PREFERENCE FOR A STIMULUS THAT FOLLOWS A RELATIVELY AVERSIVE EVENT: CONTRAST OR DELAY REDUCTION?

Several types of contrast effects have been identified including incentive contrast, anticipatory contrast, and behavioral contrast. Clement, Feltus, Kaiser, and Zentall (2000) proposed a type of contrast that appears to be different from these others and called it within-trial contrast. In this form of contrast the relative value of a reinforcer depends on the events that occur immediately prior to the reinforcer. Reinforcers that follow relatively aversive events are preferred over those that follow less aversive events. In many cases the delay reduction hypothesis proposed by Fantino (1969) also can account for such effects. The current experiments provide a direct test of the delay reduction and contrast hypotheses by manipulating the schedule of reinforcement while holding trial duration constant. In Experiment 1, preference for fixed-interval (FI) versus differential-reinforcement-of-other-behavior (DRO) schedules of reinforcement was assessed. Some pigeons preferred one schedule over the other while others demonstrated a position (side) preference. Thus, no systematic preference was found. In Experiment 2, a simultaneous color discrimination followed the FI or DRO schedule, and following training, preference was assessed by presenting the two positive stimuli simultaneously. Consistent with the contrast hypothesis, pigeons showed a significant preference for the positive stimulus that in training had followed their less preferred schedule.     

Within-trial contrast: pigeons prefer conditioned reinforcers that follow a relatively more rather than a less aversive event

When behavior suggests that the value of a reinforcer depends inversely on the value of the events that precede or follow it, the behavior has been described as a contrast effect. Three major forms of contrast have been studied: incentive contrast, in which a downward (or upward) shift in the magnitude of reinforcement produces a relatively stronger downward (or upward) shift in the vigor of a response; anticipatory contrast, in which a forthcoming improvement in reinforcement results in a relative reduction in consummatory response; and behavioral contrast, in which a decrease in the probability of reinforcement in one component of a multiple schedule results in an increase in responding in an unchanged component of the schedule. Here we discuss a possible fourth kind of contrast that we call within-trial contrast because within a discrete trial, the relative value of an event has an inverse effect on the relative value of the reinforcer that follows. We show that greater effort, longer delay to reinforcement, or the absence of food all result in an increase in the preference for positive discriminative stimuli that follow (relative to less effort, shorter delay, or the presence of food). We further distinguish this within-trial contrast effect from the effects of delay reduction. A general model of this form of contrast is proposed in which the value of a primary or conditioned reinforcer depends on the change in value from the value of the event that precedes it.     

Creation of visual long-term memory

Currently, it is not known by which mechanisms novel visual representations are stored in long-term memory (LTM). Here we report evidence that visual working memory (WM) plays an important role in the formation of visual LTM. By varying exposure times and perceptual difficulty of the stimuli, we find that the rate-limiting factor constraining storage in LTM is the amount of information that can be simultaneously kept in WM, whereas the time needed to store this information into LTM is constant irrespective of the size of the WM content. These results support the hypothesis that visual WM serves as a gate for the storage of information into LTM.     

Primary and secondary effects of parenting and stress management interventions for parents of children with developmental disabilities: a meta-analysis

A meta-analysis of the group intervention research for parents of children with developmental disabilities was conducted in order to characterize the efficacy of treatments in reducing depressive symptoms and other forms of psychological distress associated with stress in parents of children with developmental disabilities. An extensive search led to the identification of 17 studies which were divided into three categories for comparative purposes: parenting education studies usually based on behavioral parent training, coping skills education studies based primarily on cognitive behavioral training, and studies that combined these methods along with other support services. Studies were rated for the quality of the research designs and of the reports. Consistent positive benefits were found in the form of reductions in parents' distress, and these effects were comparable to those reported in other syntheses of parenting interventions for parents of children without disabilities. The studies were evaluated in order to assess whether or not they met standards for established evidence-based practices. On the basis of the quality and number of the randomized trials, we present evidence to support the claim that there are established evidence-based interventions for reducing psychological distress at least in middle-class mothers in the short term. The interventions for fathers are promising as are the data on somewhat longer-term effects. The need for replications with a more diverse group of parents and longer-term follow-up were discussed. Multiple component interventions addressing both parent well-being and behavioral parent training were significantly more effective than either behavioral parent training or cognitive behavioral training along.     

Suicide and Its Association with Individual,Family, Peer,and School Factors in an Adolescent Population in Southern Taiwan

A representative sample of 10,233 adolescent students was recruited to examine the rate of suicidal attempt and its correlates in the adolescents living in southern Taiwan. Five questions from the Kiddie Schedule for Affective Disorders and Schizophrenia (Kiddie‐SADS‐E) were used to inquire about the participants' suicidality. The associations between suicidal attempt and multidimensional factors were examined by using logistic regression analysis: 9.1% of the participants reported a suicidal attempt in the preceding year. Female gender, low self‐esteem, weekly alcohol use, illicit drugs use, depression, high family conflict, low maternal education level, poor family function, low connectedness to school, low rank, poor feeling in peer group, and drop out from school were associated with adolescent suicidal attempt. The rate of suicidal attempt was found to be high in Taiwanese adolescents, and multidimensional factors were correlated to adolescent suicidal attempt.