Adaptive Dynamics of the Leg Movement Patterns of Human Infants: I. The Effects of Posture on Spontaneous Kicking

This is the first of two articles in which we describe how infants adapt their spontaneous leg movements to changes in posture or to elicitation of behaviors by a mechanical treadmill. In this article, we compare the kinematics of kicks produced by 3-month-old infants in three postures, supine, angled (45°), and vertical, and examine the changes in muscular and nonmuscular force contributions to limb trajectory. By manipulating posture we were able to assess the sensitivity of the nascent motor system to changes in the gravitational context. The postural manipulation elicited a distinct behavioral and dynamic effect. In the more upright postures, gravitational resistance to motion at the hip was 4 to 10 times greater than resistance met in the supine posture, necessitating larger muscle torques to drive hip flexion. Kicks produced in the vertical posture showed a reduction in hip joint range of motion and an increase in synchronous joint flexion and extension at the hip and knee. At the same time, hip and knee muscle torques were also more highly correlated in kicks performed in the vertical than in the supine or angled posture. This increased correlation between muscle torques at the hip and knee implicates anatomical and energetic constraints—the intrinsic limb dynamics—in creating coordinated limb behavior out of nonspecific muscle activations.     

Gender,meaning, and psychology

Subjectivity and Method in Psychology: Gender, Meaning and Science Wendy Hollway London: Sage, 1989     

Stability and change in intelligence from age 11 to ages 70, 79, and 87: the Lothian Birth Cohorts of 1921 and 1936

Investigating the predictors of age-related cognitive change is a research priority. However, it is first necessary to discover the long-term stability of measures of cognitive ability because prior cognitive ability level might contribute to the amount of cognitive change experienced within old age. These two issues were examined in the Lothian Birth Cohorts of 1921 and 1936. Cognitive ability data were available from age 11 years when the participants completed the Moray House Test No. 12 (MHT). The Lothian Birth Cohort 1936 (LBC1936) completed the MHT a second time at age 70. The Lothian Birth Cohort 1921 (LBC1921) completed the MHT at ages 79 and 87. We examined cognitive stability and change from childhood to old age in both cohorts, and within old age in the LBC1921. Raw stability coefficients for the MHT from 11-70, 11-79, and 11-87 years were .67, .66, and .51, respectively; and larger when corrected for range restriction in the samples. Therefore, minimum estimates of the variance in later-life MHT accounted for by childhood performance on the same test ranged from 26-44%. This study also examined, in the LBC1921, whether MHT score at age 11 influenced the amount of change in MHT between ages 79 and 87. It did not. Higher intelligence from early life was apparently protective of intelligence in old age due to the stability of cognitive function across the lifespan, rather than because it slowed the decline experienced in later life.     

Group therapy as an adjunct to medication in the management of bipolar affective disorder

This paper asserts that, contrary to the beliefs of many clinicians, patients with bipolar affective disorder often experience a deteriorating course characterized by pervasive social dysfunction. It reviews the literature, identifying a rationale for group psychotherapy as an adjunct to medication in the management of these chronic patients. It outlines a theoretical approach to bipolar group therapy, and presents a retrospective study comparing the course of 43 lithium-treated bipolar patients before and after entering bipolar groups. During the year in group therapy, bipolar patients displayed significant improvements in symptom relief as well as social functioning. It is proposed that group process enhances treatment with medication, providing benefits not evident with medication alone.     

Semantic relations between encoding and retrieval in cued recall

Two experiments were conducted to test the encoding-specificity hypothesis. In Experiment 1, subjects were presented pairs of coordinates to study, followed by a cued-recall test. Semantically weak and strong coordinates (defined by the degree of featural overlap shared with the pairs) served as encoding and retrieval cues. The semantic strength of the retrieval cue proved to be the most important factor in recall, whereas the re-presentation of an unrelated cue previously seen during encoding led to no facilitation of recall. In Experiment 2, three noun coordinates of varied semantic interrelatedness were presented for study and then were cued for recall by novel semantically strong or weak coordinates. Maximum recall was achieved when a strong encoding condition was matched with a strong retrieval cue. Implications of these findings for an encoding-specificity hypothesis were discussed.