Using transcranial direct-current stimulation (tDCS) to understand cognitive processing

Noninvasive brain stimulation methods are becoming increasingly common tools in the kit of the cognitive scientist. In particular, transcranial direct-current stimulation (tDCS) is showing great promise as a tool to causally manipulate the brain and understand how information is processed. The popularity of this method of brain stimulation is based on the fact that it is safe, inexpensive, its effects are long lasting, and you can increase the likelihood that neurons will fire near one electrode and decrease the likelihood that neurons will fire near another. However, this method of manipulating the brain to draw causal inferences is not without complication. Because tDCS methods continue to be refined and are not yet standardized, there are reports in the literature that show some striking inconsistencies. Primary among the complications of the technique is that the tDCS method uses two or more electrodes to pass current and all of these electrodes will have effects on the tissue underneath them. In this tutorial, we will share what we have learned about using tDCS to manipulate how the brain perceives, attends, remembers, and responds to information from our environment. Our goal is to provide a starting point for new users of tDCS and spur discussion of the standardization of methods to enhance replicability.     

Headphone screening to facilitate web-based auditory experiments

Psychophysical experiments conducted remotely over the internet permit data collection from large numbers of participants but sacrifice control over sound presentation and therefore are not widely employed in hearing research. To help standardize online sound presentation, we introduce a brief psychophysical test for determining whether online experiment participants are wearing headphones. Listeners judge which of three pure tones is quietest, with one of the tones presented 180° out of phase across the stereo channels. This task is intended to be easy over headphones but difficult over loudspeakers due to phase-cancellation. We validated the test in the lab by testing listeners known to be wearing headphones or listening over loudspeakers. The screening test was effective and efficient, discriminating between the two modes of listening with a small number of trials. When run online, a bimodal distribution of scores was obtained, suggesting that some participants performed the task over loudspeakers despite instructions to use headphones. The ability to detect and screen out these participants mitigates concerns over sound quality for online experiments, a first step toward opening auditory perceptual research to the possibilities afforded by crowdsourcing.     

Empathy and transformative experience without the first person point of view (a reply to L. A. Paul)1

Abstract

In her very interesting ‘First-personal modes of presentation and the problem of empathy’ (2017, 315–336), L. A. Paul argues that the phenomenon of empathy gives us reason to care about the first person point of view: that as theorists we can only understand, and as humans only evince, empathy by appealing to that point of view. We are skeptics about the importance of the first person point of view, although not about empathy. The goal of this paper is to see if we can account for empathy without the ideology of the first person. We conclude that we can.     

The Irreducibility of Iterated to Single Revision

After a number of decades of research into the dynamics of rational belief, the belief revision theory community remains split on the appropriate handling of sequences of changes in view, the issue of so-called iterated revision. It has long been suggested that the matter is at least partly settled by facts pertaining to the results of various single revisions of one’s initial state of belief. Recent work has pushed this thesis further, offering various strong principles that ultimately result in a wholesale reduction of iterated to one-shot revision. The present paper offers grounds to hold that these principles should be significantly weakened and that the reductionist thesis should ultimately be rejected. Furthermore, the considerations provided suggest a close connection between the logic of iterated belief change and the logic of evidential relevance.     

Trait mindfulness at work: A meta-analysis of the personal and professional correlates of trait mindfulness

Popular and academic press alike have concluded that mindfulness significantly benefits healthy individuals as well as those suffering from physical and psychological problems. Workplace interventions, clinical therapies, and popular self-help programs aimed at enhancing mindfulness abound, and research has demonstrated the efficacy of such mindfulness interventions in enhancing mindful states. It is of importance to note that research also suggests the average frequency with which individuals experience states of mindfulness varies from person to person, underscoring the existence of a dispositional tendency toward mindfulness—trait mindfulness. We meta-analytically cumulate the results of 270 independent studies (N = 58,592 adults from nonclinical samples) of trait mindfulness in order to explore its personal and professional correlates. Results suggest the benefits of trait mindfulness extend to both personal and professional domains. With regards to personal benefits, trait mindfulness was found to be positively correlated with confidence (ρ = .39), mental health (ρ = .38), emotional regulation (ρ = .40), and life satisfaction (ρ = .36), and negatively correlated with perceived life stress (ρ = –.43), negative emotions (ρ = –.40), anxiety (ρ = –.34), and depression (ρ = –.38). Professionally, results suggest trait mindfulness may benefit job satisfaction (ρ = .29), performance (ρ = .34), and interpersonal relations (ρ = .31), while also reducing burnout (ρ = –.48) and work withdrawal (ρ = –.17). Meta-analytic regressions also suggest trait mindfulness adds incremental predictive variance over more traditional predictors of employee burnout and work performance.     

