Attention, similarity, and the identification–categorization relationship.

A unified quantitative approach to modeling Ss' identification and categorization of multidimensional perceptual stimuli is proposed and tested. Two Ss identified and categorized the same set of perceptually confusable stimuli varying on separable dimensions. The identification data were modeled using R. N. Shepard's (see record 1959-05134-001) multidimensional scaling-choice framework, which was then extended to model the Ss' categorization performance. The categorization model, which generalizes the context theory of classification developed by D. L. Medin and M. M. Schaffer (see record 1979-12633-001), assumes that Ss store category exemplars in memory. Classification decisions are based on the similarity of stimuli to the stored exemplars. It is assumed that the same multidimensional perceptual representation underlies performance in both the identification and categorization paradigms. However, because of the influence of selective attention, similarity relationships change systematically across the 2 paradigms. Findings provide some support for the hypothesis that Ss distribute attention among component dimensions so as to optimize categorization performance and that Ss may have augmented their category representations with inferred exemplars. Results demonstrate that excellent predictions of categorization performance can be made given knowledge of performance in an identification paradigm. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effect of Category Learning on the Representation of Shape: Dimensions Can Be Biased but Not Differentiated.

Recent studies have suggested a profound influence of category learning on visual perception, resulting in independent processing of previously integral dimensions. The authors reinvestigate this issue for shape dimensions. They first extend previous findings that some shape dimensions (aspect ratio and curvature) are processed in a separable way, whereas others (radial frequency components) are not. They then show that a category-learning phase improved the discrimination of a relevant with respect to an irrelevant dimension, but only for separable dimensions. No similar effect was found on the relative sensitivity for integral shape dimensions. Thus, category learning is capable of biasing separable shape dimensions but does not alter the status of dimensions in the visual system as either separable or integral. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complex decision rules in categorization: Contrasting novice and experienced performance.

The ability of novice and experienced Ss to learn complex decision rules was tested with 3 categorization tasks. Each task involved 2 categories with exemplars that were normally distributed on 2 stimulus dimensions. Three separate sets of stimuli were used, and in each task the decision rule that maximized categorization accuracy was a highly nonlinear function of the stimulus dimension values. In the 3 tasks, all experienced Ss used highly nonlinear decision rules. Quadratic rules were supported over bilinear rules, and in many cases Ss used nearly optimal decision rules. These findings did not depend on whether the stimulus components were integral or separable. Novice Ss also did not use simple linear rules. A model that assumed Ss tried a succession of different linear rules was also rejected. Instead, novices appeared to use quadratic rules, although less consistently than experienced Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separability and integrality of global and local levels of hierarchical patterns.

Used a constrained classification task to examine the perceptual relations between global and local levels in hierarchical patterns composed of many, relatively small elements and those composed of few, relatively large elements. In 4 experiments, 52 18–35 yr olds made classifications based on form or texture or according to the shape of the configuration or the elements. Results indicate that configural and elemental levels were perceptually separable for many-element patterns when processed as form and texture. Ss could attend to either level without being affected by variation along the irrelevant dimension. However, when the same many-element patterns were processed for global and local shape. Ss could not selectively attend to either level. For few-element patterns, global configuration and local elements appeared to be perceptually integral dimensions. Results are discussed in terms of the global precedence hypothesis and explanations of integral and separable dimensions. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrating information from separable psychological dimensions.

This article examines decision processes in the perception and categorization of stimuli composed of the separable psychological dimensions, orientation and size. The randomization technique (F. G. Ashby and R. Gott; see record 1989-07388-001) of general recognition theory, which allows accurate estimation of a subject's decision boundary in a categorization task, is used in 4 experiments. Even though the stimulus components are clearly separable, it was found that Ss were not constrained to use separable response strategies, nor were they constrained to attend to distance to the prototypes. Instead, they used decision rules that were nearly optimal, even if this required information integration or for the Ss to attend to higher level category properties such as component correlation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subjectively interpreted shape dimensions as privileged and orthogonal axes in mental shape space.

