Pavlovian Conditioning to a Diazepam Cue with Yohimbine as the Unconditional Stimulus

On multiple occasions, rats were administered diazepam (2.0 mg/kg, ip) followed 30 min thereafter by yohimbine hydrochloride (2.5 or 5.0 mg/kg) or isotonic saline (forward conditioning groups). Three additional groups (backward conditioning controls) were given equivalent injections, but in reverse order. After eight such pairings, the effects of a single injection of diazepam on motor performance (balancing on a rotating drum) was assessed. Rats that had received either dose of yohimbine during forward conditioning trials maintained their balance longer than the saline controls. After four additional conditioning trials, the animals’ activity patterns in a plus-maze screening test for anxiolytics were examined. Placed into the maze after a single test injection of isotonic saline, the behavior of all groups was virtually identical: less than 16% of total entries into or time spent in the four arms of the maze was spent in the two “open” arms (unprotected by surrounding walls). When tested in the maze again, but 35 min after a single injection of diazepam, the groups that had received diazepam but not yohimbine during the conditioning phase exhibited the expected increase in open-arm activity, and equivalent increases were found in backward conditioning groups. However, the group previously conditioned with 2.5 mg/kg of yohimbine following diazepam also showed an increased open-arm activity when tested with diazepam alone, but it was significantly greater than that seen in the control group. In contrast, the group conditioned with 5.0 mg/kg yohimbine following diazepam exhibited no effect of diazepam upon their plus maze activity; consequently, these animals spent less time in the open arms than either of the other groups. Yohimbine alone normally decreases open-arm activity (a putative “anxiogenic” effect) in a linear dose-dependent fashion. The fact that it had a bidirectional conditional effect on the diazepam cue drug demonstrates that a conditional response in drug → drug conditioning cannot always be predicted on the basis of the behavioral response to the signaled drug. Consideration is given to possible reasons for these effects of diazepam → yohimbine pairings in terms of the known neuropharmacological properties of yohimbine.     

Ursachen der gegenseitigen Verdeckung von taktil dargebotenen Buchstaben: Unterbrechung,Summation oder Verzögerung?

Zusammenfassung Für die Erklärung der Verdeckung von Reizen in verschiedenen Sinnesmodalitäten mit einfacher Struktur wurden in der Literature bisher im wesentlichen zwei verschiedene Erklärungskonzepte diskutiert: Die Summationshypotheses behauptet, daß die Eindrücke von schnell aufeinanderfolgenden Reizen sich zu einer Gesamtrepräsentation überlagern, aus der die Einzelreize erschwert herauszuanalysieren sind, die Unterbrechungshypothese dagegen nimmt an, daß die Verdeckung auf eine Störung der Verarbeitung des einen Reizes durch die kurzzeitig folgende Darbietung eines weiteren Reizes zurückgeht. Zur Erklärung der gegenseitigen Verdeckung von taktil dargebotenen Buchstaben sind beide Hypothesen ungeeignet, weil sie die unterschiedliche Beeinträchtigung von Form- und Positionserkennung der Buchstaben nicht erfassen können. Deshalb wurde eine neue Hypothese aufgestellt: Die Repräsentation eines Reizes im sensorischen Register wird durch die Merkmalsanalyse des vorangegangenen Reizes kaum behindert, aber dessen Übertragung aus dem analysierenden System in das Kurzzeitgedächtnis eine bestimmte Zeit verzögert. Diese Verzögerungshypothese wurde mit einem Experiment überprüft, in dem 3 Vpn je etwa 12 Versuchsstunden lang die Erkennung von Buchstabenpaaren übten. Da die Diskrimination zwischen den Buchstaben bei taktiler Darbietung sehr viel schwieriger als bei visueller ist, wurden nur 5 Buchstaben im Experiment verwendet. Die Ergebnisse des Experiments werden durch ein mathematisches Modell beschrieben. Bezüglich der numerischen Werte der freien Parameter machen die 3 Hypothesen unterschiedliche Vorhersagen. Die Parameterschätzung ergab eine gute Übereinstimmung des Modells mit den Daten und zeigte eine Überlegenheit des Konzeptes Verzögerung für die Erklärung der gegenseitigen Verdeckung taktil dargebotener Buchstaben.

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Sources of mutual masking of tactile presented letters: Interruption, summation or delay?

Summary Two different explanations of the masking phenomenon with simple structured stimuli have been discussed in the literature: The summation hypothesis and the interruption hypothesis. The summation hypothesis maintains that the images of quickly succeeding stimuli superimpose and build up one unified representation from which the single stimuli are difficult to analyse. In contrast the interruption hypothesis assumes that masking is caused by the successive stimulus disturbing the processing of its predecessor. Both hypotheses are unacceptable for an explanation of the mutual masking of tactile presented letters where a different impairment of form and position recognition is observed. Therefore a third hypothesis was tried: The processing of a preceding stimulus hardly affects the representation of the successive one in the sensory register. Rather the transfer from the analysing system to short-term memory is delayed by a certain time. This delay hypothesis was tested by an experiment in which three subjects practiced to recognize pairs of letters for a total of 12 sessions. Since discrimination between letters is much more difficult with tactile compared to visual presentation only five letters were used as stimuli. The results are described by a mathematical model. The three hypotheses predict discrepant numerical values for the free parameters. Parameter estimation revealed a close fit between the general model and the data and showed a superiority of the delay hypothesis as an explanation of mutual masking of tactile presented stimuli.

