自然颂

坦白的讲,成年人很少能发现大自然。……热爱大自然的人是精神形体和谐统一的人,是已经步入成年却仍童心未泯的人。他与天地间的交流,是他的精神食粮。尽管他的心灵深处确有悲伤,但面对自然,仍是满心喜悦。大自然说,这就是我创造的生灵,任凭他有千种悲哀,只要与我在一起,他就应     

Successive reversals of a discriminated preference for signaled tailshock

Three rats received unmodifiable tailshock at random intervals in a shuttlebox. In a continuous-choice situation, Ss could choose between an auditory signal immediately preceding or immediately following the tailshock. Over repeated daily 3-h sessions, each S acquired a spatial discrimination indicating a strong preference for the signal preceding tailshock. This preference continued undiminished through two successive reversals of the position associated with signaled shock. This demonstration precludes explanations of the preference-for-signaled-shock phenomenon based upon primary reinforcement value or acquired value of the signal, position preferences, and overt modification of the aversiveness of the reinforcer through such means as postural adjustments. An explanation of recent failures to obtain the preference-for-signaled-shock effect is offered.     

Recovery from the overexpectation effect: Contrasting performance-focused and acquisition-focused models of retrospective revaluation

In four Pavlovian conditioned lick-suppression experiments, rats had two conditioned stimuli (CSs X and A) independently paired with footshock, followed by pairings of a compound of A and X with the footshock. On subsequent tests with CS X, less conditioned suppression was observed than in control subjects that lacked the compound AX→footshock trials. Thisoverexpectation effect was reversed through posttraining extinction of CS A, a result consistent with both performance- and acquisition-focused models of retrospective revaluation. However, only performance-focused models could account for how posttraining increases or decreases in the A-footshock temporal interval attenuate the overexpectation effect.     

Cooperative research centres: The concept and its implementation

The Cooperative Research Centres Program aims to enhance the effectiveness of the overall Australian R&D effort by drawing together researchers from several institutions to create the concentrations of resources which are needed, in many research fields, to keep pace with the rapid scientific and technological progress which is occurring internationally. The Centres link together outstanding groups of researchers, from both the public and private sectors, with the users of research from appropriate industry sectors and other sectors of the economy and provide opportunities for research users to participate actively in the planning and operation of the research activities. The Program was started in 1990. Fifty-two Centres have now been approved across six major R&D and industry sectors representing, when these Centres are fully established, a commitment by the government of some $100 million per year and, from the participants, of some $200 million per year. This constitutes some six percent of the national R&D effort.