Discussion of “The Ketamine Model of the Near-Death Experience: A Central Role for the N-Methyl-D-Aspartate Receptor,” by Earl L. R. Jansen

We review strengths and weaknesses of Karl Jansen's approach to the near-death experience (NDE). Strengths include his limited goals and avoidance of the trap of explaining all features of the NDE with his theory, although he surprisingly misunderstood our previously published position. Additionally, we applaud the possible intersection of psychological and biological theories, demonstrated in Jansen's biochemical explanations for the individualized variations in manifestation and adaptive role of the NDE. However, he failed to take into account the pitfalls in the use of analogy, modeling oversimplification, and in taking association as causality and causes as meaningful, in the arguments for his theory.     

Expressing Intrinsic Motivation Through Acts of Exploration and Facial Displays of Interest

Intrinsically-motivated behavior has been defined through participants' task persistence, during a free-choice interval. While fruitful, this operational definition assesses only the person's postperformance reaction to an activity. Presumably, people experience and express intrinsic motivation during task engagement as well. The need therefore exists for a supplemental in-performance behavioral measure of intrinsic motivation. To test the viability of constructing such a measure, we recorded the extent to which five acts of exploration and four facial displays of interest corresponded to self-reports of interest, self-determination, and competence for 60 undergraduates as they solved SOMA puzzles. Correlational and LISREL analyses confirmed the validity of three acts of exploration and two facial displays of interest We concluded that just as task persistence is a valid postperformance indicator of intrinsic motivation, acts of exploration and facial displays of interest are valid in-performance indicators.     

Spatial frequency and the detection of temporal discontinuity in superimposed and adjacent gratings

The properties of the detecting mechanism involved in the resolution of temporal discontinuities of visually presented stimuli have been investigated in two experiments. In Experiment 1, observers made judgments of discontinuity when superimposed presentations of sine-wave gratings of 1, 3, 6, and 10 cycles/deg were presented for either a 20- or a 200-msec duration per presentation at a contrast of .1 and .4. Threshold separation for discontinuity detection indicated a linear increase as spatial frequency increased, with a lesser effect for longer duration exposure and higher contrast. Experiment 2 involved adjacent presentation of the second grating, and a small linear decrease in separation threshold as a function of increasing spatial frequency occurred. The effect of spatial frequency on temporal discontinuity detection is dependent on whether the second stimulus is superimposed or adjacent.     

An empirical test of two psychophysical models

Two theoretical relationships between sensitivity measures (Weber fractions, Ekman fractions, and their logarithms) and the exponents of the psychophysical power function were tested empirically with the brightness attribute. One model was based on Weber and Ekman fractions, the other on the logarithms of these measures. The stimulus parameters were time interval between standard and comparison targets and position of the standard in the luminance series. Weber fractions were based on data obtained by the method of constant stimuli, whereas Ekman fractions and exponents were based on data obtained by magnitude estimation. The results were in closer agreement with the theoretical predictions generated by the logarithmic model when group data were analyzed. With individual subjects, a detailed correspondence between fact and theory was not found with either model.     

An Examination of the Lost-letter Technique1

The results of three investigations of the validity and economics of the lost-letter technique are reported. Although the return rate of the lost-letter technique was higher than in the case of more obtrusive survey techniques involving hand-distributed postcard questionnaires and mail surveys, the more obtrusive survey techniques were more economical to carry out, were more accurate in their predictions of election outcomes, and gave results more highly consistent among themselves than with the results obtained by the lost-letter technique. Furthermore, the results indicated that the act of returning a lost letter may not be strongly affected by the identity of the sender or addressee indicated on the letter.     

Life Skills: Adolescents' Perceptions of Importance and Competence

A previous classification of life skills was used to suggest issues relating to areas of adolescents' concerns involving relationships, leisure, jobs, education, preparation for the future, work, budgeting, health, social responsibility, and personal skills such as planning and decision-making. A questionnaire relating these concerns to young people's perceptions of the facets of importance, and their own knowledge, competence, sense of improvement, problems, and striving, was administered to a sample of 1,084 adolescents in senior schools and colleges of technical and further education. The results suggested a strong general factor for each facet, with some differentiation into groups of skills. The mean ratings suggested that the skills investigated were considered to be very important by young people, who in general also seemed optimistic about their competence. However, a small proportion expressed serious problems. Responses to the various facets were further examined in terms of group differences — by age, gender, educational context, ethnicity, economic status, and educational expectations. Many small but significant group differences were isolated. Finally, implications are drawn from this related research for schools and colleges in general and for guidance and counselling in particular.     

Dissemination and evaluation of marriage education in the Army

The effectiveness of marriage education was evaluated in two separate samples of primarily married couples in which at least one member of the couple was on active duty in the U.S. Army. The intervention was delivered by Army chaplains. Effects replicated well in the two samples, and demonstrated that marriage education was well received by this population and resulted in improvements in relationship functioning. Changes in relationship quality were examined separately for males and females, and also for couples in which both members of the couple were Caucasian as compared with all other couples. There were no significant differences in changes over time (i.e., from pre- to postmarriage education) among males and females or among couples with different ethnic makeup. These results have important implications for the generalizability of marriage education to diverse samples in nontraditional contexts.