A probabilistic model of cross-categorization

Most natural domains can be represented in multiple ways: we can categorize foods in terms of their nutritional content or social role, animals in terms of their taxonomic groupings or their ecological niches, and musical instruments in terms of their taxonomic categories or social uses. Previous approaches to modeling human categorization have largely ignored the problem of cross-categorization, focusing on learning just a single system of categories that explains all of the features. Cross-categorization presents a difficult problem: how can we infer categories without first knowing which features the categories are meant to explain? We present a novel model that suggests that human cross-categorization is a result of joint inference about multiple systems of categories and the features that they explain. We also formalize two commonly proposed alternative explanations for cross-categorization behavior: a features-first and an objects-first approach. The features-first approach suggests that cross-categorization is a consequence of attentional processes, where features are selected by an attentional mechanism first and categories are derived second. The objects-first approach suggests that cross-categorization is a consequence of repeated, sequential attempts to explain features, where categories are derived first, then features that are poorly explained are recategorized. We present two sets of simulations and experiments testing the models’ predictions about human categorization. We find that an approach based on joint inference provides the best fit to human categorization behavior, and we suggest that a full account of human category learning will need to incorporate something akin to these capabilities.     

Psychopathic traits from the perspective of self and informant reports: is there evidence for a lack of insight?

It has been suggested that psychopathic individuals are incapable of providing valid reports on their own personality functioning because they are either unwilling (i.e., pathologically lie) or unable (i.e. lack insight) to do so. Despite the long-standing nature of this suggestion, almost no empirical research exists on this topic. In the current study, the authors examined the issue of psychopathy and insight by testing self and informant convergence and mean level differences across 3 indices of psychopathy in a community sample (N=64). Self- and informant-report psychopathy scores were also examined in relation to self and informant reports on traits from the Five-Factor Model (FFM). Convergence was strong across the 3 psychopathy indices and their respective factors (i.e., median r=.64), and there was only modest evidence that individuals rated themselves as less psychopathic than did informants. In addition, the same FFM domains-low Agreeableness and Conscientiousness-characterized individuals with psychopathic traits regardless of reporter. Psychopathic individuals appear capable of reporting accurately on psychopathic traits when there are no direct consequences to accurate reporting (i.e., sentencing). It may be that the lack of concern for the consequences of these traits has been mistaken for a lack of insight into them.     

Learning to learn causal models

Learning to understand a single causal system can be an achievement, but humans must learn about multiple causal systems over the course of a lifetime. We present a hierarchical Bayesian framework that helps to explain how learning about several causal systems can accelerate learning about systems that are subsequently encountered. Given experience with a set of objects, our framework learns a causal model for each object and a causal schema that captures commonalities among these causal models. The schema organizes the objects into categories and specifies the causal powers and characteristic features of these categories and the characteristic causal interactions between categories. A schema of this kind allows causal models for subsequent objects to be rapidly learned, and we explore this accelerated learning in four experiments. Our results confirm that humans learn rapidly about the causal powers of novel objects, and we show that our framework accounts better for our data than alternative models of causal learning.     

Rater Personality and Performance Dimension Weighting in Making Overall Performance Judgments

Purpose  

The present study examined the effects of rater personality on the performance appraisal process. Specifically, we determined the relative weights that raters place on different performance dimensions when making overall performance evaluations, and examined whether rater personality influenced this weighting process. The literatures on social/political values and mate/friend selection were used as guiding frameworks in developing specific hypotheses.     

Medroxyprogesterone acetate impairs memory and alters the GABAergic system in aged surgically menopausal rats

In women, medroxyprogesterone acetate (MPA) is the most commonly used progestin component of hormone therapy (HT). In vitro, MPA negatively impacts markers of neuronal health and exacerbates experimentally-induced neurotoxicity. There is in vitro evidence that these factors are driven by GABAergic and neurotrophic systems. Whether these effects translate to a negative impact on brain function has not been tested in vivo, clinically or preclinically. Here we evaluate the mnemonic and neurobiological effects of MPA in the surgically menopausal rat. Aged ovariectomized (OVX) rats were given subcutaneous vehicle, natural progesterone, low-dose MPA or high-dose MPA. Multiple cognitive domains were analyzed via the water radial-arm maze (WRAM) and Morris maze (MM). Cognitive brain regions were assayed for changes in the GABAergic system by evaluating GAD protein, the synthesizing enzyme for GABA, and neurotrophins. On the WRAM, both progestin types impaired learning. Further, high-dose MPA impaired delayed memory retention on the WRAM, and exacerbated overnight forgetting on the MM. While neurotrophins were not affected by progesterone or MPA treatment, both progestin types altered GAD levels. MPA significantly and progesterone marginally decreased GAD levels in the hippocampus, and both MPA and progesterone significantly increased GAD levels in the entorhinal cortex. These findings suggest that MPA, the most commonly used progestin in HT, is detrimental to learning and two types of memory, and modulates the GABAergic system in cognitive brain regions, in aged surgically menopausal rats. These findings, combined with in vitro evidence that MPA is detrimental to neuronal health, indicates that MPA has negative effects for brain health and function.     

