Eyewitness testimony and memory distortion

Abstract: Do memories change as we acquire new information? Recent research on memory distortion using implicit tests along with research using confidence is reviewed and new studies are presented. Two new studies asked misinformed subjects to provide reasons for their answers. In each study 15% to 27% of subjects said they remembered seeing items they had only read about. In another study subjects were asked to identify the source of misleading items they had seen in slides or read in misleading questions. Subjects were more likely to say they had seen in slides something they read about in the questions than they were to confuse information from two nearly identical sets of slides. Recent work shows that, not only is it possible to distort memory for events, it is possible to implant an entire memory for something that never happened. The evidence is now clear that we can become mentally tricked into making large as well as small changes in the way we recall the past.     

Discrimination of methadone and cocaine by pigeons without explicit discrimination training.

Pigeons were trained to peck a key on a variable-interval 2-min schedule of food reinforcement. Prior to each session, either 2.0 mg/kg methadone (n = 3), 3.0 mg/kg cocaine (n = 4), or 5.6 mg/kg cocaine (n = 2) was administered. When each pigeon's rate of pecking was stable, a range of doses of the training drug and saline were administered prior to 20-min extinction sessions separated by at least four training sessions. Rate of pecking during these extinction tests was generally an increasing function of dose, with the lowest rates obtained following saline and low doses and the highest rates obtained following doses near the training doses. Dose functions from pigeons trained with 5.6 mg/kg cocaine were steeper than those from pigeons trained with 3.0 mg/kg cocaine. Pigeons trained with methadone or 3.0 mg/kg cocaine were then given discrimination training, in which food reinforcement followed drug administration and 20-min extinction sessions followed saline administration. Rates of pecking under these conditions quickly diverged until near-zero rates were obtained following saline and high rates were obtained following drug. Discrimination training steepened dose functions for the training drugs, and the effects of several other substituted drugs depended on the pharmacology of the training drug. The pigeons trained with 5.6 mg/kg cocaine were tested with d-amphetamine, methadone, and morphine prior to discrimination training. d-Amphetamine increased rates dose dependently, and methadone and morphine did not. The results suggest that discriminative control by methadone and cocaine was established without explicit discrimination training.     

Effects of cocaine on briefly signaled versus completely signaled delays to reinforcement.

Key pecking by 4 pigeons was maintained by a multiple schedule consisting of two variable-interval 60-s schedules wherein each food presentation followed a nonresetting 27-s delay that was either briefly signaled at its outset or completely signaled. Brief-signal duration was adjusted so that response rates maintained by the briefly and completely signaled delays of reinforcement were similar. In general, acute administration of small to intermediate doses (0.3 to 3.0 mg/kg) of cocaine produced either small increases in response rates in both components or no change, and larger doses (5.6 to 13.0 mg/kg) decreased response rates. Chronic (i.e., daily) cocaine administration (10.0 mg/kg) resulted in tolerance to the rate-decreasing effects in both components. Cocaine's effects were generally similar whether delays were completely or briefly signaled. Discontinuation of cocaine administration and subsequent removal of the delay signals also had similar effects in both components of the multiple schedule. Taken together, these results are consistent with the view that the two types of delay signals were equally effective in maintaining responding during the variable-interval schedules.     

Substitution and caloric regulation in a closed economy.

Three experiments were conducted to study the effect of an imperfect substitute for food on demand for food in a closed economy. In Experiments 1 and 2, rats pressed a lever for their entire daily food ration, and a fixed ratio of presses was required for each food pellet. In both experiments, the fixed ratio was held constant during a daily session but was increased between sessions. The fixed ratio was increased over a series of daily sessions once in the absence of concurrently available sucrose and again when sucrose pellets were freely available. For both series, increases in the fixed ratio reduced food intake, but body weight was reduced only in the no-sucrose condition. In the sucrose condition, body weight and total caloric intake (sucrose plus food) were relatively unaffected by increases in the fixed ratio. At all fixed ratios, food intake was proportionally reduced by the intake of sucrose. In Experiment 3, monkeys obtained food or saccharin by pressing keys; the fixed ratio of presses per food pellet was increased once when tap water was each monkey's only source of fluid, again when each monkey's water was sweetened with saccharin, and a third time when each monkey had concurrent access to the saccharin solution and plain water. Increases in the fixed ratio, but not the intake of the saccharin solution, reduced each monkey's food intake. Because neither rats' sucrose nor monkeys' saccharin intakes affected the slope of the respective demand curves for food, monkeys and rats increased their daily output of presses and thereby defended their daily intake of those complementary elements of food. However, sucrose reduced rats' food intake. The relative constancy of body weight and total caloric intake in the sucrose condition is consistent with the possibility that rats tended to regulate caloric intake.     

