Semantic Category Effects Research Articles

The Effect of Encoding Level and Semantic Category on Associative Memory

Associative memory; Category type; Intentional coding; Unintentional coding

Cognitive consequences of the left-right asymmetry of atrophy in semantic dementia

Semantic dementia (SD) is a condition in which atrophy to the anterior temporal lobes (ATL) produces a selective deterioration of conceptual knowledge. As this atrophy is always bilateral but usually asymmetrical, differences in performance of the two SD subgroups—with left > right (L > R) versus right > left (R > L) atrophy—constitute a major source of evidence regarding the roles of the left and right sides of this region. We explored this issue using large scale case-series methodology, with a pool of 216 observations of neuropsychological data from 72 patients with SD. Anomia was significantly more severe in the L > R subgroup, even when cases from the two subgroups were matched on severity of comprehension deficits. For subgroups matched on the degree of anomia, we show that asymmetry of atrophy also affected both the nature of the naming errors produced, and the degree of a semantic category effect (living things vs artefacts). A comparison across tasks varying in their loading on verbal and visual processing revealed a greater deficit in object naming for L > R cases and in a picture-based semantic association test for R > L cases; this held true whether severity across subgroups was controlled using pairwise matching or statistically via principal components analysis. Importantly, the size of our sample allowed us to demonstrate considerable individual variation within each of the L > R and R > L subgroups, with consequent overlap between them. Our results paint a clear picture of how asymmetry of atrophy affects cognitive performance in SD, and we discuss the results in terms of two mechanisms that could contribute to these differences: variation in the information involved in semantic representations in the left and right ATL, and preferential connectivity between each ATL and other more modality specific intra-hemispheric regions.

Electrophysiological signatures of event words: Dissociating syntactic and semantic category effects in lexical processing

Numerous theories have been proposed regarding the brain's organization and retrieval of lexical information. Neurophysiological dissociations in processing different word classes, particularly nouns and verbs, have been extensively documented, supporting the contribution of grammatical class to lexical organization. However, the contribution of semantic properties to these processing differences is still unresolved. We aim to isolate this contribution by comparing ERPs to verbs (e.g. wade), object nouns (e.g. cookie), and event nouns (e.g. concert) in a paired similarity judgment task, as event nouns share grammatical category with object nouns but some semantic properties with verbs. We find that event nouns pattern with verbs in eliciting a more positive response than object nouns across left anterior electrodes 300–500ms after word presentation. This time-window has been strongly linked to lexical-semantic access by prior electrophysiological work. Thus, the similarity of the response to words referring to concepts with more complex participant structure and temporal continuity extends across grammatical class (event nouns and verbs), and contrasts with the words that refer to objects (object nouns). This contrast supports a semantic, as well as syntactic, contribution to the differential neural organization and processing of lexical items. We also observed a late (500–800ms post-stimulus) posterior positivity for object nouns relative to event nouns and verbs at the second word of each pair, which may reflect the impact of semantic properties on the similarity judgment task.

All my children: The roles of semantic category and phonetic similarity in the misnaming of familiar individuals

Despite knowing a familiar individual (such as a daughter) well, anecdotal evidence suggests that naming errors can occur among very familiar individuals. Here, we investigate the conditions surrounding these types of errors, or misnamings, in which a person (the misnamer) incorrectly calls a familiar individual (the misnamed) by someone else's name (the named). Across 5 studies including over 1,700 participants, we investigated the prevalence of the phenomenon of misnaming, identified factors underlying why it may occur, and tested potential mechanisms. We included undergraduates and MTurk workers and asked questions of both the misnamed and the misnamer. We find that familiar individuals are often misnamed with the name of another member of the same semantic category; family members are misnamed with another family member's name and friends are misnamed with another friend's name. Phonetic similarity between names also leads to misnamings; however, the size of this effect was smaller than that of the semantic category effect. Overall, the misnaming of familiar individuals is driven by the relationship between the misnamer, misnamed, and named; phonetic similarity between the incorrect name used by the misnamer and the correct name also plays a role in misnaming.

