Of mice and men, nature and nurture, and a few red herrings.

Burkart et al.'s proposal is based on three false premises: (1) theories of the mind are either domain-specific/modular (DSM) or domain-general (DG); (2) DSM systems are considered inflexible, built by nature; and (3) animal minds are deemed as purely DSM. Clearing up these conceptual confusions is a necessary first step in understanding how general intelligence evolved.

Sociocultural Influences on Moral Judgments: East-West, Male-Female, and Young-Old.

Gender, age, and culturally specific beliefs are often considered relevant to observed variation in social interactions. At present, however, the scientific literature is mixed with respect to the significance of these factors in guiding moral judgments. In this study, we explore the role of each of these factors in moral judgment by presenting the results of a web-based study of Eastern (i.e., Russia) and Western (i.e., USA, UK, Canada) subjects, male and female, and young and old. Participants (n = 659) responded to hypothetical moral scenarios describing situations where sacrificing one life resulted in saving five others. Though men and women from both types of cultures judged (1) harms caused by action as less permissible than harms caused by omission, (2) means-based harms as less permissible than side-effects, and (3) harms caused by contact as less permissible than by non-contact, men in both cultures delivered more utilitarian judgments (save the five, sacrifice one) than women. Moreover, men from Western cultures were more utilitarian than Russian men, with no differences observed for women. In both cultures, older participants delivered less utilitarian judgments than younger participants. These results suggest that certain core principles may mediate moral judgments across different societies, implying some degree of universality, while also allowing a limited range of variation due to sociocultural factors.

The mystery of language evolution.

Understanding the evolution of language requires evidence regarding origins and processes that led to change. In the last 40 years, there has been an explosion of research on this problem as well as a sense that considerable progress has been made. We argue instead that the richness of ideas is accompanied by a poverty of evidence, with essentially no explanation of how and why our linguistic computations and representations evolved. We show that, to date, (1) studies of nonhuman animals provide virtually no relevant parallels to human linguistic communication, and none to the underlying biological capacity; (2) the fossil and archaeological evidence does not inform our understanding of the computations and representations of our earliest ancestors, leaving details of origins and selective pressure unresolved; (3) our understanding of the genetics of language is so impoverished that there is little hope of connecting genes to linguistic processes any time soon; (4) all modeling attempts have made unfounded assumptions, and have provided no empirical tests, thus leaving any insights into language's origins unverifiable. Based on the current state of evidence, we submit that the most fundamental questions about the origins and evolution of our linguistic capacity remain as mysterious as ever, with considerable uncertainty about the discovery of either relevant or conclusive evidence that can adjudicate among the many open hypotheses. We conclude by presenting some suggestions about possible paths forward.

Conceptual and empirical problems with game theoretic approaches to language evolution.

The importance of game theoretic models to evolutionary theory has been in formulating elegant equations that specify the strategies to be played and the conditions to be satisfied for particular traits to evolve. These models, in conjunction with experimental tests of their predictions, have successfully described and explained the costs and benefits of varying strategies and the dynamics for establishing equilibria in a number of evolutionary scenarios, including especially cooperation, mating, and aggression. Over the past decade or so, game theory has been applied to model the evolution of language. In contrast to the aforementioned scenarios, however, we argue that these models are problematic due to conceptual confusions and empirical difficiences. In particular, these models conflate the comptutations and representations of our language faculty (mechanism) with its utility in communication (function); model languages as having different fitness functions for which there is no evidence; depend on assumptions for the starting state of the system, thereby begging the question of how these systems evolved; and to date, have generated no empirical studies at all. Game theoretic models of language evolution have therefore failed to advance how or why language evolved, or why it has the particular representations and computations that it does. We conclude with some brief suggestions for how this situation might be ameliorated, enabling this important theoretical tool to make substantive empirical contributions.

On recursion.

