Older adults recover more marginal knowledge and use feedback more effectively than younger adults: evidence using "I don't know" vs. "I don't remember" for general knowledge questions.

Through three experiments, we examined older and younger adults' metacognitive ability to distinguish between what is not stored in the knowledge base versus merely inaccessible. Difficult materials were selected to test this ability when retrieval failures were very frequent. Of particular interest was the influence of feedback (and lack thereof) in potential new learning and recovery of marginal knowledge across age groups. Participants answered short-answer general knowledge questions, responding "I do not know" (DK) or "I do not remember" (DR) when retrieval failed. After DKs, performance on a subsequent multiple-choice (Exp. 1) and short-answer test following correct-answer feedback (Exp. 2) was lower than after DRs, supporting self-reported not remembering reflects failures of accessibility whereas not knowing captures a lack of availability. Yet, older adults showed a tendency to answer more DK questions correctly on the final tests than younger adults. Experiment 3 was a replication and extension of Experiment 2 including two groups of online participants in which one group was not provided correct answer feedback during the initial short-answer test. This allowed us to examine the degree to which any new learning and recovery of access to marginal knowledge was occurring across the age groups. Together, the findings indicate that (1) metacognitive awareness regarding underlying causes of retrieval failures is maintained across different distributions of knowledge accessibility, (2) older adults use correct answer feedback more effectively than younger adults, and (3) in the absence of feedback, older adults spontaneously recover marginal knowledge.

Integration of thought and action continued: Scale errors and categorization in toddlers.

To further explore the effect of weighted arms on toddler's performance in problem solving (Arterberry et al., 2018, Infancy, 23(2), 173), the present study explored scale errors and categorization, two instances where infants appear to show more advanced knowledge than toddlers. Experiment 1 (N = 67) used a novel task for inducing scale errors among 24- to 29-month-olds. Results replicated rates of scale errors found in previous research that used different tasks. Experiment 2 used sequential touching (N = 31) and sorting measures (N = 23) to test categorization in 24-month-old children. In both measures, children showed categorization at the basic level when there was high contrast between the exemplars, but not at a basic level with low contrast or a subordinate level. In Experiments 1 and 2, half the participants were tested while wearing weighted wristbands. Weighting the arms did not affect error rates, in contrast to previous research showing that weights improved performance in search tasks. The findings are discussed in light of children's difficulty in integrating perception, cognition, and action.