Shifting from implicit to explicit knowledge: different roles of early- and late-night sleep

Sleep has been shown to promote the generation of explicit knowledge as indicated by the gain of insight into previously unrecognized task regularities. Here, we explored whether this generation of explicit knowledge depends on pre-sleep implicit knowledge, and specified the differential roles of slow-wave sleep (SWS) vs. rapid eye movement (REM) sleep in this process. Implicit and explicit knowledge (insight) related to a hidden regularity were assessed in an associative motor-learning task (number reduction task, NRT), which was performed in two sessions (initial practice and retest) separated by 3 h of either early-night sleep, rich in SWS, or of late-night sleep, rich in REM sleep. About half of the participants developed signs of implicit rule knowledge (i.e., speeded reaction times for responses determined by the hidden regularity) at initial practice preceding early or late sleep. Of these, half developed explicit knowledge across early-night sleep, significantly more than across late-night sleep. In contrast, late-night subjects preferentially remained on the level of implicit rule knowledge after sleep. Participants who did not develop implicit knowledge before sleep had comparable rates of transition to implicit or explicit knowledge across early and late sleep. If subjects gained explicit knowledge across sleep, this was associated with lower amounts of REM sleep, specifically in the late-night group. SWS predominant during the early night may restructure implicit memory representations in a way that allows creating an explicit representation afterward, whereas REM sleep in the late night appears to stabilize them in their implicit form.     

In search of clarity: self-esteem and domains of confidence and confusion

To date, research suggests that self-concept clarity is a monolithic construct: Some people have clearly defined self-concepts in all domains, whereas others do not. The authors argued that self-concept clarity is instead multifaceted and varies across trait domains. The authors predicted that social commodities (SCs; e.g., looks, popularity, social skills) would show less self-concept clarity than would communal qualities (CQs; e.g., kindness, warmth, honesty), due to domain differences in observability, ambiguity, and controllability. Results replicated past findings that self-esteem predicts self-concept clarity but also demonstrated that participants' SC self-views were less clear than their CQ self-views. Moreover, people showed greater clarity about traits that were lower in observability and higher in ambiguity and controllability. These findings suggest that everyone, regardless of self-esteem, has self-concept domains of relative confidence and confusion.     

Conduction aphasia, sensory-motor integration, and phonological short-term memory - an aggregate analysis of lesion and fMRI data

Conduction aphasia is a language disorder characterized by frequent speech errors, impaired verbatim repetition, a deficit in phonological short-term memory, and naming difficulties in the presence of otherwise fluent and grammatical speech output. While traditional models of conduction aphasia have typically implicated white matter pathways, recent advances in lesions reconstruction methodology applied to groups of patients have implicated left temporoparietal zones. Parallel work using functional magnetic resonance imaging (fMRI) has pinpointed a region in the posterior most portion of the left planum temporale, area Spt, which is critical for phonological working memory. Here we show that the region of maximal lesion overlap in a sample of 14 patients with conduction aphasia perfectly circumscribes area Spt, as defined in an aggregate fMRI analysis of 105 subjects performing a phonological working memory task. We provide a review of the evidence supporting the idea that Spt is an interface site for the integration of sensory and vocal tract-related motor representations of complex sound sequences, such as speech and music and show how the symptoms of conduction aphasia can be explained by damage to this system.     

Intentional memory and online data collection: A test of the effects of animacy and threat on episodic memory

As research in the behavioural sciences increasingly relies on Amazon’s Mechanical Turk (MTurk) for recruiting participants, it is an empirical question whether an intentional memory experiment could be conducted online and whether performance of MTurk participants and college students would be comparable. College students and MTurk participants viewed threatening and nonthreatening items that were animate or inanimate and completed a recall test. Recent research indicates that human memory systems evolved to prioritise survival-relevant information, including animacy of items. The results of both studies indicated that participants recalled more animate than inanimate items and recalled more threatening items than nonthreatening items. The results indicate that it is possible to conduct memory experiments online and that results match patterns found in laboratory studies of the animacy effect (Nairne, VanArsdall, Pandeirada, Cogdill, & LeBreton, 2013), but that researchers should include safeguards to ensure the online participants are attending to and following directions.     

Pervasive influence of semantics in letter and category fluency: a multidimensional approach

We used multidimensional statistical procedures to study semantic and lexical processes underlying word retrieval in verbal-fluency performance. Forty healthy participants were given a two-choice letter task (i.e., generate items beginning with the letter 'A' or 'F', in any order) and a two-choice category task (i.e., generate animal or fruit names, in any order). Using correspondence analysis (CoA) and hierarchical clustering (HC), we found evidence of prominent semantic organization in both letter and category fluency. For example, a striking categorical segregation between animate and inanimate entities emerged during the letter task. Analysis of inter-item times revealed strong sequential priming effects in both tasks. Taken together, these results indicate that semantic facilitation is pervasive in word retrieval processes, even in the letter-fluency task, and therefore suggest that the traditional view of letter fluency as a purely phonemically based task should be revised. Finally, our findings may help explain patterns of verbal-fluency measures obtained in focal brain lesion patients.     