It is a truism that conceptual understanding of a hypothesis is required for its empirical investigation. However, the concept of recursion as articulated in the context of linguistic analysis has been perennially confused. Nowhere has this been more evident than in attempts to critique and extend Hauseretal's. (2002) articulation. These authors put forward the hypothesis that what is uniquely human and unique to the faculty of language-the faculty of language in the narrow sense (FLN)-is a recursive system that generates and maps syntactic objects to conceptual-intentional and sensory-motor systems. This thesis was based on the standard mathematical definition of recursion as understood by Gödel and Turing, and yet has commonly been interpreted in other ways, most notably and incorrectly as a thesis about the capacity for syntactic embedding. As we explain, the recursiveness of a function is defined independent of such output, whether infinite or finite, embedded or unembedded-existent or non-existent. And to the extent that embedding is a sufficient, though not necessary, diagnostic of recursion, it has not been established that the apparent restriction on embedding in some languages is of any theoretical import. Misunderstanding of these facts has generated research that is often irrelevant to the FLN thesis as well as to other theories of language competence that focus on its generative power of expression. This essay is an attempt to bring conceptual clarity to such discussions as well as to future empirical investigations by explaining three criterial properties of recursion: computability (i.e., rules in intension rather than lists in extension); definition by induction (i.e., rules strongly generative of structure); and mathematical induction (i.e., rules for the principled-and potentially unbounded-expansion of strongly generated structure). By these necessary and sufficient criteria, the grammars of all natural languages are recursive.

What experimental experience affects dogs' comprehension of human communicative actions?

Studies of dogs report that individuals reliably respond to the goal-directed communicative actions (e.g., pointing) of human experimenters. All of these studies use some version of a multi-trial approach, thereby allowing for the possibility of rapid learning within an experimental session. The experiments reported here ask whether dogs can respond correctly to a communicative action based on only a single presentation, thereby eliminating the possibility of learning within the experimental context. We tested 173 dogs. For each dog reaching our test criteria, we used a single presentation of six different goal-directed actions within a session, asking whether they correctly follow to a target goal (container with concealed food) a (1) distal hand point, (2) step toward one container, (3) hand point to one container followed by step toward the other, (4) step toward one container and point to the other, (5) distal foot point with the experimenter's hands free, and (6) distal foot point with the experimenter's hands occupied. Given only a single presentation, dogs selected the correct container when the experimenter hand pointed, foot pointed with hands occupied, or stepped closer to the target container, but failed on the other actions, despite using the same method. The fact that dogs correctly followed foot pointing with hands occupied, but not hands free, suggests that they are sensitive to environmental constraints, and use this information to infer rational, goal-directed action. We discuss these results in light of the role of experience in recognizing communicative gestures, as well as the significance of coding criteria for studies of canine competence.

The influence of type and token frequency on the acquisition of affixation patterns: implications for language processing.

Rules, and exceptions to such rules, are ubiquitous in many domains, including language. Here we used simple artificial grammars to investigate the influence of 2 factors on the acquisition of rules and their exceptions, namely type frequency (the relative numbers of different exceptions to different regular items) and token frequency (the number of exception tokens relative to the number of regular tokens). We familiarized participants to either a prefixation pattern (where regulars started with /ZaI/ and exceptions ended with /ZaI/) or a suffixation pattern (where regulars ended with /ZaI/ and exceptions started with /ZaI/). We show that the type and the token frequency of regular items and exceptions influence in different ways what participants can learn. For the exceptions to be learned, they have to occur sufficiently often so that participants can memorize them; this can be achieved by a high token frequency. However, a high token frequency of the exceptions also impaired the acquisition of the regular pattern. In contrast, the type frequency of the patterns seemed to determine whether the regular pattern could be learned: When the type frequency of the regular items was sufficiently high, participants successfully learned the regular pattern even when the exceptions were played so often that 66% of the familiarization items were exceptions. We discuss these findings in the context of general learning mechanisms and the role they may play in language acquisition.

