Individual characteristics and career exploration in adolescence

The effects of gender, age and school grade on several career exploration dimensions measured by the Career Exploration Survey were investigated. Subjects were high school students facing an imminent career decision. Regression analyses indicated that sex and grade-level were the most significant and prevailing individual characteristics related to the adolescents' career exploration behaviours, reactions and beliefs. Implications for career exploration interventions are discussed.     

Suppes Predicates for Space-Time

We formulate Suppes predicates for various kinds of space-time: classical Euclidean, Minkowski's, and that of General Relativity. Starting with topological properties, these continua are mathematically constructed with the help of a basic algebra of events; this algebra constitutes a kind of mereology, in the sense of Lesniewski. There are several alternative, possible constructions, depending, for instance, on the use of the common field of reals or of a non-Archimedian field (with infinitesimals). Our approach was inspired by the work of Whitehead (1919), though our philosophical stance is completely different from his. The structures obtained are idealized constructs underlying extant, physical space-time.     

Improving adherence to medication regimens for children with asthma and its effect on clinical outcome.

We examined the effects of a combined education and token system intervention to improve adherence to inhaled corticosteroids for an 8-year-old girl and a 10-year-old boy with asthma. Adherence was measured by an electronic chronolog monitor, and disease outcome was assessed by repeated pulmonary function testing. A withdrawal design demonstrated improved adherence and, for 1 child, an associated improvement in pulmonary function occurred. Methodological and clinical implications are discussed, including variables other than adherence that may affect disease outcome.     

Sign- versus goal-tracking: effects of conditioned-stimulus-to-unconditioned-stimulus distance.

Three pigeons were exposed sequentially across experimental phases to five different distances between the conditioned stimulus and the site of the unconditioned stimulus in a sign-/goal-tracking procedure. A computer-controlled tracking system provided a continuous record of the bird's position by continuously monitoring the location of the bird's head in three-dimensional space. It was found that birds sign-tracked (i.e., approached the conditioned stimulus) when the conditioned stimulus was closest to the site of the unconditioned stimulus, goal-tracked (i.e., approached the site of the unconditioned stimulus in the presence of the conditioned stimulus) when the conditioned stimulus was farthest from the site of the unconditioned stimulus, and engaged in both sign- and goal-tracking (or something intermediate) at intermediate conditioned-stimulus-to-unconditioned-stimulus distances. When both sign- and goal-tracking occurred, the former tended to occur in the first half and the latter in the second half of the interval in which the conditioned stimulus was present. The results suggest (a) whether sign- or goal-tracking (or both) occurs is a function of the distance of the conditioned stimulus from the site of the unconditioned stimulus, (b) the fact that pigeons but not rats have been found to sign-track consistently throughout the duration of the conditioned stimulus may be due to quantitatively rather than qualitatively different effects of conditioned-stimulus-to-unconditioned-stimulus distance across species (i.e., a "short" conditioned-stimulus-to-unconditioned-stimulus distance for a pigeon may be a "long" one for a rat), and (c) sign- and goal-tracking may be competing behavioral tendencies that can (e.g., at intermediate conditioned-stimulus-to-unconditioned-stimulus distances) cancel each other out. The findings lend support to theories that specify an interaction between phylogenetic and reinforcement variables in determining whether sign- or goal-tracking will occur in any given experimental preparation.     

Ratio estimation of distance in a large open field

Psychophysical power functions were obtained from ratio estimation of apparent distance in a large open field with two ranges of distance. The findings showed that the exponent varied with the ranges of the distances, but less steeply than previously assumed by Kunnapas (1960). Comparisons with previous results furthermore showed that the exponents obtained from ratio estimation were greater than those obtained from magnitude estimation.