Home start: Third-grade follow-up assessment of a family-centered preschool enrichment program

This study compared third-grade achievement test scores of participants in vertical Home Start (VHS), a preschool individualized program for children from 2 to 5 years of age; with comparable scores of their older and nonprogram siblings. Nonparametric rank ordering assessment revealed significant trends for black VHS children to attain higher rankings on 11 of the 15 subtest measures; no significant ranking differences were obtained with white children. Results indicate that, especially for black children, home-based preschool enrichment may more effectively promote growth in math and basic skills areas related to Cattell's crystallized intelligence, with more limited enrichment effects in such language-linked subject areas as vocabulary and reading.     

The characteristics of iron in high frequency magnetic fields

Not many years ago it was quite generally believed that iron was unable to follow rapid magnetic changes. Experiments which showed an apparent decrease in the permeability of the iron with an increase in the frequency of the magnetic cycle furnished a basis for a theory that iron was magnetically sluggish. Further and more accurate experiments proved, however, that the effects which had previously been ascribed to a peculiarity of the material were in reality caused by eddy currents in the sample. Theoretical calculations were made which demostrated that eddy currents in an iron test piece increased as the square of the frequency and that for even the lower frequencies it was necessary to use quite thin laminations in magnetic circuits in order to eliminate deleterious effects. Furthermore, it was found that due to eddy currents and the magnetic properties of iron, the magnetization in high frequency fields was confined to a thin surface layer of the piece. This “Magnetic Skin Effect” reduced the cross section of the iron which was magnetically active even though the laminations were extremely thin. Careful experimental measurements compared with theoretical calculations proved that the real permeability of iron remained unchanged at frequencies up to about 10⁶ and that previous results had been is serious error due to neglect of the factors mentioned. This fact having been established, efforts were made to see what practical use could be made of iron in high frequency work and to that end some extensive experimental investigations of the saturation curves and core losses were made upon specimens laminated as thinly as was commercially practicable. The resulting data have furnished a basis for design.It is a demostrated fact that the permeability of all metals is unity for the magnetic cycles imposed upon them by heat and light waves. In the region between frequencies of about 10⁶, where the true permeability of iron is practically the same as at zero frequency, and frequencies of about 10¹⁰ where the true permeability of iron approaches unity, the experimental values of μ decrease smoothly with the frequency. What happens to μ in the range of frequencies between the lingest heat waves and the shortest Hertzian waves which have yet been made is a question which has many interesting features but which has not yet yielded to the experimenter.     

Perceptions of personal and familial adjustment by children from intact,single-parent,and reconstituted families

The present study investigated children's (N=566) personal and familial adjustment, and sought to determine if this varied as a function of familial configuration and gender. More specifically, these children were surveyed across a broad range of adjustment measures, including self-concept, perception of school adjustment, home adjustment, peer relationships, state and trait anxiety, as well as their evaluations of mother, father, and family. The results from these measures revealed: (a) less positive adjustment among children from divorced families (whether the remaining parent remarried or not) as opposed to children from intact families; (b) mixed findings regarding comparisons of psychosocial adjustment between single-parent and remarried groups; and (c) a pattern of effects related to significant interactions of family type and gender in which males appeared to be favorably affected within the single-parent configuration, while females were more favorably adjusted within the reconstituted family.     

FM: Clinically meaningful rorschach index with minority children?

Recent court actions have spurred psychologists to develop improved assessment tools and to utilize diagnostic measures that take into consideration developmental and affective growth patterns of disadvantaged and minority youth. The present study, working through a case vignette, has weighed the possibility that the FM index may serve as a forerunner of abstract thinking, or the capacity to internalize imagery, which, in Rorschach theory, is, with older subjects, best illustrated in M. Findings also suggest that the Z (Organizational Activity) index may not be useful in evaluating intellectual potentials of preschool minority children. Following blind analysis of the Rorschach, replicative data were obtained through a social history and an individually-administered ability test. Data from these sources support the major finding that FM may enable educational diagnosticians to estimate more accurately the intellectual capabilities of some preschool minority and other culturally disadvantaged children.     

Classically conditioned tail flexion in rats: CR-contingent modification of US intensity as a test of the preparatory response hypothesis

A classically conditioned tail flexion in rats with a white noise as the conditioned stimulus and a tailshock as the unconditioned stimulus is shown to arise as a result of contingent presentation of the two stimuli rather than from sensitization or pseudoconditioning. After achieving an asymptote for conditioned tail flexion, different groups received response-contingent tail-shock increment, decrement, or omission. None of these treatments appreciably altered the probability of a conditioned response. Evidence is presented demonstrating that the response was sensitive to changes in the relationship between the stimuli and that the subjects could differentiate the various shock levels. The present data are viewed as inconsistent with the preparatory response hypothesis, which posits that classically conditioned behavior depends upon intrinsic reinforcement of components of the conditioned response syndrome. The possibility is discussed that classically conditioned responses observed in the laboratory are often only part of a larger, perhaps more clearly instrumental, set of behaviors that would occur in the unrestrained animal.     

Trial spacing effects in pavlovian conditioning: A role for local context

Two conditioned lick-suppression experiments with rats were conducted in order to replicate and extend findings by Ewing, Larew, and Wagner (1985). Ewing et al. observed that excitatory responding to a CS paired with a footshock US was attenuated when the ITIs thatpreceded each CS-US trial were short (60 sec) relative to when they were long (600 sec). This effect was isolated in the influence of the preceding ITI because the preceding ITI was consistently short for one CS and consistently long for a different CS, while the following ITIs were equally often short and long for both CSs. Ewing et al. interpreted this finding in the framework of Wagner’s (1981) SOP model. Experiment 1 replicated this trial-spacing effect and demonstrated a similar effect under conditions in which thefollowing ITI was consistently short for one CS and consistently long for a different CS, while the durations of preceding ITIs were equally often short and long for both CSs. Experiment 2 revealed that the detrimental effect of a short preceding or a short following ITI could be alleviated by extinguishing the conditioning context after CS-US training. The latter observation indicates that the trial-spacing effect is not mediated by a failure of a CS trained with a short ITI to enter into excitatory associations with the US, a conclusion that is not wholly consistent with the SOP model. Finally, we suggest that short pretrial and short posttrial ITIs may enhance the excitatory value of local context cues that modulate responding to a CS.