Grasping follows Weber's law: How to use response variability as a proxy for JND.

Weber's law is a fundamental psychophysical principle. It states that the just noticeable difference (JND) between stimuli increases with stimulus magnitude; consequently, larger stimuli should be estimated with larger variability. However, visually guided grasping seems to violate this expectation: When repeatedly grasping large objects, the variability is similar to that when grasping small objects. Based on this result, it was often concluded that grasping violated Weber's law. This astonishing finding generated a flurry of research, with contradictory results and potentially far-reaching implications for theorizing about the functional architecture of the brain. We show that previous studies ignored nonlinearities in the scaling of the grasping response. These nonlinearities result from, for example, the finger span being limited such that the opening of the fingers reaches a ceiling for large objects. We describe how to mathematically take these nonlinearities into account and apply this approach to our own data, as well as to the data of three influential studies on this topic. In all four datasets, we found that-when appropriately estimated-JNDs increase with object size, as expected by Weber's law. We conclude that grasping obeys Weber's law, as do essentially all sensory dimensions.

Top-down resolution of visual ambiguity - knowledge from the future or footprints from the past?

Current theories about visual perception assume that our perceptual system weights the a priori incomplete, noisy and ambiguous sensory information with previous, memorized perceptual experiences in order to construct stable and reliable percepts. These theories are supported by numerous experimental findings. Theories about precognition have an opposite point of view. They assume that information from the future can have influence on perception, thoughts, and behavior. Several experimental studies provide evidence for precognition effects, other studies found no such effects. One problem may be that the vast majority of precognition paradigms did not systematically control for potential effects from the perceptual history. In the present study, we presented ambiguous Necker cube stimuli and disambiguated cube variants and systematically tested in two separate experiments whether perception of a currently observed ambiguous Necker cube stimulus can be influenced by a disambiguated cube variant, presented in the immediate perceptual past (perceptual history effects) and/or in the immediate perceptual future (precognition effects). We found perceptual history effects, which partly depended on the length of the perceptual history trace but were independent of the perceptual future. Results from some individual participants suggest on the first glance a precognition pattern, but results from our second experiment make a perceptual history explanation more probable. On the group level, no precognition effects were statistically indicated. The perceptual history effects found in the present study are in confirmation with related studies from the literature. The precognition analysis revealed some interesting individual patterns, which however did not allow for general conclusions. Overall, the present study demonstrates that any future experiment about sensory or extrasensory perception urgently needs to control for potential perceptual history effects and that temporal aspects of stimulus presentation are of high relevance.

Transcranial direct current stimulation induces long-term potentiation-like plasticity in the human visual cortex.

Transcranial direct current stimulation (tDCS) is increasingly used as a form of noninvasive brain stimulation to treat psychiatric disorders; however, its mechanism of action remains unclear. Prolonged visual stimulation (PVS) can enhance evoked EEG potentials (visually evoked potentials, VEPs) and has been proposed as a tool to examine long-term potentiation (LTP) in humans. The objective of the current study was to induce and analyze VEP plasticity and examine whether tDCS could either modulate or mimic plasticity changes induced by PVS. Thirty-eight healthy participants received tDCS, PVS, either treatment combined or neither treatment, with stimulation sessions being separated by one week. One session consisted of a baseline VEP measurement, one stimulation block, and six test VEP measurements. For PVS, a checkerboard reversal pattern was presented, and for tDCS, a constant current of 1 mA was applied via each bioccipital anodal target electrode for 10 min (Fig. S1). Both stimulation types decreased amplitudes of C1 compared to no stimulation (F = 10.1; p = 0.002) and led to a significantly smaller increase (PVS) or even decrease (tDCS) in N1 compared to no stimulation (F = 4.7; p = 0.034). While all stimulation types increased P1 amplitudes, the linear mixed effects model did not detect a significant difference between active stimulation and no stimulation. Combined stimulation induced sustained plastic modulation of C1 and N1 but with a smaller effect size than what would be expected for an additive effect. The results demonstrate that tDCS can directly induce LTP-like plasticity in the human cortex and suggest a mechanism of action of tDCS relying on the restoration of dysregulated synaptic plasticity in psychiatric disorders such as depression and schizophrenia.

Using the perceptual past to predict the perceptual future influences the perceived present - A novel ERP paradigm.

The information available through our senses is noisy, incomplete, and to varying degrees ambiguous. The perceptual system must create stable and reliable percepts out of this restricted information. It solves this perceptual inference problem by integrating memories of previous percepts and making predictions about the perceptual future. Using ambiguous figures and a new experimental approach, we studied whether generating predictions based on regularities in the past affects processing of the present and how this is done. Event-related potentials (ERPs) were measured to investigate whether a highly regular temporal context of either ambiguous or unambiguous stimulus variants differently affects processing of a current stimulus and/or task execution. Further, we tested whether symbolic announcements about the immediate perceptual future can replace the past experience of regularities as a source for making predictions. Both ERP and reaction time varied as a function of stimulus ambiguity in the temporal context of a present stimulus. No such effects were found with symbolic announcements. Our results indicate that predictions about the future automatically alter processing of the present, even if the predictions are irrelevant for the present percept and task. However, direct experiences of past regularities are necessary for predicting the future whereas symbolic information about the future is not sufficient.

