Prototypicality norms for 28 semantic categories

The extent to which an item is a prototypical exemplar of a category has been found to predict several experimental results (e.g., reaction times in category classification, free and cued recall of lists, release from proactive inhibition in recall). We present prototypicality ratings for 840 words, equally distributed over 28categories. Thecategories were taken from Battig and Montague’s (1969) normative tables; only those categories that contained “concrete” items in common usage were employed in the study. Intragroup reliability correlations were high for all categories tested, as were the correlations for prototypicality ratings between the present study and that of Rosch (1975). In addition, correlations between prototypicality ratings, production frequencies, and word frequencies of the items are given.     

Category width and differentiation in semantic categories

The hypothesis that the judgemental categorizing behaviour measured by Pettigrew's Category-Width scale is linked to semantic categorization is investigated. Individual differences in broad vs. narrow categorizing behaviour measured by the C-W scale are reconceptualized within the framework of Rosch's (1977) theory of human categorization. Two extreme groups on the C-W scale, broad categorizers and narrow categorizers, were selected as subjects. One experiment employed a short-term release-from-proactive-inhibition paradigm. The amount of discrepancy in recall between the preshift and the shift trials was used as an index to perceived semantic distance. The result showed that narrow categorizers perceived the same fuzzy items in a semantic category as less similar to the good exemplars of that category than broad categorizers did. In a further experiment using a semantic-categorization technique, narrow categorizers judged the same fuzzy items as category members less frequently than broad categorizers did, indicating that narrow categorizers possess more differentiated semantic categories than do broad categorizers. These findings are seen as an extension of the differential categorizing behaviour on artificial categories in the C-W scale to semantic categorization for which there is a pre-existing system.     

Dutch norm data for 13 semantic categories and 338 exemplars

A data set is described that includes eight variables gathered for 13 common superordinate natural language categories and a representative set of 338 exemplars in Dutch. The category set contains 6 animal categories (reptiles, amphibians, mammals, birds, fish, andinsects), 3 artifact categories (musical instruments, tools, andvehicles), 2 borderline artifact-natural-kind categories (vegetables andfruit), and 2 activity categories (sports andprofessions). In an exemplar and a feature generation task for the category nouns, frequency data were collected. For each of the 13 categories, a representative sample of 5–30 exemplars was selected. For all exemplars, feature generation frequencies, typicality ratings, pairwise similarity ratings, age-of-acquisition ratings, word frequencies, and word associations were gathered. Reliability estimates and some additional measures are presented. The full set of these norms is available in Excel format at the Psychonomic Society Web archive,www.psychonomic. org/archive/.     

Aphasics' appreciation of hierarchical semantic categories

The mental representative structure of hierarchically ordered semantic categories was explored with 66 aphasic patients and 60 normal adults by a word-verification task. Four words concerning living things and 10 line drawings depicting an object were prepared as stimuli. All possible pairings of each of the four words with each of the 10 line drawings were made to be verified. The results indicated that subjective category domains were more diffusive in aphasic patients than in normal adults, and that this alteration was exclusively due to increase of peripheral members, but not of central members. It was also revealed that normative category boundaries may be preserved vestigially or incompletely in aphasic patients except the severe fluent subgroup, in whom there may be profound disintegration of boundaries. On the other hand, some common features concerning intracategorical structure and preference among levels of abstraction across normal adults and aphasic patients permit the hypothesis that aphasic patients may retain partially normal semantic knowledge.     

Dutch norm data for 13 semantic categories and 338 exemplars.

A data set is described that includes eight variables gathered for 13 common superordinate natural language categories and a representative set of 338 exemplars in Dutch. The category set contains 6 animal categories (reptiles, amphibians, mammals, birds, fish, and insects), 3 artifact categories (musical instruments, tools, and vehicles), 2 borderline artifact-natural-kind categories (vegetables and fruit), and 2 activity categories (sports and professions). In an exemplar and a feature generation task for the category nouns, frequency data were collected. For each of the 13 categories, a representative sample of 5-30 exemplars was selected. For all exemplars, feature generation frequencies, typicality ratings, pairwise similarity ratings, age-of-acquisition ratings, word frequencies, and word associations were gathered. Reliability estimates and some additional measures are presented. The full set of these norms is available in Excel format at the Psychonomic Society Web archive, www.psychonomic.org/archive/.     

