We provide a psychometric analysis of commonly used performance indices of the d2 sustained-attention test, and give methodical guidelines and recommendations, based on this research. We examined experimental effects of repeated testing on performance speed and accuracy (omission and commission errors), and further evaluated aspects of test reliability by means of cumulative reliability function (CRF) analysis. These aspects were also examined for a number of alternative (yet commonly used) scoring techniques and valuation methods. Results indicate that performance is sensitive to change, both differentially within (time-on-task) and between (test-retest) sessions. These effects did not severely affect test reliability, since perfect score reliability was observed for measures of speed (and was even preserved with half the test length) while variability and error scores were more problematic with respect to reliability. Notably, limitations particularly hold for commission but less so for omission errors. Our recommendations to researchers and practitioners are that (a) only the speed score (and error-corrected speed score) is eligible for highly reliable assessment, that (b) error scores might be used as a secondary measure (e.g., to check for aberrant behavior), that (c) variability scores might not be used at all. Given the exceptional reliability of performance speed, and (d) test length may be reduced up to 50%, if necessary for time-economic reasons, to serve purposes of population screening and field assessment. (PsycINFO Database Record

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Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to find compelling evidence for this. The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core four-week test period. Eighty-one participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological flexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a significant placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value.

We examined the effect of motivational readiness on cognitive performance. An important but still not sufficiently elaborated question is whether individuals can voluntarily increase cognitive efficiency for an impending target event, given sufficient preparation time. Within the framework of the constant-foreperiod design (comparing reaction time performance in blocks of short and long foreperiod intervals, FPs), we examined the effect of an instruction to try harder (instructional cue: standard vs. effort) in a choice-reaction task on performance speed and variability. Proceeding from previous theoretical considerations, we expected the instruction to speed-up processing irrespective of FP length, while error rate should be increased in the short-FP but decreased in the long-FP condition. Overall, the results confirmed this prediction. Importantly, the distributional (ex-Gaussian and delta plot) analysis revealed that the instruction to try harder decreased distributional skewness (i.e., longer percentiles were more affected), indicating that mobilization ensured temporal performance stability (persistence).