Jamie Reilly

Formal Distinctiveness of High- and Low-Imageability Nouns: Analyses and Theoretical Implications

Words associated with perceptually salient, highly imageable concepts are learned earlier in life, more accurately recalled, and more rapidly named than abstract words (R. W. Brown, 1976; Walker & Hulme, 1999). Theories accounting for this concreteness effect have focused exclusively on semantic properties of word referents. A novel possibility is that word structure may also contribute to the effect. We report a corpus-based analysis of the phonological and morphological structures of a large set of nouns with imageability ratings (N = 2,023). High- and low-imageability nouns differed by length, etymology, prosody, affixation, phonological neighborhood density, and rates of consonant clustering. On average, nouns denoting abstract concepts were longer, more derivationally complex, and emerged in English from a different distribution of languages than did concrete nouns. We address implications for interactivity of word form and meaning as pertain to theories of word concreteness, lexical acquisition, and word processing.

Cognition, language, and clinical pathological features of non-Alzheimer's dementias: An overview

UNLABELLED There are many distinct forms of dementia whose pharmacological and behavioral management differ. Differential diagnosis among the dementia variants currently relies upon a weighted combination of genetic and protein biomarkers, neuroanatomical integrity, and behavior. Diagnostic specificity is complicated by a high degree of overlap in the initial presenting symptoms across dementia subtypes. For this reason, reliable markers are of considerable diagnostic value. Communication disorders have proven to be among the strongest predictors for discriminating among dementia subtypes. As such, speech-language pathologists may be poised to make an increasingly visible contribution to dementia diagnosis and its ongoing management. The value and durability of this potential contribution, however, demands an improved discipline-wide knowledge base about the unique features associated with different dementia variants. To this end we provide an overview of cognition, language, and clinical pathological features of four of the most common non-Alzheimers dementias: frontotemporal dementia, vascular dementia, Lewy body disease dementia, and Parkinsons disease dementia. LEARNING OUTCOMES Readers will learn characteristics and distinguishing features of several non-Alzheimers dementias, including Parkinsons disease dementia, frontotemporal dementia, vascular dementia, and Lewy body dementia. Readers will also learn to distinguish between several variants of frontotemporal dementia. Finally, readers will gain knowledge of the term primary progressive aphasia as it relates to the aforementioned dementia etiologies.

Anomia as a Marker of Distinct Semantic Memory Impairments in Alzheimer's Disease and Semantic Dementia

OBJECTIVE Many neurologically constrained models of semantic memory have been informed by two primary temporal lobe pathologies: Alzheimers disease (AD) and Semantic Dementia (SD). However, controversy persists regarding the nature of the semantic impairment associated with these patient populations. Some argue that AD presents as a disconnection syndrome in which linguistic impairment reflects difficulties in lexical or perceptual means of semantic access. In contrast, there is a wider consensus that SD reflects loss of core knowledge that underlies word and object meaning. Object naming provides a window into the integrity of semantic knowledge in these two populations. METHOD We examined naming accuracy, errors and the correlation of naming ability with neuropsychological measures (semantic ability, executive functioning, and working memory) in a large sample of patients with AD (n = 36) and SD (n = 21). RESULTS Naming ability and naming errors differed between groups, as did neuropsychological predictors of naming ability. Despite a similar extent of baseline cognitive impairment, SD patients were more anomic than AD patients. CONCLUSIONS These results add to a growing body of literature supporting a dual impairment to semantic content and active semantic processing in AD, and confirm the fundamental deficit in semantic content in SD. We interpret these findings as supporting of a model of semantic memory premised upon dynamic interactivity between the process and content of conceptual knowledge.

Verbal learning in semantic dementia: Is repetition priming a useful strategy?

