The consistency model: A process model for absolute judgments.

Stimuli receive higher ratings when smaller ones are presented more frequently than larger ones. A. Parducci ascribed this effect to the Ss' tendency to assign the same number of stimuli to each available category. An alternative interpretation is proposed. It is assumed that the judgment scale develops quickly and retains its initial form throughout the presentations. Because the more frequently presented stimuli are most likely to be presented first, the S's scale is centered on the range of these stimuli, thus producing (pseudo) frequency effects. Despite its simplicity, the consistency model accounts for the effects of stimulus frequency, number of stimuli, and number of categories. The model also accounts for long-term effects of previous scales. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prototypes in category learning: The effects of category size, category structure, and stimulus complexity.

Although research in categorization has sometimes been motivated by prototype theory, recent studies have favored exemplar theory. However, some of these studies focused on small, poorly differentiated categories composed of simple, 4-dimensional stimuli. Some analyzed the aggregate data of entire groups. Some compared powerful multiplicative exemplar models to less powerful additive prototype models. Here, comparable prototype and exemplar models were fit to individual-participant data in 4 experiments that sampled category sets varying in size, level of category structure, and stimulus complexity (dimensionality). The prototype model always fit the observed data better than the exemplar model did. Prototype-based processes seemed especially relevant when participants learned categories that were larger or contained more complex stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Judgments of emotional intensity in self and others: The effects of stimulus context, sex, and expressivity.

Examined 48 undergraduates' emotional reactions to evocative visual stimuli and their judgments of the reactions of others to these stimuli. Ss reported the intensity of their own reactions and then judged the category and intensity of the others' photographed facial expressions. Intensity of the stimulus (weak/strong) and of the others' facial expressions (low/high) were factorially combined in a 2?×?2 within-Ss design while the emotion category was held constant. Expressivity was objectively rated during both self and other judgment. Results reveal sex differences in expressive responses to the stimuli: Females were more modulated than males in their expressive behavior. Level of nonverbal expressivity (low/high) was found to be independent of sex. In addition, stimulus intensity systematically affected ratings of the other person. Judgments of intensity were lowest when a strong stimulus preceded a low-intensity facial expression (contrast effect) and highest when a strong stimulus preceded a high-intensity facial expression (assimilation effect). Sex and expressivity interacted to affect judgments of others, underscoring the independence of the 2 factors. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Why do categories affect stimulus judgment?

The authors tested a model of category effects on stimulus judgment. The model holds that the goal of stimulus judgment is to achieve high accuracy. For this reason, people place inexactly represented stimuli in the context of prior information, captured in categories, combining inexact fine-grain stimulus values with prior (category) information. This process can be likened to a Bayesian statistical procedure designed to maximize the average accuracy of estimation. If people follow the proposed procedure to maximize accuracy, their estimates should be affected by the distribution of instances in a category. In the present experiments, participants reproduced one-dimensional stimuli. Different prior distributions were presented. The experiments verified that people's stimulus estimates are affected by variations in a prior distribution in such a manner as to increase the accuracy of their stimulus reproductions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classification of exemplars with single- and multiple-feature manifestations: The effects of relevant dimension variation and category structure.

Most classification research focuses on cases in which each abstract feature has the same surface manifestation whenever it is presented. Previous research finds that people have difficulty learning to classify when each abstract feature has multiple surface manifestations. These studies created multiple manifestations by varying aspects of the stimuli irrelevant to the abstract feature dimension. In this article, multiple manifestations were created by varying aspects of the stimuli relevant to the abstract feature dimension. People given categories with the family resemblance category structure often used in psychology experiments had difficulty learning to classify when multiple manifestations were present, even though the variation was relevant. This effect was reversed when a family resemblance structure with nondiagnostic values was used. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity, frequency, and category representations.

This article studies the joint roles of similarity and frequency in determining graded category structure. Perceptual classification learning experiments were conducted in which presentation frequencies of individual exemplars were manipulated. The exemplars had varying degrees of similarity to members of the target and contrast categories. Classification accuracy and typicality ratings increased for exemplars presented with high frequency and for members of the target category that were similar to the high-frequency exemplars. Typicality decreased for members of the contrast category that were similar to the high-frequency exemplars. A frequency-sensitive similarity-to-exemplars model provided a good quantitative account of the classification learning and typicality data. The interactive relations among similarity, frequency, and categorization are considered in the General Discussion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Size contrast as a function of conceptual similarity between test and inducers

In four experiments, the effect of the semantic relationship between test and inducing stimuli on the magnitude of size contrast in an Ebbinghaus-type illusion was explored. In Experiments 1 and 2, the greatest illusion was found when test and inducing stimuli were identical in shape and differed only in size. Decreased size contrast was found when inducing stimuli were drawn from the same category as the test stimulus, but were not visually identical. Even less size contrast was found when inducing stimuli were from a near conceptual category, with the least effect when they were drawn from a completely different category. In Experiment 3, it was demonstrated that even if test and inducing stimuli are drawn with identical geometric elements, the size contrast illusion is greatly reduced if they represent apparently different conceptual categories (through the manipulation of orientation and perceptual set). In Experiment 4, any geometric or spatial confounds were ruled out. These results suggest that size contrast is strongly influenced by the conceptual similarity between test and inducing stimuli.     

