The Effect of Differential Post-Weaning Environment on the Rigidity of an Animal's Behavior

Seventy-two first, second and third grade boys and girls were administered seriation problems involving different combinations of shape and color variation. Success rates and latency scores were influenced by shape variation, but not by color variation or grade level. The failure to obtain predicted interactions between the effects of grade level and stimulus variation was attributed to the clarity of the relevant stimulus dimension.     

Investigations of the Behavior of Paramecium Aurelia: III. The Effect of the Presence and Absence of Light on the Occurrence of a Response

This study was designed to evaluate how a series of measures made on 77 infants at ages 3, 6, 9, 12, 18, and 24 months could be used to predict measures made at about 5 years of age. The analytical procedures were selected to be sensitive to differences among individuals in the function that relates test performance to age. Neither evidence for such heterogeneity nor incremental validity of the measures made at 18 months and earlier was obtained. It is concluded that the Gesell Developmental Schedule, the Cattell Infant intelligence Scale, and the California Infant Scale of Motor Development, administered at 18 months and earlier, are invalid both as static indicators of later performance and as dynamic indicators of development.     

Maternal Depressed Mood and Perceptions of Child Temperament

Research has suggested that women who experience postpartum depression are subsequently more likely to perceive their preschool-aged children as temperamentally difficult and maladjusted. However, previous studies have not controlled for the effects of concurrent depression levels on maternal ratings of child temperament or evaluated the accuracy of maternal reports. In the present study we assessed maternal and paternal ratings of child temperament 2 years after subjects had participated in a study of postpartum depression. The findings indicate that correlations between postpartum depression and subsequent child temperament ratings were accounted for statistically by concurrent levels of depression. Although fathers' ratings corroborated some aspects of maternal perceptions, levels of parental agreement were only moderately high. Moreover, discrepancies between the parents' reports were significantly associated with maternal depression, indicating that parental disagreement is more likely when the wife is dysphoric.     

The Semantics of Secrecy: Young Children's Classification of Secret Content

The authors explored whether young children can distinguish potential secrets from nonsecrets by their content, as can older children, adolescents, and adults. Ninety children, 4, 5, and 6 years old, rated the secrecy of items from an adult-validated list of personal information about an age- and gender-appropriate puppet. Two factors of the children's data corresponded to the adult categories of nonsecrets and secrets, and a third factor corresponded to surprises. All ages rated surprises as significantly more secret than nonsecret items; however, the surprise items contained linguistic cues to secrecy. A tendency to rate nonsecrets as secret decreased with age, but only the 6-year-olds rated secrets other than surprises as significantly more secret than nonsecrets. Thus, children acquire the implicit rules defining secret content from a somewhat later age than that reported for the cognitive or behavioral capacities for secrecy.     

Development of Postural Adjustment During Gait Initiation: Kinematic and EMG Analysis

The authors studied the development of postural adjustments associated with the initiation of gait in children by using kinematic and electromyographic (EMG) analysis. Participants (N = 28) included infants with 1-4 and 9-17 months of walking experience, children 4-5 years of age, and adults. Anticipatory postural adjustments (APA) were present in the youngest age groups, including a clear anticipatory lateral tilt of the pelvis and the stance leg, which enabled the child to unload the opposite leg shortly before its swing phase. An anticipatory activation of the hip abductor of the leg in stance phase prior to heel-off was found, suggesting pelvis stabilization. APA did not appear consistently until 4-5 years of age. A decrease in segmental oscillations occurred across the ages, indicating better control of intersegmental coordination in the frontal and sagittal planes during the postural phase of gait initiation. Young walkers presented APA involving movements of both the upper and the lower parts of the body, whereas, like adults, 4- to 5-year-olds were able to laterally shift only the pelvis and the stance leg. The oldest children and the adults also showed lower activation levels of hip and knee muscles but higher activation at the ankle level. Those kinematic and EMG results taken together suggest a clear developmental sequence from an en bloc operation of the body through an articulated operation with maturation, walking experience, or both.     

Sensitivity of Smoothness Measures to Movement Duration,Amplitude, and Arrests

ABSTRACT

Studies of sensory-motor performance, including those concerned with changes because of age, disease, or therapeutic intervention, often use measures based on jerk, the time derivative of acceleration, to quantify smoothness and coordination. However, results have been mixed: some researchers report sensitive discrimination of subtle differences, whereas others fail to find significant differences even when they are obviously present. One reason for this is that different measures have been used with different scaling factors. These measures are sensitive to movement amplitude or duration to different degrees. The authors show that jerk-based measures with dimensions vary counterintuitively with movement smoothness, whereas a dimensionless jerk-based measure properly quantifies common deviations from smooth, coordinated movement.     

Bimanual and Unimanual Convergent Goal-Directed Movement Times

Three experiments are reported, investigating the effects of using 1 or 2 hands when making convergent low index of difficulty (ID) and visually controlled movements (2 hands meeting together). The experiments involved movements in four different cases—a probe held in the right hand and moved to a target held in the stationary left hand, vice versa of this arrangement, both hands moving with the probe in the right hand and target in the left hand, and vice-versa of this arrangement. Experiments were the standard Fitts’ paradigm, moving a pin into a hole and a low-ID task. In Fitts’ task, 2-hand movements were faster than 1 hand only at higher IDs; this was also the case in the pin-to-hole transfer task and the movement times were lower when the pin was held in the preferred hand. Movements made with low ID showed a small effect of 1- or 2-handed movements, with the effective amplitude of the movement being reduced by about 20% when 2 hands were used.     

A Two-Factor Model of Defensive Pessimism and Its Relations With Achievement Motives

The author first examined the underlying factor structure of the defensive pessimism construct and its relations with achievement motives. The author used a sample of 542 Singaporean undergraduate students and found that defensive pessimism is a 2-factor construct that comprises (a) negative expectation, in which individuals worry about possible pitfalls, and (b) reflectivity, in which individuals put forth efforts to prevent possible pitfalls. Then, the author used a sample of 160 Singaporean undergraduate students for Study 2, which supported the proposed model in which mastery predicted the reflectivity factor of defensive pessimism, competition predicted the negative-expectation factor of defensive pessimism indirectly through the mediation of fear of shame, and negative-expectation factor predicted the reflectivity factor of defensive pessimism because, for the defensive pessimists, the act of worrying helps them to respond to their anxiety by initiating the planning process to direct efforts to prevent potential disasters.     

A Comparison of Single and Multi-Test Working Memory Assessments in Predicting Academic Achievement in Children

Children assessed as having low working memory capacity have also been shown to perform more poorly than their same-aged peers in measures of academic achievement. Early detection of working memory problems is, therefore, an important first step in reducing the impact of a working memory deficit on the development of academic skills. In this study, we compared a single-test assessment, the Working Memory Power Test for Children (WMPT) and a multi-test assessment, the Automated Working Memory Assessment (AWMA), in their ability to predict academic achievement in reading, numeracy, and spelling. A total of 132 Australian school children (mean age 9 years, 9 months) participated in the research. Strong positive correlations between the WMPT and AWMA total scores were found, indicating good convergent validity of the single and multi-test measures. WMPT scores correlated with each of the four AWMA subtests designed to assess verbal and visuospatial short-term and working memory. WMPT and AWMA scores separately predicted performance on Word Reading, Numerical Operations, and Spelling. Compared with either measure alone, the WMPT and the AWMA in combination predicted more of the variance in Word Reading and Numerical Operations, but not in Spelling. Theoretical and practical implications of these findings are discussed.