Threshold-like associations as a function of disturbance

Diminishing returns as a function of the association between within-individual average performance and variance

It has been demonstrated that the worst performance rule (WPR) effect can occur as a result of statistical dependencies in the data. Here, we examine whether this might also be the case for Spearman's law of diminishing returns (SLODR). Two proposed SLODR criteria are the skewness of the estimated latent ability factor and the correlation between this latent ability and within-individual residual variance. Using four publicly available datasets, covering quite different dimensions of behavior, we show that both these criteria are affected by the correlation between within-individual average performance and variance on the test scores. However, the influence of this correlation on the two criteria goes in opposite directions, which suggests that it generally might be difficult to get results that unambiguously support SLODR. These results might have far-reaching implications for the literature, to the extent that various research findings attributed to human cognitive functioning might in fact be due to trivial statistical dependencies in data. This is an important issue to address for future research.

Diminishing returns as a function of disturbance

According to Spearman's law of diminishing returns (SLODR), IQ test scores are more g saturated among those with low, compared to those with high, ability. The present simulation shows that such difference in saturation can be observed if test scores are affected by a disturbing factor, for example, low motivation, illness, or linguistic confusion, that varies in magnitude between individuals. More contemporary criteria of SLODR can also be satisfied if test scores are affected by disturbance, especially if the disturbance variable is negatively skewed. This indicates a possible threat against the validity of findings supporting SLODR and points at the importance for researchers to try to eliminate the influence of such disturbing factors from their studies.

When Low Leisure-Time Physical Activity Meets Unsatisfied Psychological Needs: Insights From a Stress-Buffer Perspective

Background: Few studies have tested whether the stress-buffering effects of leisure-time physical activity (LTPA) depend on other resources, such as the satisfaction of basic psychological needs. Therefore, the present study examines the interaction between perceived stress, LTPA and psychological need satisfaction (PNS) on occupational burnout symptoms in a sample of Swiss workers.

Methods: The sample consisted of 306 employees (48% women; M_age = 42.9 years, SD = 14.1). Perceived stress was assessed with the Perceived Stress Scale, LTPA with the International Physical Activity Questionnaire, PNS (autonomy, relatedness, and competence) with the Need Satisfaction Scale, and occupational burnout symptoms with the Shirom-Melamed Burnout Measure. A hierarchical regression analysis and single slopes tests were performed to examine two- and three-way interactions.

Results: Stress was positively correlated with burnout, and negatively correlated with LTPA and PNS levels. LTPA was positively associated with PNS, and negatively correlated with burnout. A negative association existed between PNS and burnout. In the hierarchical regression analysis, all main effects, two- and three-way interactions were significant. People who engaged in more LTPA reported fewer burnout symptoms, if they reported high stress. However, the potential of LTPA to buffer stress was particularly evident in participants who reported low PNS.

Conclusion: If adult workers are exposed to elevated stress, they are particularly likely to show increased burnout levels if they report low LTPA in combination with low PNS, specifically a lack of autonomy, competence and relatedness.

Changes in mental health in compliers and non-compliers with physical activity recommendations in patients with stress-related exhaustion

BACKGROUND

There is a lack of research regarding the long-lasting effects of a more physically active lifestyle in patients with mental disorders. In the present study, clinical data were analysed to examine if initially physically inactive patients, clinically diagnosed with stress-related exhaustion, taking part in 12-month multimodal treatment (MMT), differ at the 18-month follow-up regarding mental health, depending on whether they did or did not comply with the physical activity (PA) recommendations resembling those of the American College of Sports Medicine.

METHODS

The study population consisted of 69 patients (65% women) who were referred to a stress clinic due to stress-related exhaustion. All patients received MMT. A major goal was to increase patients' PA levels. The patients received general comprehensive instructions including personal advice regarding the positive effects of PA on mental health and could self-select for an 18-week coached exercise program. Changes in mental health symptoms over an 18-month period were compared between non-compliers (n = 26), mild compliers (n = 22) and strong compliers (n = 21) with the PA recommendations included in the MMT.

RESULTS

Non-compliers, mild and strong compliers did not differ regarding burnout, depression and anxiety at baseline. Although substantial improvements occurred in all groups, mild and strong compliers reported significantly lower burnout and depression levels at the 18-month follow-up than the non-complying group (p < .05). The general pattern of findings was corroborated, if standard cut-off criteria for clinical burnout were used.

CONCLUSIONS

Compliance with PA recommendations is associated with decreased levels of burnout and depression in patients with stress-related exhaustion. Thus, the promotion of a more active lifestyle among patients with stress-related exhaustion should be implemented as a part of MMT, to achieve a more sustainable decrease of symptoms of burnout and depression.

TRIAL REGISTRATION

This is not a clinical trial.