Performance on trials without knowledge results (KR) in reduced relative frequency presentations of KR

Following Salmoni, Schmidt, & Walter's (1984) discussion of knowledge of results (KR) as a variable influencing learning, the effect of varying relative frequency of KR while holding absolute number of trials constant was examined. In two experiments, the same treatment groups were compared in acquisition, retention (after 2 min and 24 hr), and on their pattern of responses on the sequence of no-KR trials following a KR trial. In Experiment 1, differences between groups in acquisition were consistent with the number of KR trials received, and there were no differences between groups in either of the retention conditions. Experiment 2 replicated Experiment 1 with a more difficult task. There were no between-group differences in acquisition. In Retention 1, the 100% and 33% relative frequency groups outperformed the less frequent KR groups, whereas in Retention 2, this trend was reversed. The findings from Experiment 2 provide qualified support for the hypothesis that reduced relative frequency of KR in acquisition facilitates performance in retention. The pattern of responses on the sequence of no-KR trials following a KR trial were consistent with Adams' (1971) perceptual-trace decay hypothesis.     

Fluoxetine inhibits corticotropin-releasing factor (CRF)-induced behavioural responses in rats

Corticotropin-releasing factor (CRF) is a potent neuromodulator of stress-related behaviour but the neural mechanisms underlying these effects are not clear. Studies were designed to test the hypothesis that CRF-induced behavioural arousal involves interactions with brainstem serotonergic systems. To examine interactions between CRF and serotonergic systems in the regulation of behaviour, CRF (1 microg, intracerebroventricular (i.c.v.)) or vehicle was infused in the presence or absence of the selective serotonin re-uptake inhibitor fluoxetine (0, 0.1, 1 or 10 mg/kg, intravenous (i.v.)). Fluoxetine was used at these doses because it is known to decrease serotonin cell firing rates while increasing extracellular serotonin concentrations in select forebrain regions. We then measured behavioural, neurochemical and endocrine responses. CRF increased locomotion and spontaneous non-ambulatory motor activity (SNAMA) in the home cages. Fluoxetine decreased tissue 5-hydroxyindoleacetic acid concentrations, a measure of serotonin metabolism, in specific limbic brain regions of CRF-treated rats (nucleus accumbens shell region, entorhinal cortex, central nucleus of the amygdala). Furthermore, fluoxetine inhibited CRF-induced SNAMA. CRF and fluoxetine independently increased plasma corticosterone concentrations, but the responses had distinct temporal profiles. Overall, these data are consistent with the hypothesis that CRF-induced facilitation of behavioural activity is dependent on brainstem serotonergic systems. Therefore, fluoxetine may attenuate or alleviate some behavioural responses to stress by interfering with CRF-induced responses.     

Learning strategies during fear conditioning

This paper describes a model of fear learning, in which subjects have an option of behavioral responses to impending social defeat. The model generates two types of learning: social avoidance and classical conditioning, dependent upon (1) escape from or (2) social subordination to an aggressor. We hypothesized that social stress provides the impetus as well as the necessary information to stimulate dichotomous goal-oriented learning. Specialized tanks were constructed to subject rainbow trout to a conditioning paradigm where the conditioned stimulus (CS) is cessation of tank water flow (water off) and the unconditioned stimulus (US) is social aggression from a larger conspecific. Following seven daily CS/US pairings, approximately half of the test fish learned to consistently escape the aggression to a neutral chamber through a small escape hole available only during the interaction. The learning curve for escaping fish was dramatic, with an 1100% improvement in escape time over 7 days. Fish that did not escape exhibited a 400% increase in plasma cortisol and altered brain monoamine response to presentation of the CS alone. Elevated plasma cortisol levels represent classical fear conditioning in non-escaping fish, while a lack of fear conditioning and a decreased latency to escape over the training period in escapers indicates learned escape.     

Rationalizing our Way into Moral Progress

Research suggests that the explicit reasoning we offer to ourselves and to others is often rationalization, that we act instead on instincts, inclinations, stereotypes, emotions, neurobiology, habits, reactions, evolutionary pressures, unexamined principles, or justifications other than the ones we think we’re acting on, then we tell a post hoc story to justify our actions. This is troubling for views of moral progress according to which moral progress proceeds from our engagement with our own and others’ reasons. I consider an account of rationalization, based on Robert Audi’s, to make clear that rationalization, unlike simple lying, can be sincere. Because it can be sincere, and because we also have a desire to be consistent with ourselves, I argue that rationalization sets us up for becoming better people over time, and that a similar case can be made to explain how moral progress among groups of people can proceed via rationalization.     

