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E Fantino

Publications and source records attributed to E Fantino.

At least 19 recordsLinked to original sources
PubMed1992

Downstream activating sequence within the coding region of a yeast gene: specific binding in vitro of RAP1 protein.

Using a gel retardation assay, a protein factor that specifically interacts with a 33 bp intragenic sequence of the highly expressed and glucose-inducible SRP1 gene of Saccharomyces cerevisiae has been detected. This binding site is located in a transcribed region and within the open reading frame (positions +710 to +743 relative to the first base of the initiation codon). A mutant strain carrying a deletion of this binding site showed a dramatic decrease in steady-state levels of SRP1 transcripts. This decline is not the result of a decrease in mRNA stability, since expression of hybrid genes in which the SRP1 promoter was replaced by the heterologous CYC1 promoter was not affected by the binding site deletion. These findings suggest that the 33 bp sequence contains a cis-acting downstream activating element which is involved in the transcriptional activation of the SRP1 promoter. Sequence comparisons showed similarities between a site located within the 33 bp sequence and the high-affinity consensus binding site of the RAP1/GRF1 (also named TUF) factor and methylation interference experiments confirmed that this site was involved in the protein-DNA interaction. Both the results of competition experiments with upstream activating sequences of ribosomal protein genes (UASrpg), which are targets for RAP1 binding, and determination of the apparent molecular weight of the affinity-purified DNA-binding protein indicated that RAP1 factor recognized the SRP1 33 bp element. The 33 bp sequence was found to be unable to provide UAS activity when placed upstream of the TATA box and transcription start site.

Amino Acid Sequence↗
PubMed1991

Conditioned reinforcement value and choice.

The delay-reduction hypothesis of conditioned reinforcement states that the reinforcing value of a food-associated stimulus is determined by the delay to primary reinforcement signaled by the onset of the stimulus relative to the average delay to primary reinforcement in the conditioning situation. In contrast, most contemporary models of conditioned reinforcement strength posit that the reinforcing strength of a stimulus is some simple function only of the delay to primary reinforcement in the presence of stimulus. The delay-reduction hypothesis diverges from other conditioned reinforcement models in that it predicts that a fixed-duration food-paired stimulus will have different reinforcing values depending on the frequency of its presentation. In Experiment 1, pigeons' key pecks were reinforced according to concurrent-chains schedules with variable-interval 10-second and variable-interval 20-second terminal-link schedules. The initial-link schedule preceding the shorter terminal link was always variable-interval 60 seconds, and the initial-link schedule requirement preceding the longer terminal link was varied between 1 second and 60 seconds across conditions. In Experiment 2, the initial-link schedule preceding the longer of two terminal links was varied for each of three groups of pigeons. The terminal links of the concurrent chains for the three groups were variable-interval 10 seconds and 20 seconds, variable-interval 10 seconds and 30 seconds, and variable-interval 30 seconds and 50 seconds. In both experiments, preference for the shorter terminal link was either a bitonic function or an inverse function of the initial-link schedule preceding the longer terminal-link schedule. Consistent with the predictions of the delay-reduction hypothesis, the relative values of the terminal-link stimuli changed as a function of the overall frequency of primary reinforcement. Vaughan's (1985) melioration model, which was shown to be formally similar to Squires and Fantino's (1971) delay-reduction model, can be modified so as to predict these results without changing its underlying assumptions.

Animals↗
PubMed1991

Choice and conditioned reinforcement.

A potential weakness of one formulation of delay-reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal-link stimuli occur in concurrent-chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent-chains schedules or on comparable concurrent-tandem schedules. The initial link was shortened on only one of two concurrent-chains schedules and on only one of two corresponding concurrent-tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay-reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent-chains schedules may have no independent effect on choice.

Animals↗
PubMed1990

Unification of models for choice between delayed reinforcers.

Two models for choice between delayed reinforcers, Fantino's delay-reduction theory and Killeen's incentive theory, are reviewed. Incentive theory is amended to incorporate the effects of arousal on alternate types of behavior that might block the reinforcement of the target behavior. This amended version is shown to differ from the delay-reduction theory in a term that is an exponential in incentive theory and a difference in delay-reduction theory. A power series approximation to the exponential generates a model that is formally identical with delay-reduction theory. Correlations between delay-reduction theory and the amended incentive theory show excellent congruence over a range of experimental conditions. Although the assumptions that gave rise to delay-reduction theory and incentive theory remain different and testable, the models deriving from the theories are unlikely to be discriminable by parametric experimental tests. This congruence of the models is recognized by naming the common model the delayed reinforcement model, which is then compared with other models of choice such as Killeen and Fetterman's (1988) behavioral theory of timing, Mazur's (1984) equivalence rule, and Vaughan's (1985) melioration theory.

