Publications

Abstract

"Event realisation" refers to the normal final state of the affected entity of an activity described by a verb. For example, the sentence John killed the mosquito entails that the mosquito is afterwards dead – this is the full realisation of a killing event. By contrast, a sentence such as John hit the mosquito does not entail the mosquito’s death (even though we might assume this to be a likely result). In using a certain verb, which features of event realisation are entailed and which are just likely? This questionnaire supports cross-linguistic exploration of event realisation for a range of event types.

Abstract

The advent of psycholinguistic and neurolinguistic methodologies has provided new insights into theories of language acquisition. Sequential multilingualism is no exception, and some of the most recent work on the subject has incorporated a particular focus on language processing. This chapter surveys some of the work on the processing of lexical and morphosyntactic aspects of third or further languages, with different offline and online methodologies. We also discuss how, while increasingly sophisticated techniques and experimental designs have improved our understanding of third language acquisition and processing, simpler but clever designs can answer pressing questions in our theoretical debate. We provide examples of both sophistication and clever simplicity in experimental design, and argue that the field would benefit from incorporating a combination of both concepts into future work.

Abstract

Literacy and education represent essential aspects of contemporary society and subserve important aspects of socialization and cultural transmission. The study of illiterate subjects represents one approach to investigate the interactions between neurobiological and cultural factors in cognitive development, individual learning, and their influence on the functional organization of the brain. In this chapter we review some recent cognitive, neuroanatomic, and functional neuroimaging results indicating that formal education influences important aspects of the human brain. Taken together this provides strong support for the idea that the brain is modulated by literacy and formal education, which in turn change the brains capacity to interact with its environment, including the individual's contemporary culture. In other words, the individual is able to participate in, interact with, and actively contribute to the process of cultural transmission in new ways through acquired cognitive skills.

Abstract

Language production involves the retrieval of information from memory, the planning of an articulatory program, and executive control and self-monitoring. These processes can be related to the domains of long-term memory, motor control, and executive control. Here, we argue that studying neuronal oscillations provides an important opportunity to understand how general neuronal computational principles support language production, also helping elucidate relationships between language and other domains of cognition. For each relevant domain, we provide a brief review of the findings in the literature with respect to neuronal oscillations. Then, we show how similar patterns are found in the domain of language production, both through review of previous literature and novel findings. We conclude that neurophysiological mechanisms, as reflected in modulations of neuronal oscillations, may act as a fundamental basis for bringing together and enriching the fields of language and cognition.

Abstract

Gender-(mis)matching pronouns have been studied extensively in experiments. However, a phenomenon common to various languages has thus far been overlooked: the systemic use of non-feminine pronouns when referring to female individuals. The present study is the first to provide experimental insights into the interpretation of such a pronoun: Limburgian zien ‘his/its’ and Dutch zijn ‘his/its’ are grammatically ambiguous between masculine and neuter, but while Limburgian zien can refer to women, the Dutch equivalent zijn cannot. Employing an acceptability judgment task, we presented speakers of Limburgian (N = 51) with recordings of sentences in Limburgian featuring zien, and speakers of Dutch (N = 52) with Dutch translations of these sentences featuring zijn. All sentences featured a potential male or female antecedent embedded in a stereotypically male or female context. We found that ratings were higher for sentences in which the pronoun could refer back to the antecedent. For Limburgians, this extended to sentences mentioning female individuals. Context further modulated sentence appreciation. Possible mechanisms regarding the interpretation of zien as coreferential with a female individual will be discussed.

Abstract

The structural design features of human language emerge in the process of cultural evolution, shaping languages over the course of communication, learning, and transmission. What role does this leave biological evolution? This chapter highlights the biological bases and preconditions that underlie the particular type of prosocial behaviours and cognitive inference abilities that are required for languages to emerge via cultural evolution to begin with.

Abstract

This paper deals with the Shawi nominalizing suffixes -su’~-ru’~-nu’ ‘general nominalizer’, -napi/-te’/-tun‘performer/agent nominalizer’, -pi’‘patient nominalizer’, and -nan ‘instrument nominalizer’. The goal of this article is to provide a description of nominalization in Shawi. Throughout this paper I apply the Generalized Scale Model (GSM) (Malchukov, 2006) to Shawi verbal nominalizations, with the intention of presenting a formal representation that will provide a basis for future areal and typological studies of nominalization. In addition, I dialogue with Shibatani’s model to see how the loss or gain of categories correlates with the lexical or grammatical nature of nominalizations. strong nominalization in Shawi correlates with lexical nominalization, whereas weak nominalizations correlate with grammatical nominalization. A typology which takes into account the productivity of the nominalizers is also discussed.