Category norms for 500 Spanish words in five semantic categories

This study presents a database of 500 words from five semantic categories: animals, body parts, furniture, clothing, and intelligence. Each category contains 100 words, and data on lexical availability, age of acquisition, imageability, typicality, concept familiarity, written word frequency, and word length in number of syllables are provided with each word. The full set of norms may be downloaded from www.psychonomic.org/archive.     

The abstraction of form in semantic categories

Undergraduates were asked to generate a name for a hypothetical new exemplar of a category. They produced names that had the same numbers of syllables, the same endings, and the same types of word stems as existing exemplars of that category. In addition, novel exemplars, each consisting of a nonsense syllable root and a prototypical ending, were accurately assigned to categories. The data demonstrate the abstraction and use of surface properties of words.     

Affective norms for 380 Spanish words belonging to three different semantic categories

Emotional words are increasingly used in the study of word processing. To elucidate whether the experimental effects obtained with these words are due either to their affective content or to other semantic characteristics, it is necessary to conduct experiments with affectively valenced words obtained from different semantic categories. In the present article, we present affective ratings for 380 Spanish words belonging to three semantic categories: animals, people, and objects. The norms are based on the assessments made by 504 participants, who rated about 47 words either in valence and arousal, by using the Self-Assessment Manikin (Bradley & Lang, Journal of Behavioral Therapy and Experimental Psychiatry, 25, 49-59. 1994), or in concreteness and familiarity. These ratings will help researchers select stimuli for experiments in which both the affective properties of words and their membership to a given semantic category have to be taken into account. The database is available as an online supplement for this article.     

Developmental changes in the internal structure of semantic categories

The present experiment was designed to examine the development of the cognitive representation of semantic categories. Response latencies on a classification task were compared for second, fourth, and sixth graders (8, 10, and 12 years of age, respectively) and college students. On each trial the subjects were presented with two pictures that represented either typical or atypical category exemplars. The two pictures were physically identical, nonidentical pictures from the same category, or pictures from different categories. One half of the trials were primed by presenting a category name in advance of the stimuli. In addition, stimulus degradation was manipulated in order to assess the locus of priming effects. A significant interaction of age × priming × typicality was found for physically identical stimuli. This interaction indicated that the nature of the internal representation of categories changed from the second graders to the adults. It was suggested that the second graders might weigh features inappropriately in generating semantic prototypes. The fact that stimulus degradation and priming did not interact at any age level for any of the match types indicates that priming affected a conceptual encoding stage rather than a perceptual encoding stage.     

The attentional blink is diminished for targets that form coherent semantic categories

Studies have shown that the attentional blink (AB) effect is diminished for intrinsically salient T2 stimuli, such as arousing, familiar, personally relevant words, or stimuli with salient low-level visual features. We examined whether the AB is diminished also for stimuli that do not have special inherent properties but are made salient by the context. One such contextual factor is the coherence of the T2 stimulus set. In three experiments, we found that the AB is diminished for stimuli that form a coherent semantic category within the T2 stimulus set. Both theoretical and practical implications are discussed.     

