Memories of reward and nonreward regulate the extinction and reacquisition of both excitatory and inhibitory associations

The memories of the unconditioned stimulus (US) and its absence (No US), symbolized as S^R and S^N, respectively, may be retrieved on US or No US trials giving rise to four types of associations, S^R → US, S^R → No US, S^N → US, and S^N → No US. Here, following acquisition under partial reward (PRF), rats were shifted either to different schedules of PRF (Experiment 1) or extinction (Experiments 1 and 2). Inhibitory S^R → No US associations formed in acquisition survived extinction and shifts to one, but not another type of PRF schedule (Experiments 1 and 2). Excitatory S^R → US associations also survived extinction (Experiment 2). These findings, as well as the acquisition findings of Experiment 2, are consistent with the sequential model but not with the only other two theories said to be able to explain PRF findings, the frustration hypothesis of Amsel and the attention hypothesis of Mackintosh [see Haselgrove, M., Aydin, A., & Pearce, J. M. (2004). A partial reinforcement extinction effect despite equal rates of reinforcement during Pavlovian conditioning. Journal of Experimental Psychology: Animal Behavior Processes, 30, 240–250]. Also, the reacquisition findings obtained here are inconsistent with two views applied to several learning phenomena, the rule-learning view and the position-item view.     

Predicting staff retention from employee motivation and job satisfaction

This study investigated the role of employee motivation and job satisfaction as predictors of staff retention in a foreign exchange bank. Participants were 341 employees of a South African foreign exchange bank division (female?=?62.8%; black?=?31.1%; managers?=?37%, mean years of experience?=?10 years). The employees completed the following self-report measures: Work Preference Inventory, Job Satisfaction Survey, and Employee Retention Questionnaire. Structural equation modelling was applied in the analysis to test the prediction effect of employee motivation and job satisfaction on staff retention. The findings of the model fit revealed that the model (employee motivation and employee job satisfaction) explained an estimated 46% of the variance in the employee retention construct. The job satisfaction construct in the model explained an estimated 66% of the variance in the employee retention construct; while the employee motivation construct explained only 8% of the variance. Organisational talent management should seek to identify employee motivation and job satisfaction interventions that might help to retain talented staff.     

Strain differences in zebrafish (Danio rerio) social roles and their impact on group task performance

"Key" individuals in a social group are those that are centrally connected and thus serve as a hub for information flow across the group. From this position, they have the potential to have a powerful influence on group dynamics and performance. Here, we use metrics from social network theory to identify Key individuals in groups of 3-4 zebrafish (Danio rerio), and to measure the impact of removing those individuals from the group. We compared the results for two genetically distinct strains of zebrafish and found that although their social dynamics were superficially similar, one strain (Scientific Hatcheries, SH) responded to social perturbation, whereas the other (Parganas North, PN) did not. For both strains, groups that retained their Key fish performed better on a simple group foraging-learning task than did those from which the Key fish had been removed. However, the SH strain learned the task more quickly than did the PN strain, perhaps in part because of sex differences in task performance or because of strain differences in the reaction to experimental disturbance. We also confirm the utility of measures of social dynamics and social role that can be estimated reliably from very short observation sessions and by relatively untrained observers. These results set the stage for future research into the genetic mechanisms underlying social roles and group learning in vertebrates.     

Perceptions of breastfeeding in mothers of babies born preterm in comparison to mothers of full-term babies

The purpose of the present study was: a) to describe the theme of verbalizations about breastfeeding in mothers' pre-term (M-PT) and full-term (M-FT) infants; b) to examine the association between these themes and mother's anxiety and depression indicators and socio-demographic characteristics and, neonatal characteristics of the infants. The sample consisted of 50 M-PT and 25 M-FT. The mothers were assessed through State-Trait Anxiety Inventory and Beck Depression Inventory and were interviewed using a Guide focusing breastfeeding issues. The M-PT group had significantly more mothers with clinical symptom of anxiety than the M-FT group. The M-PT reported more uncertainties and worries about breastfeeding and figured out more obstacles for the successful breastfeeding than the M-FT. These reports were associated positively with the infants' risk neonatal status; lower birth-weight, higher neonatal clinical risk, and more length time stay in NICU were associated with more mothers' worries and seeing obstacles for breastfeeding. In conclusion, the strategies to enhance the breastfeeding rate in the preterm population have to take into account the mothers' psychological status and their ideas in addition to offering information about the advantages of breastfeeding for child development.     