‘Good,you identified the suspect…but please ignore this feedback’: can warnings eliminate the effects of post‐identification feedback?

The present experiments focus on whether the post‐identification feedback effect can be reduced by providing participants with warnings. Participants viewed a crime on video and identified a suspect from a target‐absent lineup (Experiment 1) or target‐present lineup (Experiment 2). Participants then received positive feedback, negative feedback or no feedback. Half of the participants received a warning saying their feedback was randomly generated by the computer, and the other half received no warning. Robust post‐identification feedback effects were observed in both experiments in the no warning condition. These effects were largely eliminated when participants received a warning. In Experiments 3 and 4, we failed to find an ameliorative effect of a forensically realistic warning. These results indicate that warnings can reduce the effect of post‐identification feedback in principle, but the application of warnings in practice may be more difficult. Copyright © 2006 John Wiley & Sons, Ltd.     

Possible participation of D3 and D4 dopaminergic receptors on genital reflexes induced by cocaine in paradoxical sleep deprived male rats

Previous studies have demonstrated that paradoxical sleep deprivation (PSD) potentiates cocaine-induced genital reflexes in male rats and both D1 and D2 receptors may play a role in those effects, and to examine the possibility that such might involve other dopaminergic receptors, we investigated the effects of D3 and D4 receptor subtype antagonists on cocaine-induced reflexes in sleep-deprived rats. Separate groups of PSD rats received saline, D3 (U9919A; 0.75, 1.5 and 3 mg/kg) or D4 (L745870; 0.75, 1.5 and 3 mg/kg) antagonists prior to acute cocaine challenge. Results demonstrated that U9919A induced significant reduction in the number of animals that displayed erection and the frequency of erection at two smaller doses, while no significant difference was reported for the D4 receptor antagonist. Although our studies indicate that there is a relevant participation of D3 receptors in male sexual function, D4 receptors seem not to exert an essential role in this model.     

Adrenergic enhancement of consolidation of object recognition memory

Extensive evidence indicates that epinephrine (EPI) modulates memory consolidation for emotionally arousing tasks in animals and human subjects. However, previous studies have not examined the effects of EPI on consolidation of recognition memory. Here we report that systemic administration of EPI enhances consolidation of memory for a novel object recognition (NOR) task under different training conditions. Control male rats given a systemic injection of saline (0.9% NaCl) immediately after NOR training showed significant memory retention when tested at 1.5 or 24, but not 96h after training. In contrast, rats given a post-training injection of EPI showed significant retention of NOR at all delays. In a second experiment using a different training condition, rats treated with EPI, but not SAL-treated animals, showed significant NOR retention at both 1.5 and 24-h delays. We next showed that the EPI-induced enhancement of retention tested at 96h after training was prevented by pretraining systemic administration of the beta-adrenoceptor antagonist propranolol. The findings suggest that, as previously observed in experiments using aversively motivated tasks, epinephrine modulates consolidation of recognition memory and that the effects require activation of beta-adrenoceptors.     

Pentylenetetrazole as an unconditioned stimulus for olfactory and contextual fear conditioning in rats

The association of five footshocks with a neutral odor is able to establish an olfactory fear conditioning in rats. The present study sought to investigate whether the systemic administration of pentylenetetrazole (PTZ; 3.75–15 mg/kg) would turn the coffee odor in a conditioned stimulus in the fear conditioning paradigm. The results showed that rats started to display risk assessment and avoidance after PTZ (15 mg/kg)–coffee odor pairing. When three mild footshocks (0.4 mA for 2 s) were delivered during this pairing, the conditioned response exhibited was greater than before. In both cases, however, pretreatment with the benzodiazepine midazolam (MDZ. 0.5 mg/kg i.p.) fully counteracted the expression of these defensive behaviors. Moreover, after being paired with 15 mg/kg of PTZ alone or combined with footshocks, the coffee odor was able to promote a new fear conditioning related to the context where it was re-exposed. The present findings point out the usefulness of PTZ as an unconditioned stimulus to promote fear conditioning to olfactory and contextual cues in rats.     

Violent Movies and Severe Acts of Violence: Sensationalism Versus Science

Violent media has often been blamed for severe violent acts. Following recent findings that violence in movies has increased substantially over the last few decades, this research examined whether such increases were related to trends in severe acts of violence. Annual rates of movie violence and gun violence in movies were compared to homicide and aggravated assault rates between the years of 1960 and 2012. Time series analyses found that violent films were negatively, although nonsignificantly, related to homicides and aggravated assaults. These nonsignificant negative relations remained present even after controlling for various extraneous variables. Results suggest that caution is warranted when generalizing violent media research, conducted primarily in laboratories and via questionnaires, to societal trends in violent behavior.