Youth suicide

The literature on youth suicide (ages 15-24) is surveyed for the period 1980-1985. Emphasis is placed on general determinants of suicide, predictors in the form of psychological tests, precipitating events (immediate causes), and signs--clues that may signify impending attempts at self-destruction. Suggestions for prevention, and limitations of research on suicide are offered.     

Keeping juvenile delinquents in school: a prediction model

The purpose of this study was to test an empirically based prediction model of school dropout on a sample of 137 juvenile delinquents, some who have dropped out and some who have remained in school. The specific factors among the many found in previous research that are salient for predicting whether delinquent youths will drop out or remain in school were determined. An important finding of this study is that it required only four factors to yield a high level of prediction: misbehavior in school, disliking school, the negative influence of peers with respect to dropping out and getting into trouble, and a marginal or weak relationship with parents. The four factors identified create a model that is directly applicable to prevention strategies and is extremely parsimonious.     

Left-handedness in twin families: support of an environmental hypothesis

Information on handedness, assessed as writing-hand, was collected from 197 MZ twin pairs and 203 DZ twin pairs and from their parents, spouses, and children. Associations for pairs of relatives were studied by 2 X 2 tables, computing chi squared-values and tetrachoric correlations. Correlations of about .3 were obtained for mother-offspring and sibling pairs, while for cousins the correlation was .25 (in a small sample). No other significant associations were found, not even for twins. These results suggest only a small, if any, genetic effect, and only a small environmental between family effect, most of which seems to be a maternal effect. The lack of cotwin correlations and correlations for one of the twins with her/his ordinary brothers/sisters suggest the existence of an effect specific to twins, since the correlation for pairs of ordinary siblings is significant. Conclusions drawn from twin studies alone may be biased. The frequency of left-hand writers has increased from 1% to 10% in the different age groups born during the last century in Norway. This age effect is present mainly in hand writing and not so much in handedness generally, suggesting a decrease in cultural repression against left-hand writing.     

Handedness and dementia

Some researchers have speculated that left-hand dominance is more prevalent among patients suffering from dementia of the Alzheimer's type which began prior to age 65 yr. and that, in those patients, the disease runs a more rapid course. In the present study, seven left-handed dementia patients were matched with seven right-handed dementia patients on the basis of age and years of education and were compared with regard to neuropsychological compromise. While the left-handed group was somewhat more impaired than the right-handed subjects, the difference between the two groups was not statistically significant.     

Intellectual functioning and aggression

In a 22-year study, data were collected on aggressiveness and intellectual functioning in more than 600 subjects, their parents, and their children. Both aggression and intellectual functioning are reasonably stable in a subject's lifetime and perpetuate themselves across generations and within marriage pairs. Aggression in childhood was shown to interfere with the development of intellectual functioning and to be predictive of poorer intellectual achievement as an adult. Early IQ was related to early subject aggression but did not predict changes in aggression after age 8. On the other hand, differences between early IQ and intellectual achievement in middle adulthood were predictable from early aggressive behavior. A dual-process model was offered to explain the relation between intellectual functioning and aggressive behavior. We hypothesized that low intelligence makes the learning of aggressive responses more likely at an early age, and this aggressive behavior makes continued intellectual development more difficult.     

Spatial constraints on attention to speech in the blind

When sighted persons try to identify one of two speech utterances coming from different directions, they display both a frontal position advantage, i.e., better recognition of inputs from the front than of those from the rear, and a right-side advantage, better recognition of inputs from the right than of those from the left. The present study demonstrates a dissociation of the two effects in blind subjects (N = 10) who showed no frontal position advantage together with a right-side advantage superior to that of control sighted subjects (N = 16). There was no systematic difference between congenitally blind subjects and noncongenitals. The absence of frontal position advantage in the blind is consistent with the notion that this effect originates in the habit of sighted listeners to orient toward the source of heard speech. The occurrence of at least normal right-side advantage in the blind does not support recent suggestions of reduced lateralization of language functions in such subjects.     

The spacing effect in 4- to 9-year-old children

Experiment 1 of the current research failed to replicate Toppino and Di George’s (1984) finding that older children but not preschoolers showed a spacing effect. Instead, we obtained the spacing effect in all the age groups tested (preschool, kindergarten, first-grade, and third-grade children). The effect was demonstrated with two types of material, words and pictures. Experiment 2 focused on the role that very brief spacings, with no intervening items between repetitions, play in later retention. Age groups and materials were the same as in Experiment 1. Four different levels of spacing were included (0-, 1.1-,2.5-, and 5-sec intervals). The spacing effect was again obtained for all age groups with both words and pictures. The results of both experiments suggest that the spacing effect does not emerge with development.     

Long-term memory formation in chicks is blocked by 2-deoxygalactose, a fucose analog

When day-old chicks are trained on a passive avoidance task there is enhanced synthesis of glycoproteins. Bilateral intracerebral injections of 20 mumole of 2-deoxygalactose (2-D-gal), administered just before and just after training on the task, produce amnesia for the avoidance. Amnesia develops slowly over the first hour and persists for at least 24 h subsequently. If 2-D-gal injections are administered 4 h prior to the training or delayed for 3 h after training, no amnesia occurs. Apart from a brief initial suppression of pecking following injection there are no effects of 2-D-gal on other observed behaviors of the birds. Within the first hour this dose of 2-D-gal inhibits [3H]fucose incorporation into acid-insoluble material by 26% (or 68%, calculated relative to free pool fucose). The amnestic effect of 2-D-gal is not shown by galactose, glucose, fucose, or 2-D-glucose. Injecting 40 mumole of galactose simultaneously with the 2-D-gal abolishes the 2-D-gal-induced amnesia; 40 mumole of fucose, however, does not abolish the amnesia. The utility of 2-D-gal as an agent for analyzing the role of glycoproteins in memory formation is discussed.