Form follows function: Learning about function helps children learn about shape

Object functions help young children to organize new artifact categories. However, the scope of their influence is unknown. We explore whether functions highlight property dimensions that are relevant to artifact categories in general. Specifically, using a longitudinal training procedure, we assessed whether experience with functions highlights shape as important for categorization. Seventeen-month-olds were provided experience with novel categories of similarly shaped objects. In Study 1, the function group learned about the objects’ shape-based functions; a control group did not. In Study 2, 17-month-olds were trained on the same categories, but the objects’ shapes and functions were no longer causally related. Only the function group in Study 1 subsequently used shape reliably when categorizing novel objects. These results suggest that function is instrumental in establishing a ‘shape bias’ in early categorization and that it does so via conceptually based processes.     

Effective brain connectivity in children with reading difficulties during phonological processing

Using Dynamic Causal Modeling (DCM) and functional magnetic resonance imaging (fMRI), we examined effective connectivity between three left hemisphere brain regions (inferior frontal gyrus, inferior parietal lobule, fusiform gyrus) and bilateral medial frontal gyrus in 12 children with reading difficulties (M age=12.4, range: 8.11-14.10) and 12 control children (M age=12.3, range: 8.9-14.11) during rhyming judgments to visually presented words. More difficult conflicting trials either had similar orthography but different phonology (e.g. pint-mint) or similar phonology but different orthography (e.g. jazz-has). Easier non-conflicting trials had similar orthography and phonology (e.g. dime-lime) or different orthography and phonology (e.g. staff-gain). The modulatory effect from left fusiform gyrus to left inferior parietal lobule was stronger in controls than in children with reading difficulties only for conflicting trials. Modulatory effects from left fusiform gyrus and left inferior parietal lobule to left inferior frontal gyrus were stronger for conflicting trials than for non-conflicting trials only in control children but not in children with reading difficulties. Modulatory effects from left inferior frontal gyrus to inferior parietal lobule, from medial frontal gyrus to left inferior parietal lobule, and from left inferior parietal lobule to medial frontal gyrus were positively correlated with reading skill only in control children. These findings suggest that children with reading difficulties have deficits in integrating orthography and phonology utilizing left inferior parietal lobule, and in engaging phonological rehearsal/segmentation utilizing left inferior frontal gyrus possibly through the indirect pathway connecting posterior to anterior language processing regions, especially when the orthographic and phonological information is conflicting.     

Pointing with the eyes: the role of gaze in communicating danger

Facial expression and direction of gaze are two important sources of social information, and what message each conveys may ultimately depend on how the respective information interacts in the eye of the perceiver. Direct gaze signals an interaction with the observer but averted gaze amounts to "pointing with the eyes", and in combination with a fearful facial expression may signal the presence of environmental danger. We used fMRI to examine how gaze direction influences brain processing of facial expression of fear. The combination of fearful faces and averted gazes activated areas related to gaze shifting (STS, IPS) and fear-processing (amygdala, hypothalamus, pallidum). Additional modulation of activation was observed in motion detection areas, in premotor areas and in the somatosensory cortex, bilaterally. Our results indicate that the direction of gaze prompts a process whereby the brain combines the meaning of the facial expression with the information provided by gaze direction, and in the process computes the behavioral implications for the observer.     

Informed Consent in Emergency Research: A Contradiction in Terms

Improving the treatment of life threatening emergency illness or disease requires that new or novel therapies be assessed in clinical trials. As most subjects for these trials will be incapacitated there is some controversy about they might best protected whilst still allowing research to continue. Recent European and UK clinical trials legislation, which has effectively stopped research into emergency conditions, is discussed. Possible changes to these regulations are proposed.