Distinguishing Between Causes and Enabling Conditions—Through Mental Models or Linguistic Cues?

The mental model theory of naive causal understanding and reasoning (Goldvarg & Johnson-Laird, 2001, Cognitive Science, 25, 565–610) claims that people distinguish between causes and enabling conditions on the basis of sets of models that represent possible causal situations. In the tasks used to test this hypothesis, however, the proposed set of models was confounded with linguistic cues that frame which event to assume as given (the enabling condition) and which to consider as responsible for the effect under this assumption (the cause). By disentangling these two factors, we were able to show that when identifying causes and enabling conditions in these tasks, people rely strongly on the linguistic cues but not on the proposed set of models and that this set of models does not even reflect people's typical interpretation of the tasks. We propose an alternative explanation that integrates syntactic and causal considerations.     

Tests of sphericity of normal distributions and the analysis of repeated measures designs

The locally best invariant test statistic for testing sphericity of normal distributions is shown to be a simple function of the Box/Geisser-Greenhouse degrees of freedom correction factor in a repeated measures design. Because of this relationship it provides a more intuitively appealing test of the necessary and sufficient conditions for valid F-tests in repeated measures analysis of variance than the likelihood ratio test. The properties of the two tests are compared and tables of the critical values of the Box/Geisser-Greenhouse correction factor are given.     

A CLASSIFICATION SCHEME OF SOCIAL CONDITIONS OF REINFORCEMENT WITHIN GROUP OPERANT SYSTEMS1

Many different reinforcement contingencies are found in group operant systems, such as token economies and point systems. Some systems use group contingencies in which the reinforcement of any one participant may depend on the behavior of some other group member. Other programs are individual, in that participants earn reinforcers dependent only on their own behavior. The various possible arrangements of people and their response requirements are labelled “social conditions of reinforcement” in this paper. Previous attempts at classification have failed to categorize the variety of social conditions of reinforcement. In addition, some conditions that may produce behaviorally different effects have not been separated. The present paper classifies the social conditions of reinforcement found in applied programs in a three-dimensional scheme. The efficacy of the three major dimensions—reinforcing agent, recipient response requirement, and group response requirement—is supported by clinical and research data. The reinforcing agent dimension refers to the person(s) who dispenses reinforcers to group members. This major dimension is further subdivided: one or several agents may be either designated or nondesignated. Recipients are the group members who receive reinforcement. This dimension is also subdivided: one or several recipients in a social condition of reinforcement may obtain reinforcers either contingently or noncontingently. The group response requirement is a criterion that must be satisfied before any group participant is eligible for reinforcement. Some systems have no group requirement, and others have a group requirement that must be met by some designated or nondesignated participant(s). Supportive references and examples are given in the explanation of each dimension and subdimension. The behavioral impact of the various categories is emphasized. For all major dimensions, applied implications and research suggestions are discussed. Concluding remarks center on the utility of the present scheme, the classification of operant procedures other than positive reinforcement, and both theoretical and applied issues requiring further study (e.g., the long-term effects of participation in group contingencies).     

Effects on choice of reinforcement delay and conditioned reinforcement

Pigeons chose between fixed-interval schedules of different durations presented in the terminal links of concurrent-chains schedules. The pair of schedules was always in the ratio of 2:1, but the absolute duration of the fixed intervals varied. In one set of conditions, the different terminal-link schedules were associated with different keylight stimuli (cued conditions). In a second set of conditions, the different terminal-link schedules were associated with the same stimulus (uncued conditions). Results from the cued conditions replicated previous findings that preference for the shorter fixed-interval schedule increased with fixed-interval duration. Preferences in the uncued conditions were lower than in the corresponding cued conditions but also increased with fixed-interval length. In addition, the degree of control under the uncued conditions was correlated with the extent to which the schedule during the terminal link was discriminated immediately upon entry into the terminal link. The pattern of results in both conditions was inconsistent with the notion that choice behavior matches relative immediacy of reinforcement. Reanalysis of previous evidence for matching (Chung and Herrnstein, 1967) showed that matching in fact did not occur, as the preferences of their subjects for the shorter of two delays also increased with the absolute size of the delays.     

Using a multi-user driving simulator system to explore the patterns of vehicle fleet rear-end collisions occurrence under different foggy conditions and speed limits

Vehicle fleet rear-end collisions (FRECs) are an extremely fatal type of traffic collisions on freeway and they usually occur in foggy weather. This study aimed to explore the patterns of vehicle fleet rear-end collisions occurrence under different foggy conditions and speed limits on freeway. A multi-user driving simulator system was used to conduct the experiment and the driving behavior data were collected from eight participants. The experimental results showed that as the fog density increased, the length of vehicle fleet decreased significantly, and drivers tended to keep a more stable car-following distance. The fog weather and short vehicle gap prompted drivers to react faster and brake harder in respond to the leading vehicle’s brake. In spite of the compensational behaviors, more FRECs were observed under heavy fog condition. Lowering speed limit can significantly reduce the FRECs under foggy conditions. As the speed limits reduced, drivers’ brake response time and speed variance significantly reduced. The study also found that drivers’ brake response time was negatively correlated with their positions in the fleet. Drivers in the front positions of the fleet had a longer response time than drivers in the back positions and thus were more likely to encounter collisions. The study generated a better understanding of drivers’ behavioral pattern in a vehicle fleet and the patterns of vehicle fleet rear-end collisions occurrence. The findings also shed lights on the design of driver assistance system for complex driving situations such as freeway driving under adverse weather.     

Cross-National Variations in Behavioral Profiles Among Homeless Youth

Cross-national comparisons of homeless youth in Melbourne, Australia, and Los Angeles, CA, United States were conducted. Newly (n = 427) and experienced (n = 864) homeless youth were recruited from each site. Compared to Australia, homeless youth in the United States were younger, more likely to be in school or jail, demonstrated fewer sexual and substance use risk acts, fewer suicidal acts, and reported less need for social services. Across sites, experienced homeless youth were more likely to be older, male, engage in sexual and substance use, report greater need for social services, and make greater use of work, substance use, and health-related services. Homeless youth have different behavioral profiles in Australia and the United States, reflecting differences in the effectiveness of service systems in the two countries in keeping youth with fewer problems out of homelessness.     

对中医审查病机的体会

在诺贝尔生理学或医学奖105年的历史中,美国分别占了颁奖年度的52.08%,获奖成果的44.87%,获奖人数的48.91%。形成这些科学家学术优势积累和美国国家科技竞争优势的学术条件背景是:适宜的宏观政策,充足的经费投入,成功的人才政策,根本的教育改革和创新的科技管理。     

十五年来中国男性择偶标准的变化

对《中国妇女》1985年至2000年15年间每隔5年选择一年,并在每一季度中选择一期杂志,统计男性刊登的征婚启事,总共得到332例。采用统计学方法进行定量研究。发现中国男性在15年间对自身的人品、财产、相貌的重视程度显著增高,对自身的婚史和事业的重视程度明显降低;对女方的持家能力的重视程度显著增高,对女方的健康和工作的重视程度显著降低。当代中国男性的择偶标准随时间的推移有了明显的变化,但仍受到中国传统观念的影响。