The examination of labels—a beginning

Unclear terminology is a major problem for the study of anomalies, and ambiguous definitions of reality and consciousness make it particularly difficult to discuss anomalous phenomena. Researchers have used the term near-death experience to describe four different kinds of incidents. To avoid confusion, we need new labels for experiences that differ in their relationship to death and near-death and in their transformative potential.     

Pilot personality and crew coordination: implications for training and selection

The performance of pilots can be construed as a product of skill, attitude, and personality factors. Although a great deal of effort within the aviation community has been focused on ensuring technical expertise, and new efforts highlight attitudes associated with crew coordination, personality factors have been relatively unexplored. Further, it is argued that past failures to find linkages between personality and performance were due to a combination of inadequate statistical modeling, premature performance evaluation, and/or the reliance on data gathered in contrived as opposed to realistic situations. The goal of the research presented in this article is to isolate subgroups of pilots along performance-related personality dimensions and to document limits on the impact of crew coordination training between the groups. Two samples of military pilots were surveyed in the context of training in crew coordination. Three different profiles were identified through cluster analysis of personality scales. These clusters replicated across samples and predicted attitude change following training in crew coordination.     

Second-order conditioning of the rabbit's nictitating membrane response. Interstimulus interval and frequency of CS-CS pairings.

Second-order conditioning of the rabbit's nictitating membrane response (NMR) was investigated when second-order trials (CS1-CS2) were intermixed with first-order trials (CS2-US) from the outset of training. Experiment 1 showed that CR acquisition to CS1 was inversely related to the CS1-CS2 interval but nevertheless extended to an interval of 8,400 ms. Experiment 2 revealed that CR acquisition of CS1 was an inverted-U function of the number of CS1-CS2 trials relative to a fixed number of CS2-US trials. Experiment 3 directly contrasted second-order conditioning with a reinforced serial compound procedure (CS1-CS2-US) and a mixed procedure in which second-order trials were intermixed with the reinforced serial compound. Second-order conditioning was about half the strength of either the reinforced serial compound or the mixed procedure, which were similar. The present results are discussed with respect to the relative strength of excitatory and inhibitory processes in second-order conditioning.     

Improving the retrieval of information from external sources

A major barrier to successful retrieval from external sources (e.g., electronic databases) is the tremendous variability in the words that people use to describe objects of interest. The fact that different authors use different words to describe essentially the same idea means that relevant objects will be missed; conversely, the fact that the same word can be used to refer to many different things means that irrelevant objects will be retrieved. We describe a statistical method called latent semantic indexing, which models the implicit higher order structure in the association of words and objects and improves retrieval performance by up to 30%. Additional large performance improvements of 40% and 67% can be achieved through the use of differential term weighting and iterative retrieval methods.     

Performance of humans in concurrent avoidance/positive-reinforcement schedules

Performance maintained under concurrent schedules consisting of a variable-interval avoidance component and a variable-interval positive-reinforcement component was studied in three human subjects using points exchangeable for money as the reinforcer. The rate of responding in the avoidance component increased, and the rate of responding in the positive-reinforcement component declined, as a function of the frequency of point-losses avoided in the avoidance component. The performance of all three subjects conformed to equations proposed by Herrnstein to describe behavior in concurrent schedules. The logarithms of the ratios of the response rates in the two components, and the logarithms of the ratios of the times spent in the two components, were linearly related to the logarithms of the ratios of the frequency of loss avoidance in the avoidance component to the frequency of reinforcement in the positive-reinforcement component. When a changeover delay of 5.0 sec was imposed, the slopes of the linear functions were close to 1.0 in the case of two subjects, whereas the third subject exhibited significant undermatching. For two subjects the changeover delay was then reduced to 2.0 sec; in both cases the slopes of the linear functions were lower than under the 5.0-sec condition. One subject participated in a third phase, in which no changeover delay was imposed; there was a further reduction in the slopes of the linear functions.     

The acquisition of observing.

Pigeons were exposed to stimuli correlated with the presence or absence of a variable-interval 60-second schedule of reinforcement only while they depressed a crossbar or "perch." In the first experiment, the stimuli were different tilts of a line displayed on the key. When the difference in brightness between the line and the background (salience) was maximal, seven of eight birds acquired the discrimination, but when the difference was reduced by 50%, only one succeeded. In the second experiment, wavelength of chamber illumination served as the relevant dimension. Neither experiment showed a large effect attributable to the magnitude of the difference (disparity) between the positive and the negative stimulus. Individual differences in time spent observing were positively correlated with level of discrimination in the presence of the stimuli. All birds produced the positive stimulus for a greater proportion of the available time than they did the negative stimulus. This may be the mechanism that provides selective reinforcement of observing. Finally, the formation of a discrimination was analyzed in terms of changes in the proportion of time spent in contact with the discriminative stimuli.     

JOB ATTRIBUTES PREFERRED BY FEMALE HEALTH PROFESSIONALS, BEFORE AND AFTER ENTERING THE WORK FORCE

A longitudinal study of 125 female health professionals' preferences for 12 job characteristics was carried out at graduation and 20 months later. After employment respondents placed increased importance on skill development and respect received, and less emphasis on security and promotion opportunities. At follow-up the most valued attributes were skill development, chance to accomplish something worthwhile and friendliness of co-workers, while physical surroundings, pay and promotion were ranked as least important. Self concept measures derived from Bern's Sex Role Inventory (1974) had not changed since graduation. In both surveys, a significant association was found between masculinity and the importance attached to taking part in decisions. The results contribute to the debate concerning the intrinsic-extrinsic dichotomy in work motivation.