Post-training intrahippocampal injection of synthetic poly-alpha-2,8-sialic acid-neural cell adhesion molecule mimetic peptide improves spatial long-term performance in mice

Several data have shown that the neural cell adhesion molecule (NCAM) is necessary for long-term memory formation and might play a role in the structural reorganization of synapses. The NCAM, encoded by a single gene, is represented by several isoforms that differ with regard to their content of alpha-2,8-linked sialic acid residues (PSA) on their extracellular domain. The carbohydrate PSA is known to promote plasticity, and PSA-NCAM isoforms remain expressed in the CA3 region of the adult hippocampus. In the present study, we investigated the effect on spatial memory consolidation of a PSA gain of function by injecting a PSA mimetic peptide (termed pr2) into the dorsal hippocampus. Mice were subjected to massed training in the spatial version of the water maze. Five hours after the last training session, experimental mice received an injection of pr2, whereas control mice received PBS or reverse peptide injections in the hippocampal CA3 region. Memory retention was tested at different time intervals: 24 h, 1 wk, and 4 wk. The results showed that the post-training infusion of pr2 peptide significantly increases spatial performance whenever it was assessed after the training phase. By contrast, administration of the control reverse peptide did not affect retention performance. These findings provide evidence that (1) PSA-NCAM is involved in memory consolidation processes in the CA3 hippocampal region, and (2) PSA mimetic peptides can facilitate the formation of long-term spatial memory when injected during the memory consolidation phase.     

Frequency effects with visual words and syllables in a dyslexic reader

The present study investigated the nature of the inhibitory syllable frequency effect, recently reported for normal readers, in a German-speaking dyslexic patient. The reading impairment was characterized as a severe deficit in naming single letters or words in the presence of spared lexical processing of visual word forms. Three visual lexical decision experiments were conducted with the dyslexic patient, an unimpaired control person matched to the patient and a control group: Experiment 1 manipulated the frequency of words and word-initial syllables and demonstrated systematic effects of both factors in normal readers and in the dyslexic patient. The syllable frequency effect was replicated in a second experiment with a more strictly controlled stimulus set. Experiment 3 confirmed the patient's deficit in activating phonological forms from written words by demonstrating that a pseudohomophone effect as observed in the unimpaired control participants was absent in the dyslexic patient.     

Viewer-external frames of reference in the mental transformation of 3-D objects

Most models of object recognition and mental rotation are based on the matching of an object's 2-D view with representations of the object stored in memory. They propose that a time-consuming normalization process compensates for any difference in viewpoint between the 2-D percept and the stored representation. Our experiment shows that such normalization is less time consuming when it has to compensate for disorientations around the vertical than around the horizontal axis of rotation. By decoupling the different possible reference frames, we demonstrate that this anisotropy of the normalization process is defined not with respect to the retinal frame of reference, but, rather, according to the gravitational or the visuocontextual frame of reference. Our results suggest that the visual system may call upon both the gravitational vertical and the visuocontext to serve as the frame of reference with respect to which 3-D objects are gauged in internal object transformations.     

Exploring individual differences in reactions to mortality salience: does attachment style regulate terror management mechanisms?

Five studies examined the contribution of attachment style to mortality salience effects. In Study 1, mortality salience led to more severe judgments of transgressions only among anxious-ambivalent and avoidant persons but not among secure persons. In addition, whereas anxious-ambivalent persons showed immediate and delayed increases in severity judgments, avoidant persons showed this response only after a delay period. In Study 2, anxious-ambivalent persons showed immediate and delayed increases in death-thought accessibility after death reminders. Avoidant and secure persons showed this effect only after a delay period. Study 3 revealed that worldview defense in response to mortality salience reduced death-thought accessibility only among avoidant persons. Studies 4-5 revealed that mortality salience led to an increase in the sense of symbolic immortality as well as in the desire of intimacy only among secure persons, but not among avoidant and anxious-ambivalent persons.     

Assessment of Implicit Health Attitudes: A Multitrait–Multimethod Approach and a Comparison Between Patients With Hypochondriasis and Patients With Anxiety Disorders

Two adaptations of the Implicit Association Task were used to assess implicit anxiety (IAT–Anxiety) and implicit health attitudes (IAT–Hypochondriasis) in patients with hypochondriasis (n = 58) and anxiety patients (n = 71). Explicit anxieties and health attitudes were assessed using questionnaires. The analysis of several multitrait–multimethod models indicated that the low correlation between explicit and implicit measures of health attitudes is due to the substantial methodological differences between the IAT and the self-report questionnaire. Patients with hypochondriasis displayed significantly more dysfunctional explicit and implicit health attitudes than anxiety patients, but no differences were found regarding explicit and implicit anxieties. The study demonstrates the specificity of explicit and implicit dysfunctional health attitudes among patients with hypochondriasis.     

