Comparison of delayed matching-to-sample performance in monkeys and children.

Although research has consistently demonstrated that accuracy on a variety of memory tasks decreases as delay increases, relatively little research has been conducted to quantify this relationship across development in humans or directly compare rates of forgetting between humans and monkeys. This study utilized a delayed matching-to-sample (DMTS) task to compare the relative contributions of proactive interference and attention on the rate of forgetting in monkeys and children. The performance of 1125 children from four to fourteen years of age and 10 adult rhesus monkeys was compared. For this DMTS task, a shape was displayed on the center one of three press-plates. After a delay, the subjects were required to match the original shape with one of three choice shapes to receive a banana-flavored food pellet for monkeys, or a nickel for children. A modified power function provided an excellent fit for the data for monkeys and children. The forgetting rates in children decreased with age, and the forgetting rates for monkeys were most comparable to those of younger children. The data also suggest that proactive interference did not significantly contribute to the forgetting rates for monkeys or younger children. Further, the monkeys appeared to attend to the task at a level similar to that of younger children as evidenced by the similarities in response latencies. The results from this study indicate that the rate of forgetting in monkeys, as well as the mechanisms underlying this rate, appears to share more similarities with that of younger children than of older children.

The use of an incremental repeated acquisition task to assess learning in children.

The development of valid animal models of learning is especially important since learning is critical for nearly all aspects of human behavior and identifying appropriate surrogates provides additional opportunity to study various aspects of learning. Examining the factors that affect learning is often complicated by the need to administer the same task repeatedly across experimental conditions. Incremental repeated acquisition (IRA) tasks have been used extensively in animal research because they circumvent this problem by requiring a subject to learn different response chains repeatedly across sessions. The present study examined the association of age, sex of the participant, and IQ on the performance of an incremental repeated acquisition task in 837 children, aged 5-13 years. This task required children to learn to press four response levers in a specific sequence that was randomly chosen. Illumination of colored indicator lights signaled position in the required response chain. Initially, for the first link, only one of the four levers was correct: a response to it resulted in the delivery of a monetary reinforcer (5 cents). After mastery of the first link (i.e. three correct presses), the children were presented with a two-link response chain: a different lever had to be pressed before pressing the previously correct lever. After mastery of the two-link chain, the response chain length was once again increased, and so on until a response chain consisting of six links was completed or until the task timed out. Older children and children with higher IQs mastered longer response chain lengths and were more accurate in performance of this learning task than younger children. In addition, older children and children with higher IQs had higher effective response rates and lower ineffective response rates. No significant effects of the sex of the participant were demonstrated for any of the variables on this task, except overall response rate. The results indicate that this test is sensitive to developmental variables in children, with the degree of sensitivity of certain dependent variables being age-dependent. Characterization of performance of this task by humans facilitates comparisons with animal models employing the same task, thus enhancing its translational utility.

Physician risk attitudes and hospitalization of infants with bronchiolitis.

OBJECTIVES: To determine whether the risk attitudes of pediatric emergency physicians are related to the likelihood that otherwise healthy infants with bronchiolitis will be admitted for inpatient care. METHODS: Risk aversion and discomfort with diagnostic uncertainty were assessed among 46 pediatric emergency physicians from three hospitals participating in the Child Health Accountability Initiative. Study physicians managed 397 otherwise healthy infants ages 0 to 12 months presenting to their hospital emergency departments with bronchiolitis. Mean risk aversion and discomfort with diagnostic uncertainty scores were compared across physician gender, years of experience, and formal training in emergency medicine. Additional analyses based on infants as the analytic unit determined admission rates of physicians scoring high and low on risk attitude measures. This model was controlled for severity of illness. RESULTS: Scores on measures of risk aversion and discomfort with uncertainty were similar for male and female physicians and for physicians who had completed pediatric emergency medicine fellowship training and those without such training. Risk aversion scores were significantly higher for physicians with 15 or more years of experience. Admission rates for infants with bronchiolitis were no higher among physicians scoring above the median on risk attitude measures. When adjusted for severity of illness, physicians' risk attitudes were not associated with admission rates. CONCLUSIONS: Recent growth in per-capita admissions for bronchiolitis is not accounted for by physician intolerance for diagnostic uncertainty. Physician risk attitudes should be considered in the context of hospital admissions for other pediatric conditions with unclear prognoses.

Developmental aspects of timing behavior in children.

This research examined the association of age, sex, and intelligence on the performance of a time production (temporal response differentiation, TRD) task. Variations of this task have been used extensively with both animals and humans to study factors that affect aspects of timing ability. The participants in this study (720 children, ages 5 to 13 years) were required to hold down a response lever for at least 10 s, but no more than 14 s, to receive a nickel. Older children made more correct lever holds and exhibited less variability in the duration of their lever holds than did the younger children. Boys and girls performed similarly on this task, whereas children with higher IQs made more correct lever holds. Young children with below average IQs exhibited increased variability in lever hold duration compared with young children with average and above average IQs. The results of this study illustrate that both age and intelligence influence timing ability. The use of this timing task in children, which also has been widely used in animal models, provides unique opportunities for interspecies comparisons.

Effect of methylphenidate on time perception in children with attention-deficit/hyperactivity disorder.

The effects of methylphenidate (MPH) on performance of a time-production task were studied in 17 children with attention-deficit/hyperactivity disorder who participated in 1 test session on and 1 off MPH. Participants held a response lever down for at least 10 but no longer than 14 s. Administration of MPH had no effect on the number of correct responses or on the mean duration of lever holds. MPH administration significantly decreased timing response variability, increased holds of 10- to 11-s duration, and decreased lever holds of extremely short durations. These results indicate that administration of MPH resulted in more precise timing performance without changing the mean duration of lever holds, suggesting an enhancement in working memory.

Stimulant therapy in attention deficit/hyperactivity disorder.

Stimulant medication is a significant part of the multimodal management of children with ADHD. The primary care physician should coordinate the assessment and treatment of the child with this disorder. Understanding the use of stimulant medications and a thorough understanding of the challenges facing family, patients, educators and health planners is necessary in order to address issues related to the complexities of ADHD.

Knowledge versus practice: the necessity of education for successful guideline implementation.

This study assessed physicians' familiarity with a practice guideline for bronchiolitis, evaluated attitudes regarding guidelines, determined preference of educational materials for guideline accessibility and examined the relationship between guideline familiarity and attitudes with clinical practice behaviors. Six months following guideline implementation, surveys were distributed to eligible physicians. The response rate was 68%. Retrospective analyses of inhalation therapies across three study cohorts were also performed. Most physicians surveyed in this study were aware of and utilized a recently introduced guideline, though use of unproven inhalation therapies continued. Despite demonstrated efficiencies of care, continued educational intervention is necessary to sustain these gains.