The shape of an object is fundamental in object recognition but it is still an open issue to what extent shape differences are perceived analytically (i.e., by the dimensional structure of the shapes) or holistically (i.e., by the overall similarity of the shapes). The dimensional structure of a stimulus is available in a primary stage of processing for separable dimensions, although it can also be derived cognitively from a perceived stimulus consisting of integral dimensions. Contrary to most experimental paradigms, the present study asked participants explicitly to analyze shapes according to two dimensions. The dimensions of interest were aspect ratio and medial axis curvature, and a new procedure was used to measure the participants' interpretation of both dimensions (Part I, Experiment 1). The subjectively interpreted shape dimensions showed specific characteristics supporting the conclusion that they also constitute perceptual dimensions with objective behavioral characteristics (Part II): (1) the dimensions did not correlate in overall similarity measures (Experiment 2), (2) they were more separable in a speeded categorization task (Experiment 3), and (3) they were invariant across different complex 2-D shapes (Experiment 4). The implications of these findings for shape-based object processing are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Separating perceptual and decisional attention processes in the identification and categorization of integral-dimension stimuli.

Four observers performed matching, identification, and categorization with stimuli that varied along the integral dimensions: brightness and saturation. General recognition theory (F. G. Ashby & J. T. Townsend, 1986) was applied to quantify the separate influences of perceptual and decisional processes within and across tasks, with a focus on separating perceptual from decisional attention processes. Good accounts of the identification data were obtained from perceptual matching representation. This perceptual representation provided a good account of the categorization data, except when decisional selective attention to 1 stimulus dimension was required. Decisional selective attention reduced the attended-dimension perceptual variance relative to the unattended-dimension perceptual variance, with a larger reduction resulting when brightness, as opposed to saturation was attended. Implications for color vision research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Explaining category interference effects in associative memory.

Two studies with 220 undergraduates investigated the effects of categorization on the acquisition and long-term retention of AB word pairs using modeling techniques that factor the contributions of various storage and retrieval factors. In Exp I, each S memorized 1 of the 4 basic types of lists: unrelated cues/unrelated targets, categorized cues/unrelated cues, unrelated cues/categorized targets, and categorized cues/categorized targets. Ss in Exp II memorized 24-item AB lists to criterion. Acquisition data showed that there was a crossover interaction such that the effects of increasing the degree of cue or target relatedness depended on the nature of the comparison items. In contrast with the results of previous studies, the effects were larger when categorization was manipulated on the target side of AB pairs than when it was manipulated on the cue side. The degree of categorization affected retrieval difficulty but not storage difficulty. Long-term retention data indicated that, contrary to the acquisition data, the effects of categorization on retention were uniformly positive. Categorization decreased the amount of forgetting primarily by reducing the rate at which traces were lost from memory (storage failure) during the retention interval. Results are discussed in terms of modern unitary-trace theories of associative memory. (French abstract) (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible tuning of similarity in exemplar-based categorization.

Flexibility in exemplar-based categorization was investigated in 3 experiments. 24 undergraduate Ss categorized schematic drawings of individuals' faces while they received information about the kinship relation between these individuals and previously observed exemplars. In Exps 1 and 2, initial training was incidental, whereas an intentional learning task was used in Exp 3. In all experiments, the kinship manipulation systematically affected categorizations. Model-based analyses showed that the effect of the kinship manipulation could be described by similarity-based exemplar models if it was assumed that Ss applied different levels of generalization as a function of the kinship instructions. Results demonstrate that categorization is a highly flexible process, and their methodological and theoretical implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Categorization of individuals on the basis of multiple social features.

