Contrasting rule-based and similarity-based category learning: The effects of mood and prior knowledge on ambiguous categorization

This study adopts a dual-system view of category learning. The findings suggest that consumers who learn a dominant feature as a verbal rule for a product category will classify a new ambiguous product according to that feature even if it more closely resembles a different product category. The findings also demonstrate that dominant features can bias categorization toward a less prototypical category in the event that the new product breaks the rule. We refer to this phenomenon as criterial inferencing. Lastly, we offer unique empirical evidence to suggest that mood influences category learning and thus attenuates the criterial inferencing bias.     

Low environmental calcium blocks long-term memory formation in a freshwater pulmonate snail

The freshwater snail Lymnaea stagnalis (L.) is considered a calciphile and exhibits reduced growth and survival in environments containing less than 20 mg/l environmental calcium. Although it has no apparent effect on survival at 20 mg/l, reducing environmental calcium increases metabolic demand, and as such we consider that this level of calcium acts as a stressor on the snail. We exposed snails to acute periods of low environmental calcium and tested their ability to form intermediate-term memory (ITM) and long-term memory (LTM) following one trial operant conditioning (1TT) to reduce aerial respiratory activity in hypoxic conditions. We also assessed whether there were changes in the electrophysiological properties of a single neuron, right pedal dorsal 1 (RPeD1), which has been demonstrated to be necessary for LTM formation. Following training in high (80 mg/l) environmental calcium, L. stagnalis formed ITM and LTM lasting 24 h and demonstrated a significant reduction in all activity measured from RPeD1; however when snails were exposed to low (20 mg/l) environmental calcium they were able to form ITM but not LTM. Although no behavioral LTM was formed, a partial reduction in RPeD1 activtiy measured 24 h after training was observed, indicating a residual effect of training. The strong effect that environmental calcium concentration had on physiology and behavior in response to training to reduce aerial respiration in L. stagnalis suggests that it is an element of gastropod husbandry that needs to be carefully considered when studying other traits. This study also indicates that L. stagnalis found naturally in low calcium environments may be less able to adapt to novel stressors than populations found in harder waters.     

Exploratory regression analysis: A tool for selecting models and determining predictor importance

Linear regression analysis is one of the most important tools in a researcher’s toolbox for creating and testing predictive models. Although linear regression analysis indicates how strongly a set of predictor variables, taken together, will predict a relevant criterion (i.e., the multiple R), the analysis cannot indicate which predictors are the most important. Although there is no definitive or unambiguous method for establishing predictor variable importance, there are several accepted methods. This article reviews those methods for establishing predictor importance and provides a program (in Excel) for implementing them (available for direct download at . The program investigates all 2 ^p – 1 submodels and produces several indices of predictor importance. This exploratory approach to linear regression, similar to other exploratory data analysis techniques, has the potential to yield both theoretical and practical benefits.     

Heart rate responses to induced challenge situations in greylag geese (Anser anser)

Adequate short-term responses to stressors are of great importance for the health and well-being of individuals and factors modulating the physiological stress response (e.g., controllability, suddenness, familiarity) of a stimulus are well described under laboratory conditions. In the present study we aimed at investigating the stress response in greylag geese (Anser anser) in the field, confronting individuals with naturally occurring stressors. We measured beat-to-beat heart rate (HR) via fully implanted transmitters during three different experimental challenges: (1) catching and holding, (2) confrontation with a model predator, and (3) approach by different humans. We compared this to a control period and HR during agonistic encounters, a naturally occurring stressor. All three experimental situations evoked a HR increase. Highest HR responses were elicited by catching and holding the animals. In the third experiment, HR responses were greatest when the geese were approached by a human stranger (i.e., somebody the geese have never seen before). Hence, geese discriminated between different kinds of stressors and adjusted their physiological response depending on the type of stressor. Our results show that geese were able to discriminate between individual humans. In line with a number of lab studies, we suggest that particularly the controllability of certain situation determines the intensity of the HR response, also in a natural setting in the field.     

Guidelines for Multicultural Assessment: An Asian Indian American Case Study

Accurate assessment of ethnic minority clients is often hindered by clinician bias and lack of culturally sensitive instruments. Multicultural guidelines can enhance clinician awareness and sensitivity in conducting assessments with diverse populations. These guidelines are illustrated using an Asian Indian American character from Lahiri's (2008) novel Unaccustomed Earth. La evaluación precisa de clientes pertenecientes a minorías étnicas se ve con frecuencia dificultada por el sesgo de los especialistas clínicos y la falta de instrumentos culturalmente sensibles. Las directrices multiculturales pueden ampliar la conciencia de los especialistas y su sensibilidad al llevar a cabo evaluaciones con poblaciones diversas. Estas directrices se ilustran usando un personaje indoasiáticoamericano extraído de la novela Unaccustomed Earth de Lahiri (2008).     

Using Egalitarian Items to Measure Men’s and Women’s Family Roles

This study was designed to show that measuring gender ideology by egalitarian items might be problematic, as gender egalitarianism is not simply the reverse of gender traditionalism and includes very different stances. Egalitarian items are likely to lead to an insufficient discrimination between traditional and non-traditional respondents. While the former often ignore the egalitarian stance, the latter hold different egalitarian positions which prevents agreement with any specific item. Empirical evidence is reported from quantitative and qualitative data: an international survey based on random samples (n?=?5.692) and a cognitive study, which was conducted in Germany by both internet (n?=?889) and telephone (n?=?285). Here, the selection of a response category was analyzed by using probing questions.     

Three-year follow-up of same-sex couples who had civil unions in Vermont, same-sex couples not in civil unions, and heterosexual married couples

This study was a 3-year follow-up of 65 male and 138 female same-sex couples who had civil unions in Vermont during the 1st year of that legislation. These couples were compared with 23 male and 61 female same-sex couples in their friendship circles who did not have civil unions and with 55 heterosexual married couples (1 member of each was a sibling to a member of a civil union couple). Despite the legalized nature of their relationships, civil union couples did not differ on any measure from same-sex couples who were not in civil unions. However, same-sex couples not in civil unions were more likely to have ended their relationships than same-sex civil union or heterosexual married couples. Compared with heterosexual married participants, both types of same-sex couples reported greater relationship quality, compatibility, and intimacy and lower levels of conflict. Longitudinal predictors of relationship quality at Time 2 included less conflict, greater level of outness, and a shorter relationship length for men in same-sex relationships and included less conflict and more frequent sex for women in same-sex relationships at Time 1.