Proactive interference and the development of working memory

Working Memory (WM), the ability to maintain information in service to a task, is characterized by its limited capacity. Several influential models attribute this limitation in a large extent to proactive interference (Anderson & Neely, 1996; Bunting, 2006; Kane & Engle, 2000), the phenomenon that previously encoded, now-irrelevant information competes with relevant information (Keppel & Underwood, 1963). Here, we look back at the adult PI literature, spanning over sixty years, as well as recent results linking the ability to cope with PI to WM capacity (Endress & Potter, 2014; Kane & Engle, 2000). In early development, WM capacity is even more limited (Kaldy & Leslie, 2005; Simmering, 2012), yet an accounting for the role of PI has been lacking. Our Focus Article aims to address this through an integrative account: since PI resolution is mediated by networks involving the frontal cortex (particularly, the left inferior frontal gyrus) and the posterior parietal cortex (Badre & Wagner, 2005; Jonides & Nee, 2006), and since children have protracted development and less recruitment (Crone et al., 2006) of these areas, the increase in the ability to cope with PI (Kail, 2002; De Visscher & Noel, 2014) is a major factor underlying the increase in WM capacity in early development. Given this, we suggest that future research should focus on mechanistic studies of PI resolution in children. Finally, we note a crucial methodological implication: typical WM paradigms repeat stimuli from trial-to-trial, facilitating, inadvertently, PI and reducing performance; we may be fundamentally underestimating children’s WM capacity.

Early Development of ADHD and ODD Symptoms from the Toddler to Preschool Years

Objective: ADHD and ODD are commonly co-occurring, but often studied individually. This study evaluated common trajectories of these disorders and explored how they co-develop in early childhood. Method: Community parents ( N = 273) completed online surveys about their 2-year-old. Children’s inattention, hyperactivity/impulsivity, and oppositional defiant disorder symptoms over 2 years were examined using latent class, dual trajectory, and cross-lagged analyses. Results: Most children followed low symptom trajectories. A small portion showed high, moderate, or increasing trajectories. The hyperactive/impulsive domain of ADHD showed a declining symptoms group. Children in high ODD groups were likely to be in high ADHD symptom groups; the converse was true but probabilities were lower. Hyperactive/impulsive symptoms predicted ODD symptoms across time, more than vice versa. Conclusion: The study extends the small body of literature assessing early development of ADHD and ODD. Findings suggest that earlier intervention for symptoms of ADHD may mitigate risk of developing ODD.

Face-Specific Pupil Contagion in Infants

Pupil contagion is the phenomenon in which an observer’s pupil-diameter changes in response to another person’s pupil. Even chimpanzees and infants in early development stages show pupil contagion. This study investigated whether dynamic changes in pupil diameter would induce changes in infants’ pupil diameter. We also investigated pupil contagion in the context of different faces. We measured the pupil-diameter of 50 five- to six-month-old infants in response to changes in the pupil diameter (dilating/constricting) of upright and inverted faces. The results showed that (1) in the upright presentation condition, dilating the pupil diameter induced a change in the infants’ pupil diameter while constricting the pupil diameter did not induce a change, and (2) pupil contagion occurred only in the upright face presentation, and not in the inverted face presentation. These results indicate the face-inversion effect in infants’ pupil contagion.