Abstract

In the language Duna (Trans New Guinea), egophoric distributional patterns are a pervasive characteristic of verbal morphology, but do not comprise a single coherent system. Many morphemes, including evidential markers and future time inflections, show strong tendencies to co-occur with ‘informant’ subjects (the speaker in a declarative, the addressee in an interrogative), or alternatively with non-informant subjects. The person sensitivity of the Duna forms is observable in frequency, speaker judgments of sayability, and subject implicatures. Egophoric and non-egophoric distributional patterns are motivated by the individual semantics of the morphemes, their perspective-taking properties, and logical and/or conventionalised expectations of how people experience and talk about events. Distributional tendencies can also be flouted, providing a resource for speakers to convey attitudes towards their own knowledge and experiences, or the knowledge and experiences of others.

Abstract

Languages with egophoric systems require their users to pay special attention to who knows what in the speech situation, providing formal marking of whether the speaker or addressee has personal knowledge of the event being discussed. Such systems have only recently come to be studied in cross-linguistic perspective. This chapter has two aims in regard to contributing to our understanding of egophoric marking. Firstly, it presents relevant data from a relatively under-described and endangered language, Kaluli (aka Bosavi), spoken in Papua New Guinea. Unusually, Kaluli tense inflections appear to show a mix of both egophoric and first vs non-first person-marking features, as well as other contrasts that are broadly relevant to a typology of egophoricity, such as special constructions for the expression of involuntary experience. Secondly, the chapter makes a preliminary foray into issues concerning egophoric marking and child language, drawing on a naturalistic corpus of child-caregiver interactions. Questions for future investigation raised by the Kaluli data concern, for example, the potentially challenging nature of mastering inflections that are sensitive to both person and speech act type, the possible role of question-answer pairs in children’s acquisition of egophoric morphology, and whether there are special features of epistemic access and authority that relate particularly to child-adult interactions.

Abstract

This chapter describes neurolinguistic aspects of morphology, morphological theory, and especially morphological processing. It briefly mentions the main processing models in the literature and how they deal with morphological issues, i.e. full-listing models (all morphologically related words are listed separately in the lexicon and are processed individually), full-parsing or decompositional models (morphologically related words are not listed in the lexicon but are decomposed into their constituent morphemes, each of which is listed in the lexicon), and hybrid, so-called dual route, models (regular morphologically related words are decomposed, irregular words are listed). The chapter also summarizes some important findings from the literature that bear on neurolinguistic aspects of morphological processing, from both language comprehension and language production, taking into consideration neuropsychological patient studies as well as studies employing neuroimaging methods.

Abstract

This paper presents preliminary remarks on some of the central linguistic means speakers of Kilivila use in expressing their conceptions of space and for referring to objects, persons, and events in space . After a brief characterisation of the language and its speakers, I sketch how specific topological relations are encoded, how motion events are described, and what frames of spatial reference are preferred in what contexts for what means and ends.

Abstract

Die Sprachwissenschaft hat den Begriff und das Konzept ›Rituelle Kommunikation‹ von der vergleichenden Verhaltensforschung übernommen. Humanethologen unterscheiden eine Reihe von sogenannten ›Ausdrucksbewegungen‹, die in der Mimik, der Gestik, der Personaldistanz (Proxemik) und der Körperhaltung (Kinesik) zum Ausdruck kommen. Viele dieser Ausdrucksbewegungen haben sich zu spezifischen Signalen entwickelt. Ethologen definieren Ritualisierung als Veränderung von Verhaltensweisen im Dienst der Signalbildung. Die zu Signalen ritualisierten Verhaltensweisen sind Rituale. Im Prinzip kann jede Verhaltensweise zu einem Signal werden, entweder im Laufe der Evolution oder durch Konventionen, die in einer bestimmten Gemeinschaft gültig sind, die solche Signale kulturell entwickelt hat und die von ihren Mitgliedern tradiert und gelernt werden.