Strategies for generating multiple instances of common and ad hoc categories

In a free-emission procedure participants were asked to generate instances of a given category and to report, retrospectively, the strategies that they were aware of using in retrieving instances. In two studies reported here, participants generated instances for common categories (e.g. fruit) and for ad hoc categories (e.g., things people keep in their pockets) for 90 seconds and for each category described how they had proceeded in doing so. Analysis of the protocols identified three broad classes of strategy: (1) experiential, where memories of specific or generic personal experiences involving interactions with the category instances acted as cues; (2) semantic, where a consideration of abstract conceptual characteristics of a category were employed to retrieve category exemplars; (3) unmediated, where instances were effortlessly retrieved without mediating cognitions of which subjects were aware. Experiential strategies outnumbered semantic strategies (on average 4 to 1) not only for ad hoc categories but also for common categories. This pattern was noticeably reversed for ad hoc categories that subjects were unlikely to have experienced personally (e.g. things sold on the black market in Russia). Whereas more traditional accounts of semantic memory have favoured decontextualised abstract representations of category knowledge, to the extent that mode of access informs us of knowledge structures, our data suggest that category knowledge is significantly grounded in terms of everyday contexts where category instances are encountered.     

Classification in well-defined and ill-defined categories: evidence for common processing strategies

Early work in perceptual and conceptual categorization assumed that categories had criterial features and that category membership could be determined by logical rules for the combination of features. More recent theories have assumed that categories have an ill-defined structure and have prosposed probabilistic or global similarity models for the verification of category membership. In the experiments reported here, several models of categorization were compared, using one set of categories having criterial features and another set having an ill-defined structure. Schematic faces were used as exemplars in both cases. Because many models depend on distance in a multidimensional space for their predictions, in Experiment 1 a multidimensional scaling study was performed using the faces of both sets as stimuli, In Experiment 2, subjects learned the category membership of faces for the categories having criterial features. After learning, reaction times for category verification and typicality judgments were obtained. Subjects also judged the similarity of pairs of faces. Since these categories had characteristic as well as defining features, it was possible to test the predictions of the feature comparison model (Smith et al.), which asserts that reaction times and typicalities are affected by characteristic features. Only weak support for this model was obtained. Instead, it appeared that subjects developed logical rules for the classification of faces. A characteristic feature affected reaction times only when it was part of the rule system devised by the subject. The procedure for Experiment 3 was like that for Experiment 2, but with ill-defined rather than well-defined categories. The obtained reaction times had high correlations with some of the models for ill-defined categories. However, subjects' performance could best be described as one of feature testing based on a logical rule system for classification. These experiments indicate that whether or not categories have criterial features, subjects attempt to develop a set of feature tests that allow for exemplar classification. Previous evidence supporting probabilistic or similarity models may be interpreted as resulting from subjects' use of the most efficient rules for classification and the averaging of responses for subjects using different sets of rules.     

Fuzziness in semantic memory: Choosing exemplars of subjective categories

Class membership is a fundamental relationship between concepts in semantic memory. Recent research indicates that, class membership may subjectively be a continuous type of relationship. The processing of information about the degree to which items belong to a particular class was investigated in an experiment in which subjects compared two statements describing class membership relationships. The results strongly supported a simple model which describes the judgment process as directly involving subjective degree-of-truthfulness values. The success of the model indicates that the subjects were able to process this kind of fuzzy information in a consistent and systematic manner. Some of the implications of the human competancy for processing fuzzy information are discussed.     

Four semantic layers of common nouns

This article proposes a four-layer semantic structure for common nouns. Each layer matches up with a semantic entity of a certain type in Montague’s intensional semantics. It is argued that a common noun denotes a sense and a concept, which are functions. For any given context, the sense of a term determines its extensions and the concept denoted by the term specifies its intensions. Intensions are treated as sets of senses. The membership relation between a sense and an intension is a soft kind and is expressed in the form of a generic sentence. Such a layered structure explains various “degrees of publicity” of a language. The result we present clarifies the confusions existing in the ordinary understanding of “sense,” “intension,” and “concept.” It also has promising applications in interpreting metaphors and revealing the relationship between generics and metaphors.     

