Representing visual recursion does not require verbal or motor resources

The ability to form and use recursive representations while processing hierarchical structures has been hypothesized to rely on language abilities. If so, linguistic resources should inevitably be activated while representing recursion in non-linguistic domains. In this study we use a dual-task paradigm to assess whether verbal resources are required to perform a visual recursion task. We tested participants across 4 conditions: (1) Visual recursion only, (2) Visual recursion with motor interference (sequential finger tapping), (3) Visual recursion with verbal interference – low load, and (4) Visual recursion with verbal interference – high load. Our results show that the ability to acquire and use visual recursive representations is not affected by the presence of verbal and motor interference tasks. Our finding that visual recursion can be represented without access to verbal resources suggests that recursion is available independently of language processing abilities.     

The faculty of language: what's special about it?

We examine the question of which aspects of language are uniquely human and uniquely linguistic in light of recent suggestions by Hauser, Chomsky, and Fitch that the only such aspect is syntactic recursion, the rest of language being either specific to humans but not to language (e.g. words and concepts) or not specific to humans (e.g. speech perception). We find the hypothesis problematic. It ignores the many aspects of grammar that are not recursive, such as phonology, morphology, case, agreement, and many properties of words. It is inconsistent with the anatomy and neural control of the human vocal tract. And it is weakened by experiments suggesting that speech perception cannot be reduced to primate audition, that word learning cannot be reduced to fact learning, and that at least one gene involved in speech and language was evolutionarily selected in the human lineage but is not specific to recursion. The recursion-only claim, we suggest, is motivated by Chomsky's recent approach to syntax, the Minimalist Program, which de-emphasizes the same aspects of language. The approach, however, is sufficiently problematic that it cannot be used to support claims about evolution. We contest related arguments that language is not an adaptation, namely that it is "perfect," non-redundant, unusable in any partial form, and badly designed for communication. The hypothesis that language is a complex adaptation for communication which evolved piecemeal avoids all these problems.     

Is recursion language-specific? Evidence of recursive mechanisms in the structure of intentional action

In their 2002 seminal paper Hauser, Chomsky and Fitch hypothesize that recursion is the only human-specific and language-specific mechanism of the faculty of language. While debate focused primarily on the meaning of recursion in the hypothesis and on the human-specific and syntax-specific character of recursion, the present work focuses on the claim that recursion is language-specific. We argue that there are recursive structures in the domain of motor intentionality by way of extending John R. Searle’s analysis of intentional action. We then discuss evidence from cognitive science and neuroscience supporting the claim that motor-intentional recursion is language-independent and suggest some explanatory hypotheses: (1) linguistic recursion is embodied in sensory-motor processing; (2) linguistic and motor-intentional recursions are distinct and mutually independent mechanisms. Finally, we propose some reflections about the epistemic status of HCF as presenting an empirically falsifiable hypothesis, and on the possibility of testing recursion in different cognitive domains.     

The redundancy of recursion and infinity for natural language

An influential line of thought claims that natural language and arithmetic processing require recursion, a putative hallmark of human cognitive processing (Chomsky in Evolution of human language: biolinguistic perspectives. Cambridge University Press, Cambridge, pp 45–61, 2010; Fitch et al. in Cognition 97(2):179–210, 2005; Hauser et al. in Science 298(5598):1569–1579, 2002). First, we question the need for recursion in human cognitive processing by arguing that a generally simpler and less resource demanding process—iteration—is sufficient to account for human natural language and arithmetic performance. We argue that the only motivation for recursion, the infinity in natural language and arithmetic competence, is equally approachable by iteration and recursion. Second, we submit that the infinity in natural language and arithmetic competence reduces to imagining infinite embedding or concatenation, which is completely independent from the ability to implement infinite processing, and thus, independent from both recursion and iteration. Furthermore, we claim that a property of natural language is physically uncountable finity and not discrete infinity.     

