Cognitive, perceptual, and personal-social development of prematurely born preschoolers

This study was designed to determine possible differences in the cognitive, perceptual, and personal-social development of prematurely and maturely born 3-yr.-olds which might foreshadow later learning problems. The subjects were 40 prematurely born graduates of a neonatal intensive care unit (birth weight less than 2,500 gm, less than 37 wk. gestation) matched on the pair-level with full-term controls on sex, race, post-conceptual age, and socioeconomic background. All subjects were singletons and parity was matched at the group level. No differences were found between the groups on tests of higher mental processes including the General Cognitive, Verbal, Quantitative, and Memory Scales of the McCarthy Scales of Children's Abilities, and researcher-devised measures of problem-solving competence. No differences in parental reports of personal-social development were noted. Prematures did not perform as well as controls on perceptual performance tasks, and this difference was interpreted as reflecting relatively impaired visual-motor coordination.     

Decisional processing in paranoid and non-paranoid schizophrenics

40 schizophrenic subjects, divided into paranoid/non-paranoid categories and 14 normal controls were presented a task which involved making "same-different" judgments during random presentations of a series of visual comparison stimuli with a standard which represented the midpoint of the stimulus continuum. Using Sternberg's Choice RT paradigm for studying the locus of cognitive deficit, difficulty at the response-selection stage was manipulated while holding other stages constant. It was predicted that paranoids would have shorter RTs at easy decision points and longer RTs at difficult decision points relative to non-paranoids. The directions of the differences were as predicted but did not attain statistical significance. Both schizophrenic groups, compared to normals, made significantly fewer "same" responses on those trials where the comparison and standard were most similar.     

Development of hand preference in the Colorado Adoption Project

A longitudinal study of the development of hand preference in 152 adopted and 120 nonadopted (control) infants measured in natural behavioral situations at both 12 and 24 mo. of age is reported. Significant developmental trends were observed for both increasing strength and direction of handedness. Less than 10% of the infants exhibited a clear preference at 12 mo. of age, whereas about 30% were lateralized at 24 mo., with more boys than girls being left-handed. In contrast, over 90% of the parents of these children (both biological and adoptive parents of the adopted children and parents of the nonadopted children) were lateralized. Perhaps because so few infants were lateralized at either age, parent-offspring resemblances were inconsistent and the number of significant parent/child correlations was about that expected on the basis of chance alone.     

Short-term memory for colors and color names in the absence of vocalization

In a previous experiment, Allen found no release from proactive inhibition using the Brown-Peterson procedure in a group who were shifted from recalling colors to recalling the names of colors. The lack of release suggests that colors and color names are encoded in similar ways. It was argued that the similarity of encoding might have been caused by the procedure of requiring the subjects to say out loud the names of the colors at the time of stimulus presentation and recall. In the present experiment, a procedure was devised that eliminated the need for verbalization of the colors. The same pattern of results was obtained, namely, release from proactive inhibition in the group shifted from recalling color names to colors but not in the group shifted in the opposite direction. It was concluded that if subjects encode colors as a verbal label, then this encoding strategy is not caused by the procedure of requiring the subjects to verbalize the colors.     

Determination of dipeptidyl aminopeptidase activities in the cerebrospinal fluid

The investigation of enzyme activity in cerebrospinal fluid has been without relevant results for laboratories analysing spinal fluid. For neurochemical purposes, it is interesting that the Substance P is convered by Depeptidyl-aminopeptidase IV (DP IV), liberating dipeptides. The hydrolysis of nitroanilids of the form Xaa-Pro-NHNp in cerebrospinal fluid was analysed using them as peptidases substrates. Finally a method for measuring the activity was proposed.