The Dynamics of Bimanual Circle Drawing

A bimanual circle drawing task was employed to elucidate the dynamics of intralimb and interlimb coordination. Right-handed subjects were required to produce circles with both hands in either a symmetrical (mirror) mode (i.e. one hand moving clockwise, the other counter-clockwise) or in an asymmetrical mode (i.e. both hands moving clockwise or counter-clockwise). The frequency of movement was scaled by an auditory metronome from 1.50 Hz to 3.25 Hz in8 (8-sec) steps.In the asymmetrical mode,distortions ofthe movement trajectories, transient departures from the target pattern of coordination, and phase wandering were evident as movement frequency was increased. These features suggested loss of stability. Deviations from circular trajectories were most prominent for movements of the left hand. Transient departures from the required mode of coordination were also largely precipitated by the left hand. The results are discussed with reference to manual asymmetries and mechanisms of interlimb and intersegmental coordination.     

The Effect of Non-Stroke Cardiovascular Disease States on Risk for Cognitive Decline and Dementia: A Systematic and Meta-Analytic Review

Cardiovascular disease is associated with increased risk for cognitive decline and dementia, but it is unclear whether this risk varies across disease states or occurs in the absence of symptomatic stroke. To examine the evidence of increased risk for cognitive decline and dementia following non-stroke cardiovascular disease we conducted two independent meta-analyses in accordance with PRISMA guidelines. The first review examined cardiovascular diagnoses (atrial fibrillation, congestive heart failure, periphery artery disease and myocardial infarction) while the second review assessed the impact of atherosclerotic burden (as indicated by degree of stenosis, calcification score, plaque morphology or number of plaques). Studies eligible for review longitudinally assessed risk for clinically significant cognitive decline and/or dementia and excluded stroke and cognitive impairment at baseline. Summary statistics were computed via the inverse variance weighted method, utilising Cox Proportional Hazards data (Hazard Ratios, HR). Both atrial fibrillation (n = 5, HR = 1.26, 95% CI [1.12, 1.43]) and severe atherosclerosis (n = 4, HR = 1.59, 95% CI [1.12, 2.26]) emerged as significant risk factors for cognitive decline and/or dementia. A small set of studies reviewed, insufficient for meta-analysis, examining congestive heart failure, peripheral artery disease and myocardial infarction suggested that these conditions may also be associated with an increased risk of cognitive decline/dementia. In the absence of stroke, patients with atrial fibrillation or generalised atherosclerosis are at heightened risk for cognitive deterioration. Nonetheless, this paper highlights the need for methodologically rigorous and prospective investigation of the relationship between CVD and dementia.     

Reformation Humanism: Reading the Classics in the New Theology

Scholarly discussions on what constitutes Christian humanism in the Renaissance and Reformation periods have typically concentrated on its manifestations before 1536, when Erasmus died. In this period, the old arguments for the reading of the Classics once set out by Basil and Augustine still predominated. Calvin’s teaching on the Fall and the noetic effects of sin, however, provided another basis for the incorporation of pagan thought into Christian learning. Christians who followed Calvin benefited from his precise and comprehensive theological position on the place of worldly knowledge in God’s original creation as a means for justifying their study of the Classics.     

Listeners' discrimination of real and human-imitated animal sounds

To determine if listeners can accurately distinguish between real and human-imitated animal sounds, a total of 165 recorded sounds (55 real and 110 human-imitated) of cats, cows, dogs, pigs, and sheep were randomly arranged on a master tape and presented to 30 listeners for discriminative judgments. Results indicate that, in general, listeners can accurately discriminate real from human-imitated animal sounds. Suggestions for future research are discussed.     

Rhythm and the timing of movement sequences

Summary Many motor skills involve a sequence of movements phased over a period of time. The present study investigated the importance of rhythmic timing structures in the acquisition and control of a serial key-pressing task. Four groups of subjects received extensive practice on 9-element finger sequences varying in the form of the inherent temporal structure. Following a training period, the stability of the various timing patterns was examined by requiring subjects to perform the key-pressing task concurrently with a verbal memory task. The memory task involved reporting back a sequence of visually-presented words with a lag of one word. A comparison was made of performance on the two tasks under dual task and control (single task) conditions. The results suggested that natural rhythmic timing structures require less attention for production than unnatural temporal patterns. A breakdown of the temporal patterns into within-group and between-group intervals showed that patterns containing within-group intervals that related as 1:1 or 1:2 evidenced good stability under dual-task conditions. These results were taken as support for the suggestion by Fraisse (1946) that the perception and production of rhythms can be understood by an internal representation that allows only two distinct durations that relate as 1:2. Furthermore, it was suggested that relative timing may become an invariant property of motor program representation only in those instances in which the timing sequence completely fits the internal timing structure.