This study investigates the predictive value of child-related and environmental characteristics for early lexical development. The German productive vocabulary of 51 2-year-olds (27 girls), assessed via parental report, was analyzed taking children’s gender, the type of early care they experienced, and their mono- versus bilingual language composition into consideration. The children were from an educationally homogeneous group of families and state-regulated daycare facilities with high structural quality. All investigated subgroups exhibited German vocabulary size within the expected normative range. Gender differences in vocabulary composition, but not in size, were observed. There were no general differences in vocabulary size or composition between the 2 care groups. An interaction between the predictors gender and care arrangement showed that girls without regular daycare experience before the age of 2 years had a somewhat larger vocabulary than all other investigated subgroups of children. The vocabulary size of the 2-year-old children in daycare correlated positively with the duration of their daycare experience prior to testing. The small subgroup of bilingual children investigated exhibited slightly lower but still normative German expressive vocabulary size and a different vocabulary composition compared to the monolingual children. This study expands current knowledge about relevant predictors of early vocabulary. It shows that in the absence of educational disadvantages the duration of early daycare experience of high structural quality is positively associated with vocabulary size but also points to the fact that environmental characteristics, such as type of care, might affect boys’ and girls’ early vocabulary in different ways.

The Cognitive Reflection Test (CRT) is a hugely influential problem solving task that measures individual differences in the propensity to reflect on and override intuitive (but incorrect) solutions. The validity of this three-item measure depends on participants being naïve to its materials and objectives. Evidence from 142 volunteers recruited online suggests this is often not the case. Over half of the sample had previously seen at least one of the problems, predominantly through research participation or the media. These participants produced substantially higher CRT scores than those without prior exposure (2.36 vs. 1.48), with the majority scoring at ceiling level. Participants that had previously seen a specific problem (e.g., the bat and ball problem) nearly always solved that problem correctly. These data suggest the CRT may have been widely invalidated. As a minimum, researchers must control for prior exposure to the three problems and begin to consider alternative, extended measures of cognitive reflection.