Abstract

Bronislaw Malinowski – based on his experience during his field research on the Trobriand Islands – pointed out that language is first and foremost a tool for creating social bonds. It is a mode of behavior and the meaning of an utterance is constituted by its pragmatic function. Malinowski’s ideas finally led to the formation of the subdiscipline “anthropological linguistics”. This paper presents three observations of the Trobrianders’ attitude to their language Kilivila and their language use in social interactions. They illustrate that whoever wants to successfully research the role of language, culture and cognition in social interaction must be on ‘common ground’ with the researched community.

Abstract

As I have already pointed out elsewhere (Senft 2008; 2010; 2014), the Gricean conversational maxims of Quality – “Try to make your contribution one that is true” – and Manner “Be perspicuous”, specifically “Avoid obscurity of expression” and “Avoid ambiguity” (Grice 1967; 1975; 1978) – are not observed by the Trobriand Islanders of Papua New Guinea, neither in forms of their ritualized communication nor in forms and ways of everyday conversation and other ordinary verbal interactions. The speakers of the Austronesian language Kilivila metalinguistically differentiate eight specific non-diatopical registers which I have called “situational-intentional” varieties. One of these varieties is called “biga sopa”. This label can be glossed as “joking or lying speech, indirect speech, speech which is not vouched for”. The biga sopa constitutes the default register of Trobriand discourse and conversation. This contribution to the workshop on philosophy and pragmatics presents the Trobriand Islanders’ indigenous typology of non-diatopical registers, especially elaborating on the concept of sopa, describing its features, discussing its functions and illustrating its use within Trobriand society. It will be shown that the Gricean maxims of quality and manner are irrelevant for and thus not observed by the speakers of Kilivila. On the basis of the presented findings the Gricean maxims and especially Grice’s claim that his theory of conversational implicature is “universal in application” is critically discussed from a general anthropological-linguistic point of view.

Abstract

This paper presents the complex system of classifiers in Kilivila, the language of the Trobriand Islanders of Papua New Guinea. After a brief introduction to the language and its speakers, the classifier system is briefly described with respect to the role of these formatives for the word formation of Kilivila numerals, adjectives, demonstratives and one form of an interrogative pronoun/adverb. Then the functions the classifier system fulfils with respect to concord, temporary classification, the unitizing of nominal expressions, nominalization, indication of plural, anaphoric reference as well as text and discourse coherence are discussed and illustrated. The paper ends with some language specific and cross-linguistic questions for further research.

Abstract

1. Introduction 2. A generative grammar as an algorithm 3. The semantic component 4. Bibliography 1. Introduction Throughout the 20th century up to the present day grammar and semantics have been uneasy bedfellows. A look at the historical background will make it clear how this curious situation came about. 20th-century linguistics has been characterized by an almost exclusive concern with the structure of words, word groups and sentences. This concern was reinforced, especially on the American side of the Atlantic, by the sudden rise and subsequent dominance of behaviorism during the 1920s. It started in psychology but quickly permeated all the human sciences, including linguistics, until the early 1960s, when it collapsed as suddenly as it had arisen.

Abstract

Presupposition is a semantic device built into natural language to make sentences fit for use in certain contexts but not in others. A sentence carrying a presupposition thus evokes a context in which that presupposition is fulfilled. The study of presupposition was triggered by the behavior of natural language negation, which tends to preserve presuppositions either as invited inferences or as entailments. As the role of discourse became more apparent in semantics, presupposition began to be seen increasingly as a discourse-semantic phenomenon with consequences for the logic of language.

Abstract

The property of presuppositions to be sometimes preserved through embeddings, albeit often in a weakened form, is called projection. The projection problem consists in formulating the conditions under which the presuppositions of an embedded clause (a) are kept as presuppositions of the superordinate structure, or (b) remain as an invited inference that can be overruled by context, or (c) are canceled. Over the past 25 years it has been recognized that the projection problem is to be solved in the context of a wider theory of presupposition and discourse incrementation.

