A methodological assessment and evaluation of dual-task paradigms

This article outlines three major assumptions often implicitly made in dual-task experiments conducted to assess attentional capacity requirements of memorial processes. These assumptions are shown to be incorrect. Three criteria which should be met in dual-task experiments that draw inferences from secondary task decrements are proposed: (1) there should be resource trade-off with the secondary task sensitive to the resource demands of the primary task; (2) there should be equivalence of single and dual primary task performance; and (3) the secondary task must remain resource sensitive throughout the experiment. An experiment was carried out in which the primary and secondary tasks were designed according to these criteria. The results demonstrate that when the criteria are met then secondary task performance can be predictive of primary task difficulty: however, the experiment also highlights the fact that a simple assessment of capacity will not predict total task performance.     

Paraconsistent algebras

The prepositional calculiC _n , 1 n introduced by N.C.A. da Costa constitute special kinds of paraconsistent logics. A question which remained open for some time concerned whether it was possible to obtain a Lindenbaum's algebra forC _n . C. Mortensen settled the problem, proving that no equivalence relation forC _n . determines a non-trivial quotient algebra.The concept of da Costa algebra, which reflects most of the logical properties ofC _n , as well as the concept of paraconsistent closure system, are introduced in this paper.We show that every da Costa algebra is isomorphic with a paraconsistent algebra of sets, and that the closure system of all filters of a da Costa algebra is paraconsistent.     

Cognitive factors in the development of sex-typed preferences

This study considered how children coordinate their understandings of gender identity and sex stereotypes to produce sex-typed preferences. Sex-typed preferences and gender constancy were assessed at ages 4 through 8 years on a cross section of urban black and white children (N=819). Findings verified that sex-stereotyped preferences are highly developed among young children prior to the period when gender constancy is fully developed. Additionally, by age 5, most children accurately attributed sex-stereotyped preferences to peers of the opposite sex. A distinction was made between a sex stereotype and a same-sex bias as a basis for a sex-typed preference. Gender constancy was shown to strengthen the same-sex bias as a determinant of a sex-typed preference, but this effect was context specific. Under certain conditions sex-stereotyped knowledge constrained the same-sex bias as a determinant of preferential choice.     

A variable-threshold,variable-gain,infrared photoplethysmograph

The design of a versatile, low-cost, hermetically sealed, infrared photoplethysmograph is described. The device can be used for optical readings of changes in blood volume which occur with cardiovascular events. Advantages of the device are discussed.     

The categorization of sentential contexts

A new experimental method, involving the sorting of linguistic contexts, is shown to be effective in discriminating the contexts of polysemous words as well as the contexts of synonyms of those words. These results are interpreted as support for the claim that the method of sorting linguistic contexts is a valid technique for studying the contextual information available to support inferences about word meanings.The research reported in this article was part of the author's work submitted as a doctoral thesis to Princeton University. It was supported in part by Contract MDA 903-86-K-0242 between the Army Research Institute and Princeton University. The views and conclusions in this article are those of the author and should not be interpreted as representing official policies, either expressed or implied, of the Army Research Institute or Princeton University.     

The coordination of limb movements with different kinematic patterns

The principles underlying the coordination of limb movements with different spatiotemporal features were explored. After an initial training session in which the same unidirectional movement had to be performed with both upper limbs, subjects attempted to coordinate two different movements in a second session, i.e., the learned unidirectional movement in the left limb and a new double reversal movement in the right limb. The findings uncovered a wide variety in patterns of interlimb dependence among and within subjects, going from a high degree of dependence to relative independence. The relationship between limbs was studied by means of a detailed analysis of the displacement and acceleration patterns and the electromyographic activity of the major muscles involved. The general underlying principle that appeared to account for the diversity in movement organization was this: higher independence between limb movements is achieved when subjects initiate the movements to be coordinated successively. This asynchrony in movement onset can possibly be viewed as an attempt to safeguard against interference.     

A portable biofeedback device for autonomic responses

The design of a versatile and programmable transducer amplifier device with analogue display for self-monitoring of autonomic responses is described. The design features low cost, portability, and flexibility across direct-current transducer options (e.g., photoplethysmograph or thermistor). The device can be used for the visual or auditory display of continuous blood volume pulse or temperature measures where the relative amplitude or pulse rate is of concern. Auditory or visual biofeedback may be provided via the choice of a stacked bar-graph display or piezoelectric buzzer. A common circuit design to allow programming options for the estimation of heart rate, inter-beat interval, or pulse duration is provided.     

Family constellations and friendship systems

An individual friendship system is composed of the friends a person has had and/or still has. Individual friendship systems can be characterized objectively in similar ways as can family constellations. The data of a questionnaire study of individual friendship systems and respective family backgrounds of more than 400 subjects revealed greater differentiation and variation with age as well as with the presumed absence of conflict, disruption, and loss in a person's social development. Various interactions between family backgrounds could be traced. To illustrate the practical use of characteristics of a person's individual friendship system two clinical cases matched for age and family background, one with a mild neurotic problem and the other severely disturbed, were compared.Based on a lecture first given at the Family Therapy Symposium of Georgetown University, Washington, DC, on November 9, 1986.