Five experiments used a name-matching paradigm developed by S. E. Taylor et al (1978) to investigate how people use the immediately apparent features of others as a basis of social categorization. Ss were more likely to categorize targets according to their sex than their race but also tended to categorize using a single subordinate category that represented sex and race simultaneously. Racially prejudiced Ss categorized to greater degree by race than did nonprejudiced Ss, but manipulations of construct accessibility and processing goals did not influence categorization by race or sex. Processing goals did influence the use of clothing style as a categorization feature. Results are discussed in terms of the functional utility of person features as a basis of categorization and the effects of categorization on social stereotyping and prejudice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention and learning processes in the identification and categorization of integral stimuli.

Studied the relationship between identification and categorization learning of integral-dimension stimuli within the framework of an exemplar-based generalization model. The model was used to predict learning in 6 different categorization conditions on the basis of data obtained in a single identification learning condition. 34 undergraduates were tested in the identification learning condition and 191 undergraduates were tested in the categorization learning conditions. An assumption in the model is that because of selective attention to component dimensions, similarity relations may change in systematic ways across different experimental contexts. Results indicate that selective attention may play a critical role in determining the identification–categorization relationship for integral stimuli. Similarity among exemplars decreased as a function of identification learning. It is noted that alternative classification models, including prototype, multiple-prototype, average distance, and value-on-dimensions models, were unable to account for the results. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Level of analysis in the perception of ongoing instruction: An exploratory study.

The level of perceptual analysis at which learners operate during ongoing instruction is suggested to be a variable mediating the effects of instructional variables on learner outcomes. Several instructional variables were manipulated to determine whether they influence the level of perceptual analyses; Ss were 184 undergraduates. Unitization instructions, lesson difficulty, teacher effectiveness, and teacher order were found to influence perceptual analysis significantly. The relationships of perceptual analysis to concept learning and to evaluations of the instructors were also examined. Partial support was obtained for the hypotheses that finer levels of perceptual analysis are associated with more favorable instructor evaluations and with concept learning. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrality/separability of stimulus dimensions and multidimensional generalization in pigeons.

The authors present a quantitative framework for interpreting the results of multidimensional stimulus generalization experiments in animals using concepts derived from the geometrical approach to human cognition. The authors apply the model to the analysis of stimulus generalization data obtained from pigeons trained with different sets of stimuli varying along two orthogonal dimensions. Separable pigeons were trained with stimuli varying along the dimensions of circle size and line tilt, dimensions found to be separable in previous human research; integral pigeons were trained with stimuli varying along two dimensions of rotation in depth, dimensions that are intuitively integral and which hold special interest for theories of object recognition. The model accurately described the stimulus generalization data, with best fits to the City-Block metric for separable pigeons and to the euclidean metric for integral pigeons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Success, failure, and self-assessment ratings.

Investigated the effects of success and failure experiences on subsequent self-ratings of positive and negative social-psychological characteristics. 60 teacher trainees were assigned to success, failure, or control experiences on 3 achievement tasks ostensibly testing intellectual ability. Posttest minus pretest gains were assessed on variables of self-reported self-confidence, self-worth, opportunity, efficacy, and true unto self, which were categorized as positive dimensions. Similar gains were assessed on variables of self-reported need for isolation, worried and afraid, need for help, troubles and obstacles, and cynicism, categorized as negative dimensions. As hypothesized, Ss who experienced success made significantly greater gains in positive self-assessments, and failure Ss made significantly greater gains in negative self-assessments. No significant Success-Failure * Sex interaction was found. Implications for clinicians, psychotherapists, and procedures employed in self-rating scales are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intergroup discrimination and self-esteem in the minimal group paradigm.

Tested the hypothesis that intergroup discrimination (IGD) in the minimal group paradigm is related to self-esteem. According to social identity theory, IGD is a strategy for achieving self-esteem via social competition aimed at increasing the positive distinctiveness of one's own group. However, other elements of the procedure, such as categorization into groups or the opportunity to engage in a meaningful experimental task irrespective of its value for social competition, might also affect self-esteem. 135 undergraduates were randomly assigned to 8 concurrent experimental conditions. A 2-way MANOVA on the core design produced a significant interaction effect, whereby categorized Ss who had the opportunity to discriminate between groups and noncategorized Ss who did not discriminate showed higher self-esteem than did both categorized Ss who could not engage in discrimination and noncategorized Ss who could discriminate. Results support social identity theory and suggest that social categorization by itself may constitute a threat to self-esteem that can be resolved via social competition. Results from the supplementary conditions support the conclusion that it is IGD, and not merely the completion of an experimental task, that redeems self-esteem. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conserving and retaining equalities and inequalities through observation and correction.