Abstract

Logic was discovered by Aristotle when he saw that the semantic behavior of the negation word not is different in sentences with a definite and in those with a quantified subject term. Until the early 20th century, logic remained firmly language-based, but for the past century it has been mainly a tool in the hands of mathematicians, which has meant an alienation from linguistic reality. With the help of new techniques, it is now possible to revert to the logic of language, which is seen as based on a semantic analysis of the logical words (constants) involved. This new perspective, combined with much improved insights into the semantically defined discourse dependency of natural language sentences, leads to a novel and more functionally oriented approach to logic and to a reappraisal of traditional predicate calculus, whose main fault, undue existential import, evaporates when discourse dependency, in particular the presuppositional aspect, is brought into play. Traditional predicate calculus is seen to have a much greater logical power and a much greater functionality than modern predicate calculus. There is also full isomorphism, neglected in modern logic, between traditional predicate calculus and propositional calculus, which raises the question of any possible deeper causes.

Abstract

Virtual objects are objects thought up by a thinking individual. Although 20th-century philosophy has tried to ban them from ontology, they make it impossible to account for the truth of sentences such as Apollo was worshipped in the island of Delos, in which a property is assigned to the nonexisting, virtual entity Apollo. Such facts are the reason why virtual objects are slowly being recognized again.

Abstract

Some predicates are ‘factive’ in that they induce the presupposition that what is said in their subordinate that clause is true.

Abstract

The term ‘donkey sentences’ derives from the medieval philosopher Walter Burleigh, whose example sentences contain mention of donkeys. The modern philosopher Peter Geach rediscovered Burleigh's sentences and the associated problem. The problem is that natural language anaphoric pronouns are sometimes used in a way that cannot be accounted for in terms of modern predicate calculus. The solution lies in establishing a separate category of anaphoric pronouns that refer via the intermediary of a contextually given antecedent, possibly an existentially quantified expression.

Abstract

A discourse domain D is a form of middle-term memory for the storage of the information embodied in the discourse at hand. The information carried by a new utterance u is added to D (u is incremented to D). The processes involved and the specific structure of D are a matter of ongoing research.

Abstract

Discourse semantics (DSx) is based on the fact that the interpretation of uttered sentences is dependent on and co-determined by the information stored in a specialized middle-term cognitive memory called discourse domain (D). DSx studies the structure and dynamics of Ds and the conditions to be fulfilled by D for proper interpretation. It does so in the light of the truth-conditional criteria for semantics, with an emphasis on intensionality phenomena. It requires the assumption of virtual entities and virtual facts. Any model-theoretic interpretation holds between discourse structures and pre-established verification domains.

Abstract

Aristotle's importance in the professional study of language consists first of all in the fact that he demythologized language and made it an object of rational investigation. In the context of his theory of truth as correspondence, he also provided the first semantic analysis of propositions in that he distinguished two main constituents, the predicate, which expresses a property, and the remainder of the proposition, referring to a substance to which the property is assigned. That assignment is either true or false. Later, the ‘remainder’ was called subject term, and the Aristotelian predicate was identified with the verb in the sentence. The Aristotelian predicate, however, is more like what is now called the ‘comment,’ whereas his remainder corresponds to the topic. Aristotle, furthermore, defined nouns and verbs as word classes. In addition, he introduced the term ‘case’ for paradigmatic morphological variation.

Abstract

There is a growing awareness among theoretical linguists and philosophers of language that the linguistic definition of lexical meanings, which must be learned when one learns a language, underdetermines not only full utterance interpretation but also sentence meaning. The missing information must be provided by cognition – that is, either general encyclopedic or specific situational knowledge. This fact crucially shows the basic insufficiency of current standard model-theoretic semantics as a paradigm for the analysis and description of linguistic meaning.

Abstract

The lexical conditions, also known as satisfaction conditions, of a predicate P are the conditions that must be satisfied by the term referents of P for P applied to these term referents to yield a true sentence. In view of presupposition theory it makes sense to distinguish two categories of lexical conditions, the preconditions that must be satisfied for the sentence to be usable in any given discourse, and the update conditions which must be satisfied for the sentence to yield truth.

Abstract

The widely prevailing view that standard bivalent logic is the only possible sound logical system, imposed by metaphysical necessity, has been shattered by the development of multivalent logics during the 20th century. It is now clear that standard bivalent logic is merely the minimal representative of a wide variety of viable logics with any number of truth values. These viable logics can be subdivided into families. In this article, the Kleene family and the PPCn family are subjected to special examination, as they appear to be most relevant for the study of the logical properties of human language.

