Evidence that resident male albino rats are not immune to attacks by conspecific intruders

Offensive behaviors were exhibited by adult intact- and castrated-male Sprague-Dawley rats introduced into established home-cages of male conspecifics. Implications of this result for Adams' [1976] model of intraspecific fighting are presented.     

Prevalence and predictors of transitions in smoking behavior among college students.

The prevalence of smoking among college students is surprisingly high and represents a significant public health issue. However, there are few longitudinal studies of smoking in this population. This study examined the prevalence and predictors of transitions in smoking behavior among a cohort of 548 college students. Over the course of 4 years, 87% of daily smokers and almost 50% of occasional smokers continued to smoke. Among nonsmokers, 11.5% began smoking occasionally and none became daily smokers. In general, predictors of smoking behavior change were significant only among baseline occasional smokers and included gender, smoking outcome expectancies, and affect regulation expectations. Peer and parental smoking, demographics, affect, stress, and alcohol use were generally not predictive of change. Tobacco control interventions targeted at college students are clearly warranted.     

Hippocampus function predicts severity of post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is often accompanied by memory problems and abnormal brain structure, particularly within the hippocampus. We implemented a cross-species, hippocampal-dependent task--the virtual Morris Water task--to assess hippocampal function in people with PTSD and age-matched controls during functional magnetic resonance imaging (fMRI). Performance on the task was equivalent between the groups. However, when correlating fMRI-derived hippocampal activity during this task with PTSD severity, we observe a -0.84 correlation, indicating that those with reduced hippocampal activity show more severe PTSD symptoms. This correlation is not explained by differences in task performance, IQ, duration since trauma, nor time with PTSD. Hence, PTSD severity is predicted by functionally assessing the hippocampus using the virtual Morris water task, suggesting that this task may be used to identify those at risk for developing PTSD following a trauma.     

The consequences of stereotype threat on the academic performance of White and non-White lower income college students

This research examined whether socioeconomic stereotypes produce stereotype threat among lower, middle, or upper income college students who are either White or non-White. Before completing an academic test, participants were either told that the purpose of the research was to understand why lower income students generally perform worse on academic tests or to examine problem-solving processes. Results showed that lower income students exposed to stereotype threat experienced greater test anxiety and performed worse on the academic test than their middle income and higher income counterparts. However, lower income students who experienced stereotype threat exerted as much effort on the test as lower income students who did not experience stereotype threat. Nonetheless, they were less likely to identify with school-related subjects. Stereotype threat and reduced performance did not influence lower income students’ self-esteem. Participant race did not influence these findings. The research is discussed in light of cognitive dissonance theory. Portions of the results were presented at the 2004 American Psychological Society Conference, Chicago, IL. Lisa A. Harrison is an assistant professor of psychology at California State University, Sacramento. Her research interests include stereotypes and prejudice, gender role norms and female athletes, and the influence of social identity on judgments of interpersonal violence. E-mail: lharriso@csus.edu Chiesha M. Stevens is currently working toward her MA in industrial/organizational psychology at California State University, Long Beach Adrienne N. Monty is currently working toward her MA in psychology at California State University, Sacramento Christine Coakley received her BA in psychology from California State University, Sacramento where she is currently working toward her MA in industrial/organizational psychology. Her research interests include stereotype threat, optimism, motivation and employee burnout in special education. E-mail: Sac78629@saclink.csus.edu     

Detection of heteroquality taste mixtures

Detection thresholds were measured for sweet (sucrose), salty (sodium chloride), sour (citric acid), and bitter (quinine hydrochloride) and for the 11 possible mixtures of these four substances. These 11 mixtures (6 binary, 4 ternary, and 1 quaternary) all turned out to be stimulus additive, in the sense that a person could reliably detect mixtures whose individual components are weaker than their unmixed thresholds. Tastants too weak to be perceived alone can thus make impact when in mixtures. The threshold concentration for a given compound was reduced in approximate proportion to the number of compounds added to it. This liberal heteroquality additivity contests the widespread belief that heteroquality mixtures (different chemicals evoking different qualities) are nonadditive and homoquality mixtures (different chemicals evoking the same quality) are additive. Heteroquality additivity emerges on appropriate definition of the subject’s task by forced choice (unavailable to earlier investigators), in order to skirt methodological pitfalls. Operating together, homoand heteroquality additivity may concomitantly enable a person to sense natural mixtures of hosts of weak constituents, such as drinking water. In this regard, gustatory mixtures may function much as do mixtures of frequencies in audition and mixtures of gaseous compounds in olfaction.     

