The persistence of thought: evidence for a role of working memory in the maintenance of task-unrelated thinking

Tasks that tax working memory (WM) have consistently been found to decrease mind wandering. These findings may indicate that maintenance of mind wandering requires WM resources, such that mind wandering cannot persist when WM resources are being consumed by a task. An alternative explanation for these findings, however, is that mind wandering persists without the support of WM but is nonetheless decreased during any demanding task because good task performance requires that attention be restricted from task-unrelated thought (TUT). The present study tested these two competing theories by investigating whether individuals with greater WM resources mind-wander more during an undemanding task, as would be predicted only by the theory that WM supports TUT. We found that individuals with higher WM capacity reported more TUT in undemanding tasks, which suggests that WM enables the maintenance of mind wandering.     

Personalizing Behavioral Interventions Through Single‐Patient (N‐of‐1) Trials

Behavioral interventions are typically studied with the use of a conventional between‐subject randomized controlled trial (RCT) design. In this design, the effect of an intervention on one group of patients is compared with the effect of a control condition on another group of patients, such that a between‐subject change is tested. A between‐subject design has an underlying assumption that there is a homogenous treatment effect for a behavioral intervention, drug, or psychotherapy and that the way the intervention operates in the study will tend to operate in the same way in many other patients. We review some of the philosophical and practical problems with the use of this design when a clinician is attempting to decide on a course of behavioral treatment aimed at within‐subject change in patients who are likely to have heterogeneous or unique responses to behavioral treatment. We also review the biases inherent in our current clinical practice model, which does not use any empirical data collection or design for testing if a treatment is useful, and also in the conventional between‐subject personalized medicine RCT designs. We propose increased use of single‐patient (also known as N‐of‐1) trials that employ within‐subject designs, in cases where treatment response is heterogeneous – as is the case for most psychological and behavioral treatments. Limitations of such designs include that they can only be used when the treatment is potentially reversible, the patient can act as their own control, and the outcome can be measured repeatedly. Increased use of within‐subject trials may address in many more instances the more clinically relevant question of how a specific patient will respond to a specific treatment and could introduce a more harmonious scientific approach into the way we treat our patients. We have incorporated a case presentation that illustrates the complexities of applying evidence drawn from these different designs to selecting and evaluating treatments for the behavioral issues commonly faced by clinicians and patients.     

BRIEF REPORT

We employed a psychophysiological marker of directed attention (the visual scanpath) to investigate visuocognitive processing of particular facial expressions in healthy individuals (N = 47). Visual scanpaths were recorded using video-oculography while subjects viewed digitised photographs of threat-related (fear, anger) and nonthreat (sad, happy, neutral) facial expressions. Hypotheses regarding the existence of a differential viewing strategy for threat-related facial expressions were based upon the adaptive significance of rapid detection and effective appraisal of social threat from conspecific face stimuli. When compared with each of the nonthreat faces, viewing strategies for expressions of anger and fear were characterised by increased distance between fixations (extended scanning), with more fixations, of longer duration, to feature areas of these faces. The extended scanning style suggests that threat-related faces evoke a "vigilant" style of scanning, whereby longer saccadic eye movements may reflect heightened autonomic responses to threat, while the increased foveal attention to feature areas of threat-related faces may facilitate cognitive appraisal of the personal significance and direction of impending threat. These results suggest the existence of distinct visuocognitive patterns for processing threat-related facial expressions, in response to the evolutionary advantage of detecting and appraising social threat.     

Unequally masked: Indexing differences in the perceptual salience of "unseen" facial expressions

Two experiments investigated the degree to which different facial expressions, when backwardly masked by neutral faces, are blocked from different levels of perceptual access as indexed by explicit (self-reported) awareness, forced-identification performance, and stimulus sensitivity in a signal detection paradigm. Results indicate that a 16.67 ms target-mask stimulus onset asynchrony (SOA) is insufficient to reliably block either the simple detection or the forced-identification of backwardly masked expressions. This finding holds even for participants who deny possessing any explicit awareness of the masked images whatsoever. Furthermore, "unseen" happy faces are less effectively masked by neutral expressions than are unseen angry or neutral faces, an observation that might also extend to other affective expressions (e.g., fear). These results expand upon previous findings (Esteves & Öhman, 1993) and provide new information about the multitude of factors that may be operating in research that involves backwardly masked facial expressions.