Consistent contrast aids concept learning.

We suggest that coherence among concepts and correspondence between concepts and the world are important in concept learning. We identify one aspect of coherence, consistent contrast, and investigate its role in supervised concept learning. Concepts that contrast consistently carry information about the same attributes across the concepts within a contrast set. Concepts that contrast inconsistently predict and are predicted by values of different attributes. Experiment 1 revealed a large advantage for consistent contrast in learning and generalization. Experiment 2 pitted similarity against consistency and still revealed an advantage of consistency. Experiment 2 also broadened the range of tasks considered to include inductions about novel categories and subjects' category descriptions. We discuss relations to theories of concept learning, to attentional mechanism, and to alignability, and we suggest practical implications.

Prenatal cocaine/polydrug exposure: effect of race on outcome.

OBJECTIVE: To determine the effect of prenatal exposure to cocaine on development. METHODS: We tested 106 infants in the range of 4 to 30 months adjusted age with the Bayley Scales of Infant Development. RESULTS: The 46 cocaine-exposed infants had similar mental scores to those of the 60 control infants. Among the 47 black infants, motor scores were 11.2 points higher in cocaine-exposed infants than in control infants (115.1 and 103.9, respectively, p = 0.023). Among the 59 white infants, motor scores were similar in cocaine-exposed infants (102.9) and control infants (100.6). CONCLUSION: Genetic differences may account for this variation in motor development of cocaine-exposed infants.

Cardiac arrest in an extremely low birth weight infant: complication of percutaneous central venous catheter hyperalimentation.

We report a case of unexpected sudden cardiac arrest in an extremely low birth weight infant on the eighth day after a percutaneous silicone rubber central venous catheter was inserted for parenteral nutrition. The unique pathologic condition of infiltration of the myocardium with probably intralipid and degeneration of myocardial fibers over the right atrium and part of the right ventricle has not been reported in the past. There was no pericardial effusion. A brief review of the complications of central venous catheters is given.

Identification of sepsis in neonates following maternal antibiotic therapy.

To examine the value of current diagnostic tests identifying neonatal sepsis related to intrapartum treatment with antibiotics, we reviewed the charts of 219 mother-infant pairs, of which 139 mothers received intrapartum antibiotics (group 1) and 80 mothers did not (group 2). When compared with group 2 infants, group 1 infants had fewer positive blood cultures (4.3% vs 20%, P < 0.003), blood cultures positive for group B streptococci (GBS) (P < 0.001), and positive urine GBS latex agglutination (LA) tests (P < 0.001). Although the sensitivity of the white blood cell count (WBC) was 81%, the specificity was < 60% in both groups. The specificity of the urine GBS LA test was 92%. These results suggest (1) the WBC will neither confirm nor rule out neonatal septicemia; (2) blood cultures are indicated in suspected neonatal sepsis even if there was maternal intrapartum treatment with antibiotics; and (3) a urine GBS LA test is a useful adjunct in the diagnosis of neonatal GBS septicemia.

Exosurf rescue surfactant improves high ventilation-perfusion mismatch in respiratory distress syndrome.

OBJECTIVE: To assess ventilation/perfusion (VA/Q) mismatch of the high type, following rescue surfactant therapy for respiratory distress syndrome. HYPOTHESIS: Surfactant therapy reduces such mismatch. DESIGN: Randomized, double-blind, placebo-controlled study, assessing VA/Q with the arterial-alveolar difference of CO2 tension (P(a-A)CO2). This difference was determined with capnometry and arterial blood gases, using the equation: P(a-A)CO2 equals arterial CO2 minus alveolar CO2 partial pressure. SETTING: A level III nursery. PATIENTS: Ten intubated infants with respiratory distress syndrome. INTERVENTION: Infants were randomized to each receive two doses of surfactant or two doses of air placebo. RESULTS: P(a-A)CO2 improved after surfactant and worsened after placebo (P = 0.0021), comparing slopes of 12-hr regression lines. A similar pattern occurred with oxygenation. These changes in P(a-A)CO2 and in oxygenation were minimally correlated within the surfactant group. CONCLUSION: Exosurf rescue surfactant reduced VA/Q mismatch of the high type, over several hours.

Traumatic pseudodiverticulum of the pharynx.

Traumatic pseudodiverticulum of the pharynx is a rare complication of endotracheal intubation. Prompt recognition and management will help in reducing the morbidity. A case of traumatic pseudodiverticulum of the pharynx in a preterm infant and the management with a brief review are reported.

Induction from a single instance: formation of a novel category.

This study examines whether preschoolers can use information from a known category to induce a characteristic attribute of a novel, contrasting category based on a single instance. We showed 32 four-year-olds three instances of a Given Category and one instance of a Target Category. These objects could vary along two attribute dimensions, such as color and shape. All instances of the Given Category shared identical values of one attribute (e.g., all were blue), but could have different values of the other attribute (e.g., a circle, a square, and a triangle). The single instance of the Target Category was different from the Given on both attribute dimensions (e.g., a red diamond). Children gave yes/no judgements as to whether additional objects were instances of the Target Category. There were two possible sources of information about the relevance of an attribute to classification: explicit (labeling) and implicit (variation in the Given Category). There were four conditions such that each source of information was either available or not. Both types of information were effective in eliciting inductions of the relevant kind of attribute and the characteristic value of this attribute in the novel category (explicit: p = .0004; implicit: p = .031). This suggests that children use an inductive bias that the instances of two related but distinct categories tend to be alike in the same way.

Strategy knowledge and strategy change in skilled performance: a study of the game Othello.

Skill and skill development in playing the game Othello were investigated. In particular, we studied the role of strategies and strategy change, rather than focusing on knowledge of particular board patterns. The history of the development of the game suggests a shift from positional to mobility strategies, a change which also is reproduced in the development of individual players. The first two studies used historical analysis of tournament transcripts to study strategy change. The third study investigated one possible basis for the greater accessibility or ease of positional versus mobility strategy, namely differential encoding and memorability of typical board patterns. Study 3 demonstrated that completely naive as well as positional players remember positional games and moves more easily than mobility games and moves. The easier mastery of positional strategy may be caused in part by the greater ease of encoding typical positional patterns. We suggest that strategic change and conceptual reorganization may be particularly important for domains where the naive encoding of events is not the most apt. We also suggest that similarities exist between strategy change in Othello and other domains.

Development of analogical problem-solving skill.

3 experiments were performed to assess children's ability to solve a problem by analogy to a superficially dissimilar situation. Preschoolers and fifth and sixth graders were asked to solve a problem that allowed multiple solutions. Some subjects were first read a story that included an analogous problem and its solution. When the mapping between the relations involved in the corresponding solutions was relatively simple, and the corresponding instruments were perceptually and functionally similar, even preschoolers were able to use the analogy to derive a solution to the transfer problem (Experiment 1). Furthermore, salient similarity of the instruments was neither sufficient (Experiment 2) nor necessary (Experiment 3) for success by preschool subjects. When the story analog mapped well onto the transfer problem, 4-year-olds were often able to generate a solution that required transformation of an object with little perceptual or semantic similarity to the instrument used in the base analog (Experiment 3). The older children used analogies in a manner qualitatively similar to that observed in comparable studies with adults (Experiment 1), whereas the younger children exhibited different limitations.