Abstract

Traditional psycholinguistic studies take place in controlled experimental labs and typically involve testing undergraduate psychology or linguistics students. Investigating psycholinguistics in this manner calls into question the external validity of findings, that is, the extent to which research findings generalize across languages and cultures, as well as ecologically valid settings. Here we consider three ways in which psycholinguistics can be taken out of the lab. First, researchers can conduct cross-cultural fieldwork in diverse languages and cultures. Second, they can conduct online experiments or experiments in institutionalized public spaces (e.g., museums) to obtain large, diverse participant samples. And, third, researchers can perform studies in more ecologically valid settings, to increase the real-world generalizability of findings. By moving away from the traditional lab setting, psycholinguists can enrich their understanding of language use in all its rich and diverse contexts.

Abstract

The Papuan languages of the central Solomon Islands are a negatively defined areal grouping: They are those four or possibly five languages in the central Solomon Islands that do not belong to the Austronesian family. Bilua (Vella Lavella), Touo (Rendova), Lavukaleve (Russell Islands), Savosavo (Savo Island) and possibly Kazukuru (New Georgia) have been identified as non-Austronesian since the early 20th century. However, their affiliations both to each other and to other languages still remain a mystery. Heterogeneous and until recently largely undescribed, they present an interesting departure from what is known both of Austronesian languages in the region and of the Papuan languages of the mainland of New Guinea.

Abstract

The artificial grammar learning (AGL) paradigm enables systematic investigation of the acquisition of linguistically relevant structures. It is a paradigm of interest for language processing research, interfacing with theoretical linguistics, and for comparative research on language acquisition and evolution. This chapter presents a key for understanding major variants of the paradigm. An unbiased summary of neuroimaging findings of AGL is presented, using meta-analytic methods, pointing to the crucial involvement of the bilateral frontal operculum and regions in the right lateral hemisphere. Against a background of robust posterior temporal cortex involvement in processing complex syntax, the evidence for involvement of the posterior temporal cortex in AGL is reviewed. Infant AGL studies testing for neural substrates are reviewed, covering the acquisition of adjacent and non-adjacent dependencies as well as algebraic rules. The language acquisition data suggest that comparisons of learnability of complex grammars performed with adults may now also be possible with children.

Abstract

Language- and speech-related disorders are among the most frequent consequences of developmental and acquired pathologies. While classical approaches to the study of these disorders typically employed the lesion method to unveil one-to-one correspondence between locations, the extent of the brain damage, and corresponding symptoms, recent advances advocate the use of online methods of investigation. For example, the use of electrophysiology or magnetoencephalography—especially when combined with anatomical measures—allows for in vivo tracking of real-time language and speech events, and thus represents a particularly promising venue for future research targeting rehabilitative interventions. In this chapter, we provide a comprehensive overview of language and speech pathologies arising from cortical and/or subcortical damage, and their corresponding neurophysiological and pathological symptoms. Building upon the reviewed evidence and literature, we aim at providing a description of how the neurophysiology of the language network changes as a result of brain damage. We will conclude by summarizing the evidence presented in this chapter, while suggesting directions for future research.

Abstract

Field data are drawn from a particular speech community at a certain place and time. The intent of this survey is to enrich understanding of the various socio-cultural contexts in which linguistic and “cognitive” data may have been collected, so that we can explore the role which societal, cultural and contextual factors may play in this material. The questionnaire gives guidelines concerning types of ethnographic information that are important to cross-cultural and cross-linguistic enquiry, and will be especially useful to researchers who do not have specialised training in anthropology.

Abstract

How do languages encode different kinds of movement, and what features do people pay attention to when describing motion events? This document outlines topics concerning the investigation of “enter” and “exit” events. It helps contextualise research tasks that examine this domain (see 'Motion Elicitation' and 'Enter/Exit animation') and gives some pointers about what other questions can be explored.

Abstract

How do languages express ideas of movement, and how do they package features that can be part of motion, such as path and cause? This questionnaire is used to gain a picture of the lexical resources a language draws on for motion expressions. It targets issues of semantic conflation (i.e., what other semantic information besides motion may be encoded in a verb root) and patterns of semantic distribution (i.e., what types of information are encoded in the morphemes that come together to build a description of a motion event). It was originally designed for Australian languages, but has since been used around the world.

