Cross-sectional and longitudinal assessment of cognitive development in Williams syndrome.

Williams syndrome (WS) is a rare genetic syndrome. As with all rare syndromes, obtaining adequately powered sample sizes is a challenge. Here we present legacy data from seven UK labs, enabling the characterisation of cross-sectional and longitudinal developmental trajectories of verbal and non-verbal development in the largest sample of individuals with WS to-date. In Study 1, we report cross-sectional data between N = 102 and N = 209 children and adults with WS on measures of verbal and non-verbal ability. In Study 2, we report longitudinal data from N = 17 to N = 54 children and adults with WS who had been tested on at least three timepoints on these measures. Data support the WS characteristic cognitive profile of stronger verbal than non-verbal ability, and shallow developmental progression for both domains. Both cross-sectional and longitudinal data demonstrate steeper rates of development in the child participants than the adolescent and adults in our sample. Cross-sectional data indicate steeper development in verbal than non-verbal ability, and that individual differences in the discrepancy between verbal and non-verbal ability are largely accounted for by level of intellectual functioning. A diverging developmental discrepancy between verbal and non-verbal ability, whilst marginal, is not mirrored statistically in the longitudinal data. Cross-sectional and longitudinal data are discussed with reference to validating cross-sectional developmental patterns using longitudinal data and the importance of individual differences in understanding developmental progression.

Age-related differences in the removal of information from working memory.

Removal has been assumed to be a core mechanism in working memory. However, it remains unclear whether children can actively remove outdated information from working memory and how this ability develops as children age. The current study aimed to examine age-related differences in removal ability and its relations with cognitive control and working memory capacity. Children aged 7, 9, and 11 years performed a modified working memory updating task assessing removal efficiency. In addition, a battery of cognitive control and working memory capacity tasks was administered. Results indicated that updating response times decreased considerably when a longer time was given for removal, suggesting that children aged 7 to 11 years can actively remove outdated items from working memory prior to encoding the new ones and that removal efficiency increased with age. More important, age-related increases in removal efficiency occurred concurrently with the development of working memory capacity. Proactive control predicted removal efficiency over and beyond age and working memory capacity. The findings shed new light on the mechanisms underlying the development of working memory updating.

No evidence for cross-paradigm transfer of abstract task knowledge in adults and school-aged children.

Cognitive control is a hallmark of human cognition. A large number of studies have focused on the plasticity of cognitive control and examined how repeated task experience leads to the improvement of cognitive control in novel task environments. However, it has been demonstrated that training-induced changes are very selective and that transfer occurs within one task paradigm but not across different task paradigms. The current study tested the possibility that cross-paradigm transfer would occur if a common cognitive control strategy is employed across different task paradigms. Specifically, we examined whether prior experience of using reactive control in one task paradigm (i.e., either the cued task-switching paradigm or the AX-CPT) makes adults (N = 137) and 9- to 10-year-olds (N = 126) respond in a reactive way in a subsequent condition of another task paradigm in which proactive control could have been engaged. Bayesian generalized mixed-effects models revealed clear evidence of an absence of cross-paradigm transfer of reactive control in both adults and school-aged children. Based on these findings, we discuss to what extent learned control could be transferred across different task contexts and the task-specificity of proactive/reactive control strategies.

When stimulus variability accelerates the learning of task knowledge in adults and school-aged children.

Experience with instances that vary in their surface features helps individuals to form abstract task knowledge, leading to transfer of that knowledge to novel contexts. The current study sought to examine the role of this variability effect in how adults and school-aged children learn to engage cognitive control. We focused on the engagement of cognitive control in advance (proactive control) and in response to conflicts (reactive control) in a cued task-switching paradigm, and conducted four preregistered online experiments with adults (Experiment 1A: N = 100, Experiment 1B: N = 105) and 9- to 10-year-olds (Experiment 2A: N = 98, Experiment 2B: N = 97). It was shown that prior task experience of engaging reactive control makes both adults and 9- to 10-year-olds respond more slowly in a subsequent similar-structured condition with different stimuli in which proactive control could have been engaged. 9- to 10-year-olds (Experiment 2B) exhibited more negative transfer of a reactive control mode when uninformative cue and pre-target stimuli, which do not convey task-relevant information, were changed in each block, compared with when they were fixed. Furthermore, adults showed suggestive evidence of the variability effect both when cue and target stimuli were varied (Experiment 1A) and when uninformative cue and pre-target stimuli were varied (Experiment 1B). The collective findings of these experiments provide important insights into the contribution of stimulus variability to the engagement of cognitive control.

Evidence for positive and negative transfer of abstract task knowledge in adults and school-aged children.

Engaging cognitive control is essential to flexibly adapt to constantly changing environments. However, relatively little is known about how prior task experience impacts on the engagement of cognitive control in novel task environments. We aimed to clarify how individuals learn and transfer the engagement of cognitive control with a focus on the hierarchical and temporal aspects of task knowledge. Highlighting two distinct cognitive control processes, the engagement of cognitive control in advance (proactive control) and in response to conflicts (reactive control), we conducted six preregistered online experiments with both adults (Experiment 1, 3, and 5: N = 71, N = 108, and N = 70) and 9- to 10-year-olds (Experiment 2, 4, 6: N = 69, N = 108, and N = 70). Using two different experimental paradigms, we demonstrated that prior task experience of engaging reactive control makes adults and 9-to 10-year-olds respond in a reactive way in a subsequent similar-structured condition with different stimuli in which proactive control could have been engaged. This indicates that individuals do learn knowledge about the temporal structure of task goal activation and, on occasion, negatively transfer this knowledge. Furthermore, individuals exhibited these negative transfer effects in a similar-structured condition with different task goals and stimuli, indicating that they learn hierarchically-structured task knowledge. The collective findings suggest a new way of understanding how hierarchical and temporal task knowledge influences the engagement of cognitive control and highlight potential mechanisms underlying the near transfer effects observed in cognitive control training.