Ad hoc categories

People construct ad hoc categories to achieve goals. For example, constructing the category of “things to sell at a garage sale” can be instrumental to achieving the goal of selling unwanted possessions. These categories differ from common categories (e.g., “fruit,” “furniture”) in that ad hoc categories violate the correlational structure of the environment and are not well established in memory. Regarding the latter property, the category concepts, concept-to-instance associations, and instance-to-concept associations structuring ad hoc categories are shown to be much less established in memory than those of common categories. Regardless of these differences, however, ad hoc categories possess graded structures (i.e., typicality gradients) as salient as those structuring common categories. This appears to be the result of a similarity comparison process that imposes graded structure on any category regardless of type

Memory illusions and the malleability of categorical knowledge : exploring false memories in ad hoc categories

Tese de doutoramento, Psicologia (Cognição Social), Universidade de Lisboa, Faculdade de Psicologia, 2019One of the assumptions behind false memories produced by presentation of lists of related words is that they share preexistent associations and stable representations in long-term memory. The goal of this thesis is to explore the production of false memories for lists of words that do not share preexistent associations and whose semantic relatedness is set by a specific context. For this end it was used lists of exemplars from ad hoc categories, which are goal-oriented categories with an ephemeral nature and generated by specific contexts. Three empirical chapters present experiments aimed at developing the material to be used and towards testing the occurrence of memory illusions in two types of ad hoc categories: inter and intra taxonomic. Inter-taxonomic ad hoc categories are characterized by being composed of exemplars from different common taxonomic categories and, thus, having few (if any) preexistent associations among them; Intra taxonomic ad hoc categories are composed of exemplars from the same common taxonomic category (making it an unusual subcategory). Inter-taxonomic ad hoc categories show production of false recognitions even when its theme (the category’s name) is not presented. These false recognitions showed a positive correlation with the participants’ capacity of identifying the themes of the ad hoc categories. In intra-taxonomic ad hoc categories the false recognition from ad hoc representations were only more frequent than false recognitions from common taxonomic representations when both the list structure and the category name presented referred to the ad hoc category (and, in this case, results suggest that the effect stem from the consistent representation of the ad hoc category and not because of the distinctiveness of the critical item of the common taxonomic representation in the ad hoc context). These limiting conditions for the false memory effect suggest that the preexistent taxonomic representation that underlies the intra-taxonomic ad hoc categories exerts considerable influence in the production of false recognitions. The production of false memories in lists of ad hoc categories expands the scope of this phenomenon to a new type of category representation with multiple uses in daily situations and may contribute to the revision and improvement of current theories of false memories.Um dos pressupostos subjacentes às falsas memórias produzidas pela apresentação de listas de palavras relacionadas é o de que estas listas compartilham associações preexistentes e representações semânticas estáveis na memória de longo prazo. A presente tese tem como objetivo explorar a possibilidade de produção de falsas memórias com listas de palavras que não possuem associações preexistentes, sendo que sua relação semântica é condicionada por um contexto específico. Para tal, foram utilizadas listas de exemplares de categorias ad hoc, que são categorias orientadas para objetivos que tendem a ter natureza efêmera e condicionada por contextos específicos. Em três capítulos empíricos é descrita investigação realizada sobre este tema, começando pela obtenção e pre-teste do material a ser usado para os estudos de falsas memórias ad hoc e passando depois para a produção e estudo de ilusões de memória para dois tipos de categorias ad hoc: inter e intra-taxonómicas. Categorias ad hoc inter-taxonómicas são caracterizadas por serem compostas por exemplares de diferentes categorias taxonómicas e por terem menos (ou nenhuma) associação preexistente entre si; Categorias ad hoc intra-taxonómicas são compostas por exemplares de uma mesma categoria taxonómica comum (sendo assim um tipo de subcategoria pouco usual). Em categorias ad hoc inter-taxonómicas, foi encontrada produção de falsos reconhecimentos mesmo sem a explicitação do seu tema (o nome da categoria), efeito que apresentou correlação positiva com a capacidade dos participantes de identificar o tema das categorias ad hoc. Em categorias ad hoc intra-taxonómicas o efeito foi mais limitado e falsas memórias resultantes da representação ad hoc surgem com maior frequência do que falsas memórias da representação taxonómica comum apenas quando a estrutura da lista e o tema apresentados fazem referência à categoria ad hoc (e, neste caso, os resultados sugerem que o efeito ocorre pela representação consistente da categoria ad hoc, e não por uma distintividade do item crítico da representação taxonómica comum neste contexto ad hoc). Esta condicionante indica que a representação taxonómica preexistente e subjacente às categorias ad hoc intra taxonómicas exerce considerável influência na produção de falsos reconhecimentos. A produção de falsas memórias em listas de categorias ad hoc expande a abrangência deste fenómeno para um novo tipo de representação categórica com múltiplas utilizações em situações do dia-a-dia e pode contribuir para a revisão e melhoria das principais atuais teorias explicativas das falsas memórias

