RESUMEN
Studies of temporal discrimination in non-human subjects have reliably shown a choose-short effect: higher matching accuracy on short-duration-sample trials than on long-duration-sample trials. This effect occurs as a function of increasing the delay between the onset of sample and comparison stimuli in a delayed matching-to-sample procedure. The present experiment investigated whether the choose-short effect could be demonstrated in human subjects under conditions which paralleled those used with non-human subjects. Subjects responded under a discrete-trial procedure in which they were required to push one of two buttons depending on the duration of a sample stimulus (a blue square on a computer monitor). Delays (0, 8, 16, and 32s) separated sample and comparison stimuli (two white boxes) and were tested both within and across several sessions. Intermediate durations (probe stimuli between 2 and 4s) were also presented. The addition of a delay between the sample and comparison stimuli produced a bias to judge intervals as short when the 8 and 32-s delays were tested across sessions and when the 0, 16, and 32-s delays were tested within the same session. Thus, the choose-short effect was produced in human subjects using the interval bisection procedure regardless of delay length.
Asunto(s)
Conducta de Elección/fisiología , Aprendizaje Discriminativo/fisiología , Memoria a Corto Plazo/fisiología , Percepción del Tiempo/fisiología , Adulto , Femenino , Humanos , Masculino , Tiempo de Reacción/fisiología , Valores de ReferenciaRESUMEN
Acute benzodiazepine administrations typically decrease aggressive responding, but increases in aggression have been reported in some studies. The benzodiazepine lorazepam has been studied less frequently than other benzodiazepines in aggression research, although it is often used to suppress violent aggression in patients. The present study was designed to investigate the effects of acute administrations of lorazepam on aggressive responding in adult humans on a laboratory aggression task. Eight adult males participated in experimental sessions on the Point Subtraction Aggression Paradigm (PSAP), which provided subjects with aggressive, escape and monetary-reinforced response options. Acute oral doses (1, 2 and 4 mg) of lorazepam decreased both aggressive responding and monetary-reinforced responding in seven of eight subjects. In one subject, lorazepam produced dose-dependent increases in aggressive responding. The effects of lorazepam on escape responding were the same as the effects on aggressive responding. The results are consistent with prior research using the PSAP and clinical data showing that benzodiazepines generally decrease aggression, and contrast with other studies that have shown that benzodiazepines can increase aggression. Since lorazepam affected both aggressive and escape responding, it is suggested that while lorazepam often produces sedation, it also modifies human aggressive responding, in part, by suppressing reactions to aversive stimuli.
Asunto(s)
Agresión/efectos de los fármacos , Ansiolíticos/farmacología , Psicología Criminal , Lorazepam/farmacología , Prisioneros/psicología , Adulto , Relación Dosis-Respuesta a Droga , Humanos , Masculino , Pruebas Neuropsicológicas , Refuerzo en PsicologíaRESUMEN
The present experiment examined the role of stimulus functions and degree of stimulus control on the effects of drugs on behavior maintained by clocked fixed-interval (CFI) schedules. Three pigeons pecked keys under a multiple fixed-interval (FI) 1-min, CFI 1-min schedule of food presentation (the FI CFI condition). During the FI component, the key was lit amber. During the CFI component, the key colors changed in a regular manner across the interval. Three other pigeons pecked keys under a multiple schedule in which a three-link chained FI schedule alternated with a yoked-CFI schedule (the chain yoked-CFI condition). During the chain component, three successive FI 20-s links were associated with different key colors. During the yoked-CFI schedule, the clock stimuli were the same duration as, or 'yoked' to, the corresponding link in the chain component. Therefore, key colors changed at the same times as in the chain component, but independently of key pecking. All pigeons received a range of doses of morphine (1.0-17.0 mg/kg) and saline. Baseline rates of responding during the FI and chain components were generally higher than during the CFI and yoked-CFI components. Morphine decreased overall response rates during all components. During the FI component, morphine increased response rates at the beginning of the intervals. Morphine did not disrupt the patterns of responding maintained during the CFI, yoked-CFI, or chain components, despite the fact that the chained schedule required responding early in the intervals. This finding suggests that external stimulus control plays an important role in determining the drug effects on behavior maintained by CFI or chained schedules.