Innovative coconut-opening in a semi free-ranging rhesus monkey (Macaca mulatta): A case report on behavioral propensities.

The present case report provides a description of the emergence of an innovative, highly beneficial for- aging behavior in a single rhesus monkey (Macaca mulatta) on the island of Cayo Santiago, Puerto Rico. Selectively choosing the island's cement dock and nearby surrounding rocky terrain, our focal subject (ID: 84 J) opens coconuts using two types of underhand tosses: (1) a rolling motion to move it, and (2) a throwing motion up in the air to crack the shell. We discuss this innovative behavior in light of species-specific behavioral propensities.

Serotonin selectively influences moral judgment and behavior through effects on harm aversion.

Aversive emotional reactions to real or imagined social harms infuse moral judgment and motivate prosocial behavior. Here, we show that the neurotransmitter serotonin directly alters both moral judgment and behavior through increasing subjects' aversion to personally harming others. We enhanced serotonin in healthy volunteers with citalopram (a selective serotonin reuptake inhibitor) and contrasted its effects with both a pharmacological control treatment and a placebo on tests of moral judgment and behavior. We measured the drugs' effects on moral judgment in a set of moral 'dilemmas' pitting utilitarian outcomes (e.g., saving five lives) against highly aversive harmful actions (e.g., killing an innocent person). Enhancing serotonin made subjects more likely to judge harmful actions as forbidden, but only in cases where harms were emotionally salient. This harm-avoidant bias after citalopram was also evident in behavior during the ultimatum game, in which subjects decide to accept or reject fair or unfair monetary offers from another player. Rejecting unfair offers enforces a fairness norm but also harms the other player financially. Enhancing serotonin made subjects less likely to reject unfair offers. Furthermore, the prosocial effects of citalopram varied as a function of trait empathy. Individuals high in trait empathy showed stronger effects of citalopram on moral judgment and behavior than individuals low in trait empathy. Together, these findings provide unique evidence that serotonin could promote prosocial behavior by enhancing harm aversion, a prosocial sentiment that directly affects both moral judgment and moral behavior.

Word segmentation with universal prosodic cues.

When listening to speech from one's native language, words seem to be well separated from one another, like beads on a string. When listening to a foreign language, in contrast, words seem almost impossible to extract, as if there was only one bead on the same string. This contrast reveals that there are language-specific cues to segmentation. The puzzle, however, is that infants must be endowed with a language-independent mechanism for segmentation, as they ultimately solve the segmentation problem for any native language. Here, we approach the acquisition problem by asking whether there are language-independent cues to segmentation that might be available to even adult learners who have already acquired a native language. We show that adult learners recognize words in connected speech when only prosodic cues to word-boundaries are given from languages unfamiliar to the participants. In both artificial and natural speech, adult English speakers, with no prior exposure to the test languages, readily recognized words in natural languages with critically different prosodic patterns, including French, Turkish and Hungarian. We suggest that, even though languages differ in their sound structures, they carry universal prosodic characteristics. Further, these language-invariant prosodic cues provide a universally accessible mechanism for finding words in connected speech. These cues may enable infants to start acquiring words in any language even before they are fine-tuned to the sound structure of their native language.

The tuning of human neonates' preference for speech.

Human neonates prefer listening to speech compared to many nonspeech sounds, suggesting that humans are born with a bias for speech. However, neonates' preference may derive from properties of speech that are not unique but instead are shared with the vocalizations of other species. To test this, thirty neonates and sixteen 3-month-olds were presented with nonsense speech and rhesus monkey vocalizations. Neonates showed no preference for speech over rhesus vocalizations but showed a preference for both these sounds over synthetic sounds. In contrast, 3-month-olds preferred speech to rhesus vocalizations. Neonates' initial biases minimally include speech and monkey vocalizations. These listening preferences are sharpened over 3 months, yielding a species-specific preference for speech, paralleling findings on infant face perception.