Revealing criterial vagueness in inconsistencies

Sixty undergraduate students made category membership decisions for each of 132 candidate exemplar-category name pairs (e.g., chess – Sports) in each of two separate sessions. They were frequently inconsistent from one session to the next, both for nominal categories such as Sports and Fish, and ad hoc categories such as Things You Rescue from a Burning House. A mixture model analysis revealed that several of these inconsistencies could be attributed to criterial vagueness: participants adopting different criteria for membership in the two sessions. This finding indicates that categorization is a probabilistic process, whereby the conditions for applying a category label are not invariant. Individuals have various functional meanings of nominal categories at their disposal and entertain competing goals for ad hoc categories

Effect of typicality within ad hoc categories on treatment of lexical retreival deficits in aphasia

The effect of typicality within ad hoc categories on treatment of generative naming was examined in five individuals with aphasia. Ad hoc categories such as ‘things to sell at a garage sale’ do not have rigidly defining features that constitute category membership. Results revealed that training atypical examples in the category resulted in generalization to untrained typical examples with strong changes in patients P1 and P3 and smaller changes in P2 and P4. Training typical examples did not result in generalization to untrained atypical examples in P4 or P5 although changes were observed in P2. Analysis of errors reveals some explanations for the varying patterns across patients

Exemplar Verification for Common and Ad Hoc Categories in Aphasia

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An Investigation of the Role of Distinctiveness on the Production Effect

The current study examined the role of distinctive processing on the production effect (i.e., enhanced memory for words read aloud versus silently). Participants read a mixed list of thirty-six words presented one at a time for three-seconds each. Half of the items were read aloud and half were read silently; these word lists were comprised of items belonging to either natural categories or ad hoc categories. Immediately following study, participants completed a free recall test then a recognition test two days later. Results from recall and recognition tests support a distinctiveness account of the production effect. The current results support MacLeod et. al’s (2010) suggestion that distinctiveness underlies the production effect. Specifically, reading words aloud increases item-specific processing, a crucial component of distinctive processing

Simultaneous Noun and Category Learning via Cross-Situational Statistics

Abstract Previous research shows that people can acquire an impressive number of word-referent pairs after viewing a series of ambiguous trials by accumulating co-occurrence statistics (e.g., Yu & Smith, 2006). The present study extends the cross-situational word learning paradigm, which has previously dealt only with noun acquisition, and shows that humans can concurrently acquire nouns and adjectives (i.e., a natural category with a distinctive, unifying feature). Furthermore, participants are able to learn ad hoc categories of referents consistently cooccurring with a label, while simultaneously learning instance labels. Thus, humans demonstrate an impressive ability to simultaneously apprehend regularities at multiple levels in their environment

What words mean and express: semantics and pragmatics of kind terms and verbs

For many years, it has been common-ground in semantics and in philosophy of language that semantics is in the business of providing a full explanation about how propositional meanings are obtained. This orthodox picture seems to be in trouble these days, as an increasing number of authors now hold that semantics does not deal with thought-contents. Some of these authors have embraced a “thin meanings” view, according to which lexical meanings are too schematic to enter propositional contents. I will suggest that it is plausible to adopt thin semantics for a class of words. However, I’ll also hold that some classes of words, like kind terms, plausibly have richer lexical meanings, and so that an adequate theory of word meaning may have to combine thin and rich semantics