Background: Semantic dementia (SD) is a neurodegenerative disease that impacts long-term conceptual and lexical knowledge (Hodges & Patterson, 1996). Severe naming difficulties are prevalent in SD, yet little is known about the potential for word learning in this population.Aims: We assessed patterns of repetition and implicit learning in patients with moderate to advanced SD via repeated exposure to word lists varied by frequency and imageability. We propose a tentative framework for the language loss incurred in SD and open a dialogue for treatment approaches targeted towards progressive semantic anomia.Methods and Procedures: In two experiments, we examined immediate serial recall and short-term learning in five patients with SD. We predicted reduced semantic effects (imageability), preservation of lexical effects (frequency), and diminished primacy effects in serial recall, consistent with other semantically impaired populations (Martin & Saffran, 1997). We also predicted that severity of semantic impairment would modulate the facilitative effects of repeated exposure (i.e., repetition priming) on word list recall.Outcomes and Results: In immediate serial recall, all participants showed reduced imageability effects, but only one patient showed a significant word frequency advantage. Two patterns of serial position effects emerged: (1) poor recall of initial list items and (2) better recall of initial and final items. All participants showed minimal gains across repeated trials; however, patients who poorly recalled initial items showed the least benefit from repeated exposure.Conclusions: We discuss the usefulness of repetition-based interventions for SD and advocate maintenance of known vocabulary over reacquisition of forgotten words. We provide a theoretical framework for progressive language loss associated with SD; this model reflects an ordered reduction of lexical-semantic support coinciding with dementia severity.

Abstract conceptual feature ratings: the role of emotion, magnitude, and other cognitive domains in the organization of abstract conceptual knowledge.

This study harnessed control ratings of the contribution of different types of information (sensation, action, emotion, thought, social interaction, morality, time, space, quantity, and polarity) to 400 individual abstract and concrete verbal concepts. These abstract conceptual feature (ACF) ratings were used to generate a high dimensional semantic space, from which Euclidean distance measurements between individual concepts were extracted as a metric of the semantic relatedness of those words. The validity of these distances as a marker of semantic relatedness was then tested by evaluating whether they could predict the comprehension performance of a patient with global aphasia on two verbal comprehension tasks. It was hypothesized that if the high-dimensional space generated from ACF control ratings approximates the organization of abstract conceptual space, then words separated by small distances should be more semantically related than words separated by greater distances, and should therefore be more difficult to distinguish for the comprehension-impaired patient, SKO. SKO was significantly worse at identifying targets presented within word pairs with low ACF distances. Response accuracy was not predicted by Latent Semantic Analysis (LSA) cosines, any of the individual feature ratings, or any of the background variables. It is argued that this novel rating procedure provides a window on the semantic attributes of individual abstract concepts, and that multiple cognitive systems may influence the acquisition and organization of abstract conceptual knowledge. More broadly, it is suggested that cognitive models of abstract conceptual knowledge must account for the representation not only of the relationships between abstract concepts but also of the attributes which constitute those individual concepts.

Clustering, hierarchical organization, and the topography of abstract and concrete nouns

The empirical study of language has historically relied heavily upon concrete word stimuli. By definition, concrete words evoke salient perceptual associations that fit well within feature-based, sensorimotor models of word meaning. In contrast, many theorists argue that abstract words are “disembodied” in that their meaning is mediated through language. We investigated word meaning as distributed in multidimensional space using hierarchical cluster analysis. Participants (N = 365) rated target words (n = 400 English nouns) across 12 cognitive dimensions (e.g., polarity, ease of teaching, emotional valence). Factor reduction revealed three latent factors, corresponding roughly to perceptual salience, affective association, and magnitude. We plotted the original 400 words for the three latent factors. Abstract and concrete words showed overlap in their topography but also differentiated themselves in semantic space. This topographic approach to word meaning offers a unique perspective to word concreteness.

Effects of semantic impairment on language processing in semantic dementia.

Semantic dementia is a neurodegenerative disease characterized by progressive loss of conceptual and lexical knowledge. Cortical atrophy remains relatively isolated to anterior and inferior portions of the temporal lobe early in semantic dementia, later affecting more extensive regions of temporal cortex. Throughout much of the disease course, frontal and parietal lobe structures remain relatively intact. This distribution of cortical damage produces a unique language profile. Patients with semantic dementia typically experience profound deficits in language comprehension and production in the context of relatively well-preserved functioning in domains such as phonology, executive function, visuospatial processing, and speech perception. We discuss the effects of semantic impairment on language processing in semantic dementia within the context of an interactive theory of semantic cognition that assumes the active coordination of modality-neutral and modality-specific components. Finally, we argue the need for an etiology-specific language intervention for this population.

Single‐word semantic judgements in semantic dementia: Do phonology and grammatical class count?