Investigated the effects of modeling and corrective feedback on the conservation of equalities and inequalities, with items spanning 3 stimulus dimensions (length, number, and 2-dimensional space). Ss were 48 kindergartners (24 boys, 24 girls). Brief observation of a model, briefer correction training (joining positive feedback with verbal rule provision), and the combination of observation and correction were all successful in producing learning and, without further training, transfer and retention of conservation. Unlike the controls (who also never correctly answered any equality items), the trained experimental Ss gave evidence of spontaneously generalizing their new learning to a task that required nonverbal behavior to manifest conservation. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual and semantic features in children's use of the animate concept.

Investigated the development of understanding of animate and inanimate items. 52 4–7 yr olds and 15 college students received 3 tasks, including sentence completion, oddity, and sorting tasks. In all conditions, Ss were asked to choose from among animate and inanimate items the 1 which correctly completed the task requirement. Inanimate items in all tasks had 1 perceptual feature in common with the animate item, either movement, making noise, or similarity of size. It was predicted that Ss would select items on the basis of perceptual rather than semantic similarity in those tasks which contained little contextual information. It is concluded that children were aware of the difference between animate and inanimate items in certain conditions, but that perceptual features were often more salient. If contextual restrictions were not evident, the dimension of animateness may have been overlooked in favor of visible, concrete features of the items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Building object representations from parts: Tests of a stochastic sampling model.

In 2 experiments, the perceptual processing assumptions of the extended generalized context model (EGCM) of categorization were tested. The model assumes that object parts are sampled independently and in parallel in the earliest stages of categorization. In both experiments, participants categorized images of artificial objects under various levels of time pressure. Each participant also categorized partial objects, which were obtained by removing object components. The EGCM assumes that categorization judgments under time pressure can rely on incomplete object representations. The model successfully predicts performance in the speeded categorization task from the classification of partial objects. The results provide strong support for the EGCM, which performed consistently better than 2 alternative models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential sensitivity of perceptual identification for words and pseudowords to test expectations: Implications for the locus of word frequency effects.

Four experiments using a study-test paradigm provide evidence of differences in the nature of perceptual enhancement effects for words compared with results for meaningless pseudowords. Ss studied words (Exps 1, 2, and 4) or pseudowords (Exps 3 and 4) presented from 1 to 6 times in a list, then performed perceptual identification tests of studied and nonstudied items. Better identification of studied than of nonstudied items (i.e., a priming effect) was found for words and nonwords, but for words the function relating enhancement to the amount of prior exposure (i.e., a repetition effect) depended on whether Ss expected a later recall test. The results support dual-process accounts of word identification that assume a flexible use of either lexical code activation or episodic trace retrieval. A framework for understanding priming, repetition, and word frequency effects is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rule-plus-exception model of classification learning.

Proposes a rule-plus-exception model (RULEX) of classification learning. According to RULEX, people learn to classify objects by forming simple logical rules and remembering occasional exceptions to those rules. Because the learning process in RULEX is stochastic, the model predicts that individual Ss will vary greatly in the particular rules that are formed and the exceptions that are stored. Averaged classification data are presumed to represent mixtures of these highly idiosyncratic rules and exceptions. RULEX accounts for numerous fundamental classification phenomena, including prototype and specific exemplar effects, sensitivity to correlational information, difficulty of learning linearly separable vs nonlinearly separable categories, selective attention effects, and difficulty of learning concepts with rules of differing complexity. RULEX also predicts distributions of generalization patterns observed at the individual S level. (PsycINFO Database Record (c) 2010 APA, all rights reserved)