Typicality ratings for 893 exemplars of 93 categories

Although the typicality effect has been much studied in the semantic memory literature, typicality ratings exist for exemplars from only a very limited number of categories. This lack of ratings frequently limits the range of stimuli that can be used in investigations of the typicality effect. As an aid in stimulus construction, this paper reports typicality ratings of 893 exemplars from 93 different categories.     

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.     

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/.     

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/.     

Inferring category attributes from exemplar attributes: geometric shapes and social categories

Three experiments tested the hypothesis that judgments about the attributes of categories are disproportionately based on the characteristics of exemplars that best fit the category. In the first 2 experiments, subjects were presented with good and bad exemplars of categories with defining attributes (rectangles, triangles, pentagons, and ellipses) in which different colors were arbitrarily paired with the good and poor examples. In both experiments, subjects erroneously judged the colors paired with the good exemplars as more frequent than colors paired with the poor exemplars. A third experiment, using social categories, examined whether attributes associated with a single category member were more likely to generalize to the category as a whole for prototypical than for nonprototypical category members. Subjects were presented with information about individual fraternity members who varied in prototypicality, and the tendency to infer a target behavior (liberal vs. conservative voting behavior) from the individual fraternity member to the fraternity as a whole increased with the prototypicality of the category member. Implications for the contact hypothesis, category-exemplar relations, and belief stability are discussed.     

From Blickets to Synapses: Inferring Temporal Causal Networks by Observation

How do human infants learn the causal dependencies between events? Evidence suggests that this remarkable feat can be achieved by observation of only a handful of examples. Many computational models have been produced to explain how infants perform causal inference without explicit teaching about statistics or the scientific method. Here, we propose a spiking neuronal network implementation that can be entrained to form a dynamical model of the temporal and causal relationships between events that it observes. The network uses spike‐time dependent plasticity, long‐term depression, and heterosynaptic competition rules to implement Rescorla–Wagner‐like learning. Transmission delays between neurons allow the network to learn a forward model of the temporal relationships between events. Within this framework, biologically realistic synaptic plasticity rules account for well‐known behavioral data regarding cognitive causal assumptions such as backwards blocking and screening‐off. These models can then be run as emulators for state inference. Furthermore, this mechanism is capable of copying synaptic connectivity patterns between neuronal networks by observing the spontaneous spike activity from the neuronal circuit that is to be copied, and it thereby provides a powerful method for transmission of circuit functionality between brain regions.     

Dissociable neural subsystems underlie visual working memory for abstract categories and specific exemplars

An ongoing debate concerns whether visual object representations are relatively abstract, relatively specific, both abstract and specific within a unified system, or abstract and specific in separate and dissociable neural subsystems. Most of the evidence for the dissociable subsystems theory has come from experiments that used familiar shapes, and the usage of familiar shapes has allowed for alternative explanations for the results. Thus, we examined abstract and specific visual working memory when the stimuli were novel objects viewed for the first and only time. When participants judged whether cues and probes belonged to the same abstract visual category, they performed more accurately when the probes were presented directly to the left hemisphere than when they were presented directly to the right hemisphere. In contrast, when participants judged whether or not cues and probes were the same specific visual exemplar, they performed more accurately when the probes were presented directly to the right hemisphere than when they were presented directly to the left hemisphere. For the first time, results from experiments using visual working memory tasks support the dissociable subsystems theory.     

Inferring Learners' Knowledge From Their Actions

Watching another person take actions to complete a goal and making inferences about that person's knowledge is a relatively natural task for people. This ability can be especially important in educational settings, where the inferences can be used for assessment, diagnosing misconceptions, and providing informative feedback. In this paper, we develop a general framework for automatically making such inferences based on observed actions; this framework is particularly relevant for inferring student knowledge in educational games and other interactive virtual environments. Our approach relies on modeling action planning: We formalize the problem as a Markov decision process in which one must choose what actions to take to complete a goal, where choices will be dependent on one's beliefs about how actions affect the environment. We use a variation of inverse reinforcement learning to infer these beliefs. Through two lab experiments, we show that this model can recover people's beliefs in a simple environment, with accuracy comparable to that of human observers. We then demonstrate that the model can be used to provide real‐time feedback and to model data from an existing educational game.     