Background: Listeners make active use of phonological regularities such as word length to facilitate higher‐level syntactic and semantic processing. For example, nouns are longer than verbs, and abstract words are longer than concrete words. Patients with semantic dementia (SD) experience conceptual loss with preserved syntax and phonology. The extent to which patients with SD exploit phonological regularities to support language processing remains unclear. Aims: We examined the ability of patients with SD (1) to perceive subtle acoustic–phonetic distinctions in English, and (2) to bootstrap their accuracy of lexical‐semantic and syntactic judgements from regularities in the phonological forms of English nouns and verbs. Methods and Procedures: Four patients with SD made minimal pair judgements (same/different) for auditorily presented stimuli selectively varied by voice, place, or manner of the initial consonant (e.g., pa –ba). In Experiment 2 patients made forced‐choice semantic judgements (abstract or concrete) for single words varied by (1) concreteness (abstract or concrete); (2) grammatical class (noun or verb); and (3) word length (one‐ or three‐syllable words). Outcomes and Results: The most semantically impaired patients paradoxically showed the highest accuracy of minimal pair phonologic discrimination. Judgements of word concreteness were less accurate for verbs than nouns. Among verbs, accuracy was worse for concrete than abstract items (e.g., eat was worse than think). Patients were more likely to misclassify longer concrete words (e.g., professor) as abstract, demonstrating sensitivity to an underlying phonologically mediated semantic property in English. Conclusions: Single‐word semantic judgements were sensitive to both grammatical class and phonological properties of the words being evaluated. Theoretical and clinical implications are addressed in the context of an anatomically constrained model of SD that assumes increasing reliance on phonology as lexical‐semantic knowledge degrades.

Short-term/working memory impairments in aphasia: Data, models, and their application to aphasia rehabilitation

Much of the extant research in language processing and language impairment has focused on elements of linguistic representation that are accessed and retrieved in comprehension, repetition, and production of words and sentences. These studies have provided important information about the effects of characteristics of words (e.g., frequency, imageability) and sentences (e.g., syntactic and semantic argument structure) on language processing. A smaller but nonetheless rapidly growing body of research has been directed to understanding those cognitive processes that mediate access, maintenance, and retrieval of those representations. This line of investigation has increased dramatically in the last two decades. One impetus for this increased interest in the relations of language and other cognitive processes is intuitive: language function involves content and process. Language representations comprise the content, but the abilities that support access, maintenance and retrieval of these representations are not specifically linguistic in nature. Rather, they reflect the mechanics of language processing that act as the essential “supporting cast” or substrate upon which many other linguistic functions rely (e.g., working memory supports both naming and complex syntactic tranformations). A second impetus is motivated by clinical and empirical considerations: individuals with aphasia frequently present with co-morbid impairments of extra-linguistic cognitive processes such as verbal STM (Martin & Ayala, 2004; R. Martin, Shelton & Yaffee, 1994) and executive functioning (Murray & Ramage, 2000). The two language support systems addressed in this special issue of Aphasiology are short-term memory (STM) and working memory (WM). These are overlapping abilities in two ways. STM refers to a person’s capacity to maintain activation of language representations and is typically measured by span tasks such as serial immediate

Frontal lobe damage impairs process and content in semantic memory: Evidence from category-specific effects in progressive non-fluent aphasia

Portions of left inferior frontal cortex have been linked to semantic memory both in terms of the content of conceptual representation (e.g., motor aspects in an embodied semantics framework) and the cognitive processes used to access these representations (e.g., response selection). Progressive non-fluent aphasia (PNFA) is a neurodegenerative condition characterized by progressive atrophy of left inferior frontal cortex. PNFA can, therefore, provide a lesion model for examining the impact of frontal lobe damage on semantic processing and content. In the current study we examined picture naming in a cohort of PNFA patients across a variety of semantic categories. An embodied approach to semantic memory holds that sensorimotor features such as self-initiated action may assume differential importance for the representation of manufactured artifacts (e.g., naming hand tools). Embodiment theories might therefore predict that patients with frontal damage would be differentially impaired on manufactured artifacts relative to natural kinds, and this prediction was borne out. We also examined patterns of naming errors across a wide range of semantic categories and found that naming error distributions were heterogeneous. Although PNFA patients performed worse overall on naming manufactured artifacts, there was no reliable relationship between anomia and manipulability across semantic categories. These results add to a growing body of research arguing against a purely sensorimotor account of semantic memory, suggesting instead a more nuanced balance of process and content in how the brain represents conceptual knowledge.