Representational Similarity Analysis Reveals Commonalities and Differences in the Semantic Processing of Words and Objects

Understanding the meanings of words and objects requires the activation of underlying conceptual representations. Semantic representations are often assumed to be coded such that meaning is evoked regardless of the input modality. However, the extent to which meaning is coded in modality-independent or amodal systems remains controversial. We address this issue in a human fMRI study investigating the neural processing of concepts, presented separately as written words and pictures. Activation maps for each individual word and picture were used as input for searchlight-based multivoxel pattern analyses. Representational similarity analysis was used to identify regions correlating with low-level visual models of the words and objects and the semantic category structure common to both. Common semantic category effects for both modalities were found in a left-lateralized network, including left posterior middle temporal gyrus (LpMTG), left angular gyrus, and left intraparietal sulcus (LIPS), in addition to object- and word-specific semantic processing in ventral temporal cortex and more anterior MTG, respectively. To explore differences in representational content across regions and modalities, we developed novel data-driven analyses, based on k-means clustering of searchlight dissimilarity matrices and seeded correlation analysis. These revealed subtle differences in the representations in semantic-sensitive regions, with representations in LIPS being relatively invariant to stimulus modality and representations in LpMTG being uncorrelated across modality. These results suggest that, although both LpMTG and LIPS are involved in semantic processing, only the functional role of LIPS is the same regardless of the visual input, whereas the functional role of LpMTG differs for words and objects.

Semantic categories and contexts of written words affect the early ERP component

We investigated the spatiotemporal patterns of event-related potentials to examine how semantic categories affect early stages of written word processing in the brain. We used a semantic priming paradigm in which the categories of prime and target words were the same (animate or inanimate). Event-related potentials were recorded while native Japanese participants made semantic-relatedness judgments of word pairs. Semantic category effects were observed approximately 150 ms after the target item was presented. Inanimate words elicited greater positive deflection than animate words, but no significant difference was observed for prime item processing. Source modeling estimated that the observed effects were induced by neural mechanisms occurring in the anterior temporal region, the posterior portion of the inferior temporal region, and the inferior parietal regions in both the hemispheres. Our results suggest that semantic category effects in the early stages of word processing are evoked by multiple cortical regions related to top-down processing of the preceding semantic information.

Factors in action-object semantic disorder for Chinese-speaking persons with or without Alzheimer's disease

The present study aimed to elucidate the nature of action-object semantic impairment, as revealed in a category fluency task and a picture naming task completed by Chinese-speaking persons with or without Alzheimer's disease (AD). Also, the predictive power of semantic variables on the severity of dementia was addressed. Speech samples were collected from twenty AD persons, twenty control seniors and twenty control adults in Taiwan. Each participant individually completed two tasks: a category fluency task and a picture naming task. Results of the category fluency task indicated that the content of information in Chinese-speaking AD participants was seriously deteriorated, thus producing significantly smaller number of semantic-lexical items. Category Effect was only significant for healthy controls in the semantic fluency task; no significant Category Effect was found in AD participants. Additionally, results of Multiple regression analyses demonstrated that action fluency, action naming and frequency of pictures could reliably predict the severity of dementia. Findings in the present study helped characterize the nature of semantic disorders in Chinese-speaking AD participants and contributed to the predictive power of semantic variables and of pictorial variables on the severity of dementia. ► We elucidated the nature of semantic impairment in a category fluency task. ► We examined the semantic category effects in a picture naming task. ► Our findings shed light on the predictive power of semantic variables on the severity of AD. ► Our findings are of theoretical and clinical implications for AD persons.

Is the semantic category effect in the lateral temporal cortex due to motion property differences?

Two specific areas within the posterior lateral temporal cortex (PLTC), the posterior superior temporal sulcus (pSTS) and the posterior middle temporal gyrus (pMTG), have been proposed to store different types of conceptual properties of motion: the pSTS encodes knowledge of articulated, biological motion, and the pMTG encodes knowledge about unarticulated, mechanical motion. We examined this hypothesis by comparing activation patterns evoked by verbs denoting biological motion (e.g., walk), mechanical motion (e.g., rotate), and low-motion events (e.g., ferment). Classical noun categories with different motion types (animals, tools, and buildings) were also tested and compared with previous findings of the categorical effects in PLTC. Replicating previous findings of different types of nouns, we observed stronger activation for animals than tools in the pSTS and stronger activation for tools compared to other types of nouns in the pMTG. However, such motion-type specific activation patterns only partly extended to verbs. Whereas the pSTS showed preferences for biological-motion verbs, no region within the pMTG was sensitive to verbs denoting mechanical motion. We speculate that the pMTG preference for tools is driven by properties other than mechanical motion, such as strong mappings between the visual form and motor-related representations.

