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31.
Mediaeval logicians inherited from Boethius an account of conditional propositions and the syllogisms which may be constructed using them. In the following paper it is shown that there are considerable difficulties with Boethius' account which arise from his failure to understand the nature of compound propositions and in particular to provide for their negation. Boethius suggests that there are two different conditions which may be imposed for the truth of a conditional proposition but he really gives no adequate account of how such propositions may be obtained. The true greatness of Peter Abaelard as a philosophical logician is revealed in what he is able to do with the material which he found in Boethius. It is shown that he developed a precise theory of conditionals giving an account of how true conditionals may be obtained and principles which may be used to reject others as false. Unlike Boethius Abaelard properly appreciates that conjunctions must be treated as logical units. Even he, however, falls victim to difficulties which arise when this connective is brought into contact with negation and the conditions which he lays down for the truth of a conditional.  相似文献   
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Video games vary in terms of the emotional states they elicit from players. These differences in emotional reactions, in turn, help account for differential preferences of individual games. The three independent dimensions of pleasure-displeasure, arousal-nonarousal, and dominance-submissiveness were used to assess emotional impacts of individual games. In addition, a preference measure was constructed to evaluate attraction toward, versus avoidance of, specific games. In Study One, a group of subjects provided data on emotional responses to 22 common arcade video games and a different group rated their preferences for the same games. The emotional impact of video games was highly unpleasant, moderately arousing, and moderately dominance-inducing; thus, the predominant emotional response to these games was aggression, anger, or hostility. I n Study Two, subjects visiting a video game arcade were recruited and assigned to play two games each and to report their reactions to each game immediately after playing the game. Results showed that greater feelings of pleasure, and separately of arousal, while playing video games resulted in higher preferences for the games and that greater dominance (significant only for males) also led to higher preferences. It may be beneficial, therefore, to experiment with more arousing and more dominance-inducing game designs which are not necessarily unpleasant or which definitely yield high pleasure.  相似文献   
34.
Visual control of step length during running over irregular terrain   总被引:1,自引:0,他引:1  
Running over uneven ground requires visually regulating step length to secure proper footing. To examine how this is achieved, we studied subjects running on a treadmill on a series of irregularly spaced targets. The movements of their lower limbs and coccyx relative to the targets were monitored opto-electronically by a Selspot system. The results indicated that step length was adjusted to strike the targets primarily by varying the vertical component of impulse applied to the ground during the stance phase. In contrast, horizontal impulse was not varied significantly, and changing the reach forward of the foot on landing contributed little to variation in step length. Changing the vertical impulse simply altered the step time proportionately. Thus the data are consistent with a time-based model in which vertical impulse is modulated by the optic variable delta tau (Lee, 1976) specifying the time gap that has to be bridged by the runner between two targets.  相似文献   
35.
Motor activity level is one dimension of infant temperament for which parental judgment can be validated against a truly independent criterion. Two studies were conducted, the first involving a 27-min sample of behavior in a structured, attention-getting situation, and the second involving a 24-hr sample of in-home behavior. In both studies, parent perception of the 3- or 4-month-old as measured by the Activity Level (AL) scale of the Rothbart Infant Behavior Questionnaire was compared to the composited readings from four mechanical motion recorders (actometers) worn, one per limb, by the infant. The AL scale did not correlate with the actometer measure, r=.05 and R=.00, and the expected convergence of the 3-month version of the IBQ activity scale with its mechanical counterpart was not found. In the 24-hr study, birth order and ponderal index were significantly correlated with 24-hr actometer scores; first-borns and thin infants were most active.  相似文献   
36.
Twenty of 150 boys living in a residential setting who were emitting high levels of impulsive/aggressive behavior participated in a study of the effectiveness of a cognitive-behavioral group treatment procedure designed to equip them with skills conducive to alternate and more socially appropriate behavior. Treatment involved 13 meetings of 55 minutes duration over a six-week period. The results indicated significant behavioral changes in school regarding: (1) the intensity of physical fighting, (2) the frequency and intensity of verbal fighting, (3) noncompliance, and (4) being in an inappropriate location. These behavioral changes did not generalize beyond the school setting. Significant increases in the number of identified logical consequences of aggressive behavior and in the number of alternative responses to aggressive behavior were observed compared to control boys. The behavioral changes observed in school largely extinguished during the five weeks between the last treatment session and the follow-up observations.  相似文献   
37.
R Warren  G Good  E Velten 《Adolescence》1984,19(75):643-648
This paper provides some initial normative and validity data on the Social Avoidance and Distress (SAD) and the Fear of Negative Evaluation (FNE) scales for junior high school students. Findings indicated: the level of social-evaluative anxiety does not significantly vary during the junior high school years or between sexes, junior high school students report similar levels of FNE to college students but less SAD, a significant positive correlation between treatment subjects' SAD scores and peer sociometric ratings of social-evaluative anxiety, and subjects treated for social anxiety reported significantly less SAD and FNE at follow-up assessment. Recommendations for future research and clinical use of the SAD and FNE are offered.  相似文献   
38.
The mechanical events of bouncing and breaking are acoustically specified by single versus multiple damped quasi-periodic pulse patterns, with an initial noise burst in the case of breaking. Subjects show high accuracy in categorizing natural tokens of bouncing and breaking glass as well as tokens constructed by adjusting only the temporal patterns of components, leaving their spectral properties constant. Differences in average spectral frequency are, therefore, not necessary for perceiving this contrast, though differences in spectral consistency over successive pulses may be important. Initial noise corresponding to glass rupture appears unnecessary to categorize breaking and bouncing. The data indicate that higher order temporal properties of the acoustic signal provide information for the auditory perception of these events.  相似文献   
39.
Learned helplessness theory predicts that animals exposed to inescapable shock acquire an expectancy of response-reinforcer independence, which proactively interferes with learning of response-reinforcer dependence. The theory also predicts that this expectancy can increase sensitivity to subsequent instances of response-reinforcer independence. These experiments test the latter prediction in a paradigm that minimizes the confounding effects of shock-induced activity deficits. Rats were trained to respond for food, then given either escapable, inescapable, or no shock. Subsequently, they received two sessions of response-contingent food followed by sessions of noncontingent food deliveries. During this phase, inescapably shocked animals decreased responding faster than did controls. Experiment 2 replicated this finding with a different schedule of food delivery and a procedure that more directly minimized the possibility that the outcome is due to either direct or indirect shock-induced activity changes. These results support the prediction that uncontrollable aversive events can increase an animal's sensitivity to noncontingent response-reinforcer relationships.  相似文献   
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