Abstract

Contrastive reference, where a speaker presents or identifies one item in explicit contrast to another (I like this book but that one is boring), has special communicative and information structure properties. This can be reflected in rules of demonstrative use. For example, in some languages, terms equivalent to this and that can be used for contrastive reference in almost any spatial context. But other two-term languages stick more closely to “distance rules” for demonstratives, allowing a this-like term in close space only. This task elicits data concerning one context of contrastive reference, focusing on whether (and how) non-proximal demonstratives can be used to distinguish objects within a proximal area. The task runs like a memory game, with the consultant being asked to identify the locations of two or three hidden items arranged within arm’s reach.

Abstract

How do languages encode different kinds of movement, and what features do people pay attention to when describing motion events? This task investigates the expression of “enter” and “exit” activities, that is, events involving motion in(to) and motion out (of) container-like items. The researcher first uses particular stimuli (a ball, a cup, rice, etc.) to elicit descriptions of enter/exit events from one consultant, and then asks another consultant to demonstrate the event based on these descriptions. See also the related entries Enter/Exit Animation and Background Questions for Enter/Exit Research.

Abstract

Demonstrative terms (e.g., this and that) are key to understanding how a language constructs and interprets spatial relationships. They are tricky to pin down, typically having functions that do not match “idealized” uses, and that can become invisible in narrow elicitation settings. This questionnaire is designed to identify the range(s) of use of certain spatial demonstrative terms, and help assess the roles played by gesture, access, attention, and addressee knowledge in demonstrative use. The stimuli consist of 25 diagrammed “elicitation settings” to be created by the researcher.

Abstract

Angelika Wittek untersuchte Zustandsveränderungsverben bei vier- bis sechsjährigen Kindern. Englischsprechende Kinder verstehen bis zum Alter von 8 Jahren diese Verben als Bewegungsverben und ignorieren, daß sie zusätzlich die Information über einen Endzustand im Sinne der Negation des Ausgangszustands beeinhalten. Wittek zeigte, daß entgegen der Erwartung transparente, morphologisch komplexe Formen (wachmachen), in denen die Partikel den Endzustand explizit macht, nicht besser verstanden werden als Simplizia (wecken). Zudem diskutierte sie, inwieweit die Verwendung des Adverbs wieder in restitutiver Lesart Hinweise auf den Erwerb dieser Verben geben kann.

Abstract

Although sign language-using communities exist in all areas of the world, few sign languages have been documented in detail. Sign languages occur in a variety of sociocultural contexts, ranging from sign languages used in closed village communities to officially recognized national sign languages. They may be grouped into language families on historical grounds or may participate in various language contact situations. Systematic cross-linguistic comparison reveals both significant structural similarities and important typological differences between sign languages. Focusing on information from non-Western countries, this article provides an overview of the sign languages of the world.

Abstract

Word learning happens in everyday contexts with many words and many potential referents for those words in view at the same time. It is challenging for young learners to find the correct referent upon hearing an unknown word at the moment. This problem of referential uncertainty has been deemed as the crux of early word learning (Quine, 1960). Recent empirical and computational studies have found support for a statistical solution to the problem termed cross-situational learning. Cross-situational learning allows learners to acquire word meanings across multiple exposures, despite each individual exposure is referentially uncertain. Recent empirical research shows that infants, children and adults rely on cross-situational learning to learn new words (Smith & Yu, 2008; Suanda, Mugwanya, & Namy, 2014; Yu & Smith, 2007). However, researchers have found evidence supporting two very different theoretical accounts of learning mechanisms: Hypothesis Testing (Gleitman, Cassidy, Nappa, Papafragou, & Trueswell, 2005; Markman, 1992) and Associative Learning (Frank, Goodman, & Tenenbaum, 2009; Yu & Smith, 2007). Hypothesis Testing is generally characterized as a form of learning in which a coherent hypothesis regarding a specific word-object mapping is formed often in conceptually constrained ways. The hypothesis will then be either accepted or rejected with additional evidence. However, proponents of the Associative Learning framework often characterize learning as aggregating information over time through implicit associative mechanisms. A learner acquires the meaning of a word when the association between the word and the referent becomes relatively strong. In this chapter, we consider these two psychological theories in the context of cross-situational word-referent learning. By reviewing recent empirical and cognitive modeling studies, our goal is to deepen our understanding of the underlying word learning mechanisms by examining and comparing the two theoretical learning accounts.