Many pregnant women do not meet guidelines for physical activity, and women with twin pregnancies are less likely to be physically active compared with singleton pregnancies. During and following pregnancy, physical activity patterns and their related predictors have not been previously explored in women pregnant with twins. Therefore, we aimed to examine stability and change in leisure-time physical activity (LTPA) from pre-pregnancy, during pregnancy, and up to 18 months after childbirth in women pregnant with twins and identify predictors of their LTPA patterns. This study was based on data from a nationwide, prospective cohort study, the Norwegian Mother, Father and Child Cohort Study (1999-2008), and the Medical Birth Registry of Norway. We used latent class growth analysis and logistic regression to identify patterns of LTPA and associated predictors among women pregnant with twins (n = 1,796). Two patterns were identified: low/moderate (53.3%) and high (46.7%). Parity, pre-pregnancy overweight and obesity, and primary education were associated with 36-60% lower odds of belonging to the high LTPA class compared to the low-to-moderate LTPA class. There is an urgent need to study the potential consequences of physical activity in twin pregnancies on maternal and fetal health.

Although in recent years some studies have found evidence suggesting that working memory (WM) may operate on unconscious perceptual contents, decisive demonstrations of the existence of unconscious WM are lacking. In the present Registered Report, we replicate the first study on this topic by Soto et al. (Working memory without consciousness. Curr Biol 2011;21:R912–3.): a visual discrimination task asking participants to report the direction in which a subliminal Gabor grating was rotated after a 2-s delay. We acquired a multisite sample from 19 laboratories, with a larger number of participants (N = 531) and trials (720 in two sessions) than those typically used in previous studies. As a result, a large-sample, international, and open-access dataset is now available for researchers and future analyses. Furthermore, some minimal baseline requirements were guaranteed for the experimental task (i.e. number of valid trials, motivation, and consistent labels for the Perceptual Awareness Scale). The results showed (1) above-chance WM performance in cue-present trials reported as unseen (.55 accuracy), (2) a significant positive correlation between WM performance and cue detection sensitivity (r = .228), and (3) a significant above-chance intercept in the regression of performance on sensitivity (β0 = .521). These findings suggest that WM can operate on unconscious representations, although it remains positively associated with perceptual sensitivity. Crucially, because measurement error could compromise the interpretation of these three results, we provide evidence for our measures’ excellent reliability and, more fundamentally, for their validity.

It is important to understand how persuasive the most-cited climate change messaging strategies are. In five replication studies, we found limited evidence of persuasive effects of three highly cited strategies (N = 3,216). We then conducted a registered report megastudy (N = 13,544) testing the effects of the 10 most-cited climate change messaging strategies on Americans’ pro-environmental attitudes and behaviour. Six messages significantly affected multiple preregistered attitudes, with effects ranging from 1 to 4 percentage points. Persuasiveness varied little across party lines, inconsistent with theories predicting heterogeneous effects for targeted messages. No message increased pro-environmental donations, suggesting costly behaviours are difficult to influence with messaging alone. Inference of mechanisms driving effects was limited as the most impactful messages influenced multiple mediating variables. Taken together, these results identify several persuasive strategies, while also highlighting the limits of short-form messages for increasing Americans’ support for action to address climate change.