Healthy aging is associated with many cognitive, linguistic, and behavioral changes. For example, adults’ reaction times slow on many tasks as they grow older, while their memories, appear to fade, especially for apparently basic linguistic information such as other people’s names. These changes have traditionally been thought to reflect declines in the processing power of human minds and brains as they age. However, from the perspective of the information-processing paradigm that dominates the study of mind, the question of whether cognitive processing capacities actually decline across the life span can only be scientifically answered in relation to functional models of the information processes that are presumed to be involved in cognition. Consider, for example, the problem of recalling someone’s name. We are usually reminded of the names of friends on a regular basis, and this makes us good at remembering them. However, as we move through life, we inevitably learn more names. Sometimes we hear these new names only once. As we learn each new name, the average exposure we will have had to any individual name we know is likely to decline, while the number of different names we know is likely to increase. This in turn is likely to make the task of recalling a particular name more complex. One consequence of this is as follows: If Mary can only recall names with 95% accuracy at age 60—when she knows 900 names—does she necessarily have a worse memory than she did at age 16, when she could recall any of only 90 names with 98% accuracy? Answering the question of whether Mary’s memory for names has actually declined (or improved even) will require some form of quantification of Mary’s knowledge of names at any given point in her life and the definition of a quantitative model that predicts expected recall performance for a given amount of name knowledge, as well as an empirical measure of the accuracy of the model across a wide range of circumstances. Until the early 21st century, the study of cognition and aging was dominated by approaches that failed to meet these requirements. Researchers simply established that Mary’s name recall was less accurate at a later age than it was at an earlier one, and took this as evidence that Mary’s memory processes had declined in some significant way. However, as computational approaches to studying cognitive—and especially psycholinguistic—processes and processing became more widespread, a number of matters related to the development of processing across the life span began to become apparent: First, the complexity involved in establishing whether or not Mary’s name recall did indeed become less accurate with age began to be better understood. Second, when the impact of learning on processing was controlled for, it became apparent that at least some processes showed no signs of decline at all in healthy aging. Third, the degree to which the environment—both in terms of its structure, and its susceptibility to change—further complicates our understanding of life-span cognitive performance also began to be better comprehended. These new findings not only promise to change our understanding of healthy cognitive aging, but also seem likely to alter our conceptions of cognition and language themselves.
Sign phonetics is the study of how sign languages are produced and perceived, by native as well as by non-native signers. Most research on sign phonetics has focused on American Sign Language (ASL), but there are many different sign languages around the world, and several of these, including British Sign Language, Taiwan Sign Language, and Sign Language of the Netherlands, have been studied at the level of phonetics. Sign phonetics research can focus on individual lexical signs or on the movements of the nonmanual articulators that accompany those signs. The production and perception of a sign language can be influenced by phrase structure, linguistic register, the signer’s linguistic background, the visual perception mechanism, the anatomy and physiology of the hands and arms, and many other factors. What sets sign phonetics apart from the phonetics of spoken languages is that the two language modalities use different mechanisms of production and perception, which could in turn result in structural differences between modalities. Most studies of sign phonetics have been based on careful analyses of video data. Some studies have collected kinematic limb movement data during signing and carried out quantitative analyses of sign production related to, for example, signing rate, phonetic environment, or phrase position. Similarly, studies of sign perception have recorded participants’ ability to identify and discriminate signs, depending, for example, on slight variations in the signs’ forms or differences in the participants’ language background. Most sign phonetics research is quantitative and lab-based.
Daniel Schmidtke and Victor Kuperman
Lexical representations in an individual mind are not given to direct scrutiny. Thus, in their theorizing of mental representations, researchers must rely on observable and measurable outcomes of language processing, that is, perception, production, storage, access, and retrieval of lexical information. Morphological research pursues these questions utilizing the full arsenal of analytical tools and experimental techniques that are at the disposal of psycholinguistics. This article outlines the most popular approaches, and aims to provide, for each technique, a brief overview of its procedure in experimental practice. Additionally, the article describes the link between the processing effect(s) that the tool can elicit and the representational phenomena that it may shed light on. The article discusses methods of morphological research in the two major human linguistic faculties—production and comprehension—and provides a separate treatment of spoken, written and sign language.
