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.     

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.     

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.     

Sensory noise explains auditory frequency discrimination learning induced by training with identical stimuli

Thresholds in various visual and auditory perception tasks have been found to improve markedly with practice at intermediate levels of task difficulty. Recently, however, there have been reports that training with identical stimuli, which, by definition, were impossible to discriminate correctly beyond chance, could induce as much discrimination learning as could training with different stimuli. These surprising findings have been interpreted as evidence that discrimination learning can occur in the absence of perceived differences between stimuli and need not involve the fine-tuning of a discrimination mechanism. Here, we show that these counterintuitive findings of discrimination learning without discrimination can be understood simply by considering the effect of internal noise on sensory representations. Because of such noise, physically identical stimuli are unlikely to be perceived as being strictly identical. We show that, given empirically derived levels of sensory noise, perceived differences evoked by identical stimuli are actually not much smaller than those induced by the physical differences typically used in discrimination-learning experiments. We suggest that findings of discrimination learning with identical stimuli can be explained without implicating any fundamentally new learning mechanism.     

Preferences for Dispute Resolution Procedures as a Function of Intentionality,Consequences, Expected Future Interaction,and Power1

Two studies investigated preferences for dispute resolution procedures as a function of several situational factors. Study 1 varied intentionality of the conflict, consequences, and expected future interaction between the disputants. The data indicated that 3rd-party procedures were most preferred when the wrongdoing was intentional and when there were high consequences. Study 2 varied intentionality, consequences and the power relationship between the 2 disputants. The relevant effects of Study 1 were replicated, and it was found that arbitration and advisory arbitration were most preferred when the conflict involved parties of equal power. The study supports the general view that research in several domains can be integrated into a coherent pattern of effects relevant for dispute resolution.     

Virtual reality goes to war: a brief review of the future of military behavioral healthcare

Numerous reports indicate that the incidence of posttraumatic stress disorder (PTSD) in returning OEF/OIF military personnel is creating a significant healthcare challenge. These findings have served to motivate research on how to better develop and disseminate evidence-based treatments for PTSD. Virtual Reality delivered exposure therapy for PTSD has been previously used with reports of positive outcomes. This article details how virtual reality applications are being designed and implemented across various points in the military deployment cycle to prevent, identify and treat combat-related PTSD in OIF/OEF Service Members and Veterans. The summarized projects in these areas have been developed at the University of Southern California Institute for Creative Technologies, a U.S. Army University Affiliated Research Center, and this paper will detail efforts to use virtual reality to deliver exposure therapy, assess PTSD and cognitive function and provide stress resilience training prior to deployment.