Modulatory influence of dopamine receptors on consolidation of object recognition memory

The role of dopamine receptors in regulating the formation of recognition memory remains poorly understood. Here we show the effects of systemic administration of dopamine receptor agonists and antagonists on the formation of memory for novel object recognition in rats. In Experiment I, rats received an intraperitoneal (i.p.) injection of vehicle, the selective D1 receptor agonist SKF38393 (1.0 and 5.0mg/kg), or the D2 receptor agonist quinpirole (1.0 and 5.0mg/kg) immediately after training. In Experiment II, rats received an injection of vehicle, the dopamine receptor antagonist SCH23390 (0.1 and 0.05 mg/kg), or the D2 receptor antagonist raclopride (0.5 and 0.1mg/kg) before training, followed by an injection of vehicle or the nonselective dopamine receptor agonist apomorphine (0.05 mg/kg) immediately after training. SKF38393 at 5mg/kg produced an enhancement of novel object recognition memory measured at both 24 and 72 h after training, whereas the dose of 10mg/kg impaired 24-h retention. Posttraining administration of quinpirole did not affect 24-h retention. Apomorphine enhanced memory in rats given pretraining raclopride, suggesting that the effect was mediated by selective activation of D1 receptors. The results indicate that activation of D1 receptors can enhance recognition memory consolidation. Importantly, pharmacological activation of D1 receptors enhanced novel object recognition memory even under conditions in which control rats showed significant retention.     

How children perceive fractals: Hierarchical self-similarity and cognitive development

The ability to understand and generate hierarchical structures is a crucial component of human cognition, available in language, music, mathematics and problem solving. Recursion is a particularly useful mechanism for generating complex hierarchies by means of self-embedding rules. In the visual domain, fractals are recursive structures in which simple transformation rules generate hierarchies of infinite depth. Research on how children acquire these rules can provide valuable insight into the cognitive requirements and learning constraints of recursion.     

The impact of holiday eating cues on self-regulatory bolstering for dieters and non-dieters

Objective: Two studies examined the hypothesis that the presence vs. absence of holiday food cues leads dieters to bolster self-regulatory resources and reduce consumption of a snack food. Study 1 evaluated snack-food consumption on a holiday vs. a non-holiday and in Study 2, the proposed underlying mechanism – the bolstering of self-regulatory resources when facing holiday-related cues – was explored.

Methods: Study 1 followed a quasi-experimental design in which participants (N?=?152) consumed candies either on a holiday or a non-holiday. Dieting behaviour was measured and the main outcome measure was consumption quantity. In Study 2, a true experiment, participants (N?=?110) read primes associated with holiday eating, holiday history or a neutral topic. Self-regulatory bolstering was assessed as the main outcome measure.

Results: Study 1 showed that dieters consume more of a food item on an ordinary day relative to a holiday; the consumption patterns of non-dieters did not vary based on holiday cues. Study 2 demonstrated that dieters, but not non-dieters, bolster self-regulatory resources to a greater extent in the presence vs. absence of a holiday food cue.

Conclusion: Dieters are better equipped to defend their diet-related goals when facing strong holiday-related temptations than weaker, everyday temptations.     

Acquired Procedural Dyscalculia Associated to a Left Parietal Lesion in a Child

We report the case of an 11-year-old boy who developed an anarithmetia in association with a left temporo-parietal tumor. His oral and written language were normal as well as his ability to judge magnitudes, process numbers, read operation signs and retrieve number facts. He had a specific difficulty in performing the procedures of subtraction, especially when it involved borrowing. These skills had been mastered before the present illness. This case shows that the components of calculation can be dissociated by brain lesions sustained during childhood, while arithmetic abilities are being acquired, thus reinforcing findings from developmental dyscalculias, that suggest a modular organisation of those skills during development.