The co-evolution of cooperation and communication: Alternative accounts.

We challenge the proposal that partner-choice ecology explains the evolutionary emergence of ostensive communication in humans. The good fit between these domains might be because of the opposite relation (ostensive communication promotes the evolution of cooperation) or because of the dependence of both these human-specific traits on a more ancient contributor to human cognitive evolution: the use of technology.

Images of objects are interpreted as symbols: A case study of automatic size measurement.

Are photographs of objects presented on a screen in an experimental context treated as the objects themselves or are they interpreted as symbols standing for objects? We addressed this question by investigating the size Stroop effect-the finding that people take longer to judge the relative size of two pictures when the real-world size of the depicted objects is incongruent with their display size. In Experiment 1, we replicated the size Stroop effect with new stimuli pairs (e.g., a zebra and a watermelon). In Experiment 2, we replaced the large objects in Experiment 1 with small toy objects that usually stand for them (e.g., a toy zebra), and found that the Stroop effect was driven by what the toys stood for, not by the toys themselves. In Experiment 3, we showed that the association between an image of a toy and the object the toy typically stands for is not automatic: when toys were pitted against the objects they typically represent (e.g., a toy zebra vs. a zebra), images of toys were interpreted as representations of small objects, unlike in Experiment 2. We argue that participants interpret images as discourse-bound symbols and automatically compute what the images stand for in the discourse context of the experimental situation. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Infants' representation of asymmetric social influence.

In social groups, some individuals have more influence than others, for example, because they are learned from or because they coordinate collective actions. Identifying these influential individuals is crucial to learn about one's social environment. Here, we tested whether infants represent asymmetric social influence among individuals from observing the imitation of movements in the absence of any observable coercion or order. We defined social influence in terms of Granger causality; that is, if A influences B, then past behaviors of A contain information that predicts the behaviors and mental states of B above and beyond the information contained in the past behaviors and mental states of B alone. Infants (12-, 15-, and 18-month-olds) were familiarized with agents (imitators) influenced by the actions of another one (target). During the test, the infants observed either an imitator who was no longer influenced by the target (incongruent test) or the target who was not influenced by an imitator (neutral test). The participants looked significantly longer at the incongruent test than at the neutral test. This result shows that infants represent and generalize individuals' potential to influence others' actions and that they are sensitive to the asymmetric nature of social influence; upon learning that A influences B, they expect that the influence of A over B will remain stronger than the influence of B over A in a novel context. Because of the pervasiveness of social influence in many social interactions and relationships, its representation during infancy is fundamental to understand and predict others' behaviors.

Nonverbal Action Interpretation Guides Novel Word Disambiguation in 12-Month-Olds.

Whether young infants can exploit sociopragmatic information to interpret new words is a matter of debate. Based on findings and theories from the action interpretation literature, we hypothesized that 12-month-olds should distinguish communicative object-directed actions expressing reference from instrumental object-directed actions indicative of one's goals, and selectively use the former to identify referents of novel linguistic expressions. This hypothesis was tested across four eye-tracking experiments. Infants watched pairs of unfamiliar objects, one of which was first targeted by either a communicative action (e.g., pointing) or an instrumental action (e.g., grasping) and then labeled with a novel word. As predicted, infants fast-mapped the novel words onto the targeted objects after pointing (Experiments 1 and 4) but not after grasping (Experiment 2) unless the grasping action was preceded by an ostensive signal (Experiment 3). Moreover, whenever infants mapped a novel word onto the object indicated by a communicative action, they tended to map a different novel word onto the distractor object, displaying a mutual exclusivity effect. This reliance on nonverbal action interpretation in the disambiguation of novel words indicates that sociopragmatic inferences about reference likely supplement associative and statistical learning mechanisms from the outset of word learning.

Infants expect agents to minimize the collective cost of collaborative actions.

This paper argues that human infants address the challenges of optimizing, recognizing, and interpreting collaborative behaviors by assessing their collective efficiency. This hypothesis was tested by using a looking-time study. Fourteen-month-olds (N = 32) were familiarized with agents performing a collaborative action in computer animations. During the test phase, the looking times were measured while the agents acted with various efficiency parameters. In the critical condition, the agents' actions were individually efficient, but their combination was either collectively efficient or inefficient. Infants looked longer at test events that violated expectations of collective efficiency (p = .006, d = 0.79). Thus, preverbal infants apply expectations of collective efficiency to actions involving multiple agents.

Structural asymmetries in the representation of giving and taking events.

