Two metamodels of causal effects

Two metamodels, termed Model S and Model V, are proposed for definition, measurement, and generalization of quantitative causal effects. The effect is defined as a part change in score in Model S and as a part change in variance in Model V. Two additional changes, total and remainder change, are defined. The latter is due to all other factors or variables than the cause, while total change is the sum of remainder and effect change. Furthermore, it is shown how contrafactual concepts, which imply that some parts of the study situation are supposed to be otherwise, enter into the metamodels. Casual effects are defined and measured in terms of non-contrafactual concepts, except that statistical induction includes contrafactual as well as non-contrafactual inferences. Non-statistical generalization involves both kinds of inferences. Contrafactual definitions are considered inadequate, and a contrafactual interpretation of statistical adjustment is unnecessary and should be replaced by a non-contrafactual one.     

Periodicities within a fixed-interval session

Within-session periodicities in number of responses per interval and postreinforcement pauses were investigated on fixed-interval schedules of 1, 2, and 3 minutes with rats. Postreinforcement pause values and the number of responses in successive intervals were not systematically related. The direction of change of these variables from one pair of intervals to the next revealed periodicities in that the direction of change varied more than would be expected by chance. A response prevention technique used to manipulate the length of time spent responding in an interval had little effect on the postreinforcement pause value of the next interval except when only a single response was permitted in an interval. This procedure tended to reduce the postreinforcement pause value of the next interval to an abnormally low level.     

Issues associated with repeated neuropsychological assessments

Distinguishing practice effects from other factors in repeated neuropsychological assessments are discussed in the context of research studies and clinical/forensic assessments. Potential methodological procedures for reducing the impact of practice effects in research settings are outlined. In contrast, the potential clinical utility and interpretation of practice effects in clinical assessments and forensic evaluations are highlighted.     

Bias in self-evaluation: Signal probability effects

Two experiments examined apparent signal probability effects in simple verbal self-reports. After each trial of a delayed matching-to-sample task, young adults pressed either a “yes” or a “no” button to answer a computer-presented query about whether the most recent choice met a point contingency requiring both speed and accuracy. A successful matching-to-sample choice served as the “signal” in a signal-detection analysis of self-reports. Difficulty of matching to sample, and thus signal probability, was manipulated via the number of nonmatching sample and comparison stimuli. In Experiment 1, subjects exhibited a bias (log b) for reporting matching-to-sample success when success was frequent, and no bias or a bias for reporting failure when success was infrequent. Contingencies involving equal conditional probabilities of point consequences for “I succeeded” and “I failed” reports had no systematic effect on this pattern. Experiment 2 found signal probability effects to be evident regardless of whether referent-response difficulty was manipulated in different conditions or within sessions. These findings indicate that apparent signal probability effects in self-report bias that were observed in previous studies probably were not an artifact of contingencies intended to improve self-report accuracy or of the means of manipulating signal probability. The findings support an analogy between simple self-reports and psychophysical judgments and bolster the conclusion of Critchfield (1993) that signal probability effects can influence simple self-reports much as they do reports about external stimuli in psychophysical experiments.     

Neighborhood Risk Factors for Recidivism: For Whom do they Matter?

Justice‐involved people vary substantially in their risk of reoffending. To date, recidivism prediction and prevention efforts have largely focused on individual‐level factors like antisocial traits. Although a growing body of research has examined the role of residential contexts in predicting reoffending, results have been equivocal. One reason for mixed results may be that an individual’s susceptibility to contextual influence depends upon his or her accumulated risk of reoffending. Based on a sample of 2218 people on probation in San Francisco, California, this study draws on observational and secondary data to test the hypothesis that individual risk moderates the effect of neighborhood factors on recidivism. Results from survival analyses indicate that individual risk interacts with neighborhood concentrated disadvantage and disorder—and these factors increase recidivism among people relatively low in individual risk, but not those at higher risk. This is consistent with the disadvantage saturation perspective, raising the possibility that some people classified as low risk might not recidivate but for placement in disadvantaged and disorderly neighborhoods. Ultimately, residential contexts “matter” for lower risk people and may be useful to consider in efforts to prevent recidivism.     

