Detection of auditory signals occurring at random times: Intensity and duration

Observers attempted to detect a weak auditory signal presented in noise. The onset of the signal was determined by a Poisson process, and only responses occurring 1 sec after signal onset were considered detections. Three latency distributions were measured, the time to a signal onset, the reaction time distribution, and the false-alarm distribution (of responses occurring before a signal onset). A simple two-state model is proposed to account for a discrepancy between the distribution of signal waits and the distribution of false alarms. The hazard functions of the reaction time distributions are considered in detail and a simple accumulation model is proposed to account for the results.     

Two classes of models for magnitude estimation

One class of models assumes that presentation of a signal results in an internal representation as a random variable. Depending on whether the signal is close to or far from the preceding signal, the variance of the representation is smaller or larger. Responses are determined largely by this random variable; however, when the signal is close to the preceding one, the response is generated by modifying the representation multiplicatively by some function of the ratio of the previous response to its representation. Power and linear functions are explored. The form of the random variable is assumed to be that arising from either the timing or the counting model operating on a Poisson process. Detailed analyses are carried out successfully only for the timing model with neural sample sizes independent of intensity; however, the data require the sample to increase with intensity. The linear response function coupled with the constant sample size counting model appears somewhat viable, but detailed calculations are very difficult to carry out. The second class of models postulates a power function relation between magnitude estimates and signals intensity for which the exponent is a Gaussian distributed random variable and the unit is the product of two log normal random variables. Again we assume an attention band such that succesive stimuli that are widely separated in intensity lead to independent samples of the random variables while a variety of assumptions is explored for successive stimuli that are near each other in intensity. Although they each give rise to the qualitative features of the data, estimates of parameters are sufficiently inconsistent that we are led to reject all of the submodels studied.     

THE ROLE OF SELF-ESTEEM IN COMPETITIVE CHOICE BEHAVIOR1

Le rôle de L'estime de soi dans les choix compétitifs — Un programme transnational de recherche sur les déterminants des processus de décision s'est concentré dans une première phase sur la relation entre L'estime de soi et le comportement compétitif dans un jeu de type « Dilemme du prisonnier ». Des étudiants américains, chez lesquels une grande estime de soi avait été induite, firent davantage de choix compétitifs que les sujets chez lesquels on avait induit une faible estime de soi. Une des deux expériences avec des étudiants français a reproduit les mêmes résultats, alors que des expériences avec des sujets italiens ont produit des résultats inverses. Différentes interprétations théoriques des résultats sont proposées et critiquées.     

Predicting College Achievement of Students from Farm Backgrounds

Academic achievement in various types of colleges was studied for a statewide population of college freshmen from farm backgrounds. As a group, farm freshmen obtained lower scholastic aptitude test scores, had achieved higher grades in high school, and continued to achieve higher grades in college than did freshmen from other backgrounds. They did not appear to be handicapped by their lower verbal test scores. Patterns of academic achievement among farm students did not differ in most of the different types of colleges studied. Differing patterns were found among those farm students who attended certain colleges at the state university.