The development of visual short-term memory for multifeature items during middle childhood

Visual short-term memory (VSTM) research suggests that the adult capacity is limited to three or four multifeature object representations. Despite evidence supporting a developmental increase in capacity, it remains unclear what the unit of capacity is in children. The current study employed the change detection paradigm to investigate both the capacity and nature of the representations of VSTM in 7-year-olds, 10-year-olds, and adults. Two experimental conditions were used to compare memory performance for single-feature objects with that for multifeature objects. Results provided further and more convincing evidence for a developmental increase in VSTM. Furthermore, the “loading up” of features in the multifeature condition was found to incur no significant performance deficit in all age groups. These findings are explained in terms of a developmental increase in the number of integrated multifeature object representations in VSTM.     

Under what conditions do children have difficulty in inhibiting imitation? Evidence for the importance of planning specific responses

The response set effect has been observed in a number of developmental tasks that are proposed to required inhibition. This effect has been interpreted as evidence that the specific responses children plan to make in these tasks become prepotent. Here we investigated whether there is a response set effect in the hand game. In this task, children need to suppress imitation and make a fist in response to a finger and point a finger in response to a fist. Following pilot data, we tested 7- and 11-year-olds (N=36, Experiment 1) and then 5- and 6-year-olds (N=40, Experiment 2). A response set effect was observed in the hand game with children 6years of age and older. Thus, we obtained evidence consistent with a domain-general intentional mechanism that modulates prepotency. In the General discussion, we consider how this mechanism may work and how our findings relate to current theories of imitation.     

Three- and 4-year-olds encode modeled actions in two ways leading to immediate imitation and delayed emulation

When copying a model's behavior with a tool, children tend to imitate (copy the specific actions to replicate the model's goal) rather than emulate (bring about the model's goal in the most efficient way). Tasks producing these findings test children immediately after the behavior is modeled. In 2 experiments, we investigated children's copying behavior after a delay (of a week). In Experiment 1 (n = 90), we found that although 3- and 4-year-olds often imitate in the short term, they are more likely to emulate in the long term. Data from Experiment 2 (n = 80) were consistent with children remembering actions that were relevant to a causal narrative of the task. Overall, our data suggest that children simultaneously encode modeled behavior in 2 ways that lead to both imitation and emulation. In the discussion, we consider what kind of information leads children to emulate in the long term.     

Sex ratio and women's career choice: does a scarcity of men lead women to choose briefcase over baby?

Although the ratio of males to females in a population is known to influence behavior in nonhuman animals, little is known about how sex ratio influences human behavior. We propose that sex ratio affects women's family planning and career choices. Using both historical data and experiments, we examined how sex ratio influences women's career aspirations. Findings showed that a scarcity of men led women to seek high-paying careers and to delay starting a family. This effect was driven by how sex ratio altered the mating market, not just the job market. Sex ratios involving a scarcity of men led women to seek lucrative careers because of the difficulty women have in finding an investing, long-term mate under such circumstances. Accordingly, this low-male sex ratio produced the strongest desire for lucrative careers in women who are least able to secure a mate. These findings demonstrate that sex ratio has far-reaching effects in humans, including whether women choose briefcase over baby.     

Statistical learning is related to reading ability in children and adults

There is little empirical evidence showing a direct link between a capacity for statistical learning (SL) and proficiency with natural language. Moreover, discussion of the role of SL in language acquisition has seldom focused on literacy development. Our study addressed these issues by investigating the relationship between SL and reading ability in typically developing children and healthy adults. We tested SL using visually presented stimuli within a triplet learning paradigm and examined reading ability by administering the Wide Range Achievement Test (WRAT-4; Wilkinson & Robertson, 2006). A total of 38 typically developing children (mean age of 9;5 years, range 6;4-12;5) and 37 healthy adults (mean age of 21 years, range 18-34) were assessed. In children, SL was significantly related to reading ability. Importantly, this relationship was independent of grade and also age. The adult data, too, revealed that SL was significantly related to reading ability. A regression analysis of the combined child and adult data revealed that SL accounted for a unique amount of variance in reading ability, after age and attention had been taken into consideration. For the first time, this study provides empirical evidence that a capacity for more effective SL is related to higher reading ability in the general population.     

Patient and partner correlates of couple relationship functioning in bipolar disorder

Extensive research in unipolar depressed and population-based samples has shown cross-partner associations between depressive symptoms and relationship adjustment. Yet despite evidence that bipolar disorder (BPD) is a more chronic and severe illness than unipolar depression, that individuals with BPD are at risk for interpersonal dysfunction, and that critical, unsupportive relationships are predictive of the course of depressive symptoms in BPD, there have been limited efforts to understand the correlates of relationship functioning within BPD. The current study addresses this gap in the literature by examining the associations between the depressive and manic symptoms of individuals with BPD, their partner's depressive symptoms, and relationship functioning, using a multimethod, multi-informant approach. Results revealed that the depressive symptoms of the individual with BPD were associated with poorer relationship functioning, particularly when the partner without BPD also had elevated depressive symptoms. In addition, an interaction between the individual with BPD's depressive and manic symptoms was observed, such that manic symptoms were associated with increased observed hostility and poorer partner relationship adjustment, but only when depressive symptoms were also elevated. These effects persisted even after overall mental health of both partners was controlled.     

Refining the understanding of inhibitory processes: how response prepotency is created and overcome

Understanding (a) how responses become prepotent provides insights into when inhibition is needed in everyday life. Understanding (b) how response prepotency is overcome provides insights for helping children develop strategies for overcoming such tendencies. Concerning (a), on tasks such as the day‐night Stroop‐like task, is the difficulty with inhibiting saying the name of the stimulus due to the name being semantically related to the correct response or to its being a valid response on the task (i.e. a member of the response set) though incorrect for this stimulus? Experiment 1 (with 40 4‐year‐olds) suggests that prepotency is caused by membership in the response set and not semantic relation. Concerning (b), Diamond, Kirkham and Amso (2002) found that 4‐year‐olds could succeed on the day‐night task if the experimenter sang a ditty after showing the stimulus card, before the child was to respond. They concluded that it was because delaying children’s responses gave them time to compute the correct answer. However, Experiment 2 (with 90 3‐year‐olds) suggests that such a delay helps because it gives the incorrect, prepotent response time to passively dissipate, not because of active computation during the delay.