Does late preterm birth impact trunk control and early reaching behavior?

The aims of the study were to 1) verify the level of trunk control longitudinally and reaching behavior while sitting in two positions in late preterm (LPT) and full-term (FT) infants, 2) determine whether the level of trunk control relates to reaching outcomes. Twenty LPT infants and 36 infants born FT were assessed via three in-lab visits: at 6, 7, and 8 months. At each visit, the Segmental Assessment of Trunk Control (SATCo) and reaching assessment were performed, where the infants were positioned sitting in the ring and at 90° of flexion of hips, knees, and ankles. Accurate manual support to the trunk was provided in each visit. LPT infants presented a lower level of trunk control over time. LPT infants presented a higher percentage of unimanual reaches and successful grasping at 7 months' visit, and a higher number of reaches at 8 months' visit compared to FT infants. The sitting positions did not influence reaching performance. The level of trunk control relates to functional reaching strategies only in FT infants. This study might provide insights for clinicians for understanding the level of trunk control, the importance of reaching behaviors for exploration, and considering these behaviors as strategies for intervention.     

Discounting of food and water in rats shows trait- and state-like characteristics

Delay discounting is the loss in value of an outcome as a function of its delay. The present study focused on examining a trait-like characteristic of delay discounting in a preclinical animal model. Specifically, we were interested in whether there was a positive relation between discounting of 2 different outcomes in rats. That is, would rats that discount delayed food steeply also discount delayed water steeply? In addition, we examined how session-to-session variability in discounting could be attributed to differences between subjects (trait variability) and to differences within subjects (state variability). Finally, we measured discounting from early- to mid-adulthood, allowing us to examine changes in discounting as a function of age. Overall, we found a moderate, positive correlation between discounting of food and discounting of water in rats, providing further evidence that the relative consistency with which individuals discount different outcomes is a trait-like characteristic. In addition, we found a high degree of within-subject variability in discounting, indicating strong state-like differences from session to session. Finally, overall, discounting decreased as a function of age; however, individual-subject data showed variability in how discounting changed across time. Overall, our results show that differences in delay discounting between individuals reflect variability in both trait- and state-like characteristics.     

大学生智能手机成瘾与抑制控制能力的关系:手机位置和认知负荷的调节作用

本研究以66名大学生为被试,采用Flanker效应和工作记忆的双任务设计来探讨手机位置、认知负荷在智能手机成瘾与抑制控制能力之间的调节作用。结果发现：（1）在低认知负荷下,无论是否智能手机成瘾,手机存在视线之外比手机在视线之内时抑制控制能力更差;（2）在高认知负荷下,智能手机成瘾与手机位置交互作用显著：当手机在视线之内时,智能手机成瘾者的抑制控制能力显著差于非成瘾者;而当手机在视线之外时,两者没有显著差异。结果表明,智能手机成瘾大学生的抑制控制能力不仅会受到手机位置的影响,还会受到任务本身所带来的认知负荷的调节。     

Dynamic probability of reinforcement for cooperation: Random game termination in the centipede game

Experimental games have previously been used to study principles of human interaction. Many such games are characterized by iterated or repeated designs that model dynamic relationships, including reciprocal cooperation. To enable the study of infinite game repetitions and to avoid endgame effects of lower cooperation toward the final game round, investigators have introduced random termination rules. This study extends previous research that has focused narrowly on repeated Prisoner's Dilemma games by conducting a controlled experiment of two‐player, random termination Centipede games involving probabilistic reinforcement and characterized by the longest decision sequences reported in the empirical literature to date (24 decision nodes). Specifically, we assessed mean exit points and cooperation rates, and compared the effects of four different termination rules: no random game termination, random game termination with constant termination probability, random game termination with increasing termination probability, and random game termination with decreasing termination probability. We found that although mean exit points were lower for games with shorter expected game lengths, the subjects' cooperativeness was significantly reduced only in the most extreme condition with decreasing computer termination probability and an expected game length of two decision nodes.