Vocabulary teaching strategies and conceptual representations of words in L2 in children: Evidence with novice learners

A controversial issue in bilingual research is whether in the early stages of L2 learning, access to the conceptual system involves mediation of L1 lexical representations [Kroll, J. F., & Stewart, E. (1994). Category interference in translation and picture naming: Evidence for asymmetric connections between bilingual memory representations. Journal of Memory and Language, 33, 149–174] or a direct route from the L2 word [Altarriba, J., & Mathis, K. M. (1997). Conceptual and lexical development in second language acquisition. Journal of Memory and Language, 36, 550–568; Finkbeiner, M., & Nicol, J. (2003). Semantic category effects in second language word learning. Applied Psycholinguistics, 24, 369–383]. The main goal of this paper is to study, in a child population, whether the creation of conceptual representations for L2 words is possible, even after only one session of learning of the L2 vocabulary. Furthermore, we do so by examining the efficacy of two different L2 learning methods: L2–L1 association learning vs. L2-picture association learning. A translation recognition task was employed to test whether there was a difference between a semantically related pair and an unrelated pair across conditions (i.e., a semantic interference effect). Results showed a significant semantic interference effect—a conceptual effect—in children after just one vocabulary learning session. Importantly, the L2-picture method produced a greater semantic interference effect than the L2–L1 method. The implications of these findings for models of bilingual memory are examined.

Speeded naming, frequency and the development of the lexicon in Williams syndrome

Atypical vocabulary has been reported as one of the most notable features of the language of adolescents and adults with Williams syndrome (WS), including use of unusual or low frequency words. Two hypotheses were identified regarding the developmental origins of this phenomenon. The intra-lexicon hypothesis views the cause in terms of domain-specific anomalies of structure or activation dynamics in the WS lexicon. The extra-lexicon hypothesis views the cause in terms of pragmatic influences, whereby individuals with WS use social engagement devices in their language in service of their “hyper-social” profile (Jones et al., 2000), and domain-general deficits to lexical-semantic representations in line with the level of learning disability present in WS. The hypotheses were evaluated using a speeded picture-naming task, in which frequency and semantic category were manipulated as implicit variables. The performance of 16 adolescents and adults with WS was compared with two individually matched control groups, one matched on chronological age (CA) and the other on receptive vocabulary age (RVA). Developmental trajectories were also constructed to assess the relationship between performance and age. Results indicated slower and less accurate naming in the WS group compared with both CA and RVA groups, but frequency and semantic category effects in line with the RVA group. Trajectories were delayed but not atypical. The data support a normal encoding of word frequency (rarity) in the WS lexicon, with rare-word usage explained as a pragmatic aspect of the WS social profile. The finding sets bounds on the domain-specificity of the complex developmental pathway between atypical genotype and atypical phenotype in WS.

An investigation of a relative impairment in naming non-living items: theoretical and methodological implications

This paper presents a study of PH, a woman with aphasia, who shows a robust impairment in naming pictures of non-living relative to living things. Un-timed investigations of feature knowledge show similar performance across categories suggesting that, as in previous studies, the category effect may be arising at a post-semantic level. However, her performance on a timed feature verification task was slower for non-living than living things (relative to matched controls), in line with her naming. This suggests that the source of PH's category deficit is in fact semantic and that thorough investigation is necessary before claiming a post-semantic category specific deficit in word production. Finally, the results of an intervention study, which apparently eliminated the effect of semantic category on PH's naming, are reported.

Semantic category effect and emotional valence in female university students

The semantic category effect represents a category dissociation between biological and nonbiological objects in picture naming. The aim of this preliminary study was to further examine this phenomenon, and to explore the possible association between the effect and subjective emotional valence for the named objects. Using a speeded picture naming task, vocal reaction times for 45 items were divided into four categories based on emotional valence rating and semantic category, and examined in 36 female university students. Analyses of the data indicated an “animate/inanimate” category dissociation favouring animate objects, in tandem with a potential relationship between subjective emotional valence and semantic processing underlying picture naming.

