This paper suggests that, at present, a science of natural developmental processes does not exist because few studies are concerned with development as it transpires in naturalistic environments and because truly developmental data are not collected or analyzed. (Author/JMB)

This critique points out weaknesses regarding the test measures used by Munsinger and Douglass and questions the validity of these measures for the ages of the children used in their study. (JMB)

Results are discussed in terms of why children of the same age fail to conserve number in the standard conservation task and how complex number concepts might develop. (Author)

The logical extension of results may be valuable in adding to our understanding of the variety of phenomena involving mediational processes, such as transposition, reversal and nonreversal shifts, imagery, concept formation, word meaning, and the effectiveness of verbal stimuli in discrimination and generalization. (Authors)

Two field studies of high school students' sense of obligation to nonclass school activities are reported. "Sense of obligation" is conceived of as mediating some relations between the student and the school environment and is defined as a personal feeling of "I ought to..." or "I must...," i.e., a personal constraint, with reference to attending…

Quantitative growth curve models for estimating individual developmental functions from various types of longitudinal data are discussed in the context of investigator assumptions and research design characteristics. Linear and nonlinear models that estimate growth curves are illustrated, and contrasted when they are fit to speech development…