Selective auditory grouping by zebra finches: testing the iambic–trochaic law

Humans have a strong tendency to spontaneously group visual or auditory stimuli together in larger patterns. One of these perceptual grouping biases is formulated as the iambic/trochaic law, where humans group successive tones alternating in pitch and intensity as trochees (high–low and loud–soft) and alternating in duration as iambs (short–long). The grouping of alternations in pitch and intensity into trochees is a human universal and is also present in one non-human animal species, rats. The perceptual grouping of sounds alternating in duration seems to be affected by native language in humans and has so far not been found among animals. In the current study, we explore to which extent these perceptual biases are present in a songbird, the zebra finch. Zebra finches were trained to discriminate between short strings of pure tones organized as iambs and as trochees. One group received tones that alternated in pitch, a second group heard tones alternating in duration, and for a third group, tones alternated in intensity. Those zebra finches that showed sustained correct discrimination were next tested with longer, ambiguous strings of alternating sounds. The zebra finches in the pitch condition categorized ambiguous strings of alternating tones as trochees, similar to humans. However, most of the zebra finches in the duration and intensity condition did not learn to discriminate between training stimuli organized as iambs and trochees. This study shows that the perceptual bias to group tones alternating in pitch as trochees is not specific to humans and rats, but may be more widespread among animals.     

Do nonhuman animals reason about prestige-based status?

Status is a complex, but crucially important, aspect of life across species. In recent decades, researchers have made significant contributions to our understanding of both the pathways by which status can be attained, as well as our underlying capacities for reasoning about these pathways. In 2001, Henrich & Gil-White proposed a prestige-based pathway to status where low status actors willingly defer to competent or knowledgeable high status actors, as a means of facilitating social learning and cultural transmission. Although this type of status hierarchy, and the capacity to reason about it, was hypothesized to be unique to humans, here I argue that there are several reasons why we might observe prestige-based status, and the capacity for reasoning about this pathway to status, in some nonhuman species as well. These reasons focus on the prevalence, importance, and sophistication of social learning in certain taxa, as well as the marked variation in hierarchy characteristics and structure across species. I point out places where our current methodologies encounter difficulties distinguishing whether a hierarchy in the wild is based on dominance or prestige, where our experimental methods leave us unable to assess whether an individual is reasoning about a high status actor as being prestigious or formidable, and provide suggestions for addressing these limitations. Adopting a comparative approach will clarify whether prestige-based status truly is unique to humans, and—if not—precisely what selective pressures facilitate the emergence of prestige-based status and the capacity for reasoning about it.     

Do adolescents help and share?

Although developmental and social psychologists have studied prosocial behavior for the past twenty years, its occurrence in adolescents has received little attention. In the present paper, observational and self-report data were collected on 37 nonhandicapped and handicapped (behaviorally disordered) adolescents in public school settings. Helping, sharing, cooperating, comforting, defending, donating, and rescuing were the prosocial behaviors investigated. The adolescents with handicaps displayed significantly more prosocial behavior than did the nonhandicapped adolescents. However, the nonhandicapped adolescents perceived themselves as engaging more frequently in prosocial behavior than did their handicapped peers. The teachers of the handicapped adolescents used a prosocial teaching style more frequently than did the teachers of the nonhandicapped adolescents. Implications for future research and training are discussed.     

Do humans ape? Or do apes human? Imitation and intention in humans (Homo sapiens) and other animals

A. Whiten, D. M. Custance, J.-C. Gomez, P. Teixidor, and K. A. Bard (1996) tested chimpanzees' (Pan troglodytes) and human children's (Homo sapiens) skills at imitation with a 2-action test on an "artificial fruit." Chimpanzees imitated to a restricted degree; children were more thoroughly imitative. Such results prompted some to assert that the difference in imitation indicates a difference in the subjects' understanding of the intentions of the demonstrator (M. Tomasello, 1996). In this experiment, 37 adult human subjects were tested with the artificial fruit. Far from being perfect imitators, the adults were less imitative than the children. These results cast doubt on the inference from imitative performance to an ability to understand others' intentions. The results also demonstrate how any test of imitation requires a control group and attention to the level of behavioral analysis.     

Does the mastery of center-embedded linguistic structures distinguish humans from nonhuman primates?

In a recentScience article, Fitch and Hauser (2004; hereafter, F&H) claimed to have demonstrated that cotton-top tamarins fail to learn an artificial language produced by a phrase structure grammar (Chomsky, 1957) generating center-embedded sentences, whereas adult humans easily learn such a language. We report an experiment replicating the results of F&H in humans but also showing that subjects learned the language without exploiting in any way the center-embedded structure. When the procedure was modified to make the processing of this structure mandatory, the subjects no longer showed evidence of learning. We propose a simple interpretation for the difference in performance observed in F&H’s task between humans and tamarins and argue that, beyond the specific drawbacks inherent in F&H’s study, researching the source of the inability of nonhuman primates to master language within a framework built around Chomsky’s hierarchy of grammars is a conceptual dead end.     

Do reading and spelling share a lexicon?