Mayan morality: an exploration of permissible harms.

Anthropologists have provided rich field descriptions of the norms and conventions governing behavior and interactions in small-scale societies. Here, we add a further dimension to this work by presenting hypothetical moral dilemmas involving harm, to a small-scale, agrarian Mayan population, with the specific goal of exploring the hypothesis that certain moral principles apply universally. We presented Mayan participants with moral dilemmas translated into their native language, Tseltal. Paralleling several studies carried out with educated subjects living in large-scale, developed nations, the Mayan participants judged harms caused as the means to a greater good as more forbidden than harms caused as a side-effect (i.e., side-effect bias). However, unlike these other populations living in large-scale societies, as well as a more educated and less rural Mayan comparison group, the target rural Mayan participants did not judge actions causing harm as worse than omissions (i.e., omission bias). A series of probes targeting the action-omission distinction suggest that the absence of an omission bias among the rural Mayan participants was not due to difficulties comprehending the dilemmas, using the judgment scale, or in attributing a greater causal role for actions over omissions. Thus, while the moral distinction between means and side-effect may be more universal, the moral distinction between actions and omission appears to be open to greater cross-cultural variation. We discuss these results in light of issues concerning the role of biological constraints and cultural variation in moral decision-making, as well as the limitations of such experimental, cross-cultural research.

Psychopaths know right from wrong but don't care.

Adult psychopaths have deficits in emotional processing and inhibitory control, engage in morally inappropriate behavior, and generally fail to distinguish moral from conventional violations. These observations, together with a dominant tradition in the discipline which sees emotional processes as causally necessary for moral judgment, have led to the conclusion that psychopaths lack an understanding of moral rights and wrongs. We test an alternative explanation: psychopaths have normal understanding of right and wrong, but abnormal regulation of morally appropriate behavior. We presented psychopaths with moral dilemmas, contrasting their judgments with age- and sex-matched (i) healthy subjects and (ii) non-psychopathic, delinquents. Subjects in each group judged cases of personal harms (i.e. requiring physical contact) as less permissible than impersonal harms, even though both types of harms led to utilitarian gains. Importantly, however, psychopaths' pattern of judgments on different dilemmas was the same as those of the other subjects. These results force a rejection of the strong hypothesis that emotional processes are causally necessary for judgments of moral dilemmas, suggesting instead that psychopaths understand the distinction between right and wrong, but do not care about such knowledge, or the consequences that ensue from their morally inappropriate behavior.

The linguistic analogy: motivations, results, and speculations.

Inspired by the success of generative linguistics and transformational grammar, proponents of the linguistic analogy (LA) in moral psychology hypothesize that careful attention to folk-moral judgments is likely to reveal a small set of implicit rules and structures responsible for the ubiquitous and apparently unbounded capacity for making moral judgments. As a theoretical hypothesis, LA thus requires a rich description of the computational structures that underlie mature moral judgments, an account of the acquisition and development of these structures, and an analysis of those components of the moral system that are uniquely human and uniquely moral. In this paper we present the theoretical motivations for adopting LA in the study of moral cognition: (a) the distinction between competence and performance, (b) poverty of stimulus considerations, and (c) adopting the computational level as the proper level of analysis for the empirical study of moral judgment. With these motivations in hand, we review recent empirical findings that have been inspired by LA and which provide evidence for at least two predictions of LA: (a) the computational processes responsible for folk-moral judgment operate over structured representations of actions and events, as well as coding for features of agency and outcomes; and (b) folk-moral judgments are the output of a dedicated moral faculty and are largely immune to the effects of context. In addition, we highlight the complexity of the interfaces between the moral faculty and other cognitive systems external to it (e.g., number systems). We conclude by reviewing the potential utility of the theoretical and empirical tools of LA for future research in moral psychology.

The apes' edge: positional learning in chimpanzees and humans.

