Pharmacological dissociation of trace and long-delay fear conditioning in young rats

In most studies comparing trace and delay conditioning, CS duration is kept constant across training conditions but the interstimulus interval (ISI), the time from CS onset to US onset, is confounded. In the infrequently used long-delay condition, however, ISI is kept constant across the trace and delay conditions but CS duration varies. A recent study reported that trace and long-delay fear conditioning have the same developmental trajectory, with both emerging later in development than standard-delay conditioning (). Past studies have shown that trace conditioning is mediated by the cholinergic system; given the parallel developmental emergence of trace and long-delay conditioning, the present study examined whether the cholinergic system also mediates long-delay conditioning. Two experiments, both involving Sprague-Dawley-derived rats and using freezing as a measure of learned fear, showed that the cholinergic system is critically involved in trace conditioning but is not involved in long-delay conditioning. Specifically, pre-training injections of the muscarinic receptor antagonist scopolamine impaired acquisition of a CS-US association in 32-day-old rats trained with a trace procedure but had no effect on rats this age trained with a long-delay procedure (Experiment 1). Similarly, pre-training injections of physostigmine, a cholinesterase inhibitor, enhanced acquisition of trace conditioning in 25-day-old rats but had no effect on long-delay conditioning in rats this age (Experiment 2). Taken together, the results indicate that despite the similarities between trace and long-delay conditioning in terms of developmental emergence and level of conditioned responding, they are mediated by different physiological systems.     

Practice and feedback effects on the confidence-accuracy relation in eyewitness memory

It has been claimed that the lack of a reliable confidence-accuracy relation in eyewitness memory stems from eyewitnesses' lack of knowledge concerning their relative expertise. Two studies tested this idea by contrasting the effects of practice alone with practice with feedback in three successive eyewitness tests. Experiment 1 tested recall for events, and Experiment 2 used recognition of faces as test materials. Both studies showed that practice alone did not increase the confidence-accuracy relation, but practice with feedback on relative performance produced robust increases in the confidence-accuracy relation. This suggests that lack of calibration is one factor that causes the reported lack of association between confidence and accuracy for eyewitness memory.     

Post-training ethanol disrupts trace conditioned fear in rats: effects of timing of ethanol, dose and trace interval duration

Ethanol has complex effects on memory performance, although hippocampus-dependent memory may be especially vulnerable to disruption by acute ethanol intoxication occurring during or shortly after a training episode. In the present experiments, the effects of post-training ethanol on delay and trace fear conditioning were examined in adolescent rats. In Experiment 1, 30-day-old Sprague-Dawley rats were given delay or trace conditioning trials in which a 10s flashing light CS was paired with a 0.5 mA shock US. For trace groups, the trace interval was 10 s. On days 31-33, animals were administered ethanol once daily (0.0 or 2.5 g/kg via intragastric intubation), and on day 34 animals were tested for CS-elicited freezing. Results showed that post-training ethanol affected the expression of trace, but had no effect on delay conditioned fear. Experiment 2 revealed that this effect was dose-dependent; doses lower than 2.5 g/kg were without effect. Experiment 3 evaluated whether proximity of ethanol to the time of training or testing was critical. Results show that ethanol administration beginning 24h after training was more detrimental to trace conditioned freezing than administration that was delayed by 48 h. Finally, in Experiment 4 animals were trained with one of three different trace intervals: 1, 3 or 10s. Results indicate that post-training administration of 2.5 g/kg ethanol disrupted trace conditioned fear in subjects trained with a 10s, but not with a 1 or 3s, trace interval. Collectively the results suggest that ethanol administration impairs post-acquisition memory processing of hippocampus-dependent trace fear conditioning.     

The Influence of Abnormal Sex Differences in Life Expectancy on National Happiness

Countries with better health, as indexed by life expectancy, score higher on subjective well-being (SWB). It was predicted that deviations from the average sex difference in life expectancy (reflecting reproductive competition among males and discrimination against females) would be inversely related to happiness. Regression analysis of SWB for 178 countries found that deviations from the average sex difference in life expectancy were predictive of unhappiness controlling for life expectancy, national wealth, and income inequality. Countries with a relative scarcity of female children (used as an index of parental bias) were less happy. Societies in which there is an undue burden on the health and survival of either sex are thus unhappy ones due to gender-specific disadvantage and associated gender conflict.     