Toward a Connectionist Model of Recursion in Human Linguistic Performance

Naturally occurring speech contains only a limited amount of complex recursive structure, and this is reflected in the empirically documented difficulties that people experience when processing such structures. We present a connectionist model of human performance in processing recursive language structures. The model is trained on simple artificial languages. We find that the qualitative performance profile of the model matches human behavior, both on the relative difficulty of center-embedding and cross-dependency, and between the processing of these complex recursive structures and right-branching recursive constructions. We analyze how these differences in performance are reflected in the internal representations of the model by performing discriminant analyses on these representations both before and after training. Furthermore, we show how a network trained to process recursive structures can also generate such structures in a probabilistic fashion. This work suggests a novel explanation of people's limited recursive performance, without assuming the existence of a mentally represented competence grammar allowing unbounded recursion.     

How children perceive fractals: Hierarchical self-similarity and cognitive development

The ability to understand and generate hierarchical structures is a crucial component of human cognition, available in language, music, mathematics and problem solving. Recursion is a particularly useful mechanism for generating complex hierarchies by means of self-embedding rules. In the visual domain, fractals are recursive structures in which simple transformation rules generate hierarchies of infinite depth. Research on how children acquire these rules can provide valuable insight into the cognitive requirements and learning constraints of recursion.     

Is there a structural limit to ‘branch’ recursively between more than two tasks?

The term ‘branching’ refers to processes needed for successful reuptake of a task after interruption by another task. Based on a model of human prefrontal cognitive architecture, it has been postulated that people cannot branch recursively between more than two tasks due to a capacity limit built into the cognitive architecture (Koechlin and Hyafil in Science 318:594–598, 2007). As an alternative to a structural limit for recursive branching between more than two tasks we put forward the hypothesis that working memory capacity is the limiting factor in recursive branching. We tested this hypothesis by independently varying working memory load and number of recursive branching steps. Successful branching between up to four tasks was observed, as long as working memory load was kept low. Our data, thus, do not support the proposition of a structural limit to recursive branching beyond two tasks. Instead, they suggest that working memory capacity limit is the most important factor that limits the capacity for branching. We further observed that the requirement to retain task sets and task contents additively contributed to the difficulty of recursive branching. In a broader context, our data thus support working memory models that conceptualize working memory and executive functions not as separate modules, but as tightly interactive processes.     

The nature of the language faculty and its implications for evolution of language (Reply to Fitch, Hauser, and Chomsky)

In a continuation of the conversation with Fitch, Chomsky, and Hauser on the evolution of language, we examine their defense of the claim that the uniquely human, language-specific part of the language faculty (the “narrow language faculty”) consists only of recursion, and that this part cannot be considered an adaptation to communication. We argue that their characterization of the narrow language faculty is problematic for many reasons, including its dichotomization of cognitive capacities into those that are utterly unique and those that are identical to nonlinguistic or nonhuman capacities, omitting capacities that may have been substantially modified during human evolution. We also question their dichotomy of the current utility versus original function of a trait, which omits traits that are adaptations for current use, and their dichotomy of humans and animals, which conflates similarity due to common function and similarity due to inheritance from a recent common ancestor. We show that recursion, though absent from other animals' communications systems, is found in visual cognition, hence cannot be the sole evolutionary development that granted language to humans. Finally, we note that despite Fitch et al.'s denial, their view of language evolution is tied to Chomsky's conception of language itself, which identifies combinatorial productivity with a core of “narrow syntax.” An alternative conception, in which combinatoriality is spread across words and constructions, has both empirical advantages and greater evolutionary plausibility.     

Recursive messages in quantitative communication

The article concerns quantitative messages as opposed to "classifying" messages described in traditional communication theory. Recursive statements are an important part of quantitative messages. The structure and function of recursive statements are analysed. The mathematical principle of recursion is briefly outlined and the article offers a general method of analysing quantitative communication in terms of simple computer simulation. The relationship between recursive and paradoxical communication is pointed out. Finally, the possible application of recursive messages in therapy is discussed.     