Language teaching

Language teaching

Semantic category effects in second language word learning

The present study addresses a long-standing assumption in the field of applied linguistics: that presenting new second language (L2) vocabulary in semantically grouped sets is an effective method of teaching. Participants learned 32 new L2 labels for concepts from four different semantic categories in either a related or unrelated condition. At test, participants translated words in both translation directions. We found a semantic interference effect both during the encoding of information into memory and during the retrieval of information in translation. We discuss these findings in terms of theoretical models of L2 lexical representation and development, as well as in more practical terms of L2 curriculum design and vocabulary instruction.

The semantic category effect increases with worsening anomia in Alzheimer’s type dementia

A large number of patients ( n=72) with probable Alzheimer’s type dementia (DAT) and mild cognitive impairment (MCI) carried out a picture naming task which comprised stimuli from biological and nonbiological categories. The results were stratified into five ranges of overall naming ability. Every group except those with scores within the range of elderly normal individuals demonstrated better nonbiological naming than biological naming, an effect which increased with worsening impairment. In general, patients diagnosed with other dementia ( n=15) did not fit well within the pattern of the DAT/MCI participants, except those known to have a significant semantic impairment. A category effect favoring nonbiological items appears to be robust and produce a predictable pattern across progressive levels of impairment in AD.

Why Is a Verb Like an Inanimate Object? Grammatical Category and Semantic Category Deficits

Semantic category effects, such as difficulties in naming animate things relative to inanimate objects, have been explained in terms of the relative weightings of perceptual and functional features within the semantic representations of these concepts. We argue that grammatical category deficits, such as difficulties in naming nouns relative to verbs, can be explained within the same framework. We hypothesize that verb concepts are richer in functional than sensory features and present a model of the semantic representations of animate nouns, inanimate nouns, and verbs. The model demonstrates that sensory feature damage results in a deficit for naming living things but spares verb naming, and functional feature damage results in a deficit for naming inanimate objects and verbs. We then report the assessment results of two patient groups. In accordance with the model's predictions, the “verb spared” patients were consistently worse at naming living things than inanimate objects, and their definitions of both living and nonliving items were lacking in sensory information. We conclude that damage to sensory features in semantic representations causes difficulties in naming concrete nouns relative to action verbs, and within the grammatical category of nouns, animate items will be more severely affected. Imageability was shown to be a strong predictor of naming performance in the “verb deficit” patients, and when this variable was controlled no class effect remained. Production of definitions revealed no differential damage to sensory or functional features, and no consistent effect of animacy in naming was shown. While the model suggests that verb deficits might occur in patients for whom functional features are damaged relative to sensory features, we conclude that the “verb deficit” shown in our patients (and potentially in many previously reported cases) was an artifact of the lower imageability of verbs in confrontation naming tasks.

Word and picture matching: a PET study of semantic category effects

We report two positron emission tomography (PET) studies of cerebral activation during picture and word matching tasks, in which we compared directly the processing of stimuli belonging to different semantic categories (animate and inanimate) in the visual (pictures) and verbal (words) modality. In the first experiment, brain activation was measured in eleven healthy adults during a same/different matching task for textures, meaningless shapes and pictures of animals and artefacts (tools). Activations for meaningless shapes when compared to visual texture discrimination were localized in the left occipital and inferior temporal cortex. Animal picture identification, either in the comparison with meaningless shapes and in the direct comparison with non-living pictures, involved primarily activation of occipital regions, namely the lingual gyrus bilaterally and the left fusiform gyrus. For artefact picture identification, in the same comparison with meaningless shape-baseline and in the direct comparison with living pictures, all activations were left hemispheric, through the dorsolateral frontal (Ba 44/6 and 45) and temporal (Ba 21, 20) cortex. In the second experiment, brain activation was measured in eight healthy adults during a same/different matching task for visually presented words referring to animals and manipulable objects (tools); the baseline was a pseudoword discrimination task. When compared with the tool condition, the animal condition activated posterior left hemispheric areas, namely the fusiform (Ba 37) and the inferior occipital gyrus (Ba 18). The right superior parietal lobule (Ba 7) and the left thalamus were also activated. The reverse comparison (tools vs animals) showed left hemispheric activations in the middle temporal gyrus (Ba 21) and precuneus (Ba 7), as well as bilateral activation in the occipital regions. These results are compatible with different brain networks subserving the identification of living and non-living entities; in particular, they indicate a crucial role of the left fusiform gyrus in the processing of animate entities and of the left middle temporal gyrus for tools, both from words and pictures. The activation of other areas, such as the dorsolateral frontal cortex, appears to be specific for the semantic access of tools only from pictures.