Inferring the Meaning of Work From the Effects of Unemployment

Questionnaire data from 148 unemployed individuals were analyzed to investigate the meaning for work. Both economic and experiential functions of work were examined. The data revealed that, as predicted, increasing length of unemployment was associated with increasing economic and experiential deprivation. Economic deprivation, in turn, was associated with both more experiential deprivation and lower subjective well-being. Unexpectedly, experiential deprivation was not related to subjective well-being. The results indicate the importance of the economic functions of work in people's lives.     

Wanted: a new psychology of exemplars.

Present-day exemplar theory faces difficult challenges, and important questions have arisen about the kinds of exemplar effects and processes that are empirically supported, and about the kind of exemplar theory that could still be constructive. One question concerns whether exemplar generalization in memory and categorization is broad and collective--extending to many related exemplars stored in memory--or whether it is focused and singular--extending only to highly similar (nearly identical) exemplars. The present article considers this continuum from broad to narrow generalization. I demonstrate that in prominent memory and category tasks--tasks in which exemplar theory predicts broad generalization--generalization is in psychological reality very tightly focused. These demonstrations could ground a new, productive exemplar theory that is true to psychological process as humans conduct themselves in memory and category tasks. This new psychology may actually reprise the traditional exemplar theory that predated our sophisticated, mathematical exemplar models.     

Enhancing interest in science: exemplars as cues to communal affordances of science

A deterrent to recruiting students into STEM pathways is the stereotype that STEM fields do not afford communal goals to work with or help others. We investigate the challenges to cueing communal opportunities in science via brief exposure to scientist exemplars. Both male and female scientists depicted as engaged in communal work increased beliefs that science afforded communal goals and positivity toward science careers (Study 1). Without the direct performance of communal activities, communal affordances were cued only when a female scientist was prototypic of her gender category and respondents were highly communally oriented (Study 2). To change stereotypes that science does not involve communal goals, both female and male scientists can highlight communal aspects of their work.     

Essentialist theory of ‘hybrids’: From animal kinds to ethnic categories and race

This article presents a theory of the perception of hybrids, resulting from cross‐breeding natural animals that pertain to different species and of children parented by couples with a mixed ethnic or racial background. The theory states that natural living beings, including humans, are perceived as possessing a deeply ingrained characteristic that is called ‘essence’ or ‘blood’ or ‘genes’ in everyday discourse and that uniquely determines their category membership. If, by whatever means, the genes or essences of two animals of different species are combined in a hybrid, the two incompatible essences collapse, leaving the hybrid in a state of non‐identity and non‐belonging. People despise this state and reject the hybrid (Study 1). This devaluation effect holds with cross‐kind hybrids and with hybrids that arise from genetically combining animals from incompatible habitats across three cultures: Austria, India and Japan (Study 2). In the social world, groups and ethnic or racial categories frequently are essentialized in an analogue way. When people with an essentialist mindset judge ethnically or racially mixed offspring, they perceive a collapse of ethnic or racial essence and, consequently, denigrate these children, as compared to children from ‘pure’ in‐group or out‐group parents (Study 3). The findings are discussed in terms of the widespread ‘yuck factor’ against genetically modified animals, in terms of the cultural concepts of monstrosity and of racism and prejudice.     

Multiple levels of representation of song by European starlings (Sturnus vulgaris): open-ended categorization of starling song types and differential forgetting of song categories and exemplars

Four European starlings (Sturnus vulgaris) were trained to discriminate among conspecific and heterospecific song segments in a go/no-go operant task. In Experiment 1, the starlings discriminated among novel starling and heterospecific songs, indicating an open-ended category of conspecific song types. The starlings also showed excellent memory for reinforced conspecific songs and discriminated among subordinate categories of conspecific song. In Experiment 2, the starlings were presented with the song segments from Experiment 1 after an 8-month delay period. The starlings retained the discrimination between conspecific and heterospecific songs but not among conspecific songs. The starlings also retained memory for individual singers over the 8-month delay. Starlings categorize song at the level of species, and at subordinate categories of song types, and may have superior long-term retention of song categories relative to song exemplars.     