学前期儿童执行功能和语言的双向关系:社会经济地位的调节

采用追踪研究考察258名学前儿童执行功能与语言的双向关系,及二者关系是否受社会经济地位调节。交叉滞后结果表明,学前儿童语言发展与执行功能三个子成分（抑制控制、认知灵活性、工作记忆）存在双向关系;T1时儿童语言对T2时认知灵活性的预测作用受家庭社会经济地位调节：在高社会经济地位家庭中,T1时间儿童的语言能显著正向预测T2时认知灵活性,低社会经济地位家庭中预测作用不显著;其余双向关系中调节作用均不显著。本研究表明,学前儿童执行功能三个子成分与语言均存在双向关系,且社会经济地位在部分关系中起到调节作用。     

汉、英工作记忆的加工和储存对中学生英语阅读理解的影响

本研究采用"视空间和言语交替"任务范式分离言语工作记忆的加工和储存两个成分,分别探讨了英语工作记忆的加工和储存成分对我国中学生英语阅读理解的作用及其途径,以及汉语工作记忆的加工和储存成分对中学生英语阅读理解是否具有跨语言影响。98名初中二年级学生完成了一般认知能力、英语阅读理解、汉语和英语工作记忆任务。结果表明:(1)英语工作记忆的加工和储存成分对英语阅读理解均有显著的独立预测作用;(2)英语工作记忆的储存成分对英语阅读理解的作用部分是由加工成分引起的;(3)汉语工作记忆的加工成分对英语阅读理解没有显著的直接预测作用,但却以英语工作记忆的加工成分为中介间接作用于英语阅读理解;汉语工作记忆的储存成分对英语阅读理解没有显著的预测作用。可见,言语工作记忆是一个多成分系统,加工和储存两个成分是相对分离的,并且它们具有不同的跨语言特性,加工存在跨语言一般性,而储存则具有语言特异性。     

The Contribution of Executive Function to Source Memory Development in Early Childhood

Age-related differences in episodic memory judgments assessing recall of fact information and the source of this information were examined. The role of executive function (EF) in supporting early episodic memory ability was also explored. Four- and 6-year-old children were taught 10 novel facts from two different sources (experimenter or puppet), and memory for both fact and source information was later tested. Measures of working memory, inhibitory control, and set shifting were obtained to produce an indicator of children's EF. Six-year-olds recalled more fact and source information than did 4-year-olds. Regression analyses revealed that age, language ability, and EF accounted for unique variance in children's fact recall and source recall performance. These findings suggest a link between episodic memory and EF, and we propose that developmental investigations should further explore this association.     

Reassessing working memory: comment on Just and Carpenter (1992) and Waters and Caplan (1996)

M. A. Just and P. A. Carpenter's (1992) capacity theory of comprehension posits a linguistic working memory functionally separated from the representation of linguistic knowledge. G. S. Waters and D. Caplan's (1996) critique of this approach retained the notion of a separate working memory. In this article, the authors present an alternative account motivated by a connectionist approach to language comprehension. In their view, processing capacity emerges from network architecture and experience and is not a primitive that can vary independently. Individual differences in comprehension do not stem from variations in a separate working memory capacity; instead they emerge from an interaction of biological factors and language experience. This alternative is argued to provide a superior account of comprehension results previously attributed to a separate working memory capacity.     

The role of working memory in decoding emotions

Decoding facial expressions of emotion is an important aspect of social communication that is often impaired following psychiatric or neurological illness. However, little is known of the cognitive components involved in perceiving emotional expressions. Three dual task studies explored the role of verbal working memory in decoding emotions. Concurrent working memory load substantially interfered with choosing which emotional label described a facial expression (Experiment 1). A key factor in the magnitude of interference was the number of emotion labels from which to choose (Experiment 2). In contrast the ability to decide that two faces represented the same emotion in a discrimination task was relatively unaffected by concurrent working memory load (Experiment 3). Different methods of assessing emotion perception make substantially different demands on working memory. Implications for clinical disorders which affect both working memory and emotion perception are considered.     

