Histamine enhances inhibitory avoidance memory consolidation through a H2 receptor-dependent mechanism

Several evidences suggest that brain histamine is involved in memory consolidation but the actual contribution of the hippocampal histaminergic system to this process remains controversial. Here, we show that when infused into the CA1 region of the dorsal hippocampus immediately after training in an inhibitory avoidance task, but not later, histamine induced a dose-dependent promnesic effect without altering locomotor activity, exploratory behavior, anxiety state or retrieval of the avoidance response. The facilitatory effect of intra-CA1 histamine was mimicked by the histamine N-methyltransferase inhibitor SKF-91844 as well as by the H2 receptor agonist dimaprit and it was blocked completely by the H2 receptor antagonist ranitidine. Conversely, the promnesic action of histamine was unaffected by the H1 receptor antagonist pyrilamine, the H3 receptor antagonist, thioperamide, and the NMDAr polyamine-binding site antagonist ifenprodil. By themselves, ranitidine, pyrilamine, thioperamide, and ifenprodil did not affect IA memory consolidation. Our data indicate that, when given into CA1, histamine enhances memory consolidation through a mechanism that involves activation of H2 receptors; however, endogenous CA1 histamine does not seem to participate in the consolidation of IA memory at least at the post-training times analyzed.     

Con-fusing contours & pieces of glass

We present a new illusory display in which illusory contours are misaligned with physical contours. In these displays, illusory Kanizsa squares, induced by the so-called pacmen, are positioned on top of a background grid of bars. The misalignment of the illusory contours with respect to physical contours of the grid of bars induces an overall 'restless' appearance and evokes the impression that parts of the grid within the illusory square are shifted. To test this impression, we created stimuli in which illusory squares were superimposed on a grid at different positions, where the grid could consist of either straight bars or indented bars. After briefly flashing these stimuli, observers reported indentations of the background grid for those cases in which physical and illusory contours were misaligned. In a control condition, the pacmen were replaced by crosses (not inducing an illusory square) at the same positions; as expected much less illusory shifts were reported in this condition. In a second experiment, we further tested the direction of the perceived shifts, revealing similar trends as in the first experiment and a consistent result with respect to the reported direction of the shifts. We explore and discuss possible underlying mechanisms with regard to our illusory display.     

Phenomenological reports diagnose accuracy of eyewitness identification decisions

This study investigated whether measuring the phenomenology of eyewitness identification decisions aids evaluation of their accuracy. Witnesses (N = 502) viewed a simulated crime and attempted to identify two targets from lineups. A divided attention manipulation during encoding reduced the rate of remember (R) correct identifications, but not the rates of R foil identifications or know (K) judgments in the absence of recollection (i.e., K/[1 − R]). Both RK judgments and recollection ratings (a novel measure of graded recollection) distinguished correct from incorrect positive identifications. However, only recollection ratings improved accuracy evaluation after identification confidence was taken into account. These results provide evidence that RK judgments for identification decisions function in a similar way as for recognition decisions; are consistent with the notion of graded recollection; and indicate that measures of phenomenology can enhance the evaluation of identification accuracy.     

Moral Foundations and Heterogeneity in Ideological Preferences

Scholars have documented numerous examples of how liberals and conservatives differ in considering public policy. Recent work in political psychology has sought to understand these differences by detailing the ways in which liberals and conservatives approach political and social issues. In their moral foundations theory, Haidt and Joseph contend the divisions between liberals and conservatives are rooted in different views of morality. They demonstrate that humans consistently rely on five moral foundations. Two of these foundations—harm and fairness—are often labeled the individualizing foundations, as they deal with the role of individuals within social groups; the remaining three foundations—authority, ingroup loyalty, and purity—are the binding foundations as they pertain to the formation and maintenance of group bonds. Graham, Haidt, and Nosek demonstrate that liberals tend to disproportionately value the individualizing foundations, whereas conservatives value all five foundations equally. We extend this line of inquiry by examining whether different types of liberals and conservatives value the moral foundations to varying degrees. Using survey data (n = 745), we rely on a mixed‐mode latent class analysis and identify six ideological classes that favor unique social and fiscal policy positions. While most of the respondents belonging to these classes self‐identify as conservative, they endorse the moral foundations in varying degrees. Since our findings demonstrate considerable heterogeneity with respect to ideology and moral preferences, we conclude by encouraging scholars to consider this heterogeneity in detailing the motivational and psychological foundations of ideological belief.     

Maintaining a healthy diet: Effects of personality and self-reward versus self-punishment on commitment to and enactment of self-chosen and assigned goals

Abstract

A theory decomposing volition into four modes of central organization of executive control functions is outlined. These modes include (1) an autonomy-oriented mode (“self-regulation”) which is facilitated by challenging conditions and positive mood, (2) a self-suppressive mode oriented toward external-control (“self-control”) facilitated by negative mood and two modes associated with volitional inhibition (“state orientation”). Two experiments are reported that test predicted interactions between dispositional and situational factors in determining commitment to and actual enactment of self-chosen versus assigned activities directed at changing nutritional behavior. The results confirm the predicted disordinal interactions: The degree of commitment to and enactment of intended behavioral changes depends upon an interaction between personality (volitional styles), type of self-regulatory task (eat more healthy versus avoid unhealthy food), and instructional focus on easy versus difficult steps (Study 1) or self-reward versus self-punishment strategies (Study 2). Practical implications for designing intervention procedures according to individual personality characteristics and situational constraints are discussed.