Propensity to Sexually Harass: An Exploration of Gender Differences

This research explored the propensity ofpredominantly white male and female college students toengage in severe forms of sexual harassment. Inaddition, this research assessed the extent to whichmales' and females' intentions to harass are based onsimilar aspects of harassment situations. Resultsindicated that males had significantly higherpropensities to harass members of the opposite sex thanfemales. Additionally, the distributions of male andfemale scores on an instrument measuring propensity toharass were significantly different. Finally, analysessuggested that males and females attended to different aspects of harassment situations. Femalesappeared to attend to the nature of the powerrelationship between the potential harasser and target,which they defined more broadly than males, whereasmales attended to the sexual aspects of thesituation, which they defined more broadly than females.These results are discussed and their implicationsconsidered.     

LTP诱导期向维持或转化过程中的突触形态学特征

该研究探讨了视皮层ＬＴＰ由诱导期向维持期转化过程的突触形态学特征。实验选用１８－３０天龄的健康ＳＤ大鼠,分实验组、空白对照组及实验对照组进行电镜观测和图象分析。结果发现,在常规ＬＴＰ实验程序中强直刺激后有ＬＴＰ产生并记录８０分钟的实验组脑片标片,局部有界面曲率大于２的较大Ｕ型突触形成,这种突触多有两个以上活性区。图象分析结果显示,实验组与对照组相比较,突触的界面曲率明显增大（Ｐ〈０．０５）,活性区     

Treatment of traumagenic beliefs among sexually abused girls and their mothers: An evaluation study

The objective of this study was to evaluate and compare the efficacy of two short-term individual therapy interventions for sexually abused girls and their nonoffending female caretakers. Thirty-two girls, ages 8 to 13, and their caretakers from primarily low-income, African-American families were randomly assigned to a theoretically based, structured experimental treatment program or to a relatively unstructured comparison intervention. Measures of child outcome were completed before and after the treatment program by each parent and child, and by a clinician blind to treatment condition. Pre- and postmeasures of maternal outcome were completed by the caretaker and a clinician not involved in the treatment. Both treatment programs yielded decreases in children's posttraumatic stress disorder symptoms and traumagenic beliefs reflecting self-blame and powerlessness, and increases in children's overall psychosocial functioning. The experimental intervention was more effective than the comparison program in increasing abuse-related caretaker support of the child and in decreasing caretaker self-blame and expectations of undue negative impact of the abuse on the child. Clinical impfications of these findings include the development of interventions targeting sexually abused children's traumagenic beliefs and nonoffending parents' support of their victimized children.This research was supported by the Emory Medical Care Foundation and the Children's Trust Fund of Georgia. Preliminary findings were presented at the Society for Research in Child Development, New Orleans, March 1993.The authors thank the clinic families, volunteer therapists, and project staff members whose work together made this research possible. Core project staff members other than the authors include Milonne Ambroise, Mary Lynn Dell, Sherry Dey, Beth Dreelin, Jenny Gould, Katherine January, Suzann Lawry, Marie Simmons, and Lisseth Rojas.     

Characteristics and consequences of help-giving practices in contrasting human services programs

Relationships between human services program models and help-giving practices, and between both program models and help-giving practices and help-seeker control appraisals were examined in a study of 107 low socioeconomic background families. Three kinds of human services agencies were included in the study, each of which differed in terms of their implicit and explicit assumptions about the families they served and the roles professionals and families played as part of helping relationships. Results support the hypotheses that (a) a program philosophy that was family centered would be associated with more empowering help-giving practices compared to more professionally centered philosophies and (b) a family-centered program philosophy and empowering help-giving practices would be related to an enhanced sense of personal control over needed supports and resources from a target help-giver.