A novel mentorship programme for residents integrating academic development, clinical teaching and graduate medical education assessment.

INTRODUCTION: Mentorship fosters career development and growth. During residency training, mentorship should support clinical development along with intellectual and academic interests. Reported resident mentoring programmes do not typically include clinical components. We designed a programme that combines academic development with clinical feedback and assessment in a four-year emergency medicine residency programme. METHODS: Incoming interns were assigned an advisor. At the conclusion of the intern year, residents actively participated in selecting a mentor for the duration of residency. The programme consisted of quarterly meetings, direct clinical observation and specific competency assessment, assistance with lecture preparation, real-time feedback on presentations, simulation coaching sessions, and discussions related to career development. Faculty participation was recognized as a valuable component of the annual review process. Residents were surveyed about the overall programme and individual components. RESULTS: Over 88 % of the respondents said that the programme was valuable and should be continued. Senior residents most valued the quarterly meetings and presentation help and feedback. Junior residents strongly valued the clinical observation and simulation sessions. CONCLUSIONS: A comprehensive mentorship programme integrating clinical, professional and academic development provides residents individualized feedback and coaching and is valued by trainees. Individualized assessment of clinical competencies can be conducted through such a programme.

An Innovative Educational and Mentorship Program for Emergency Medicine Women Residents to Enhance Academic Development and Retention.

Given the discrepancy between men and women's equal rates of medical school matriculation and their rates of academic promotion and leadership role acquisition, the need to provide mentorship and education to women in academic medicine is becoming increasingly recognized. Numerous large-scale programs have been developed to provide support and resources for women's enrichment and retention in academic medicine. Analyses of contributory factors to the aforementioned discrepancy commonly cite insufficient mentoring and role modeling as well as challenges with organizational navigation. Since residency training has been shown to be a critical juncture for making the decision to pursue an academic career, there is a need for innovative and tailored educational and mentorship programs targeting residents. Acknowledging residents' competing demands, we designed a program to provide easily accessible mentorship and contact with role models for our trainees at the departmental and institutional levels. We believe that this is an important step towards encouraging women's pursuit of academic careers. Our model may be useful to other emergency medicine residencies looking to provide such opportunities for their women residents.

Implementation of small-group reflection rounds at an emergency medicine residency program.

Few residency curricular interventions have focused on improving well-being and promoting humanism. We describe the implementation of a novel curriculum based on small-group reflection rounds--the Emergency Medicine Reflection Rounds (EMRR)--at a 4-year US emergency medicine (EM) residency. During the inaugural year (2010-2011), nine residents volunteered to take part in 1-hour monthly sessions with faculty facilitators. Residents were provided with a confidential environment to discuss difficult ethical and interpersonal encounters from their clinical experiences. Ongoing feedback from participants was solicited, culminating with a four-question survey in which all respondents remarked that the EMRR contributed to improving their own well-being and agreed that it provided an important forum for residents to discuss difficult issues in a safe environment. In this article, we describe our innovation as an example of a wellness initiative that has promoted reflective practice and fostered cooperative learning around the communication, professional, and ethical challenges inherent in EM practice. Our EMRR model may be useful to other EM residences looking to supplement their wellness curriculum.

High fidelity case-based simulation debriefing: everything you need to know.

In this 30-minute talk, the authors take an in-depth look at how to debrief high-fidelity case-based simulation sessions, including discussion on debriefing theory, goals, approaches, and structure, as well as ways to create a supportive and safe learning environment, resulting in successful small group learning and self-reflection. Emphasis is placed on the "debriefing with good judgment" approach. Video clips of sample debriefing attempts, highlighting the "dos and don'ts" of simulation debriefing, are included. The goal of this talk is to provide you with the necessary tools and information to develop a successful and effective debriefing approach. There is a bibliography and a quick reference guide in Data Supplements S1 and S2 (available as supporting information in the online version of this paper).

Back to the bedside: the 8-year evolution of a resident-as-teacher rotation.

BACKGROUND: Teaching our residents to teach is a vital responsibility of Emergency Medicine (EM) residency programs. As emergency department (ED) overcrowding may limit the ability of attending physicians to provide bedside instruction, senior residents are increasingly asked to assume this role for more junior trainees. Unfortunately, a recent survey suggests that only 55% of all residencies provide instruction in effective teaching methods. Without modeling from attending physicians, many residents struggle with this responsibility. OBJECTIVES: We introduced a "Resident-as-Teacher" curriculum in 2002 as a means to address a decline in bedside instruction and provide our senior residents with a background in effective teaching methods. DISCUSSION: Here, we describe the evolution of this resident-as-teacher rotation, outline its current structure, cite potential pitfalls and solutions, and discuss the unique addition of a teach-the-teacher curriculum. CONCLUSION: A resident-as-teacher rotation has evolved into a meaningful addition to our senior residents' training, fostering their growth as educators and addressing our need for bedside instruction.