Animals↗
PubMed1990

Observing behavior in a computer game.

Contingencies studied in lever-pressing procedures were incorporated into a popular computer game, "Star Trek," played by college students. One putative reinforcer, the opportunity to destroy Klingon invaders, was scheduled independently of responding according to a variable-time schedule that alternated unpredictably with equal periods of Klingon unavailability (mixed variable time, extinction schedule of reinforcement). Two commands ("observing responses") each produced stimuli that were either correlated or uncorrelated with the two components. In several variations of the basic game, an S-, or bad news, was not as reinforcing as an S+, or good news. In addition, in other conditions for the same subjects observing responses were not maintained better by bad news than by an uninformative stimulus. In both choices, more observing tended to be maintained by an S- for response-independent Klingons when its information could be (and was) used to advantage with respect to other types of reinforcement in the situation (Parts 1 and 2) than when the information could not be so used (Part 3). The findings favor the conditioned reinforcement hypothesis of observing behavior over the uncertainty-reduction hypothesis. This extends research to a more natural setting and to multialternative concurrent schedules of events of seemingly intrinsic value.

Adult↗
PubMed1989

Responding on concurrent-chains schedules in open and closed economies.

Pigeons' key pecks were reinforced according to concurrent-chains schedules of reinforcement. The programmed average time from the onset of the initial links to a terminal link entry was held constant across conditions while the value of variable-interval schedules in the terminal links was varied. Performance was assessed under two economic conditions: (a) an open economy in which session duration was limited to 1 hr and subjects were maintained at 80% of their free-feeding body weights with postsession food when necessary; and (b) a closed economy in which sessions were 23.5 hr long and no deprivation regimen was in effect. In all cases, the relative rate of responding in the initial links matched the reduction in overall delay to primary reinforcement correlated with entry into one terminal link relative to the reduction in delay correlated with entry into the other terminal link. Although the sum of responses made in the initial links and terminal links was found to increase, then decrease, as the rate of food presentation decreased in the closed economy, there was no consistent effect of overall rate of food presentation on total responding in the open economy. The choice data suggest that relative delay reduction predicts choice accurately, regardless of economic context.

Animals↗
PubMed1988

Gene cloning from yeast chromosome-specific mini-library. Isolation of the SRP1-related DNA sequence located on chromosome XV.

We have isolated and purified chromosome XV DNA molecules from the yeast S. cerevisiae using contour-clamped homogeneous electric field (CHEF) gel electrophoresis. A chromosome-specific mini-library was constructed and the element of the SRP1 (serine-rich protein) related sequence family located within chromosome XV was isolated by in situ colony hybridization with an SRP1 probe. Results indicated that (i) a single-copy sequence homologous to SRP1 is present within chromosome XV; (ii) this sequence lies within the 2.3 kb HindIII fragment of the plasmid pXVAc6; (iii) the lack of a specific transcript from this SRP1-related element suggests that it could be considered as a pseudogene.

Chromosome Mapping↗
PubMed1988

Effects of reinforcement context on choice.

Two experiments investigated the effects of successive reinforcement contexts on choice. In the first, concurrent variable-interval schedules of primary reinforcement operated during the initial links of concurrent chains. The rate of this reinforcement arranged by the concurrent schedules was decreased across conditions: When it was higher than the terminal-link rate, preference for the higher frequency initial-link schedule increased relative to baseline. (During baseline, a standard concurrent-schedule procedure was in effect). When the initial-link reinforcement rate was lower than the terminal-link rate, preference converged toward indifference. In the second experiment, a chain schedule was available on a third key while a concurrent schedule was in effect on the side keys. When the terminal link of the chain schedule was produced, the side keys became inoperative. Availability of the chain schedule did not affect choice between the concurrent schedules. These results show that only when successive reinforcement contexts are produced by choice responding do those successive contexts affect choice in concurrent schedules.

Animals↗
PubMed1988

Choice and foraging: the effects of accessibility on acceptability.