Across languages, GIVE and TAKE verbs have different syntactic requirements: GIVE mandates a patient argument to be made explicit in the clause structure, whereas TAKE does not. Experimental evidence suggests that this asymmetry is rooted in prelinguistic assumptions about the minimal number of event participants that each action entails. The present study provides corroborating evidence for this proposal by investigating whether the observation of giving and taking actions modulates the inclusion of patients in the represented event. Participants were shown events featuring an agent (A) transferring an object to, or collecting it from, an animate target (B) or an inanimate target (a rock), and their sensitivity to changes in pair composition (AB vs. AC) and action role (AB vs. BA) was measured. Change sensitivity was affected by the type of target approached when the agent transferred the object (Experiment 1), but not when she collected it (Experiment 2), or when an outside force carried out the transfer (Experiment 3). Although these object-displacing actions could be equally interpreted as interactive (i.e., directed towards B), this construal was adopted only when B could be perceived as putative patient of a giving action. This evidence buttresses the proposal that structural asymmetries in giving and taking, as reflected in their syntactic requirements, may originate from prelinguistic assumptions about the minimal event participants required for each action to be teleologically well-formed.

Young domestic chicks spontaneously represent the absence of objects.

Absence is a notion that is usually captured by language-related concepts like zero or negation. Whether nonlinguistic creatures encode similar thoughts is an open question, as everyday behavior marked by absence (of food, of social partners) can be explained solely by expecting presence somewhere else. We investigated 8-day-old chicks' looking behavior in response to events violating expectations about the presence or absence of an object. We found different behavioral responses to violations of presence and absence, suggesting distinct underlying mechanisms. Importantly, chicks displayed an avian signature of novelty detection to violations of absence, namely a sex-dependent left-eye-bias. Follow-up experiments excluded accounts that would explain this bias by perceptual mismatch or by representing the object at different locations. These results suggest that the ability to spontaneously form representations about the absence of objects likely belongs to the initial cognitive repertoire of vertebrate species.

Three cognitive mechanisms for knowledge tracking.

We welcome Phillips et al.'s proposal to separate the understanding of "knowledge" from that of "beliefs." We argue that this distinction is best specified at the level of the cognitive mechanisms. Three distinct mechanisms are discussed: tagging one's own representations with those who share the same reality; representing others' representations (metarepresenting knowledge); and attributing dispositions to provide useful information.

For 19-Month-Olds, What Happens On-Screen Stays On-Screen.

Humans rely extensively on external representations such as drawings, maps, and animations. While animations are widely used in infancy research, little is known about how infants interpret them. In this study, we asked whether 19-month-olds take what they see on a screen to be happening here and now, or whether they think that on-screen events are decoupled from the immediate environment. In Experiments 1-3, we found that infants did not expect a falling animated ball to end up in boxes below the screen, even though they could track the ball (i) when the ball was real or (ii) when the boxes were also part of the animation. In Experiment 4, we tested whether infants think of screens as spatially bounded physical containers that do not allow objects to pass through. When two location cues were pitted against each other, infants individuated the protagonist of an animation by its virtual location (the animation to which it belonged), not by its physical location (the screen on which the animation was presented). Thus, 19-month-olds reject animation-reality crossovers but accept the depiction of the same animated environment on multiple screens. These results are consistent with the possibility that 19-month-olds interpret animations as external representations.

Computing Joint Action Costs: Co-Actors Minimize the Aggregate Individual Costs in an Action Sequence.

Successful performance in cooperative activities relies on efficient task distribution between co-actors. Previous research found that people often forgo individual efficiency in favor of co-efficiency (i.e., joint-cost minimization) when planning a joint action. The present study investigated the cost computations underlying co-efficient decisions. We report a series of experiments that tested the hypothesis that people compute the joint costs of a cooperative action sequence by summing the individual action costs of their co-actor and themselves. We independently manipulated the parameters quantifying individual and joint action costs and tested their effects on decision making by fitting and comparing Bayesian logistic regression models. Our hypothesis was confirmed: people weighed their own and their partner's costs similarly to estimate the joint action costs as the sum of the two individual parameters. Participants minimized the aggregate cost to ensure co-efficiency. The results provide empirical support for behavioral economics and computational approaches that formalize cooperation as joint utility maximization based on a weighted sum of individual action costs.

Facilitation of object encoding in infants by the observation of giving.

We propose that humans are prepared to interpret giving as a diagnostic cue of reciprocal-exchange relations from infancy. A prediction following from this hypothesis is that infants will represent the identity of an object they see being given, because this information is critical for evaluating potential future reciprocation. Across three looking-time experiments we tested whether the observation of a transfer action induces 12-month-olds to encode the identity of a single object handled by an agent. We found that infants encoded the object identity when the agent gave the object (Experiment 1), but not when she took it (Experiment 2), despite being able to represent the goal of both actions (Experiments 1 and 3). Consistent with our hypothesis, these results suggest that the infants' representation of giving comprises information necessary for comparing the value of transferred goods across sharing episodes.

