Transcranial direct-current stimulation enhances implicit motor sequence learning in persons with Parkinson's disease with mild cognitive impairment

Implicit motor sequence learning (IMSL) is affected in Parkinson's disease (PD). Research in healthy young participants shows the potential for transcranial direct-current stimulation (tDCS) over the primary motor cortex (M1) to enhance IMSL. In PD, only null effects have been reported to date. We determined concurrent, short-term, and long-term effects of anodal tDCS over M1 on IMSL, as measured by the serial reaction time (SRT) task, in persons with PD with mild cognitive impairment (MCI). Concurrent (anodal/sham tDCS intervention during the SRT task), short-term (5 min post-intervention), and long-term (1 week post-intervention) effects on IMSL were evaluated in persons with idiopathic PD (Hoehn and Yahr stage II-III) with MCI. Results of 11 persons with PD (8 men and 3 women; mean age = 77.1 years; mean disease duration = 7.7 years) showed significant IMSL in the anodal (p = .016), but not in the sham tDCS condition (p = .937). Post-hoc analyses showed that IMSL reached statistical significance at 1 week post-intervention (p < .001). Anodal tDCS over M1 exerted beneficial effects on IMSL in persons with PD with MCI, in particular one week post-intervention. Our study is the first to report a positive effect of tDCS on IMSL in PD. Further research should include a larger, more cognitively diverse sample and additional follow-up periods.     

To go or not to go? Pupillometry elucidates inhibitory mechanisms in motor imagery

Motor imagery (MI) involves consciously performing an action in our minds without engaging in overt physical movement. Although inhibition is crucial to MI, few studies have explored the nature of inhibitory mechanisms underlying this construct. Therefore, little progress has been made in elucidating how or when inhibition is implemented during MI. The present study addressed this unresolved issue by measuring participants’ pupil dilation (an index of attentional effort) as they performed an inhibitory-control (Go/NoGo) procedure in a modified task-switching paradigm. The results showed that inhibitory mechanisms in MI may be implemented via various routes. When MI was the only movement mode used, minimal attentional effort was invested during the Go/NoGo responses, suggesting an early implemented, proactive inhibitory strategy. Conversely, when imagery was preceded by physical movement responses, inhibition required greater attentional effort and it appears as though more active and attention-demanding inhibitory processes must be employed.     

Detection and Selection Decisions with Conditional Feedback: Interaction of Task Uncertainty and Base Rate

Effects of task uncertainty on decision thresholds in a multiple cue decision task were examined under two types of feedback and three base rate conditions. In most such decision experiments, participants receive feedback after every trial (full feedback) with a single (usually .5) base rate. Our experiment explored conditional (decision‐contingent) feedback, in a task representing a detection problem (passenger screening) in which the decision maker receives no feedback unless the decision is positive (search the passenger). Increased uncertainty made all dependent measures worse. Task uncertainty had detrimental effects on both judgment and decision making, and interacted with effects of feedback and base rate. Decision performance was better with full feedback than with conditional feedback, but not by much. There may be no single unifying explanation for results of our base rate manipulation. Conditional feedback generally resulted in fewer positive decisions than full feedback, but not in the low (.1) base rate condition. Results provide partial support for constructivist encoding and for accuracy maximization with moderate and high base rates, but not with a low base rate. Our results indicated lower selection rates with conditional feedback compared with full feedback in moderate and high base rate conditions, and a more exploratory strategy with higher selection rates with conditional feedback compared with full feedback when base rate was low. Copyright © 2018 John Wiley & Sons, Ltd.     

More than 50% or Less than 70% Chance: Pragmatic Implications of Single‐Bound Probability Estimates

Probability estimates can be given as ranges or uncertainty intervals, where often only one of the interval bounds (lower or upper) is specified. For instance, a climate forecast can describe La Niña as having “more than 70% chance” or “less than 90% chance” of occurring. In three experiments, we studied how research participants perceived climate‐related forecasts expressed with lower‐bound (“over X% chance”) or upper‐bound (“under Y% chance”) probability statements. Results indicate that such single‐bound statements give pragmatic information in addition to the numeric probabilities they convey. First, the studies show that these statements are directional, leading the listeners' attention in opposite directions. “Over” statements guide attention towards the possible occurrence of the event and are explained by reasons for why it might happen, while “under” statements direct attention to its possible non‐occurrence and are more often explained by reasons for why the target event might not appear, corresponding to positive (it is possible) versus negative (it is uncertain) verbal probabilities. Second, boundaries were found to reveal the forecaster's beliefs and could be perceived as indicative of an increasing or a decreasing trend. Single‐bound probability estimates are therefore not neutral communications of probability level but might “leak” information about the speaker's expectations and about past and future developments of the forecast. Copyright © 2017 John Wiley & Sons, Ltd.     

