composition, stand structure, microclimate and light conditions, landscape and historical variables; while at tree level host tree species, tree size and light were studied. Species richness of the two epiphyte groups was positively correlated. Both for lichen and bryophyte plot level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for bryophytes the presence of large trees, while for lichens amount and heterogeneity of light were important. Tree level richness was mainly determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size generally increased tree level species richness, except on pine for bryophytes and on hornbeam for lichens. The key variables for epiphytic diversity of the region were directly influenced by recent forest management; historical and landscape variables were not influential. Forest management oriented to the conservation of epiphytes should focus on: (i) the maintenance of tree species diversity in mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks); (iii) conserving large trees within the stands; (iv) providing the presence of shrub and regeneration layer; (v) creating heterogeneous light conditions. For these purposes tree selection and selective cutting management seem more appropriate than shelterwood system.

Communicating Shared Knowledge in Infancy

Object-directed emotion expressions provide two types of information: They can convey the expressers’ person-specific subjective disposition toward objects, or they can be used communicatively as referential symbolic devices to convey culturally shared valence-related knowledge about referents that can be generalized to other individuals. By presenting object-directed emotion expressions in communicative versus noncommunicative contexts, we demonstrated that 18-month-olds can flexibly assign either a person-centered interpretation or an object-centered interpretation to referential emotion displays. When addressed by ostensive signals of communication, infants generalized their object-centered interpretation of the emotion display to other individuals as well, whereas in the noncommunicative emotion-expression context, they attributed to the emoting agent a person-specific subjective dispositional attitude without generalizing this attribution as relevant to other individuals. The findings indicate that, as proposed by natural pedagogy theory, infants are prepared to learn shared cultural knowledge from nonverbal communicative demonstrations addressed to them at a remarkably early age.

The effect of the model's presence and of negative evidence on infants' selective imitation

This study demonstrated selective rational imitation in infants in two testing conditions: in the presence or absence of the model during the response phase. In the study, 14-month-olds were more likely to imitate a tool-use behavior when a prior failed attempt emphasized the logical reason and relevance of introducing this novel means, making it cognitively transparent for the infants. Infants also learned imitatively from the cognitively opaque (yet socially communicated) modeling situation, but to a lesser degree. Furthermore, the presence of the model as a social partner during testing influenced the performance of infants in that they were more likely to imitate the novel means when the model was present during testing. These results highlight the important interaction of interpretive schemas (e.g., causality, teleological stance) and social communicative cues in action interpretation guiding imitative learning.

Do infants bind mental states to agents

Recent findings suggest that infants understand others preferential choice and can use the perspectives and beliefs of others to interpret their actions. The standard interpretation in the field is that infants understand preferential choice as a dispositional state of the agent. It is possible, however, that these social situations trigger the acquisition of more general, not person-specific knowledge. In a looking-time study we showed an Agent A demonstrating a choice, that only could have been interpreted as preferential based on the perspective (and thus the belief) of the agent, not the observer. Then we introduced a new agent (Agent B), who chose consistently or inconsistently with Agent A; also varying whether Agent B was an adult or a child. Results show that infants expected Agent B (both the adult and the child) to choose as Agent A, but only in the condition where according to Agent As knowledge two objects were present in familiarization(confirming previous evidence on the importance of contrastive choice). We interpret these results in the following way: (1) infants do not encode the perspectives of other agents as person-specific sources of knowledge and (2) they learn about the object, rather than the agents disposition towards that object. We propose that early theory of mind processes lack the binding of belief content to the belief holder. However, such limitation may in fact serve an important function, allowing infants to acquire information through the perspectives of others in the form of universal access to general information.

Social Category Formation Is Induced by Cues of Sharing Knowledge in Young Children

Previous research has shown that human infants and young children are sensitive to the boundaries of certain social groups, which supports the idea that the capacity to represent social categories constitutes a fundamental characteristic of the human cognitive system. However, the function this capacity serves is still debated. We propose that during social categorization the human mind aims at mapping out social groups defined by a certain set of shared knowledge. An eye-tracking paradigm was designed to test whether two-year-old children differentially associate conventional versus non-conventional tool use with language-use, reflecting an organization of information that is induced by cues of shared knowledge. Children first watched videos depicting a male model perform goal-directed actions either in a conventional or in a non-conventional way. In the test phase children were presented with photographs taken of the model and of a similarly aged unfamiliar person while listening to a foreign (Experiment 1) or a native language (Experiment 2) text. Upon hearing the foreign utterance children looked at the model first if he had been seen to act in an unconventional way during familiarization. In contrast, children looked at the other person if the model had performed conventional tool use actions. No such differences were found in case of the native language. The results suggest that children take the conventionality of behavior into account in forming representations about a person, and they generalize to other qualities of the person based on this information.

Enhanced encoding of the co-actor's target stimuli during a shared non-motor task

Task co-representation has been proposed to rely on the motor brain areas’ capacity to represent others’ action plans similarly to ones own. The joint memory (JM) effect suggests that working in parallel with others influences the depth of incidental encoding: Other-relevant items are better encoded than non-task-relevant items. Using this paradigm, we investigated whether task co-representation could also emerge for non-motor tasks. In Experiment 1, we found enhanced recall performance to stimuli relevant to the co-actor also when the participants’ task required non-motor responses (counting the target words) instead of key-presses. This suggests that the JM effect did not depend on simulating the co-actors motor responses. In Experiment 2, direct visual access to the co-actor and his actions was found to be unnecessary to evoke the JM effect in case of the non-motor, but not in case of the motor task. Prior knowledge of the co-actors target category is sufficient to evoke deeper incidental encoding. Overall, these findings indicate that the capacity of task co-representation extends beyond the realm of motor tasks: Simulating the others motor actions is not necessary in this process.