The acquisition of lever pressing by naive rats, in the absence of shaping, was studied as a function of different rates and unsignaled delays of reinforcement. Groups of 3 rats were each exposed to tandem schedules that differed in either the first or the second component. First-component schedules were either continuous reinforcement or random-interval 15, 30, 60 or 120 s; second-component schedules were fixed-time 0, 1, 3, 6, 12, or 24 s. Rate of responding was low under continuous immediate reinforcement and higher under random-interval 15 s. Random interval 30-s and 60-s schedules produced lower rates that were similar to each other. Random-interval 120 s controlled the lowest rate in the immediate-reinforcement condition. Adding a constant 12-s delay to each of the first-component schedule parameters controlled lower response rates that did not vary systematically with reinforcement rate. The continuous and random-interval 60-s schedules of immediate reinforcement controlled higher global and first-component response rates than did the same schedules combined with longer delays, and first-component rates showed some graded effects of delay duration. In addition, the same schedules controlled higher second-component response rates in combination with a 1-s delay than in combination with longer delays. These results were related to those from previous studies on acquisition with delayed reinforcement as well as to those from similar reinforcement procedures used during steady-state responding.
Los propósitos del presente estudio fueron construir una Escala de Claridad Subjetiva del Autoconcepto para adultos, y aportar evidencias de su configuración y red nomológica. Participaron 697 voluntarios de entre 18 y 60 años, residentes de la Ciudad de México y área metropolitana. El instrumento se construyó basándose en dos estudios exploratorios y en un modelo que propone que la claridad del autoconcepto (CA) se compone por la certeza, congruencia y estabilidad de las autodescripciones. Con base en la realización de análisis factoriales exploratorios y de consistencia interna, se obtuvo un instrumento conformado por 18 reactivos, distribuidos en cuatro factores que explican el 49% de la varianza, con una Alfa de Cronbach de .84. y con evidencias de validez convergente al estar relacionado con la autoestima. En conclusión, se aporta un instrumento con evidencias de validez y confiabilidad para medir la CA en México, el cual permitirá conocer el papel de este constructo para el bienestar y salud mental de los adultos.
The study determined the sensitivity of adults to detect subtle differences in male and female body parts (face, arms, chest, waist, hips, thighs and calves). A total of 202 adults (84 men and 118 women) with a mean age of 34.9 years adjusted the size of each part of a comparison silhouette until it matched that of a sample silhouette. The sensitivity to detect subtle differences was greater for the male than for the female silhouette (mean Weber Fractions, WF = .032, .036, respectively). The greatest sensitivity for both silhouettes was in the waist and hips (WF = .019 in both cases) and the smallest in the arms and face (WF = .048, .049, respectively). Men, young participants and those with high education (WF between .017 and .043) detected subtle differences to a greater degree than their counterparts (WF between .019 and .053). According to the environmental approach of social psychology, the latter suggests that members of those subgroups have been subjected to more social pressures to sharpen their discrimination of small differences in the body shape of their conspecifics. This study adds evidence to previous knowledge about how cultural variables shape visual perception.
Tanto con animales como con humanos se ha demostrado que el estrés puede causar daños en la salud. También se ha mostrado que algunas variables psicológicas modulan la relación entre el estrés y la enfermedad. En el presente trabajo se sumarizan los resultados de varios estudios realizados en México sobre distintas variables psicológicas relacionadas con la salud de las personas. Se mencionan resultados de estudios para validar cuestionarios para medir estrés vital y apoyo social percibido. También se muestra evidencia de que es factible medir el apoyo social como una auténtica variable independiente, utilizando los juicios de otras personas sobre su disposición para interactuar con un individuo. Se muestra evidencia de que las primeras personas que brindan apoyo son las responsables del efecto benéfico del apoyo social, mientras que prestadores de ayuda adicionales tienen efectos cada vez menos pronunciados. Se reseñan estudios que mostraron que al igual que en otras culturas el estrés tiene un efecto nocivo sobre la salud de los mexicanos y que el apoyo social mitiga dichos efectos nocivos. Diferente de otras culturas, en México la feminidad y no la masculinidad es el factor que mitiga los efectos dañinos del estrés, mientras que el afrontar los problemas no modula la relación estrés-enfermedad.
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