Teenage parenting in different cultures,family constellations,and caregiving environments: Effects on infant development

Teenage parenting was investigated in different ethnic groups (Cuban and American Black), family constellations (single-parent, nuclear, and extended families), and primary caregiving arrangements (mother versus other). One hundred sixty-four infants born to a representative sample of teenage mothers were observed during interactions with their mothers and were given developmental assessments when they were 12, 18, and 24 months of age. Being a Cuban mother, living in a nuclear family, and being a secondary caregiver were each associated independently with stronger social support systems and more positive child-rearing attitudes and mother-infant play interactions. Despite these early advantages, maternal stimulation and infant performance decreased over the second year of life irrespective of ethnic group, family constellation, and caregiving arrangements.     

Structuring knowledge retrieval: An analysis of decomposed quantitative judgments

Subjects were asked to estimate the answers to 16 questions concerning uncertain quantities like, “How many people are employed by hospitals in the U.S.?” under five different aiding conditions. The most-aided group (Full Algorithm) was given a complete algorithm and asked to make estimates for all the parts of the algorithm and to combine the parts as indicated to arrive at an estimate of the desired quantity. The second group (Partial Algorithm) was given the same algorithm without indications of how to combine the parts. After making estimates of the parts, these subjects then estimated the desired quantity. The third group (List & Estimate) was asked to list components or factors they thought were relevant, make an estimate of each item on their list, and then estimate the desired quantity. The fourth group (List) was asked to make such a list, but they were not asked to make estimates of each item before making an estimate of the desired quantity. The fifth group received no aid. The results generally showed improved performance in terms of both accuracy and consistency across subjects with increasing structure of the aid. Generalization of these results to practical estimation situations is possible but limited by the need, in real situations, for the estimator to develop the algorithm, a task that was done here by the experimenters.     

Reliability of an idiographic Q-sort measure of defense mechanisms

Despite the important insights the concept of defense mechanisms may offer to our understanding of human behavior, no standardized definitions of defense mechanisms have been universally accepted. Inconsistencies in the definition and conceptualization of defense mechanisms has limited the practical utility of research involving these constructs. In addition, lack of interrater reliability, use of anecdotal evidence, and reliance on self-reports has retarded their investigation. Conducting methodologically rigorous investigations with a psychometrically sound instrument is the first step in addressing some of the issues concerning defense mechanisms and their theoretical postulates. This study was conducted to determine the reliability associated with the Defense-Q, an observer-based Q-sort measure of defense mechanisms. Thirty participants who had undergone an interpersonally stressful interview (the Type A Structured Interview; Rosenman, 1978) were rated by 11 trained coders, both for their use of the 25 defense mechanisms and for their ego strength. Reliability was assessed using Cronbach's alpha. Individual defense mechanisms demonstrated reliability ranging from .28 (undoing) to .92 (humor), with an average reliability of .73. Coder reliability ranged from .63 to .76, with an average of .69. These results indicate that defense mechanisms can be reliably assessed by the Defense-Q. Reliability of the Defense-Q is compared to existing observational measures of defense mechanisms.     

Spatial and contextual factors in human performance on the travelling salesperson problem

The travelling salesperson problem (TSP) provides a realistic and practical example of a visuo-spatial problem-solving task. In previous research, we have found that the quality of solutions produced by human participants for small TSPs compares well with solutions from a range of computer algorithms. We have proposed that the ability of participants to find solutions reflects the natural properties of human perception, solutions being found through global perceptual processing of the problem array to extract a best figure from the TSP points. In this paper, we extend the study of human performance on the task in order to understand further how human abilities are utilised in solving real-world TSPs. The results of experiment 1 show that high levels of solution quality are maintained in solving larger TSPs than had been investigated previously with human participants, and that the presence of an implied real-world context in the problems has no effect upon performance. Experiment 2 demonstrated that the presence of regularity in the point layout of a TSP can facilitate performance. This was confirmed in experiment 3, where effects of the internality of point clusters were also found. All three experiments were consistent with a global, perceptually based approach to the problem by participants. We suggest that the role of perceptual processing in spatial problem-solving is an important area for further research in both theoretical and applied domains.     

It looks easy! Heuristics for combinatorial optimization problems

Human performance on instances of computationally intractable optimization problems, such as the travelling salesperson problem (TSP), can be excellent. We have proposed a boundary-following heuristic to account for this finding. We report three experiments with TSPs where the capacity to employ this heuristic was varied. In Experiment 1, participants free to use the heuristic produced solutions significantly closer to optimal than did those prevented from doing so. Experiments 2 and 3 together replicated this finding in larger problems and demonstrated that a potential confound had no effect. In all three experiments, performance was closely matched by a boundary-following model. The results implicate global rather than purely local processes. Humans may have access to simple, perceptually based, heuristics that are suited to some combinatorial optimization tasks.     

Act first, think later: The presence and absence of inferential planning in problem solving

Planning is fundamental to successful problem solving, yet individuals sometimes fail to plan even one step ahead when it lies within their competence to do so. In this article, we report two experiments in which we explored variants of a ball-weighing puzzle, a problem that has only two steps, yet nonetheless yields performance consistent with a failure to plan. The results fit a computational model in which a solver’s attempts are determined by two heuristics: maximization of the apparent progress made toward the problem goal and minimization of the problem space in which attempts are sought. The effectiveness of these heuristics was determined by lookahead, defined operationally as the number of steps evaluated in a planned move. Where move outcomes cannot be visualized but must be inferred, planning is constrained to the point where some individuals apply zero lookahead, which with n-ball problems yields seemingly irrational unequal weighs. Applying general-purpose heuristics with or without lookahead accounts for a range of rational and irrational phenomena found with insight and noninsight problems.