The study of second language phonetics is concerned with three broad and overlapping research areas: the characteristics of second language speech production and perception, the consequences of perceiving and producing nonnative speech sounds with a foreign accent, and the causes and factors that shape second language phonetics. Second language learners and bilinguals typically produce and perceive the sounds of a nonnative language in ways that are different from native speakers. These deviations from native norms can be attributed largely, but not exclusively, to the phonetic system of the native language. Non-nativelike speech perception and production may have both social consequences (e.g., stereotyping) and linguistic–communicative consequences (e.g., reduced intelligibility). Research on second language phonetics over the past ca. 30 years has resulted in a fairly good understanding of causes of nonnative speech production and perception, and these insights have to a large extent been driven by tests of the predictions of models of second language speech learning and of cross-language speech perception. It is generally accepted that the characteristics of second language speech are predominantly due to how second language learners map the sounds of the nonnative to the native language. This mapping cannot be entirely predicted from theoretical or acoustic comparisons of the sound systems of the languages involved, but has to be determined empirically through tests of perceptual assimilation. The most influential learner factors which shape how a second language is perceived and produced are the age of learning and the amount and quality of exposure to the second language. A very important and far-reaching finding from research on second language phonetics is that age effects are not due to neurological maturation which could result in the attrition of phonetic learning ability, but to the way phonetic categories develop as a function of experience with surrounding sound systems.
D. H. Whalen
Phonetics is the branch of linguistics that deals with the physical realization of meaningful distinctions in spoken language. Phoneticians study the anatomy and physics of sound generation, acoustic properties of the sounds of the world’s languages, the features of the signal that listeners use to perceive the message, and the brain mechanisms involved in both production and perception. Therefore, phonetics connects most directly to phonology and psycholinguistics, but it also engages a range of disciplines that are not unique to linguistics, including acoustics, physiology, biomechanics, hearing, evolution, and many others. Early theorists assumed that phonetic implementation of phonological features was universal, but it has become clear that languages differ in their phonetic spaces for phonological elements, with systematic differences in acoustics and articulation. Such language-specific details place phonetics solidly in the domain of linguistics; any complete description of a language must include its specific phonetic realization patterns. The description of what phonetic realizations are possible in human language continues to expand as more languages are described; many of the under-documented languages are endangered, lending urgency to the phonetic study of the world’s languages. Phonetic analysis can consist of transcription, acoustic analysis, measurement of speech articulators, and perceptual tests, with recent advances in brain imaging adding detail at the level of neural control and processing. Because of its dual nature as a component of a linguistic system and a set of actions in the physical world, phonetics has connections to many other branches of linguistics, including not only phonology but syntax, semantics, sociolinguistics, and clinical linguistics as well. Speech perception has been shown to integrate information from both vision and tactile sensation, indicating an embodied system. Sign language, though primarily visual, has adopted the term “phonetics” to represent the realization component, highlighting the linguistic nature both of phonetics and of sign language. Such diversity offers many avenues for studying phonetics, but it presents challenges to forming a comprehensive account of any language’s phonetic system.
Niels O. Schiller
Neurolinguistic approaches to morphology include the main theories of morphological representation and processing in the human mind, such as full-listing, full-parsing, and hybrid dual-route models, and how the experimental evidence that has been acquired to support these theories uses different neurolinguistic paradigms (visual and auditory priming, violation, long-lag priming, picture-word interference, etc.) and methods (electroencephalography [EEG]/event-related brain potential [ERP], functional magnetic resonance imaging [fMRI], neuropsychology, and so forth).
Yu-Ying Chuang and R. Harald Baayen
Naive discriminative learning (NDL) and linear discriminative learning (LDL) are simple computational algorithms for lexical learning and lexical processing. Both NDL and LDL assume that learning is discriminative, driven by prediction error, and that it is this error that calibrates the association strength between input and output representations. Both words’ forms and their meanings are represented by numeric vectors, and mappings between forms and meanings are set up. For comprehension, form vectors predict meaning vectors. For production, meaning vectors map onto form vectors. These mappings can be learned incrementally, approximating how children learn the words of their language. Alternatively, optimal mappings representing the end state of learning can be estimated. The NDL and LDL algorithms are incorporated in a computational theory of the mental lexicon, the ‘discriminative lexicon’. The model shows good performance both with respect to production and comprehension accuracy, and for predicting aspects of lexical processing, including morphological processing, across a wide range of experiments. Since, mathematically, NDL and LDL implement multivariate multiple regression, the ‘discriminative lexicon’ provides a cognitively motivated statistical modeling approach to lexical processing.