We present a novel way of accounting for similarity judgments. Our approach posits that similarity stems from three main sources—familiarity, priming, and inherent perceptual likeness. Here, we explore each of these constructs and demonstrate their individual and combined effectiveness in explaining similarity judgments. Using these three measures, our account of similarity explains ratings of simple, color-based perceptual stimuli that display asymmetry effects, as well as more complicated perceptual stimuli with structural properties; more traditional approaches to similarity solve one or the (...) other and have difficulty accounting for both. Overall, our work demonstrates the importance of each of these components of similarity in explaining similarity judgments, both individually and together, and suggests important implications for other similarity approaches. (shrink)

Since Tversky argued that similarity judgments violate the three metric axioms, asymmetrical similarity judgments have been particularly challenging for standard, geometric models of similarity, such as multidimensional scaling. According to Tversky, asymmetrical similarity judgments are driven by differences in salience or extent of knowledge. However, the notion of salience has been difficult to operationalize, especially for perceptual stimuli for which there are no apparent differences in extent of knowledge. To investigate similarity judgments between perceptual stimuli, across three experiments, we collected (...) data where individuals would rate the similarity of a pair of temporally separated color patches. We identified several violations of symmetry in the empirical results, which the conventional multidimensional scaling model cannot readily capture. Pothos et al. proposed a quantum geometric model of similarity to account for Tversky's findings. In the present work, we extended this model to a more general framework that can be fit to similarity judgments. We fitted several variants of quantum and multidimensional scaling models to the behavioral data and concluded in favor of the quantum approach. Without further modifications of the model, the best-fit quantum model additionally predicted violations of the triangle inequality that we observed in the same data. Overall, by offering a different form of geometric representation, the quantum geometric framework of similarity provides a viable alternative to multidimensional scaling for modeling similarity judgments, while still allowing a convenient, spatial illustration of similarity. (shrink)

In the present dissertation, I propose a general, robust, and objective characteristic of the information environment, according to which negative information is more diverse than positive information. I present an explanatory framework for this phenomenon based on the non-extremity of positive qualities. Specifically, most attribute dimensions host one “positive” range which is surrounded by two distinct “negative” ranges, resulting in a greater diversity of negative compared to positive attributes, stimuli, and information in general. Chapter 1 of my dissertation reviews evidence (...) for the proposed greater diversity of negative information, showing that positive stimuli are consistently perceived as more similar than negative stimuli. Chapter 2 presents a line of research that demonstrates the same phenomenon in the domain of person perception. People perceive other people they like as more similar to one another than other people they dislike. I further suggest that the greater diversity of negative information as an “extrapsychic” phenomenon can account for a number of valence asymmetries in information processing that have previously been explained based on “intrapsychic” affective reactions. In line with this idea, Chapter 3 presents research showing that negative words enjoy a recognition advantage over positive words because they are more diverse. Chapter 4 discusses limitations, open questions and further implications of the current empirical findings and of the explanatory framework provided. (shrink)