An examination of mindfulness skills in terms of affect tolerance among individuals with elevated levels of health anxiety

Background and Objectives: Affect tolerance factors, including anxiety sensitivity, intolerance of uncertainty, and emotional distress tolerance, have been implicated in the exacerbation of health anxiety. Therefore, identifying methods to improve affect tolerance in health anxious populations is imperative. Despite the link between mindfulness and greater affect tolerance in non-clinical populations, no work has examined the role of mindfulness skills in terms of affect tolerance among individuals with elevated health anxiety. The aim of the current study was to examine the unique contribution of mindfulness skills in terms of distress tolerance, anxiety sensitivity, and intolerance of uncertainty.

Methods: Participants were 218 undergraduates with clinically elevated levels of health anxiety (75.7% female; M_age?=?19.53, SD?=?3.16, Range?=?18–45) who completed self-report measures for course credit.

Results: Findings indicated that, after controlling for theoretically relevant covariates, greater acting with awareness, non-judgment, and non-reactivity were uniquely associated with greater distress tolerance, and greater non-reactivity was associated with lower levels of intolerance of uncertainty. Though none of the mindfulness skills emerged as specific individual predictors of anxiety sensitivity, these skills collectively accounted for unique variance in anxiety sensitivity.

Conclusions: These findings suggest that mindfulness skills may be helpful in targeting affect tolerance factors among individuals with elevated health anxiety.     

Examining incremental explanatory power in accounting for worry severity: negative metacognitive beliefs uniquely predict worry severity following a worry episode

Background and Objectives: Contemporary conceptual models posit that different core variables contribute to worry, including intolerance of uncertainty (IU), metacognitive beliefs, and experiential avoidance. To date, a concurrent investigation of the incremental explanatory power of these variables in accounting for worry severity remains unexamined. The present study sought to address that gap in the literature.

Design/Methods: Participants endorsing frequent worry (N?=?127) completed self-report measures assessing IU, metacognitive beliefs, and experiential avoidance during an online session. Participants later attended an in-person lab-based session where they completed a worry episode and in-vivo worry severity was assessed following the worry episode.

Results: IU, negative metacognitive beliefs, and experiential avoidance each shared a bivariate association with post-episode worry severity. However, in multivariate analyses, only baseline worry severity and negative metacognitive beliefs surrounding the dangerousness and uncontrollability of worry predicted post-episode worry severity.

Conclusions: The present results further underscore links between negative metacognitive beliefs and worry.     

Effects of hands-free cellular phone conversational cognitive tasks on driving stability based on driving simulation experiment

Driver distraction due to cellular phone usage is a major contributing factor to road crashes. This study compares the effects of conversational cognitive tasks using hands-free cellular phone on driving performance under three distraction conditions: (1) no distraction (no cellular conversation), (2) normal conversation (non-emotional cellular conversation), and (3) seven-level mathematical calculations. A car-following scenario was implemented using a driving simulator. Thirty young drivers with an average age of 24.1 years maintained a constant speed and distance between the subject vehicle and a leading vehicle on the driving simulator, and then respond to the leading vehicle’s emergency stop. The driving performances were assessed by collecting and statistically analyzing several variables of maneuver stability: the drivers’ brake reaction times, driving speed fluctuation, car-following distance undulation, and car-following time-headway undulation. The results revealed that normal conversation on a hands-free cellular phone impaired driving performance. The degree of impairment caused by normal calculation was equivalent to the distraction caused by Level 3 mathematical calculations according to the seven-level calculation baseline. The calculation difficulty of Level 3 is one double-digit figure plus a single-digit figure, and non-carry addition mental arithmetic is required, e.g., 44 + 4. The results indicated that an increase in the level of complexity of the calculation task was associated with an increase in brake reaction time. The seven-level calculation-task baseline could be applied to measure additional distraction effects on driving performance for further comparison.     

Effects of age and type of picture on visuospatial working memory assessed with a computerized jigsaw-puzzle task

We investigated the effect of age and color in a computerized version of the jigsaw-puzzle task. In Experiment 1, young and older adults were presented with puzzles in color and black-and-white line drawings, varying in difficulty from 4 to 9 pieces. Older adults performed the task better with the black-and-white stimuli and younger adults performed better with the color ones. In Experiment 2, new older and young adults identified the same fragmented pictures as fast and accurately as possible. The older group identified the black-and-white stimuli faster than those presented in color, while the younger adults identified both similarly. In Experiment 3A, new older and young groups performed the puzzle task with the same color pictures and their monochrome versions. In Experiment 3B, participants performed a speeded identification task with the two sets. The findings of these experiments showed that older adults have a memory not a perceptual difficulty.