Motor strategies in lifting movements: a comparison of adult and child performance

The experiment compares the performances of children six to nine years old and adults in a simple, monoarticular lifting task. Overt behaviors, as described by the kinematic features of the movement, do not differ qualitatively in the two groups. The patterns of motor commands, as expressed by the electromyographic recordings, are however strikingly different. Adults plan the movement with a careful balance between agonist muscle activity and passive, viscoelastic forces, whereas children use both agonist and antagonist active forces. It is argued that the motor strategy adopted by adults depends upon an internal representation of the properties of the motor system and of the size/weight covariation in natural objects, and that this representation is not yet fully developed at nine years of age.     

The development of walking: new findings and old assumptions

I have argued that a behavioral-cognitive perspective may shed light on some aspects of motor development generally, and unaided walking, specifically. Individual components of walking-stepping, standing, and placing, for example-are present at birth and can be maintained with practice. Moreover, consistent use can produce an earlier onset of unaided walking. Nonetheless, independent erect locomotion rarely occurs before about 9 months in most societies, implying that there is a maturational constraint. Independent research on changes in the quality of object use imply that the maturational limitation may be cognitive, in part. Changes in motor development-both the onset of unaided walking and the emergence of functional use-may be dictated by an underlying change in information processing ability. It is hypothesized that the infant's capacity to generate ideas or access different associations from memory rapidly may define the nature of this change. Improved access to memory may permit the necessary integrative capacity for balance and coordination to occur, thereby permitting unaided walking to develop. Weiss and Zelazo found that the capacity to perform two distinct actions in rapid succession in an independent environment-water-also appears to emerge from about 9 through 12 months. Not only may a cognitive change influence motor development, but mental and motor ability may develop asynchronously in some instances-a particularly important implication for developmental assessment. Procedures to distinguish information processing ability independent of gross and fine motor measures and productive language can lead to treatment that will reduce delays on conventional tests and contribute to the validity of this argument.     

Speaker bias in children's evaluation of the external consistency of statements

The hypothesis of this study is that an assumption of speaker credibility affects children's judgments of the external consistency of statements. In two experiments, first and third grade children (6 and 8 years of age, respectively) and college adults were read short paragraphs containing contradictory information from a contextual source and a speaker. The contextual source was described as either authoritative or nonauthoritative and discredited. The speaker was either an adult or child. Thus the contextual source was either more or less reliable than the speaker. Subjects were asked to affirm or contradict the speaker's statement, and to choose either the source or the speaker as most believable. The results showed that adult responses varied with the contextual source alone, while the responses of the first graders varied primarily with the speaker's age. The responses of the third graders varied with both factors. The results suggest young children can assess the external consistency of statements but frequently do not because of their assumptions about speakers and other performance factors.     

A voice-operated method for administering the MMPI

Paper/pencil psychological tests such as the Minnesota Multiphasic Personality Inventory (MMPI) are difficult to complete independently by patients with limited hand function. This paper describes a voice recognition system developed to allow patients with no hand function to take the MMPI independently. Profiles generated by this system are not statistically different from those generated by standard MMPI booklet format. Limitations and possible extensions of the system as it currently exists are discussed.     

Artistic style and personality in creative painters

The present study attempted to demonstrate a correspondence between artistic style and the personality of the creator. Personality style, defined as a cognitive-affective system of defenses and controls, was identified for 20 renowned painters through an analysis of their individual Rorschach protocols. Their creative work was classified independently by a jury of 4 persons (one art critic; two eminent painters and the junior author) into stylistic categories similar to those elaborated by the senior author for the Rorschach. The overall correspondence achieved was statistically significant (.72, p < .01), with individual correlations ranging from .75 to .86 (p < .01).     

A review of projective test findings with older adults

The projective test literature on aging is reviewed. It was concluded that, while much critical research remains to be done and many of the studies are flawed, projective testing has contributed a great deal to the understanding of the aging process and has yielded a core of consistent findings. Suggestions for future research which would help resolve some current ambiguities were made.     

Sensation seeking, augmenting-reducing, and absolute auditory threshold: a strength-of-the-nervous-system perspective

The following measures were obtained from 42 student volunteers: the General and the Disinhibition subscales of the Sensation Seeking Scale (Form IV), the Reducer-Augmenter Scale, and the Absolute Auditory Threshold. General sensation seeking correlated significantly with the Reducer-Augmenter Scale, r(40) = .59, p less than .001, and the Absolute Auditory Threshold, r(40) = .45, p less than .005. Both results proved general across sex. These findings, that high-sensation seekers tend to be reducers and to lack sensitivity to weak stimulation, were interpreted as supporting strength-of-the-nervous-system theory more than the formulation of Zuckerman and his associates.     

The reliability and concurrent validity of alternative methods for assessing ego development

This study demonstrates that an unstructured interview (INT) and the Thematic Apperception Test (TAT) are suitable alternatives to Loevinger's Sentence Completion Test of Ego Development. Seventy subjects were solicited from six groups varying widely with respect to age and education level. Each subject was asked to complete the SCI, an INT and the TAT. Two raters using Loevinger and Wessler's self-training exercises and Loevinger, Wessler, and Redmore's scoring manual rated subjects' responses to each instrument. Reliability was found between raters and concurrent validity between instruments. Subjects scoring high on the SCT were found to score higher on the INT and TAT.     

Factor analysis of the interpersonal trust scale with a noncollege population

This study tested the invariance of the factorial structure of Rotter's Interpersonal Trust Scale (ITS) in a noncollege population. Exploratory factor analysis of the responses of 214 volunteers yielded three factors interpreted as Exploitation, Sincerity, and Institutional Trust. This factor solution was cross-validated in a confirmation sample of 196 volunteers. Cosines between corresponding factors were high across samples and across sex. The similarity was pointed out between the present factor structure and the results of earlier studies with college students. Implications for possible refinement of the ITS were discussed.     

A critique of Plomin and Foch's "A Twin Study of Objectively Assessed Personality in Childhood"

Plomin and Foch's (1980) study of objectively assessed personality in childhood is critiqued on five points: (a) conceptual validity of the measures, (b) stability of the measures for the population age range, (c) comparability of populations, (d) accuracy of literature review, and (e) appropriate interpretation of broad heritability data. The Plomin and Foch study contains major errors; it is theoretically and methodologically flawed. Their report is especially significant because it is representative of problems critical to the study of the genetic correlates of personality.