Pigeons responded in a successive-encounters choice procedure in which accessibility of the less profitable of two outcomes varied either in terms of probability of encounter or search time to encounter (keeping search time to the more profitable outcome constant). When the less profitable outcome was made more probable its acceptance became more likely. However, when search time to encounter the less profitable outcome was shortened, its acceptance became less likely. Both results are consistent with the delay-reduction hypothesis and with an optimality model developed for application to the successive-encounters choice procedure.

Animals↗
PubMed1988

The effects of component duration on multiple-schedule performance in closed and open economies.

Pigeons responded on multiple variable-interval variable-interval schedules of reinforcement in an open and a closed economy. Equal duration components were increased in duration while the component rates of reinforcement were held constant, the component schedules were reversed, and component duration was decreased. In the open economy, daily sessions were limited to 1 hr, and subjects were maintained at 80% of their free-feeding weights through supplemental feeding when necessary in their home cages. In the closed economy, subjects were housed in their experimental chambers and no deprivation regimen was enforced. Relative response rate decreased as components were lengthened in the open economy, whereas in the closed economy relative rate increased as components were lengthened. Response proportions overmatched reinforcer proportions to a greater extent at long component durations in the closed economy, but there was no systematic effect of component duration on responding in the open economy.

Animals↗
PubMed1987

Effects of delayed conditioned reinforcement in chain schedules.

The contingency between responding and stimulus change on a chain variable-interval 33-s, variable-interval 33-s, variable-interval 33-s schedule was weakened by interposing 3-s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial-link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable-interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditioned reinforcement.

Animals↗
PubMed1987

A molecular analysis of choice on concurrent-chains schedules.

Six pigeons responded on concurrent-chains schedules with either independent or interdependent equal variable-interval schedules in the initial links and unequal variable-interval schedules, always in a 2:1 ratio, in the terminal links. Relative response rates in the initial links increased across conditions as initial-link duration was shortened and decreased across conditions as terminal-link duration was shortened, replicating previous findings. Responses in the initial links were recorded in 5-s bins, and local or molecular relative response rates were calculated in order to ascertain how relative response rate varied as a function of time since the onset of the initial links. Two distinct molecular patterns were found. With interdependent initial links, relative response rates for the preferred key were elevated for the first 10 or 20 s of the initial links and then declined to an asymptotic value. With independent initial links, a negative recency effect was found similar to that reported by Killeen (1970). These two molecular patterns were related to the different momentary reinforcement probabilities resulting from independent and interdependent scheduling.

Animals↗
PubMed1986

Choice, foraging, and reinforcer duration.

Pigeons were exposed to a foraging schedule characterized by three different states, beginning with a search state in which completion of a variable interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule offered. If the subject accepted the schedule, it entered a handling state in which the appropriate reinforcer amount was presented according to a variable-interval schedule. In Experiment 1 the shorter duration reinforcer was more likely to be accepted the longer the duration of the search state and the shorter the equal durations of the handling states. In Experiment 2 the shorter duration reinforcer was more likely to be accepted the longer the handling time preceding the longer duration reinforcer. All of the results were in qualitative--and some were in quantitative--agreement with those predicted by the delay-reduction hypothesis and the optimal-diet model.

Animals↗
PubMed1985

Human observing: maintained by negative informative stimuli only if correlated with improvement in response efficiency.

Two experiments investigated the effect of observing responses that enabled college students to emit more efficient distributions of reinforced responses. In Experiment 1, the gains of response efficiency enabled by observing were minimized through use of identical low-effort response requirements in two alternating variable-interval schedules. These comprised a mixed schedule of reinforcement; they differed in the number of money-backed points per reinforcer. In each of three choices between two stimuli that varied in their correlation with the variable-interval schedules, the results showed that subjects preferred stimuli that were correlated with the larger average amount of reinforcement. This is consistent with a conditioned-reinforcement hypothesis. Negative informative stimuli--that is, stimuli correlated with the smaller of two rewards--did not maintain as much observing as stimuli that were uncorrelated with amount of reward. In Experiment 2, savings in effort made possible by producing S- were varied within subjects by alternately removing and reinstating the response-reinforcement contingency in a mixed variable-interval/extinction schedule of reinforcement. Preference for an uncorrelated stimulus compared to a negative informative stimulus (S-) decreased for each of six subjects, and usually reversed when observing permitted a more efficient temporal distribution of the responses required for reinforcement; in this case, the responses were pulls on a relatively high-effort plunger. When observing the S- could not improve response efficiency, subjects again chose the control stimulus. All of these results were inconsistent with the uncertainty-reduction hypothesis.

Attention↗