In the reading and spelling literature, an ongoing debate concerns whether reading and spelling share a single orthographic lexicon or rely upon independent lexica. Available evidence tends to support a single lexicon account over an independent lexica account, but evidence is mixed and open to alternative explanation. In the current work, we propose another, largely ignored account – separate-but-shared lexica – according to which reading and spelling have separate orthographic lexica, but information can be shared between them. We report three experiments designed to competitively evaluate these three theoretical accounts. In each experiment, participants learned new words via reading training and/or spelling training. The key manipulation concerned the amount of reading versus spelling practice a given item received. Following training, we assessed both response time and accuracy on final outcome measures of reading and spelling. According to the independent lexica account, final performance in one modality will not be influenced by the level of practice in the other modality. According to the single lexicon account, final performance will depend on the overall amount of practice regardless of modality. According to the separate-but-shared account, final performance will be influenced by the level of practice in both modalities but will benefit more from same-modality practice. Results support the separate-but-shared account, indicating that reading and spelling rely upon separate lexica, but information can be shared between them.     

What do humans feel with mistreated humans,animals, robots,and objects? Exploring the role of cognitive empathy

Motivation and Emotion - The aim of this paper is to present a study in which we compare the degree of empathy that a convenience sample of university students expressed with humans, animals,...     

Attention in humans and animals: is there a capacity limitation at the time of encoding?

Investigators have suggested that pigeons have a limited capacity input channel and that as a result performance suffers when information load is great. This information overload hypothesis is based on converging findings from experiments using the matching-to-sample paradigm. Fundamental among these findings are that (a) performance improves as sample duration increases, (b) performance is better when the sample contains one relevant feature (elements) than when it contains two (compounds), and (c) this element superiority effect can be reduced by making the relevant feature of compound samples predictable. Experiments 1 and 2 show that these effects occur for humans as well. However, Experiments 3, 4, and 5 show that in humans at least some of these effects do not result from information overload at the time of encoding. Thus, the assertion that these effects do reflect such a limitation in pigeons must be reevaluated.     

Are animals moral?: Zhu Xi and Jeong Yakyong’s views on nonhuman animals

One significant feature of Jeong Yakyong’s丁若鏞 (1762–1836) thought is his deconstruction of Zhu Xi’s 朱熹 (1130–1200) moral universe based on li 理 and qi 氣. For Zhu Xi, the world in its entirety was a moral place, but Jeong Yakyong distinguished nonmoral domains from the moral domain. One question that follows in pursuing a comparison of their philosophies on this topic is what each thinker meant by ‘moral’ and, in particular, whether they meant the same thing. In this paper, I delve deeper into this topic by comparing their respective perspectives on whether nonhuman animals are moral. Interestingly, they held exactly opposite views: Zhu Xi believed that certain actions on the part of nonhuman animals manifest moral values, whereas Jeong Yakyong claimed that none of the actions of nonhuman animals has moral value. In comparing their views, I introduce Mark Rowlands’ distinction between ‘moral subjects’ and ‘moral agents.’     

Is the asymmetry in young infants’ categorization of humans versus nonhuman animals based on head,body, or global gestalt information?

Quinn and Eimas (1998) reported an asymmetry in the exclusivity of the category representations that young infants form for humans and nonhuman animals: category representations for nonhuman animal species were found to exclude humans, whereas a category representation for humans was found to include nonhuman animal species (i.e., cats, horses). The present experiment utilized the familiarization/novelty-preference procedure with 3- and 4-month-olds to determine the perceptual cues (i.e., whole stimulus, head alone, body alone) that provided the basis for this asymmetry. The data revealed the asymmetry to be observable only with the whole animal stimuli and not when infants were provided with information from just the head or the body of the exemplars. The results indicate that the incorporation of nonhuman animal species into a category representation for humans is based on holistic information.     

Do animals have rights?

A right, unlike an interest, is a valid claim, or potential claim, made by a moral agent, under principles that govern both the claimant and the target of the claim. Animals cannot be the bearers of rights because the concept of rights is essentially human; it is rooted in and has force within a human moral world.     

Do dyslexia and stuttering share a processing deficit?

This study assessed the prevalence of childhood stuttering in adults with dyslexia (AWD) and the prevalence of dyslexia in adults who stutter (AWS). In addition, the linguistic profiles of 50 AWD, 30 AWS and 84 neurotypical adults were measured. We found that 17 out of 50 AWD (34 %) reported stuttering during childhood compared to 1 % of the neurotypical population. This was moderated by the severity of dyslexia: People with mild dyslexia showed a lower prevalence rate (15 %) of childhood stuttering than those with severe dyslexia (47 %). In addition, we observed that 50 % of the AWS (n = 30) fulfilled the diagnostic criteria of dyslexia, even though they had never been diagnosed as dyslexic. Compared to neurotypical adults, phonological working memory, awareness, and retrieval were similarly reduced in AWS and AWD. The findings supports the view that stuttering and dyslexia may share a phonological deficit.     

Do humans produce the speed–accuracy trade-off that maximizes reward rate?