A wide variety of organisms produce actions and signals in particular temporal sequences, including the motor actions recruited during tool-mediated foraging, the arrangement of notes in the songs of birds, whales and gibbons, and the patterning of words in human speech. To accurately reproduce such events, the elements that comprise such sequences must be memorized. Both memory and artificial language learning studies have revealed at least two mechanisms for memorizing sequences, one tracking co-occurrence statistics among items in sequences (i.e., transitional probabilities) and the other one tracking the positions of items in sequences, in particular those of items in sequence-edges. The latter mechanism seems to dominate the encoding of sequences after limited exposure, and to be recruited by a wide array of grammatical phenomena. To assess whether humans differ from other species in their reliance on one mechanism over the other after limited exposure, we presented chimpanzees (Pan troglodytes) and human adults with brief exposure to six items, auditory sequences. Each sequence consisted of three distinct sound types (X, A, B), arranged according to two simple temporal rules: the A item always preceded the B item, and the sequence-edges were always occupied by the X item. In line with previous results with human adults, both species primarily encoded positional information from the sequences; that is, they kept track of the items that occurred in the sequence-edges. In contrast, the sensitivity to co-occurrence statistics was much weaker. Our results suggest that a mechanism to spontaneously encode positional information from sequences is present in both chimpanzees and humans and may represent the default in the absence of training and with brief exposure. As many grammatical regularities exhibit properties of this mechanism, it may be recruited by language and constrain the form that certain grammatical regularities take.

Syntax-induced pattern deafness.

Perceptual systems often force systematically biased interpretations upon sensory input. These interpretations are obligatory, inaccessible to conscious control, and prevent observers from perceiving alternative percepts. Here we report a similarly impenetrable phenomenon in the domain of language, where the syntactic system prevents listeners from detecting a simple perceptual pattern. Healthy human adults listened to three-word sequences conforming to patterns readily learned even by honeybees, rats, and sleeping human neonates. Specifically, sequences either started or ended with two words from the same syntactic category (e.g., noun-noun-verb or verb-verb-noun). Although participants readily processed the categories and learned repetition patterns over nonsyntactic categories (e.g., animal-animal-clothes), they failed to learn the repetition pattern over syntactic categories, even when explicitly instructed to look for it. Further experiments revealed that participants successfully learned the repetition patterns only when they were consistent with syntactically possible structures, irrespective of whether these structures were attested in English or in other languages unknown to the participants. When the repetition patterns did not match such syntactically possible structures, participants failed to learn them. Our results suggest that when human adults hear a string of nouns and verbs, their syntactic system obligatorily attempts an interpretation (e.g., in terms of subjects, objects, and predicates). As a result, subjects fail to perceive the simpler pattern of repetitions--a form of syntax-induced pattern deafness that is reminiscent of how other perceptual systems force specific interpretations upon sensory input.

Five-month-old infants' identification of the sources of vocalizations.

Humans speak, monkeys grunt, and ducks quack. How do we come to know which vocalizations animals produce? Here we explore this question by asking whether young infants expect humans, but not other animals, to produce speech, and further, whether infants have similarly restricted expectations about the sources of vocalizations produced by other species. Five-month-old infants matched speech, but not human nonspeech vocalizations, specifically to humans, looking longer at static human faces when human speech was played than when either rhesus monkey or duck calls were played. They also matched monkey calls to monkey faces, looking longer at static rhesus monkey faces when rhesus monkey calls were played than when either human speech or duck calls were played. However, infants failed to match duck vocalizations to duck faces, even though infants likely have more experience with ducks than monkeys. Results show that by 5 months of age, human infants generate expectations about the sources of some vocalizations, mapping human faces to speech and rhesus faces to rhesus calls. Infants' matching capacity does not appear to be based on a simple associative mechanism or restricted to their specific experiences. We discuss these findings in terms of how infants may achieve such competence, as well as its specificity and relevance to acquiring language.