Gestalt and dynamic processes in decision making

People sometimes prefer a sure gain to a risky but possibly larger gain, a tendency known as risk-aversion. On the other hand, they may prefer a possibly larger loss to a smaller sure loss, a tendency known as risk-seeking. Experiment 1 showed that, by repeating the event, these tendencies could be substantially reduced, but not eliminated, when expected value was held constant between the sure alternative and the risky one. Experiment 2 demonstrated that risk-aversion can be reversed to risk-seeking within the gain situation, and vice versa within the loss situation, by changing the probabilities and the payoffs associated with the probabilities. It was suggested that the results of both experiments can be understood by a concept of Gestalt organization and dynamic processes in decision making.

Hydatidosis in a Chapman's zebra (Equus burchelli antiquorum)

A 14-year-old male Chapman's zebra had been treated for a cervical granulomatous cellulitis for 3 months prior to sudden death associated with myocardial fibrosis. Incidental findings at necropsy included multiple 3-8-cm unilocular cysts in the liver and lungs. Cysts contained either a clear fluid with or without hydatid sand or a gelatinous substance with foci of mineralization. Light and scanning electron microscopic examination of the hydatid sand revealed free protoscolices as well as intact and ruptured brood capsules with protoscolices attached to the germinal membrane. The protoscolices had 2 rows of 36-38 rostellar hooks with a length of 25-30 microm. The cyst wall consisted of inner germinal, intermediate laminated, and outer adventitial layers. Hydatidosis caused by Echinococcus granulosus was diagnosed based on the unilocular cysts, multiple protoscolices formed in a brood capsule, typical trilayered cyst wall, and herbivorous intermediate host. This is the first reported case of animal hydatidosis in Taiwan. The infection is thought to have been established 12 years ago in South Africa prior to importation.

Memory representation of alphabetic position and interval information

The authors conducted 3 sets of experiments. In the 1st set of experiments, participants made alphabetic position estimations. In the 2nd set, participants made interletter distance estimations. In the 3rd set, they made comparative judgments of the alphabetic order of a pair of letters. The results showed that participants had highly accurate ordinal level information about the alphabet in memory but that interval level information was systematically distorted. In addition, alphabetic serial information was found to be used in 2 distinct modes in memory, depending on whether the representation could be contained within the span of immediate memory.

Memory representation of alphabetic position and interval information

The authors conducted 3 sets of experiments. In the 1st set of experiments, participants made alphabetic position estimations. In the 2nd set, participants made interletter distance estimations. In the 3rd set, they made comparative judgments of the alphabetic order of a pair of letters. The results showed that participants had highly accurate ordinal level information about the alphabet in memory but that interval level information was systematically distorted. In addition, alphabetic serial information was found to be used in 2 distinct modes in memory, depending on whether the representation could be contained within the span of immediate memory.

Why is the alphabetically middle letter in a multiletter array so hard to determine? Memory processes in linear-order information processing

In 3 experiments, participants identified target letters in multiletter strings of different interletter steps. Results show that the alphabetically extreme targets in the arrays (A or C in BCA) were consistently identified faster than were the interior letters, with the alphabetically middle target (B in BCA) identified most slowly. Distance effects were not consistent across different targets. The findings are not consistent with the ends-inward serial search, comparison, and serial search plus comparison models. The data suggest that an interior target was identified by first identifying the terminal letter and then mentally constructing the linear order inward by probabilistically using either a comparison or an interitem serial search process to achieve maximal efficacy. This suggestion is consistent with the ends-inward construction theory of linear-order learning.

Why is the alphabetically middle letter in a multiletter array so hard to determine? Memory processes in linear-order information processing

In 3 experiments, participants identified target letters in multiletter strings of different interletter steps. Results show that the alphabetically extreme targets in the arrays (A or C in BCA) were consistently identified faster than were the interior letters, with the alphabetically middle target (B in BCA) identified most slowly. Distance effects were not consistent across different targets. The findings are not consistent with the ends-inward serial search, comparison, and serial search plus comparison models. The data suggest that an interior target was identified by first identifying the terminal letter and then mentally constructing the linear order inward by probabilistically using either a comparison or an interitem serial search process to achieve maximal efficacy. This suggestion is consistent with the ends-inward construction theory of linear-order learning.

An information processing view of framing effects: the role of causal schemas in decision making

People prefer a sure gain to a probable larger gain when the two choices are presented from a gain perspective, but a probable larger loss to a sure loss when the objectively identical choices are presented from a loss perspective. Such reversals of preference due to the context of the problem are known as framing effects. In the present study, schema activation and subjects' interpretations of the problems were examined as sources of the framing effects. Results showed that such effects could be eliminated by introducing into a problem a causal schema that provided a rationale for the reciprocal relationship between the gains and the losses. Moreover, when subjects were freed from framing they were consistently risk seeking in decisions about human life, but risk averse in decisions about property. Irrationality in choice behaviors and the ecological implication of framing effects are discussed.

Synthesis and characterization of a new photocrosslinking CTP analog and its use in photoaffinity labeling E. coli and T7 RNA polymerases

A new photocrosslinking CTP analog that functioned as a substrate during transcription was synthesized and used to photoaffinity label E. coli and bacteriophage T7 RNA polymerases. This analog, 5-((4-azidophenacyl)thio) cytidine-5'-triphosphate (5-APAS-CTP) contains an aryl azide group approximately 10 A from the nucleotide base and specifically replaced CTP during synthesis of RNA by both polymerases. Analog was placed at the 3' end or internally within RNA. Both polymerases inefficiently incorporated two 5-APAS-CMP molecules sequentially, as was found for the related 5-APAS-UMP. Analog was placed at the 3' end of RNA in transcription complexes paused at the site of Q-modification of E. coli RNA polymerase, downstream of the lambda PR' promoter (+16), a pause that requires specific DNA sequences but no apparent RNA hairpin. Crosslinking was examined in the presence and absence of the NusA protein, which enhances the transcriptional pause at this site and is required for Q modification of the polymerase. Crosslinking of the 3' end of the RNA to NusA was not observed, consistent with our earlier results involving a NusA-enhanced pause site downstream from an RNA hairpin.