In this paper we investigate trade-offs between speed and accuracy that are produced by humans when confronted with a sequence of choices between two alternatives. We assume that the choice process is described by the drift diffusion model, in which the speed–accuracy trade-off is primarily controlled by the value of the decision threshold. We test the hypothesis that participants choose the decision threshold that maximizes reward rate, defined as an average number of rewards per unit of time. In particular, we test four predictions derived on the basis of this hypothesis in two behavioural experiments. The data from all participants of our experiments provide support only for some of the predictions, and on average the participants are slower and more accurate than predicted by reward rate maximization. However, when we limit our analysis to subgroups of 30–50% of participants who earned the highest overall rewards, all the predictions are satisfied by the data. This suggests that a substantial subset of participants do select decision thresholds that maximize reward rate. We also discuss possible reasons why the remaining participants select thresholds higher than optimal, including the possibility that participants optimize a combination of reward rate and accuracy or that they compensate for the influence of timing uncertainty, or both.     

Why do the effects of delaying reinforcement in animals and delaying feedback in humans differ? A working-memory analysis

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.     

Why do the effects of delaying reinforcement in animals and delaying feedback in humans differ? A working-memory analysis

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.     

Do humans and baboons use the same information when categorizing human and baboon faces?

What information is used for sorting pictures of complex stimuli into categories? We applied a reverse correlation method to reveal the visual features mediating categorization in humans and baboons. Two baboons and 6 humans were trained to sort, by species, pictures of human and baboon faces on which random visual noise was superimposed. On ambiguous probe trials, a human-baboon morph was presented, eliciting "human" responses on some trials and "baboon" responses on others. The difference between the noise patterns that induced the two responses made explicit the information mediating the classification. Unlike the humans, the baboons based their categorization on information that closely matched that used by a theoretical observer responding solely on the basis of the pixel similarities between the probe and training images. We show that the classification-image technique and principal components analysis provide a method to make explicit the differences in the information mediating categorization in humans and animals.     

Do emotion-induced blindness and the attentional blink share underlying mechanisms? An event-related potential study of emotionally-arousing words

When two targets are presented within approximately 500 ms of each other in the context of rapid serial visual presentation (RSVP), participants’ ability to report the second target is reduced compared to when the targets are presented further apart in time. This phenomenon is known as the attentional blink (AB). The AB is increased in magnitude when the first target is emotionally arousing. Emotionally arousing stimuli can also capture attention and create an AB-like effect even when these stimuli are presented as to-be-ignored distractor items in a single-target RSVP task. This phenomenon is known as emotion-induced blindness (EIB). The phenomenological similarity in the behavioral results associated with the AB with an emotional T1 and EIB suggest that these effects may result from similar underlying mechanisms – a hypothesis that we tested using event-related electrical brain potentials (ERPs). Behavioral results replicated those reported previously, demonstrating an enhanced AB following an emotionally arousing target and a clear EIB effect. In both paradigms highly arousing taboo/sexual words resulted in an increased early posterior negativity (EPN) component that has been suggested to represent early semantic activation and selection for further processing in working memory. In both paradigms taboo/sexual words also produced an increased late positive potential (LPP) component that has been suggested to represent consolidation of a stimulus in working memory. Therefore, ERP results provide evidence that the EIB and emotion-enhanced AB effects share a common underlying mechanism.     

Do monkeys think in metaphors? Representations of space and time in monkeys and humans

Research on the relationship between the representation of space and time has produced two contrasting proposals. ATOM posits that space and time are represented via a common magnitude system, suggesting a symmetrical relationship between space and time. According to metaphor theory, however, representations of time depend on representations of space asymmetrically. Previous findings in humans have supported metaphor theory. Here, we investigate the relationship between time and space in a nonverbal species, by testing whether non-human primates show space–time interactions consistent with metaphor theory or with ATOM. We tested two rhesus monkeys and 16 adult humans in a nonverbal task that assessed the influence of an irrelevant dimension (time or space) on a relevant dimension (space or time). In humans, spatial extent had a large effect on time judgments whereas time had a small effect on spatial judgments. In monkeys, both spatial and temporal manipulations showed large bi-directional effects on judgments. In contrast to humans, spatial manipulations in monkeys did not produce a larger effect on temporal judgments than the reverse. Thus, consistent with previous findings, human adults showed asymmetrical space–time interactions that were predicted by metaphor theory. In contrast, monkeys showed patterns that were more consistent with ATOM.     

To share or not to share? Explaining willingness to share in the context of social distance

Sharing can help make goods available to many people who would otherwise have no access to them. In the effort of motivating more people to participate in the sharing economy, it is useful to know the variables that influence the willingness to share (WTS). Our study aims to identify these variables. Applying field theory, we conducted an experiment based on nonmonetary sharing situations. Complementing existing research directed towards users of goods, we focused on the providers of goods, thus broadening the understanding of sharing contexts. We demonstrate that WTS can be explained by several variables. In particular, a low social distance increases individuals' WTS their belongings with others. Product involvement is also a predictor of whether or not people are willing to share. In contrast, consumer characteristics such as materialism, altruism, and interpersonal trust have no impact on sharing intentions. Our findings provide significant implications for consumer research and for the marketing of sharing organizations.