The Effects of Semantic Category and Knowledge Type on Lexical-Semantic Access: A PET Study

Neuropsychological studies of patients with category-specific recognition disorders, as well as PET investigations of semantic category effects in visual recognition tasks, have led some authors to the hypothesis that visual-perceptual knowledge plays a crucial role in the recognition of natural items, such as animals, while functional-associative information is more important for the recognition of man-made tools. To study the cerebral correlates of the retrieval of different types of semantic knowledge about living and nonliving entities, we performed a PET experiment in which normal subjects were required to access visual- and functional-associative information related to visually presented words corresponding to animals and tools. The experimental conditions were the following: (1) Rest. (2) Baseline: letter detection in pseudo-words. (3) Animal, visual knowledge: decide whether the animal has a long or short tail with respect to the body. (4) Animal, associative knowledge: decide whether the animal is typically found in Italy. (5) Tool, visual knowledge: decide whether the object is longer than wider or vice versa. (6) Tool, functional knowledge: decide whether the object is typically used as a kitchen tool. Lexical-semantic access (all lexical conditions pooled) activated the prefrontal cortex on the left and the parietal–occipital junction and posterior cingulate cortex bilaterally. An analysis of the individual experimental conditions in comparison with the nonword baseline showed that accessing visual versus associative knowledge was associated with different activation patterns: predominantly frontal in the case of visual features, temporoparietal for associative knowledge. While the activation patterns involved similar areas for living and nonliving entities, in the case of the latter they were restricted to the left hemisphere. The analysis of main effects confirmed these findings: there were several significant differences in the visual-associative comparison, while category-related differences were less prominent. These findings indicate that the retrieval of different types of knowledge is associated with distinct patterns of brain activation; on the other hand, category-related differences were less evident than in picture matching and naming tasks.

The Production of Specific and Generic Associates of Living and Nonliving, High- and Low-Familiarity Stimuli in Alzheimer's Disease

The goal of this paper was to address three issues relevant to the semantic–lexical deficit of Alzheimer's disease (AD) patients: (1) the nature of the deficit (contrasting the loss of information with the difficulty of intentional access hypothesis), (2) stimulus familiarity effects, (3) semantic category effects (contrasting living with nonliving categories). Sixteen patients affected by AD and 11 matched control subjects were given a naming task, a word–picture matching task and a generative associative naming task, constructed by using as stimuli the same 40 items. Stimuli were either living or nonliving items of high, medium, and low familiarity. Responses given on the generative associative naming task were classified as generic (poorly informative) or specific (more informative). As expected, AD patients were poorer than controls both in naming and in word-to-picture matching tasks. In the generative associative naming task, AD patients tended to produce fewer specific than generic associations with respect to controls. Category effects had a significant influence on performance only on the naming task, but not on the word-to-picture matching or on the generative associative naming task. Stimulus familiarity, on the other hand, strongly influenced performance both in AD patients and in controls: naming and comprehension were better for high familiarity items with respect to low familiarity items. For generative associative naming, the tendency of AD patients to produce fewer specific than generic associations was mainly significant for low familiarity items.

The naming impairment of living and nonliving items in Alzheimer's disease.

Several studies of semantic abilities in Dementia of the Alzheimer Type (DAT) suggest that their semantic disorders may affect specific categories of knowledge. In particular, the existence of a category-specific semantic impairment affecting, selectively, living things has frequently been reported in association with DAT. We report here results from two naming tasks of 25 DAT patients and two subgroups within this population. The first naming task used 48 black and white line drawings from Snodgrass and Vanderwart (1980) which controlled the visual complexity of stimuli from living and nonliving categories. The second task used 44 colored pictures (to assess the influence of word frequency in living vs. nonliving categories). Within the set of black and white pictures, both DAT patients and controls obtained significantly lower scores on high visual complexity stimuli than on stimuli of low visual complexity. A clear effect of semantic category emerged for DAT patients and controls, with a lower performance on the living category. Within the colored set, pictures corresponding to high frequency words gave rise to significantly higher scores than pictures corresponding to low frequency words. No significant difference emerged between living versus nonliving categories, either in DAT patients or in controls. In the two tasks, the two subgroups of DAT patients presented a different profile of performance and error type. As color constitutes the main difference between the two sets of pictures, our results point to the relevance of this cue in the processing of semantic information, with visual complexity and frequency also being very relevant.