Contributions of metaknowledge to retrieval of natural categories in semantic memory

Retrieving the answer to a general knowledge question has been shown to involve two metacognitive processes--a feeling-of-knowing that initiates the search of long-term memory and a willingness to continue searching until an answer can be confidently stated. To extend this model, college students were asked to retrieve as many members of 2 natural categories as they could in 1 min. Examination of the points at which they switched categories revealed that they searched longer in categories of higher potency, and they switched earlier when the other category was of higher potency. They also searched the first category longer when they were allowed to switch only once during a trial rather than as often as they wished. It was concluded that feeling-of-knowing maintained search of a category and also contributed to the willingness to continue searching, and the constraint on switching impacted the willingness to continue.     

Subliminal words activate semantic categories (not automated motor responses)

Semantic priming by visually masked, unidentifiable (“subliminal”) words occurs robustly when the words appearing as masked primes have been classified earlier in practice as visible targets. It has been argued (Damian, 2001) that practice enables robust subliminal priming by automatizing learned associations between words and the specific motor responses used to classify them. Two experiments demonstrate that, instead, the associations formed in practice that underlie subliminal priming are between words and semantic categories. Visible words classified aspleasant or unpleasant in practice with one set of response key assignments functioned later as subliminal primes with appropriate valence, even when associations of keys with valences were reversed before the test. This result shows that subliminal priming involves unconscious categorization of the prime, rather than just the automatic activation of a practiced stimulus-response mapping.     

In search of common foundations for cortical computation

It is worthwhile to search for forms of coding, processing, and learning common to various cortical regions and cognitive functions. Local cortical processors may coordinate their activity by maximizing the transmission of information coherently related to the context in which it occurs, thus forming synchronized population codes. This coordination involves contextual field (CF) connections that link processors within and between cortical regions. The effects of CF connections are distinguished from those mediating receptive field (RF) input; it is shown how CFs can guide both learning and processing without becoming confused with the transmission of RF information. Simulations explore the capabilities of networks built from local processors with both RF and CF connections. Physiological evidence for synchronization, CFs, and plasticity of the RF and CF connections is described. Coordination via CFs is related to perceptual grouping, the effects of context on contrast sensitivity, amblyopia, implicit influences of color in achromotopsia, object and word perception, and the discovery of distal environmental variables and their interactions through self-organization. Cortical computation could thus involve the flexible evaluation of relations between input signals by locally specialized but adaptive processors whose activity is dynamically associated and coordinated within and between regions through specialized contextual connections.     

Convergent cortical representation of semantic processing in bilinguals

This study examined whether semantic processes in two languages (English and Spanish) are mediated by a common neural system in fluent bilinguals who acquired their second language years after acquiring their first language. Functional magnetic resonance imaging was performed while bilingual participants made semantic and nonsemantic decisions about words in Spanish and English. There was greater activation for semantic relative to nonsemantic decisions in left and right frontal regions, with greater left frontal activation. The locations of activations were similar for both languages, and no differences were found when semantic decisions for English and Spanish words were compared directly. These results demonstrate a shared frontal lobe system for semantic analysis of the languages and are consistent with cognitive research on bilingualism indicating that the two languages of a bilingual person access a common semantic system.     

Processing category terms in context: instantiation and the structure of semantic categories

The present study sought to determine if semantic categories processed in context are encoded as particular exemplars. In Experiment 1 we replicated previous results on an extended and modified set of stimuli by showing that when subjects read sentences containing a category term in a context designed to bias encoding toward an atypical exemplar, the atypical exemplar serves as a better retrieval cue than a typical exemplar. In Experiment 2 we tested whether these cued-recall results were due to processes operating at encoding or retrieval. The pattern of semantic interference obtained in a modified Stroop paradigm clearly contradicted the position that readers routinely encode general terms as examples, or "instantiations." In particular, there was significant color-naming interference when typical exemplars served as targets even when preceded by sentences designed to bias encoding toward an atypical exemplar. No significant color-naming interference was generated to atypical exemplars. Experiment 3 ruled out the possibility that differences between the cued-recall and Stroop results in the first two experiments were due to encoding strategy differences. It was concluded that assigning a referent to a category term is not a routine activity in sentence encoding and that processing category terms entails activation of summary representations.