Biomedical subjects

Zachary Estes

Publications and source records attributed to Zachary Estes.

4 recordsLinked to original sources

PubMed2005

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.

Color Perception↗

PubMed2004

The importance of being nonalignable: a critical test of the structural alignment theory of similarity.

The structural alignment theory of similarity distinguishes 2 types of difference that may occur between stimuli: Alignable differences are those related to a commonality, whereas nonalignable differences are not related to a commonality. Alignment theory predicts that alignable differences should be more heavily weighted than nonalignable differences in similarity judgment. Experiments 1 and 2 demonstrate that, contrary to this prediction, nonalignable differences exerted a greater impact than alignable differences in similarity and difference judgments of geometric stimuli. Experiment 3 revealed that the relative weight accorded a given difference was also affected by contextual constraints. Thus, although the experiments supported the validity of the distinction between alignable and nonalignable differences, results were discordant with the specific prediction of structural alignment theory.

Form Perception↗

PubMed2004

Confidence and gradedness in semantic categorization: definitely somewhat artifactual, maybe absolutely natural.

Artifacts tend to be categorized in a graded (i.e., continuous) manner, whereas natural categorization tends to be absolute (i.e., discrete). This domain-specific categorization is assumed to reflect a domain difference in representation. However, another tenable but untested explanation is that graded categorization arises from uncertainty, which is greater in artifact categories than in natural categories. Confidence ratings were used as an index of certainty in two experiments that tested whether confidence in category judgments can explain the apparent gradedness of those categories. Both experiments revealed that artifact categories were more graded and were judged with greater confidence than were natural categories. Confidence and gradedness were negatively correlated within both domains. Thus, confidence did indeed predict gradedness within the artifact and natural domains but failed to predict the difference in gradedness between those domains. There is more to gradedness than just uncertainty.

Cognition↗

PubMed2003

Domain differences in the structure of artifactual and natural categories.

In three experiments, different methodologies, measures, and items were employed to address the question of whether, and to what extent, membership in a semantic category is all or none (i.e., absolute) or a matter of degree (i.e., graded). Resemblance theory claims that categorization is based on similarity, and because similarity is graded, category membership may also be graded. Psychological essentialism asserts that categorization is based on the presumption of the category essence. Because artifactual (e.g., FURNITURE) and natural (e.g., FRUIT) categories have different sorts of essences, artifacts and natural kinds may be categorized in qualitatively different manners. The results converged onthe finding of a robust domain difference in category structure: Artifactual categories were more graded than natural categories. Furthermore, typicality reliably predicted absolute category membership, but failed to predict graded category membership. These results suggest that resemblance theory and psychological essentialism may provide a concerted account of representation and categorization across domains.

Humans↗