The effect of source claims on statement believability and speaker accountability.

What is the effect of source claims (such as "I saw it" or "Somebody told me") on the believability of statements, and what mechanisms are responsible for this effect? In this study, we tested the idea that source claims impact statement believability by modulating the extent to which a speaker is perceived to be committed to (and thereby accountable for) the truth of her assertion. Across three experiments, we presented participants with statements associated with different source claims, asked them to judge how much they believed the statements, and how much the speaker was responsible if the statement turned out to be false. We found that (1) statement believability predicted speaker accountability independently of a statement's perceived prior likelihood or associated source claim; (2) being associated with a claim to first-hand ("I saw that . . .") or second-hand ("Somebody told me that . . .") evidence strengthened this association; (3) bare assertions about specific circumstances were commonly interpreted as claims to first-hand evidence; and (4) (everything else being equal) claims to first-hand evidence increased while claims to second-hand evidence decreased both statement believability and speaker accountability. These results support the idea that the believability of a statement is closely related to how committed to its truth the speaker is perceived to be and that source claims modulate the extent of this perceived commitment.

Twelve-month-olds disambiguate new words using mutual-exclusivity inferences.

Representing objects in terms of their kinds enables inferences based on the long-term knowledge made available through kind concepts. For example, children readily use lexical knowledge linked to familiar kind concepts to disambiguate new words (e.g., "find the toma"): they exclude members of familiar kinds falling under familiar kind labels (e.g., a ball) as potential referents and link new labels to available unfamiliar objects (e.g., a funnel), a phenomenon dubbed as 'mutual exclusivity'. Younger infants' failure in mutual exclusivity tasks has been commonly interpreted as a limitation of early word-learning or inferential abilities. Here, we investigated an alternative explanation, according to which infants do not spontaneously represent familiar objects under kind concepts, hence lacking access to the information necessary for rejecting them as referents of novel labels. Building on findings about conceptual development and communication, we hypothesized that nonverbal communication could prompt infants to set up kind-based representations which, in turn, would promote mutual exclusivity inferences. This hypothesis was tested in a looking-while-listening task involving novel word disambiguation. Twelve-month-olds saw pairs of objects, one familiar and one unfamiliar, and heard familiar kind labels or novel words. Across two experiments providing a cross-lab replication in two different languages, infants successfully disambiguated novel words when the familiar object had been pointed at before labeling, but not when it had been highlighted in a non-communicative manner (Experiment 1) or not highlighted at all (Experiment 2). Nonverbal communication induced infants to recruit kind-based representations of familiar objects that they failed to recruit in its absence and that, once activated, supported mutual-exclusivity inferences. Developmental changes in children's appreciation of communicative contexts may modulate the expression of early inferential and word learning competences.

The effect of disagreement on children's source memory performance.

Source representations play a role both in the formation of individual beliefs as well as in the social transmission of such beliefs. Both of these functions suggest that source information should be particularly useful in the context of interpersonal disagreement. Three experiments with an identical design (one original study and two replications) with 3- to 4-year-old-children (N = 100) assessed whether children's source memory performance would improve in the face of disagreement and whether such an effect interacts with different types of sources (first- vs. second-hand). In a 2 x 2 repeated-measures design, children found out about the contents of a container either by looking inside or being told (IV1). Then they were questioned about the contents of the container by an interlocutor puppet who either agreed or disagreed with their answer (IV2). We measured children's source memory performance in response to a free recall question (DV1) followed by a forced-choice question (DV2). Four-year-olds (but not three-year-olds) performed better in response to the free recall source memory question (but not the forced-choice question) when their interlocutor had disagreed with them compared to when it had agreed with them. Children were also better at recalling 'having been told' than 'having seen'. These results demonstrate that by four years of age, source memory capacities are sensitive to the communicative context of assertions and serve social functions.

Can infants adopt underspecified contents into attributed beliefs? Representational prerequisites of theory of mind.

