Stimulus factors in aversive controls: conditioned suppression after equal training to two stimuli

Pigeons trained to peck a key for food were periodically presented with tones ending with electrical shock until tone presentation consistently suppressed ongoing pecks. Shock was then discontinued and gradients of stimulus generalization were assessed by presenting tones with frequencies above, below, and at the frequencies of those used to develop conditioned suppression. When the training tones had frequencies at 670 and 1500 cps, resulting gradients were bi-modal with peak suppression at 670 and 1500 cps. Of the other test tones, 1000 cps produced the most suppression. When the training tones had frequencies at 450 and 2250 cps, bi-modal gradients were again obtained with peak suppression to the 450 and 2250 cps tones. Of the other test tones, 1000 cps produced the least suppression. These results support the hypothesis that generalized response tendencies summate.     

Lightness matching for different visual routes through a compound scene

Left and right halves of a visual display were covered with inducing fields (IFs) of different lightnesses. S’s monocular gaze moved over an irreversible route from a neutral Munsell target to a CO series through either the left- or right-side IFs. For the 16 Ss there were 8 different IFs, varying from light to dark. For each of three different gray targets Munsell CO choices varied directly with the lightness of the IFs through which the gaze was routed rather than with the lightness of the total presented display. A replication with modifications is also reported.     

Stimulus aspects of aversive controls: the effects of response contingent shock

A tone ending with electrical shock was periodically presented to pigeons while they pecked a key for food. Pairs of birds were run simultaneously under a yoked program which insured that both birds received the same number and temporal distribution of shocks. For one of the birds, shock was always initiated by a peck; for the other, shock was unavoidable. Both procedures led to reduced rates of pecking in the presence of the tone, and gradients of stimulus generalization were obtained. But the effects of response contingent shock extinguished more rapidly than the effects of unavoidable shock. In general, birds exposed to unavoidable shock tended to respond at intermediate rates throughout tone, whereas those exposed to response contingent shock ceased to peck for part or all of the tone period.     

Medium-chain acyl CoA dehydrogenase deficiency: Its relationship to SIDS and the impact on genetic counseling

Sudden infant death syndrome (SIDS) is defined as the sudden and unexpected death of an apparently healthy infant under 1 year of age. Routine autopsies often provide few clues as to the cause of death and rarely include a biochemical evaluation. Genetic counseling for SIDS can be difficult as recurrence risks vary depending on the age at death and the number of deaths which have occurred in the family. Biochemical disorders may account for up to 5% of SIDS. Of the metabolic disorders known to be involved in SIDS, the most commonly found is medium-chain acyl CoA dehydrogenase deficiency (MCAD). MCAD is an autosomal recessive disorder of fatty acid oxidation which accounts for up to 1% of SIDS. For some families, the addition of a postmortem biochemical investigation can identify an unsuspected metabolic disorder as the cause of death. Once the diagnosis is established, accurate genetic counseling can then be provided. Metabolic testing of the surviving siblings of victims of sudden death, and the subsequent identification of those due to MCAD can prevent the tragedy of recurrent SIDS in some families. In addition, screening the survivors of an acute life threatening event (ALTE) may also prevent a recurrence.     

Child and adolescent services research at the national institute of mental health: Research opportunities in an emerging field

This article describes an important new area of research on services for children and adolescents with mental disorders at the National Institute of Mental Health, the parameters of mental health services research for youth, and the opportunities that are available for grant-funded investigations in this area.     

Using focus groups to facilitate culturally anchored research

Scholars have acknowledged the need to anchor scientific knowledge about social and psychological processes in the norms, values, and experiences of the partticular population under study. This article describes how focus groups can be incorporated into the planning stages of a research pogram to facilitate these goals. After a brief overview of teh central components of focus group research, and example from a program of research involving dual-earner African American families is used to as an illustration. The article describes how (a) the identification of cultural knowledge and (b)access to the language participants use to think and talk about a topic can help researchers formulate a conceptual framework, identify important constructs, and develop appropriate instruments for assessing constructs. Some strengths and limitations of focus group research are discussed.     

The stability of individual differences in gender typing: Implications for understanding gender segregation

The stability of individual differences has important implications for understanding the origins of gender-typed behaviors. For example, if some children have a stronger preference for same-sex playmates (gender segregation) than do others, then exploring characteristics that may differentiate these children from their peers (e.g., preference for gender-typed toys or teacher proximity) should prove fruitful. Otherwise, research might be focused more appropriately on group-level processes or situational factors rather than individual differences. In the current study, 57 2 1/2- to 3-year-olds from middle-class Canadian homes were observed repeatedly during free play at their preschools. Four aspects of gender typing (gender segregation, use of masculine and feminine gender-typed toys, teacher proximity) were measured so that the stability of individual differences and relations among the measures could be assessed. Stable individual differences were found for all four measures among boys, and for two of the measures (feminine toy play, teacher proximity) among girls. In addition, boys who played most frequently with masculine toys rarely were observed in proximity to the teacher. However, there was no relation between gender segregation and the other indices of gender typing.