The Campbell Paradigm as a Conceptual Alternative to the Expectation of Hypocrisy in Contemporary Attitude Research

Hypocrisy—professing a general attitude without implementing corresponding attitude-relevant behavior—is, according to Ajzen and Fishbein (2005), commonly found in attitude research that aims to explain individual behavior. We conducted two studies that adopted the Campbell paradigm, an alternative to the traditional understanding of attitudes. In a laboratory experiment, we found that specific attitude-relevant cooperation in a social dilemma was a function of people’s pre-existing general environmental attitude. In a quasi-experiment, we corroborated the reverse as well; engagement in attitude-relevant dietary practices was indicative of environmental attitude. When using Campbellian attitude measures, there is no room for hypocrisy: People put their general attitudes into specific attitude-relevant practices, and differences in people’s general attitudes can be derived from their attitude-relevant behavior.     

P300 amplitude variations,prior probabilities,and likelihoods: A Bayesian ERP study

The capability of the human brain for Bayesian inference was assessed by manipulating probabilistic contingencies in an urn-ball task. Event-related potentials (ERPs) were recorded in response to stimuli that differed in their relative frequency of occurrence (.18 to .82). A veraged ERPs with sufficient signal-to-noise ratio (relative frequency of occurrence > .5) were used for further analysis. Research hypotheses about relationships between probabilistic contingencies and ERP amplitude variations were formalized as (in-)equality constrained hypotheses. Conducting Bayesian model comparisons, we found that manipulations of prior probabilities and likelihoods were associated with separately modifiable and distinct ERP responses. P3a amplitudes were sensitive to the degree of prior certainty such that higher prior probabilities were related to larger frontally distributed P3a waves. P3b amplitudes were sensitive to the degree of likelihood certainty such that lower likelihoods were associated with larger parietally distributed P3b waves. These ERP data suggest that these antecedents of Bayesian inference (prior probabilities and likelihoods) are coded by the human brain.     

Anomalies in the detection of change: When changes in sample size are mistaken for changes in proportions

Detecting changes, in performance, sales, markets, risks, social relations, or public opinions, constitutes an important adaptive function. In a sequential paradigm devised to investigate detection of change, every trial provides a sample of binary outcomes (e.g., correct vs. incorrect student responses). Participants have to decide whether the proportion of a focal feature (e.g., correct responses) in the population from which the sample is drawn has decreased, remained constant, or increased. Strong and persistent anomalies in change detection arise when changes in proportional quantities vary orthogonally to changes in absolute sample size. Proportional increases are readily detected and nonchanges are erroneously perceived as increases when absolute sample size increases. Conversely, decreasing sample size facilitates the correct detection of proportional decreases and the erroneous perception of nonchanges as decreases. These anomalies are however confined to experienced samples of elementary raw events from which proportions have to be inferred inductively. They disappear when sample proportions are described as percentages in a normalized probability format. To explain these challenging findings, it is essential to understand the inductive-learning constraints imposed on decisions from experience.     

Scalar Implicatures Versus Presuppositions: The View from Acquisition

This paper reports an experimental investigation of presuppositions and scalar implicatures in language acquisition. Recent proposals (Chemla 2009; Romoli 2012, Romoli in J Semant 1–47, 2014) posit the same mechanisms for generating both types of inferences, in contrast to the traditional view. We used a Covered Box picture selection task to compare the interpretations assigned by two groups of children (4/5 and 7 year olds) and by adults, in response to sentences with presuppositions and ones with either ‘direct’ or ‘indirect’ scalar implicatures. The main finding was that the behavior of children and adults differed across inference types. This asymmetry is consistent with the traditional perspective, but poses a challenge for the more recent uniform accounts. We discuss how the latter could be amended to account for these findings, and also relate the findings to previous results on presupposition processing. Finally, we discuss an unexpected difference found between direct and indirect scalar implicatures.     

Spotlight on Age‐Diversity Climate: The Impact of Age‐Inclusive HR Practices on Firm‐Level Outcomes

This study investigates the emergence and the performance effects of an age‐diversity climate at the organizational level of analysis. Building upon Kopelman and colleagues’ (Kopelman, Brief, & Guzzo, 1990 ) climate model of firm productivity as well as Cox's ( 1994 ) interactional model of cultural diversity, we hypothesize a positive influence of age‐inclusive HR practices on the development of an organization‐wide age‐diversity climate, which in turn should be directly related to collective perceptions of social exchange and indirectly to firm performance and employees’ collective turnover intentions. The assumed relationships are tested in a sample of 93 German small and medium‐sized companies with 14,260 employees participating. To circumvent common source problems, information for the various constructs was gathered from 6 different sources. To test our assumed relationships, we applied structural equation modeling and executed bootstrapping procedures to test the significance of the indirect effects. We received support for all assumed relationships. The paper concludes with practical recommendations on how to establish and make use of a positive age‐diversity climate.