Comparing Categorization Models.

Four experiments are presented that competitively test rule- and exemplar-based models of human categorization behavior. Participants classified stimuli that varied on a unidimensional axis into 2 categories. The stimuli did not consistently belong to a category; instead, they were probabilistically assigned. By manipulating these assignment probabilities, it was possible to produce stimuli for which exemplar- and rule-based explanations made qualitatively different predictions. F. G. Ashby and J. T. Townsend's (1986) rule-based general recognition theory provided a better account of the data than R. M. Nosofsky's (1986) exemplar-based generalized context model in conditions in which the to-be-classified stimuli were relatively confusable. However, generalized context model provided a better account when the stimuli were relatively few and distinct. These findings are consistent with multiple process accounts of categorization and demonstrate that stimulus confusion is a determining factor as 10 which process mediates categorization. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A constructive–associative model of contextual dependence of unidimensional similarity.

Conditions under which pairwise dissimilarity ratings should reflect manipulations of the stimulus distribution were outlined by a model that proposed these effects. These conditions arise from either a context dependent process for constructing implicit scale values or a process that uses previously established stimulus–response associates. Consistent with the model, results from 3 experiments using unidimensional psychophysical stimuli demonstrated disordinal context effects on pairwise dissimilarity ratings when (a) there was a 3-s delay between presentation of pair members or (b) a unidimensional rating task preceded the pairwise dissimilarity ratings. Global effects of density were fit well by a model that extended A. Parducci's (1983) range–frequency theory to dissimilarity ratings. Local density effects were generally consistent with predictions from C. L. Krumhansl's (see record 1979-22539-001) distance–density theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A constructive-associative model of the contextual dependence of unidimensional similarity

Conditions under which pairwise dissimilarity ratings should reflect manipulations of the stimulus distribution were outlined by a model that proposed these effects. These conditions arise from either a context dependent process for constructing implicit scale values or a process that uses previously established stimulus-response associates. Consistent with the model, results from 3 experiments using unidimensional psychophysical stimuli demonstrated disordinal context effects on pairwise dissimilarity ratings when (a) there was a 3-s delay between presentation of pair members or (b) a unidimensional rating task preceded the pairwise dissimilarity ratings. Global effects of density were fit well by a model that extended A. Parducci's (1983) range-frequency theory to dissimilarity ratings. Local density effects were generally consistent with predictions from C.L.Krumhansl's (1978) distance-density theory.     

Testing the speech unit hypothesis with the primed matching task: phoneme categories are perceptually basic

The basic speech unit (phoneme or syllable) problem was investigated with the primed matching task. In primed matching, subjects have to decide whether the elements of stimulus pairs are the same or different. The prime should facilitate matching in as far as its representation is similar to the stimuli to be matched. If stimulus representations generate graded structure, with stimulus instances being more or less prototypical for the category, priming should interact with prototypicality because prototypical instances are more similar to the activated category than are low-prototypical instances. Rosch (1975a, 1975b) showed that, by varying the matching criterion (matching for physical identity or for belonging to the same category), the specific patterns of the priming x prototypicality interaction could differentiate perceptually based from abstract categories. By testing this pattern for phoneme and syllable categories, the abstraction level of these categories can be studied. After finding reliable prototypicality effects for both phoneme and syllable categories (Experiments 1 and 2), primed phoneme matching (Experiments 3 and 4) and primed syllable matching (Experiments 5 and 6) were used under both physical identity instructions and same-category instructions. The results make clear that phoneme categories are represented on the basis of perceptual information, whereas syllable representations are more abstract. The phoneme category can thus be identified as the basic speech unit. Implications for phoneme and syllable representation are discussed.     

Comparison and Contrast in Perceptual Categorization.

People categorized pairs of perceptual stimuli that varied in both category membership and pairwise similarity. Experiments 1 and 2 showed categorization of 1 color of a pair to be reliably contrasted from that of the other. This similarity-based contrast effect occurred only when the context stimulus was relevant for the categorization of the target (Experiment 3). The effect was not simply owing to perceptual color contrast (Experiment 4), and it extended to pictures from common semantic categories (Experiment 5). Results were consistent with a sign-and-magnitude version of N. Stewart and G. D. A. Brown's (2005) similarity-dissimilarity generalized context model, in which categorization is affected by both similarity to and difference from target categories. The data are also modeled with criterion setting theory (M. Treisman & T. C. Williams, 1984), in which the decision criterion is systematically shifted toward the mean of the current stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From sunshine to double arrows: An evaluation window account of negative compatibility effects.