Further evaluation of morphine aversion: maintenance of a taste aversion using a low, nonaversive morphine dose

Previously, in an investigation of morphine-conditioned taste aversion (CTA), we found that limited preexposure to a low, nonaversive (non-CTA-inducing) dose of morphine (2.5 mg/kg) was as effective as preexposure to a higher, CTA-inducing dose (15 mg/kg) in blocking the formation of a subsequent morphine CTA. In the present study, we examined the capacity of this low, 2.5-mg/kg morphine dose to maintain a CTA initially induced by the 15-mg/kg dose. A standard CTA procedure was used. Results indicated that rats given three initial taste-drug pairings with 15 mg/kg morphine followed on subsequent pairing days by treatment with the low, non-CTA-inducing, 2.5-mg/kg dose continued to exhibit a strong CTA over 8 pairing days. A similar pattern was observed for animals continuing to receive taste-drug pairings with the 15-mg/kg dose. Animals receiving only one taste-drug pairing with the 15-mg/kg dose, followed on subsequent pairing days by 2.5-mg/kg conditioning, failed to show such a pattern of CTA. An intermediate CTA pattern was seen with animals conditioned with 15, 10, 5, and repeated 2.5-mg/kg doses over consecutive pairing days. These data suggest that exposure to a low dose of morphine, with no apparent CTA-inducing properties, is sufficient to maintain a previously established morphine taste aversion. Potential implications for understanding the apparent discriminative complexity of morphine's motivational properties are discussed.     

Pre-Reflective Ethical Know-How

In recent years there has been growing attention paid to a kind of human action or activity which does not issue from a process of reflection and deliberation and which is described as, e.g., ‘engaged coping’, ‘unreflective action’, and ‘flow’. Hubert Dreyfus, one of its key proponents, has developed a phenomenology of expertise which he has applied to ethics in order to account for ‘everyday ongoing ethical coping’ or ‘ethical expertise’. This article addresses the shortcomings of this approach by examining the pre-reflective ethical know-how individuals first develop and on which all later forms of ethical expertise are dependent. In the first section an account is given of the ‘ethical second nature’ which every individual develops from childhood onwards and which forms the basis of pre-reflective ethical know-how. The acquisition of an ethical second nature early on opens up the very domain of ‘the ethical’ for us in the first place and is constitutive of our sensitivity to it. The second section turns to pre-reflective ethical know-how and whether it is conceptual in nature. Just as sensorimotor understanding forms the basis of our reflective perceptual concepts, pre-reflective ethical know-how is similarly proto-conceptual and is the source of our reflective ethical and moral concepts. Finally, the third section examines the process whereby ethical second nature and pre-reflective ethical know-how are actually acquired, namely, through immersion in an ‘ethical world’. This world consists of both the web of ethical meanings and significances which has evolved in a particular society or community as well as its members whose actions and interactions continually reproduce that web.     

The time course of semantic and associative priming effects is different in an attentional blink task

When two targets are presented using rapid serial visual presentation (RSVP) and the interval between the targets is 200–500 ms, report of the second target is impaired, a phenomena known as the attentional blink (AB). This study examined the time course of semantic-only and associate–semantic priming effects during an AB task. Three RSVP experiments were conducted using targets that shared either a semantic-only or an associative–semantic relationship. The results of the three experiments demonstrated semantic-only priming effects at the shortest stimulus onset asynchronies (SOAs). Associative–semantic priming was evident at shorter and longer SOAs. This suggests that priming in an AB task is driven by conceptual overlap facilitating lexical access at short SOAs and with longer SOAs lexical access benefits from word associations links between targets.     

Racial differences in socially desirable responding in selection contexts: magnitude and consequences

Two studies were conducted to examine the magnitude and consequences of racial differences on social desirability (SD) scales. Study 1 included 1,063 job applicants, and Study 2 included 3 sets of incumbents (total N = 534). In both studies, participants were administered several personality measures and an SD scale. Across all samples, Whites scored lower on the SD scale than Blacks (average d = .37), Hispanics (average d = .47), and Asians (average d = 1.04), but these differences were not observed on the personality scales. The consequence of differences in socially desirable responding (SDR) is that fewer minority group members would be selected if SD scales were used to derive cut scores to eliminate individuals from the applicant pool or if the scales were used to correct personality test scores for SDR. However, applying the SD correction did not affect the validity of the personality test for any of the racial groups. Overall, our findings suggest that researchers and practitioners should consider the use of SD scales very carefully, as their use may have unintended consequences. These studies also demonstrate a need to closely examine the construct validity of SD measures across diverse groups.