PubMed · 11958101
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C Emery. Pectus deformities: causes and effects.. https://pubmed.ncbi.nlm.nih.gov/11958101/
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Psychological distance to reward, or the segmentation effect, refers to the preference for a terminal link of a concurrent-chains schedule consisting of a simple reinforcement schedule (e.g. fixed interval [FI] 30s) relative to its chained-schedule counterpart (e.g. chained FI 15s FI 15s). This experiment was conducted to examine whether the segmentation effect is due to the number of terminal-link stimulus and response segments per se. Three pigeons pecked under a concurrent-chains schedule in which identical variable-interval (VI) schedules operated in the initial links. In each session, half the terminal-link entries followed one initial-link key and the other half followed the other initial-link key. The initial-link keys correlated with the different terminal links were manipulated across conditions. In the first three conditions, each terminal link contained a chained fixed-time (FT) FT schedule, and in the final three conditions, each terminal link contained a chained FI FI schedule. In each condition, in one terminal link (alternating), the order of two key colors correlated with the different schedule segments alternated across terminal-link entries, whereas in the other terminal link (constant), the order of two other key colors was identical for each entry. With the chained FT FT schedule terminal links, there was indifference between the alternating and constant terminal links within and across pigeons, as indexed by initial-link choice proportions. In addition, terminal-link response rates were relatively low. With the chained FI FI schedule terminal links, for each pigeon, there was relatively more preference for the alternating terminal link and terminal-link response rates increased relative to conditions with the chained FT FT schedule terminal links. These data suggest that the segmentation effect is not due simply to the number of terminal-link stimulus or response segments per se, but rather to a required period of responding during a stimulus segment that never is paired with reinforcement.
Sibling illness may contribute to an increased risk of adjustment problems in healthy siblings. Previous studies have reported a variety of effects on healthy individuals who have an ill sibling, but the psychosocial effects of treatable inherited disease on healthy siblings have not yet been investigated. We report the results of a survey study conducted in families with both unaffected and affected children with classic phenylketonuria (PKU), an inherited inborn error of metabolism. The survey included a knowledge test about PKU, and four previously validated instruments designed to assess psychosocial adjustment of unaffected siblings compared to age and sex matched norms. The responses revealed that unaffected adolescent and adult siblings had gaps in their knowledge about the genetic basis of PKU, and had evidence for the presence of adverse psychosocial sequelae. These findings suggest a role for genetic services providers, including genetic counselors, in assisting all members of a family adjust, when the diagnosis of an inborn error of metabolism has been made.
Since predictive testing has been available for Huntington disease (HD) and similar adult-onset neurodegenerative disorders, research into the psychosocial impact of test results has focussed on those receiving results, and to a lesser extent, on their partners. Few studies have examined the impact of predictive testing on the couple relationship, particularly from the perspective of family systems theory. This longitudinal study compared the level of marital adjustment of 23 couples in which the at-risk partner is undergoing predictive testing for HD (the testing group) with that of 20 couples in which the at-risk partner is not undergoing testing (the non-testing group). Participating couples completed a relationship measure, the Dyadic Adjustment Scale, at baseline and on two subsequent occasions. Using non-parametric tests, comparisons were made at each phase between the couple scores of the testing and non-testing groups but no significant differences were found in the levels of marital adjustment. Within the testing group the same comparisons were made for the carrier and non-carrier subgroups, and a significant difference was found at the final phase. There was an increase in the level of marital adjustment for the carrier group and a decrease for the non-carrier group. Together with trends observed in the data, this finding suggests a need for greater attention to be given to the potential impact of predictive testing on the couple relationship. Offering couples pre-result relationship assessment and referral for couple therapy, if warranted, may enhance the quality of professional support during the predictive testing process.