In category priming, target stimuli are to be sorted into 2 categories. Prime stimuli preceding targets typically facilitate processing of targets when primes and targets are members of the same category, relative to the case in which both stem from different categories, a positive compatibility effect (PCE). But negative compatibility effects (NCEs) are also sometimes observed. An evaluation window account (Klauer, Teige-Mocigemba, & Spruyt, 2009) of PCE and NCE in evaluative priming (category good versus category bad) is applied to masked arrow priming (Eimer & Schlaghecken, 1998; category left versus category right). Key principles of the account are that participants evaluate incoming evidence across a time window, and decisions about stimulus category are driven by changes in evidence weighted according to the Weber-Fechner law, leading to NCE for primes falling outside the time window and PCE for primes inside the time window. In Experiments 1–4, factors considered obligatory for NCE by current accounts of arrow priming are successively removed; yet, NCE remained intact as predicted by the evaluation window account. Furthermore, the evaluation window account, but none of the current accounts, predicts NCE without a stimulus intervening between prime and target at intermediate prime–target stimulus-onset asynchrony (Experiment 5) and when target onset comes as a surprise (Experiment 6). We conclude that the evaluation window account describes a hitherto overlooked mechanism that contributes to PCE and NCE in arrow priming and that it appears to generalize beyond the confines of evaluative priming to the diverse class of category-priming paradigms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conjunctions of visually based categories: Overextension and compensation.

The degree to which overextension effects found with conjunctions of semantic categories of visual stimuli was tested in 4 experiments. Overextension occurs when participants categorize a stimulus in the conjunction of 2 categories but fail to categorize the same stimulus as belonging to 1 of the 2 constituent categories considered individually. Stimuli for the present experiments were ambiguous colored letter shapes and cartoon faces that could vary along dimensions of happiness and either apparent intelligence or apparent age. Overextension was found with both stimulus sets, thus showing that the phenomenon is not restricted to categorization in superordinate semantic categories. There was also evidence that typicality in 1 category could compensate for borderline membership of the other. More overextension was found for faces than for letters, and there was evidence for asymmetric compensation between category dimensions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification and Bisection of Temporal Durations and Tone Frequencies: Common Models for Temporal and Nontemporal Stimuli.

Two experiments examined identification and bisection of tones varying in temporal duration (Experiment 1) or frequency (Experiment 2). Absolute identification of both durations and frequencies was influenced by prior stimuli and by stimulus distribution. Stimulus distribution influenced bisection for both stimulus types consistently, with more positively skewed distributions producing lower bisection points. The effect of distribution was greater when the ratio of the largest to smallest stimulus magnitude was greater. A simple mathematical model, temporal range frequency theory, was applied. It is concluded that (a) similar principles describe identification of temporal durations and other stimulus dimensions and (b) temporal bisection point shifts can be understood in terms of psychophysical principles independently developed in nontemporal domains, such as A. Parducci's (1965) range frequency theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of category length and strength on familiarity in recognition.

In most recognition models a decision is based on a global measure often termed familiarity. However, a response criterion is free to vary across lists varying in length and strength, making familiarity changes immeasurable. We presented a single list with a mixture of exemplars from many categories, so that the criterion would be unlikely to vary with length or strength of the category of the test item. False alarms rose with category length but not category strength, suggesting that familiarity does not change much with changes in strength of other items but grows when additional items are studied. The results were well fit by an extension of the search of associative memory (SAM) model presented by R. M. Shiffrin, R. Ratcliff, and S. E. Clark (see record 1990-13917-001). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus size and eccentricity in visually induced perception of horizontally translational self-motion

The effects of the size and eccentricity of the visual stimulus upon visually induced perception of self-motion (vection) were examined with various sizes of central and peripheral visual stimulation. Analysis indicated the strength of vection increased linearly with the size of the area in which the moving pattern was presented, but there was no difference in vection strength between central and peripheral stimuli when stimulus sizes were the same. Thus, the effect of stimulus size is homogeneous across eccentricities in the visual field.     

A connectionist account of asymmetric category learning in early infancy.

Young infants show unexplained asymmetries in the exclusivity of categories formed on the basis of visually presented stimuli. A connectionist model is described that shows similar exclusivity asymmetries when categorizing the same stimuli presented to infants. The asymmetries can be explained in terms of an associative learning mechanism, distributed internal representations, and the statistics of the feature distributions in the stimuli. The model was used to explore the robustness of this asymmetry. The model predicts that the asymmetry will persist when a category is acquired in the presence of mixed category exemplars. An experiment with 3–4-month-olds showed that asymmetric exclusivity persisted in the presence of mixed-exemplar familiarization, thereby confirming the model's prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)