Visual illusions and ethnocentrism: exemplars for teaching cross-cultural concepts

This article discusses the origins of cross-cultural interest in two concepts fundamental to psychology students' views of the world: simple visual illusions and ethnocentrism. Although students encounter these ideas in introductory psychology, textbooks rarely describe the nature or origin of cross-cultural knowledge about them. The article presents a brief account of the history of these concepts and relates them to contemporary notions of psychology and culture. Using visual perception and ethnocentrism as examples, the article suggests the importance of teaching that different people see the world in different ways and the role of that lesson in a future demanding increased cross-cultural understanding.     

Cognitive categories and memory span: I. Shifting between categories

Broadbent and Gregory's hypothesis that shifting selection between cognitive classes is at least inefficient is tested by varying the number of transitions from consonants to digits and back in a mixed list memory span situation. No orderly decrease is found as a function of the number of transitions, which renders the attention hypothesis unlikely. An alternative position in terms of interference theory could explain the data qualitatively. Tests of further predictions of this theory need first an estimate of the degree of difference between cognitive classes.     

Case-like categories in children: The actor and some related categories

Case categories were investigated using a method in which pictures are presented accompanied by a sentence describing the scene: Preschool children learn to put tokens on the objects in the pictures according to the role each object plays in the scene as described. Generalization trials explore what the children include within the various roles. Children rapidly learn to associate tokens with case-like categories during the training phase, and readily transfer to new stimuli in generalization trials. The experiments demonstrate that children have a broad Actor category. The Actor “does” the action, and Actors are not necessarily animate. However, animacy is a class property of stimuli to which the children were very sensitive. There was evidence that User and Instrument are subcategories of Actor that are differentiated only when a sentence contains both. The data also suggest a Locative category, and Patient as a category of the grammatical object. Finally, the children appeared to treat subjects of predicate adjectives as a separate category, here called the Subject of Attribution, distinct from Actor, and functionally independent of objects of transitive verbs.     

Cues and categories: Revisiting paths to racial phenotypicality bias

We conducted a targeted review of the literature exploring racial phenotypicality bias (RPB): perceivers' sensitivity to within-race variation in facial target features in perceptions and judgment of others. This review revealed evidence that two distinct mechanisms underlying these effects, categorical and featural, tend to be conflated in the literature. The categorical route suggests that the pathway from target cues to stereotype application is mediated by category activation. The featural route suggests that the pathway from target cues to stereotype application is direct, bypassing category activation. The categorical route is more closely represented when researchers discuss RPB, and more often of empirical focus. With a focus on research exploring RPB toward African American people, we explain the two routes and evidence supporting their distinction. We next offer evidence estimating the degree to which they may be conflated in the empirical literature and discuss limitations to our approach. Next, we describe some potential implications of this conflation for theory, research, and applications concerning RPB. Finally, we end with some recommendations for future empirical research.     

Estimating stimuli from contrasting categories: truncation due to boundaries

In this article, the authors present and test a formal model that holds that people use information about category boundaries in estimating inexactly represented stimuli. Boundaries restrict stimuli that are category members to fall within a particular range. This model posits that people increase the average accuracy of stimulus estimates by integrating fine-grain values with boundary information, eliminating extreme responses. The authors present 4 experiments in which people estimated sizes of squares from 2 adjacent or partially overlapping stimulus sets. When stimuli from the 2 sets were paired in presentation, people formed relative size categories, truncating their estimates at the boundaries of these categories. Truncation at the boundary of separation between the categories led to exaggeration of differences between stimuli that cross categories. Yet truncated values are shown to be more accurate on average than unadjusted values.