Unraveling the race paradox of achievement and self-views

Considerable evidence indicates that African American students achieve less academically than European American students. Yet, African American students hold more positive self-views than their European American counterparts. Previous studies that address these seemingly paradoxical findings focus on students in a relatively narrow age range and/or convenience samples. Therefore, the current study examines two common explanations for these seemingly paradoxical findings, among a large and diverse sample of African American and European American students (N = 1, 493) from elementary to post-secondary school and across the socioeconomic spectrum. Results indicate that among a diverse group of students and conceptualized in two different ways, African American students do not devalue academics. However, African American students are more likely than European American students to discount academic feedback.     

Prototype abstraction by monkeys (Macaca mulatta)

The authors analyze the shape categorization of rhesus monkeys (Macaca mulatta) and the role of prototype- and exemplar-based comparison processes in monkeys' category learning. Prototype and exemplar theories make contrasting predictions regarding performance on the Posner-Homa dot-distortion categorization task. Prototype theory--which presumes that participants refer to-be-categorized items to a representation near the category's center (the prototype)--predicts steep typicality gradients and large prototype-enhancement effects. Exemplar theory--which presumes that participants refer to-be-categorized items to memorized training exemplars-predicts flat typicality gradients and small prototype-enhancement effects. Across many categorization tasks that, for the first time, assayed monkeys' dot-distortion categorization, monkeys showed steep typicality gradients and large prototype-enhancement effects. These results suggest that monkeys--like humans--refer to-be-categorized items to a prototype-like representation near the category's center rather than to a set of memorized training exemplars.     

Process demands of rejection mechanisms of recognition memory

A surge of research has been conducted to examine memory editing mechanisms that help distinguish accurate from inaccurate memories. In the present experiment, the authors examined the ability of participants to use novelty detection, recollection rejection, and plausibility judgments to reject lures presented on a recognition memory test. Participants studied a list of word pairs that were arranged in a category relationship (both words from the same category) or an unrelated relationship (both words from different categories) under full or divided attention. At test, participants were given a yes/no recognition test in which they were to respond after seeing the test items for 400 ms or 2,800 ms. Some of the test items were rearranged word pairs that were consistent with the study relationship, whereas others were inconsistent with the study relationship. The results demonstrate that the participants required full attention at study to use novelty detection, recollection rejection, and plausibility judgments to reject lures. Moreover, the results indicate that a long response deadline at test was needed for participants to use both recollection rejection and plausibility judgments to reject lures.     

Mapping the scale of the narcissism epidemic: Increases in narcissism 2002–2007 within ethnic groups

[Twenge, J. M., Konrath, S., Foster, J. D., Campbell, W. K., & Bushman, B. J. (2008a). Egos inflating over time: A cross-temporal meta-analysis of the Narcissistic Personality Inventory. Journal of Personality, 76, 875–901.] found that Narcissistic Personality Inventory (NPI) scores increased between 1982 and 2006 among college students nationwide, but [Trzesniewski, K. H., Donnellan, M. B., & Robins, R. W. (2008). Do today’s young people really think they are so extraordinary? An examination of secular changes in narcissism and self-enhancement. Psychological Science, 19, 181–188.] found that NPI scores remained unchanged over that time in samples from the University of California (UC) campuses. The increasing numbers of Asian-Americans at the UCs over time may have masked changes in narcissism, as Asian-Americans score lower on the NPI. When examined within ethnic groups, Trzesniewski et al.’s data show that NPI scores increased significantly between 2002 and 2007 at twice the rate of the yearly change found over 24 years in Twenge et al. (2008a). The overall means also show a significant increase 2002–2007. Thus the available evidence suggests that college students are endorsing progressively more narcissistic personality traits over the generations.     

Is Character Fate,or Is There Hope to Change My Personality Yet?

Different perspectives on personality development propose a range of possible degrees to which traits are free to change, from hardly at all to very much. This essay reviews the empirical evidence on just how consistent and changeable personality traits are across the life course. To gain a thorough perspective on personality trait development, we review developmental studies that focus on three different types of change: rank‐order consistency, mean level change, and individual level change. Starting in late childhood, personality traits exhibit modest levels of rank‐order consistency that increase with age. In addition personality traits show mean level changes, especially in young adulthood, that are consistent with the idea of increasing maturity. Finally, despite these general trends in personality continuity and change, there is evidence that individuals may change in ways that contradict general trends and that these individual differences in change are related to life experiences.