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Für die wertvolle Beratung bei der Erstellung des endgültigen Textes danken wir besonders Herrn Professor Dr. K. F. Wender und Herr Dr. K. Nippert.     

Launching the effect: Representations of causal movements are influenced by what they lead to

We investigated whether the representation of an observed causal movement is influenced by its observed effect. Subjects watched displays showing collisions between two objects. In this 'launching event' (Michotte, 1946/1963), one of the two objects (Object A) started to move and set a second, initially stationary, object (Object B) into motion, which gave a strong impression of apparent causality. The apparent effectiveness of A's movement was manipulated by varying the velocities of A and B. When the velocity of B was higher than that of A, the effectiveness of the collision was high; when it was smaller it was low. Then, subjects were asked to reproduce the velocity of the causal movement. Reproduced velocity followed the velocity of both Object A and Object B, which supports the hypothesis that the effect of a movement is integrated with its apparent cause. However, when apparent causality was reduced by changing the direction of motion of B or by covering the point of collision, the influence of the effect on the representation of the cause persisted, suggesting that retroactive interference may account for the findings. The interference effect could not be reduced to temporal recency or spatial integration and was not obtained in the reverse temporal order (proactive interference). Rather, the two successive movements were blended in memory.     

United with Christ in the spirit: The pneumatological dimension of the doctrine of justification

An important aspect of the consensus reached in the Joint Declaration on the Doctrine of Justification was the understanding of justification as union with Christ. From the Lutheran side, this understanding was dependent on the contributions of the Finnish school of Luther research. The Finns’ understanding of justification has been criticized for its insufficient pneumatological basis, and this criticism might also be applied to the Joint Declaration. This article points to resources in Luther's theology as well as perspectives from Pentecostal theology that might contribute to developing the pneumatological dimension of the doctrine of justification.     

Interactive effects of social network centrality and social identification on stress

The present study aimed to integrate the social identity approach to health and well-being with social network analysis. Previous research on the effects of social network centrality on stress has yielded mixed results. Building on the social identity approach, we argued that these mixed results can be explained, in part, by taking into account the degree to which individuals identify with the social network. We hence hypothesized that the effects of social network centrality on stress are moderated by social identification. Using a full roster method, we assessed the social network of first-year psychology students right after the start of their study programme and three months later. The effects of network centrality (betweenness, closeness, eigenvector centrality) and social identification on stress were examined using structural equation models. As predicted, our results revealed a significant interaction between network centrality and social identification on stress: For weakly or moderately identified students, network centrality was positively related to stress. By contrast, for strongly identified students, network centrality was unrelated to stress. In conclusion, our results point to the perils of being well-connected yet not feeling like one belongs to a group.     

Is identity illusory?

Certain of our traits are thought more central to who we are: they comprise our individual identity. What makes these traits privileged in this way? What accounts for their identity centrality? Although considerations of identity play a key role in many different areas of moral philosophy, I argue that we currently have no satisfactory account of the basis of identity centrality. Nor should we expect one. Rather, we should adopt an error theory: we should concede that there is nothing in reality corresponding to the perceived distinction between the central and peripheral traits of a person.     

Reliability and Validity of a Paper-and-Pencil Test Measuring Hemisphere Preference

The present studies examined the reliability and validity of the Preference Test (PT), a widely used self-report index of preferred hemisphere thinking styles. The PT consists of items that intend to tap left-hemisphere and right-hemisphere cognitions. In the first study (N=47), PT scores were found to have reasonable test–retest stability. In the second study (N=334), a factor analysis of PT scores showed that the PT has a two-factor solution that can best be interpreted in terms of putative left- and right-hemisphere items. In the third study (N=29), background EEG activity (F3, F4, P3 and P4) of subjects was recorded. PT scores were found to be related to EEG asymmetry patterns for frontal, but not for parietal, recording sites. More specifically, subjects with a left-hemisphere preference displayed relatively stronger left frontal activity than subjects with a right-hemisphere preference. By and large, the present findings provide strong support for the reliability and some suggestive evidence for the validity of the PT.     

Moderating Loss Aversion: Loss Aversion Has Moderators,But Reports of its Death are Greatly Exaggerated

Loss aversion, the principle that losses impact decision making more than equivalent gains, is a fundamental idea in consumer behavior and decision making, though its existence has recently been called into question. Across five unique samples (N_total = 17,720), we tested several moderators of loss aversion, which supported a preference construction account. Across studies, more domain knowledge and experience were associated with lower loss aversion, though people of all knowledge and experience levels were loss averse. Among car buyers, those who knew more about a particular car attribute (e.g., fuel economy) were less loss averse for that attribute but not other attributes (e.g., comfort), consistent with the idea that people with less attribute knowledge are more likely to construct preferences, thereby increasing loss aversion. Additionally, older consumers were more loss averse across different loss aversion measures and studies. We discuss implications for several accounts of loss aversion, including accounts rooted in status quo bias, emotion, or ownership. In addition to discovering loss aversion moderators, we cast doubt on recent claims that loss aversion is a fallacy or is fully explained by status quo bias, risk aversion, or the educated laboratory samples often used to study loss aversion.