A test of the reward-value hypothesis

Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.     

Sharing genes fosters identity fusion and altruism

Researchers have shown that the more genes twins share, the more they care about one another. Here, we examine a psychological mediator of such genetic influences, “identity fusion” (a visceral sense of oneness with them). Results supported this hypothesis. Relative to dizygotic twins, monozygotic twins reported stronger fusion and elevated desire to have contact and share experiences with their twin (Study 1), to forgive and grant favors to their twin after being disappointed by him/her (Study 2), and willingness to make sacrifices for their twin (Study 3). Fusion with the twin mediated the impact of zygosity on these outcomes. These findings demonstrate that genetic relatedness fosters a powerful feeling of union with one’s twin that predicts sharing, tolerance, and self-sacrificial behavior toward him or her.     

A cluster-based approach to selecting representative stimuli from the International Affective Picture System (IAPS) database

The International Affective Picture System (IAPS; Lang, Bradley, & Cuthbert, 2008) is a stimulus database that is frequently used to investigate various aspects of emotional processing. Despite its extensive use, selecting IAPS stimuli for a research project is not usually done according to an established strategy, but rather is tailored to individual studies. Here we propose a standard, replicable method for stimulus selection based on cluster analysis, which re-creates the group structure that is most likely to have produced the valence arousal, and dominance norms associated with the IAPS images. Our method includes screening the database for outliers, identifying a suitable clustering solution, and then extracting the desired number of stimuli on the basis of their level of certainty of belonging to the cluster they were assigned to. Our method preserves statistical power in studies by maximizing the likelihood that the stimuli belong to the cluster structure fitted to them, and by filtering stimuli according to their certainty of cluster membership. In addition, although our cluster-based method is illustrated using the IAPS, it can be extended to other stimulus databases.     

Interference and facilitation among personal goals: differential associations with subjective well-being and persistent goal pursuit

Three studies demonstrate that mutual facilitation and interference among personal goals are distinct characteristics rather than mutually exclusive opposites and have different functions for psychological well-being and goal pursuit. The three studies vary in design (cross-sectional, short-termlongitudinal) and follow a multimethod approach using questionnaires, diaries, and objective behavioral information. Results show that interference among goals (resulting from resource constraints and incompatible goal attainment strategies) is negatively associated with trait and state well-being, whereas mutual facilitation among goals (resulting from instrumental goal relations and overlapping goal attainment strategies) is positively associated with involvement in goal pursuit.     

A secreted form of the beta-amyloid precursor protein (sAPP695) improves spatial recognition memory in OF1 mice

The beta-amyloid precursor protein (APP) plays a central role in Alzheimer's disease (AD) and appears to be a multifunctional protein. Secreted forms of APP (sAPP) have memory-enhancing effects in certain behavioral paradigms. To investigate sAPP's role in spatial memory processes, we adapted a spatial recognition task and evaluated (1) the performance of OF1 mice after massed training (single 15-min acquisition session) and distributed training (three 5-min acquisition sessions), (2) the decline of spatial recognition performance by introducing different delays (5min, 1, 3, and 24h) between the acquisition and retention phases, and (3) the effects of sAPP(695) on spatial recognition memory. In the present study, mice selectively reacted to a change in the spatial configuration of five objects. Indeed, 3min post-acquisition, mice performed similarly in the massed and distributed versions of the task, by re-exploring the two displaced objects only, whereas mice exposed to the same spatial configuration did not. Additionally, all mice did react to a novel object in a subsequent object recognition phase. Mice detected object displacements 5min, 1h, or 3h post-acquisition, but no more at a 24h-delay. Finally, mice treated with sAPP(695) intracerebroventricularly at a dose of 0.5pg/4microL/mouse, 20-min pre-acquisition or 5-min post-acquisition, still reacted to a spatial change in objects position 24h post-acquisition, in marked contrast to NaCl-treated mice. Our data demonstrate that sAPP(695) significantly improves a form of spatial memory, and confirms the hypothesis of an action of this protein on early memory processes.     

Perceived verbal aggressiveness of coaches in volleyball and basketball: a preliminary study

This study examined verbal aggressiveness of coaches as perceived by their athletes, 108 senior athletes (57 boys and 51 girls) ages 15-19 years. Participants were basketball players (56 athletes) and volleyball players (52 athletes) who completed questionnaires. The scale of verbal aggressiveness showed high internal consistency. A two-way analysis of variance, conducted using sex and sport as independent variables to examine interactions, yielded significant differences between adolescent volleyball and basketball athletes. Volleyball athletes had lower scores on the Verbal Aggressiveness Scale than basketball players. Research with larger samples and other sports is recommended.     

Skinner boxes for psychotics: operant conditioning at Metropolitan State Hospital

Between 1953 and 1965, Ogden Lindsley and his associates conducted free-operant research with psychiatric inpatients and normal volunteers at Metropolitan State Hospital in Waltham, Massachusetts. Their project, originally named "Studies in Behavior Therapy," was renamed "Harvard Medical School Behavior Research Laboratory" in 1955. This name change and its implications were significant. The role of the laboratory in the history of the relationship between the experimental analysis of behavior and applied behavior analysis is discussed. A case is made for viewing Lindsley's early work as foundational for the subfield of the experimental analysis of human behavior that formally coalesced in the early 1980s. The laboratory's work is also contextualized with reference to the psychopharmacological revolution of the 1950s. Finally, a four-stage framework for studying the historical and conceptual development of behavior analysis is proposed.     

The Effects of Children's Exposure to Domestic Violence: A Meta-Analysis and Critique

A wide range of children's developmental outcomes are compromised by exposure to domestic violence, including social, emotional, behavioral, cognitive, and general health functioning. However, there are relatively few empirical studies with adequate control of confounding variables and a sound theoretical basis. We identified 41 studies that provided relevant and adequate data for inclusion in a meta-analysis. Forty of these studies indicated that children's exposure to domestic violence was related to emotional and behavioral problems, translating to a small overall effect (Z _r = .28). Age, sex, and type of outcome were not significant moderators, most likely due to considerable heterogeneity within each of these groups. Co-occurrence of child abuse increased the level of emotional and behavioral problems above and beyond exposure alone, based on 4 available studies. Future research needs are identified, including the need for large-scale longitudinal data and theoretically guided approaches that take into account relevant contextual factors.