Discrimination between outcomes in instrumental learning: Effects of preexposure to the reinforcers

In two experiments rats received instrumental training with two response levers, one response being reinforced by sucrose solution and the other by sucrose pellets. Prior to a test session, on which both levers were made available in the absence of reinforcement, the rats were given free access to one of the reinforcers, a procedure known to reduce its value. It was found that the rats responded at a lower rate on the lever that had produced the now-devalued reinforcer, but that this effect was substantial only in rats that had received preexposure to the two reinforcers before instrumental training was begun (Experiment 1). Experiment 2 demonstrated that this effect was obtained only when presentations of the two reinforcers were presented according to an inter-mixed schedule during preexposure. It is suggested that this result constitutes an instance of the perceptual learning effect in which intermixed preexposure to similar events enhances their discriminability.     

SIMILARITIES AND DIFFERENCES IN WOMEN'S SEXUAL ASSAULT EXPERIENCES BASED ON TACTICS USED BY THE PERPETRATOR

Only a few studies have examined the characteristics of sexual assault based on the tactics used by the perpetrator. In this study we compared the experiences of women who were forced to engage in vaginal, anal, or oral intercourse due to verbal coercion, physical force, or intoxication. Random-digit dialing was used to obtain a sample of 272 single African American and Caucasian women between the ages of 18 and 49 from the Detroit metropolitan area. Participants completed a computer-assisted self-interview that asked detailed questions about a past sexual assault and their reactions to it. Among the 139 women who were forced to engage in vaginal, anal, or oral intercourse, sexual assaults that involved physical force produced the most severe negative outcomes. Situations that involved the woman being too intoxicated to resist differed from others primarily in terms of how much alcohol the man and woman consumed. Although all types of sexual assault were perceived as being at least moderately serious, verbally coerced assaults were on average perceived as being least serious. These findings suggest that the perpetrators' tactics affect women's responses to sexual assault.