Case-to-Case Arguments

Arguers sometimes cite a decision made in an earlier situation as a reason for making the equivalent decision in a later situation. I argue that there are two kinds of “case-to-case arguments”. First, there are arguments by precedent, which cite the mere existence of the past decision as a reason to decide in the same way again now, independent of the past decision’s merits. Second, there are case-to-case arguments from parralel reasoning which presuppose that the past decision was justified and are used to show that an equivalent present decision would also be justified. Both arguments are a type of argument by analogy. They differ in their structures and conditions of cogency, even though they often look the same in presentation. Their similar appearance poses a risk of miss-evaluation and fallacious use. Therefore a clearly theorized distinction is important.     

Intertemporal Similarity: Discounting as a Last Resort

Standard models of intertemporal choice assume that individuals discount future payoffs by integrating reward amounts and time delays to generate a discounted value. Alternative models propose that, rather than integrate across them, individuals compare within attributes (amounts and delays) to determine if differences in one attribute outweigh differences in another attribute. For instance, the similarity model 1) compares the two reward amounts to determine whether they are similar, 2) compares the similarity of the two time delays, and then 3) makes a decision based on these similarity judgments. Here, I tested discounting models against attribute‐based models that use similarity judgments to make choices. I collected intertemporal choices and similarity judgments for the reward amounts and time delays from participants in three experiments. All experiments tested the ability of discounting and similarity models to predict intertemporal choices. Model generalization analyses showed that the best predicting models started with similarity judgments and then, if similarity failed to make a prediction, resorted to discounting models. Similarity judgments also matched intertemporal choice data demonstrating both the magnitude and sign effects, thereby accounting for behavioral data that contradict many discounting models. These results highlight the possibility that attribute‐based models such as the similarity models provide alternatives to discounting that may offer insights into the process of making intertemporal choices. Copyright © 2015 John Wiley & Sons, Ltd.     

Positive and Negative Peer Influence in Residential Care

The potential for negative peer influence has been well established in research, and there is a growing interest in how positive peer influence also impacts youth. No research, however, has concurrently examined positive and negative peer influence in the context of residential care. Clinical records for 886 residential care youth were used in a Hierarchical Linear Model analysis to examine the impact of negative and positive peer influence on naturally occurring patterns of serious problem behavior over time. Negative peer influence, where the majority of youth in a home manifested above the average number of serious behavior problems, occurred 13.7% of the time. Positive peer influence, where the majority of youth manifested no serious problem behaviors for the month, occurred 47.7% of the time. Overall, youth problem behavior improved over time. There were significantly lower rates of serious problem behavior in target youth during positive peer influence months. Conversely, there were significantly higher rates of serious problem behaviors in target youth during negative peer influence months. Negative peer influence had a relatively greater impact on target peers’ serious behavior problems than did positive peer influence. Caregiver experience significantly reduced the impact of negative peer influence, but did not significantly augment positive peer influence. Months where negative peer influence was combined with inexperienced caregivers produced the highest rates of serious problem behavior. Our results support the view that residential programs for troubled youth need to create circumstances that promote positive and control for negative peer influence.     

Jungian approach to human aggression with special emphasis on war

Cross-cultural and interdisciplinary agreement as to the universality of aggressive behavior and warfare is compatible with Jung's [(1959): “The Archetypes and the Collective Unconscious. The Collected Works of C. G. Jung, Vol 9, Part I, Para 3.” London: Routledge] theory of archetypes functioning as components of the human collective unconscious. Jungian formulations involve a phylogenetic view of psychic phenomena since archetypes are conceived as neuropsychic entities which evolved through natural selection. It is argued that the banding together of young males for the purpose of aggressive pursuits such as hunting, intergroup conflict, and warfare is a biologically transmitted propensity mediated by archetypal structures in the human brain-psyche. Universally apparent patterns of affiliative and hostile behaviors are linked to Chance's [(1988): “Social Fabrics of the Mind.” London: Lawrence Erlbaum Associates] hedonic and agonic modes and seen as later ontological expressions of archetypal structures responsible in childhood for formation of bonds of attachment to familiars and avoidance and wariness of strangers. Erikson's [(1984): Yale Review 73(4): 481–486] concept of pseudospeciation is associated with Jung's concept of shadow projection to elucidate the phenomena of patriotism, xenophobia, national paranoia, Lorenz's [(1966): “On Aggression.” London: Methuen & Co.] “militant enthusiasm,” propaganda, and mobilization for war. Finally, it is argued that peace between nations can be promoted through conscious awareness of archetypally determined patterns of intergroup conflict and a collective resolve not to pseudospeciate our neighbors. © 1995 Wiley-Liss, Inc.