Recent evidence suggests that young infants, as well as nonhuman apes, can anticipate others' behavior based on their false beliefs. While such behaviors have been proposed to be accounted by simple associations between agents, objects, and locations, human adults are undoubtedly endowed with sophisticated theory of mind abilities. For example, they can attribute mental contents about abstract or non-existing entities, or beliefs whose content is poorly specified. While such endeavors may be human specific, it is unclear whether the representational apparatus that allows for encoding such beliefs is present early in development. In four experiments we asked whether 15-month-old infants are able to attribute beliefs with underspecified content, update their content later, and maintain attributed beliefs that are unknown to be true or false. In Experiment 1, infants observed as an agent hid an object to an unspecified location. This location was later revealed in the absence or presence of the agent, and the object was then hidden again to an unspecified location. Then the infants could search for the object while the agent was away. Their search was biased to the revealed location (that could be represented as the potential content of the agent's belief when she had not witnessed the re-hiding), suggesting that they (1) first attributed an underspecified belief to the agent, (2) later updated the content of this belief, and (3) were primed by this content in their own action even though its validity was unknown. This priming effect was absent when the agent witnessed the re-hiding of the object, and thus her belief about the earlier location of the object did not have to be sustained. The same effect was observed when infants searched for a different toy (Experiment 2) or when an additional spatial transformation was introduced (Experiment 4), but not when the spatial transformation disrupted belief updating (Experiment 3). These data suggest that infants' representational apparatus is prepared to efficiently track other agents' beliefs online, encode underspecified beliefs and define their content later, possibly reflecting a crucial characteristic of mature theory of mind: using a metarepresentational format for ascribed beliefs.

Electrophysiological investigation of infants' understanding of understanding.

Social cognition might play a critical role in language acquisition and comprehension, as mindreading may be necessary to infer the intended meaning of linguistic expressions uttered by communicative partners. In three electrophysiological experiments, we explored the interplay between belief attribution and language comprehension of 14-month-old infants. First, we replicated our earlier finding: infants produced an N400 effect to correctly labelled objects when the labels did not match a communicative partner's beliefs about the referents. Second, we observed no N400 when we replaced the object with another category member. Third, when we named the objects incorrectly for infants, but congruently with the partner's false belief, we observed large N400 responses, suggesting that infants retained their own perspective in addition to that of the partner. We thus interpret the observed social N400 effect as a communicational expectancy indicator because it was contingent not on the attribution of false beliefs but on semantic expectations by both the self and the communicative partner. Additional exploratory analyses revealed an early, frontal, positive-going electrophysiological response in all three experiments, which was contingent on infants' computing the comprehension of the social partner based on attributed beliefs.

Do 15-month-old infants prefer helpers? A replication of Hamlin et al. (2007).

Hamlin et al. found in 2007 that preverbal infants displayed a preference for helpers over hinderers. The robustness of this finding and the conditions under which infant sociomoral evaluation can be elicited has since been debated. Here, we conducted a replication of the original study, in which we tested 14- to 16-month-olds using a familiarization procedure with three-dimensional animated video stimuli. Unlike previous replication attempts, ours uniquely benefited from detailed procedural advice by Hamlin. In contrast with the original results, only 16 out of 32 infants (50%) in our study reached for the helper; thus, we were not able to replicate the findings. A possible reason for this failure is that infants' preference for prosocial agents may not be reliably elicited with the procedure and stimuli adopted. Alternatively, the effect size of infants' preference may be smaller than originally estimated. The study addresses ongoing methodological debates on the replicability of influential findings in infant cognition.

Giving, but not taking, actions are spontaneously represented as social interactions: Evidence from modulation of lower alpha oscillations.

Unlike taking, which can be redescribed in non-social and object-directed terms, acts of giving are invariably expressed across languages in a three-argument structure relating agent, patient, and object. Developmental evidence suggests this difference in the syntactic entailment of the patient role to be rooted in a prelinguistic understanding of giving as a patient-directed, hence obligatorily social, action. We hypothesized that minimal cues of possession transfer, known to induce this interpretation in preverbal infants, should similarly encourage adults to perceive the patient of giving, but not taking, actions as integral participant of the observed event, even without cues of overt involvement in the transfer. To test this hypothesis, we measured a known electrophysiological correlate of action understanding (the suppression of alpha-band oscillations) during the observation of giving and taking events, under the assumption that the functional grouping of agent and patient should have induced greater suppression that the representation of individual object-directed actions. As predicted, the observation of giving produced stronger lower alpha suppression than superficially similar acts of object disposal, whereas no difference emerged between taking from an animate patient or an inanimate target. These results suggest that the participants spontaneously represented giving, but not kinematically identical taking actions, as social interactions, and crucially restricted this interpretation to transfer events featuring animate patients. This evidence gives empirical traction to the idea that such asymmetry, rather than being an interpretive propensity circumscribed to the first year of life, is attributable to an ontogenetically stable system dedicated to the efficient identification of interactions based on active transfer.