Individual differences in young children's suggestibility: Relations to event memory,language abilities,working memory,and executive functioning

In this paper, two empirical studies are presented in which an attempt was made to explain individual differences in two different aspects of 4-year-olds’ suggestibility, that is, their ability to resist false suggestions and memory impairments due to prior misinformation. As sources of individual differences cognitive skills along the information processing pathways were chosen: executive functioning (Study 1) and working memory (Study 2). Additionally, memory for the observed event and language proficiency were included in the studies. The results revealed that overall individual differences in language skills made a significant and consistent contribution to individual differences in the included measures of children's susceptibility to suggestions. Executive function and working memory skills were not directly related to children's tendency to yield false suggestions and their memory impairments in a recognition test after being misled. However, both executive function and working memory were related to children's language proficiency pointing to a possible indirect effect and underlining the importance of language competencies in early childhood.     

Computational principles of working memory in sentence comprehension

Understanding a sentence requires a working memory of the partial products of comprehension, so that linguistic relations between temporally distal parts of the sentence can be rapidly computed. We describe an emerging theoretical framework for this working memory system that incorporates several independently motivated principles of memory: a sharply limited attentional focus, rapid retrieval of item (but not order) information subject to interference from similar items, and activation decay (forgetting over time). A computational model embodying these principles provides an explanation of the functional capacities and severe limitations of human processing, as well as accounts of reading times. The broad implication is that the detailed nature of cross-linguistic sentence processing emerges from the interaction of general principles of human memory with the specialized task of language comprehension.     

Effects of verbal working memory deficits on metaphor comprehension in patients with Parkinson's disease

This research studied one aspect of pragmatic language processing, the ability to understand metaphorical language, to determine whether patients with Parkinson disease (PD) are impaired for these abilities, and whether cognitive resource limitations/fronto-striatal dysfunction contributes to these deficits. Seventeen PD participants and healthy controls (HC) completed a series of neuropsychological tests and performed a metaphor comprehension task following the methods of Gernsbacher and colleagues [Gernsbacher, M. A., Keysar, B., Robertson, R. R. W., & Werner, N. K. (2001). The role of suppression and enhancement in understanding metaphors. Journal of Memory and Language, 45, 433-450.] When participants in the PD group were identified as "impaired" or "unimpaired" relative to the control group on a measure of verbal working memory span, we found that only PD participants with impaired working memory were simultaneously impaired in the processing of metaphorical language. Based on our findings we argue that certain "complex" forms of language processing such as metaphor interpretation are highly dependent on intact fronto-striatal systems for working memory which are frequently, although not always, compromised during the early course of PD.     

Perceptual expertise enhances the resolution but not the number of representations in working memory

Despite its central role in cognition, capacity in visual working memory is restricted to about three or four items. Curby and Gauthier (2007) examined whether perceptual expertise can help to overcome this limit by enabling more efficient coding of visual information. In line with this, they observed higher capacity estimates for upright than for inverted faces, suggesting that perceptual expertise enhances visual working memory. In the present work, we examined whether the improved capacity estimates for upright faces indicates an increased number of "slots" in working memory, or improved resolution within the existing slots. Our results suggest that perceptual expertise enhances the resolution but not the number of representations that can be held in working memory. These results clarify the effects of perceptual expertise in working memory and support recent suggestions that number and resolution represent distinct facets of working memory ability.     

Individual differences in the ability to avoid distracting sounds

The present work aims to establish a greater understanding of the cognitive mechanisms involved in avoiding distraction from speech and nonspeech sounds. Although mixed results have been presented by research investigating the hypothesis that individuals with superior working memory abilities are better able to avoid acoustic distraction, we found that working memory correlated with some aspects of performance during distraction when carefully examined. This is consistent with the view that working memory involves resisting interference. In a large sample, we examined two different tasks accompanied by acoustic distraction—serial recall and rapid colour naming—as well as two different measures of working memory (operation span and running span). We show that the previous inability to find relations between working memory and avoidance of distraction may stem from the use of inadequate correlational techniques. Additionally, the level of difficulty of the serial recall task may be an important factor. The results illustrate that commonly used statistical techniques can be misleading and furthermore that the ability to avoid distraction from irrelevant items may not be a unitary construct.