To associate the identical drug state with both a loeation and a flavor, rats were given intraperitoneal amphetamine injeetions and then eonfined for 20 min in one side of a shuttlebox with aecess to a flavored solution; on control trials without injections, they were confined for 20 min in the opposite side with a different flavor. In the first experiment, the rats were plaeed in the shuttlebox immediately after injections; in the second experiment, they were placed in the shuttlebox 20 min after injections. Subsequent free-choice tests in both experiments revealed an increased choice of the side of the shuttlebox associated with amphetamine but also an aversion to the flavored solution associated with the drug.In attempts to eharaeterize the reinforeing properties of abused drugs, a paradox has arisen. Cappell and l..e Blane (1973) found aversive taste eonditioning by intraperitoneal amphetamine within the range of doses which Pickens and Harris (1968) found rats would selfinjeet intravenously. Thus, a single pharmaeologieal stimulus may aet as both a positive and a negative reinforeer depending on the associated stimuli and responses.Wise, Yokel, and deWit (1976) pointed out, however, that these seemingly paradoxical effeets eould be explained by differenees in proeedural variables such as route of drug administration, extent of drug habituation, and delay of reinforeement. Wise et al. therefore attempted to eontrol for these faetors in demonstrating positive and negative reinforeement by intravenous amphetamine and apomorphine. Their first experiment circumvented habituation diffieulties by giving rats that had previously shown amphetamine self-administration a IO-min exposure to saccharin followed by an amphetamine injection. A subsequent test indicated moderate suppression of saccharin drinking. However, as the report aeknowledges, this does "not ... establish that a particular drug injection can be both reinforcing and aversive" (p. 1273). The difficulty is that positive reinforcement was demonstrated by self-adrninistered amphetamine immediately following leverpressing, while negative reinforcement was demonstrated by a single, experimenter-administered amphetamine injection given only after a IO-min drinking period. In the second experiment by Wise et al., rats previously trained to selfadminister amphetamine were given aceess to saccharin followed immediately by an apomorphine self-injection session. Some of the rats continued to leverpress for apomorphine, yet subsequently showed an aversion to the saccharin. As Wise et al. mentioned, however, there were still difficulties in this proeedure, including the difference in the delay of reinforcement for leverpressing and saccharin-drinking, as weIl as the possible ambiguity created by first training the rats to self-administer amphetamine and then suddenly switching to apomorphine.The present experiments avoided some of these problems by associating the same injections with a compound stimulus consisting of a distinctive flavor and a distinctive loeation...
This paper describes a computerized alternative to glottochronology for estimating elapsed time since parent languages diverged into daughter languages. The method, developed by the Automated Similarity Judgment Program (ASJP) consortium, is different from glottochronology in four major respects: (1) it is automated and thus is more objective, (2) it applies a uniform analytical approach to a single database of worldwide languages, (3) it is based on lexical similarity as determined from Levenshtein (edit) distances rather than on cognate percentages, and (4) it provides a formula for date calculation that mathematically recognizes the lexical heterogeneity of individual languages, including parent languages just before their breakup into daughter languages. Automated judgments of lexical similarity for groups of related languages are calibrated with historical, epigraphic, and archaeological divergence dates for 52 language groups. The discrepancies between estimated and calibration dates are found to be on average 29% as large as the estimated dates themselves, a figure that does not differ significantly among language families. As a resource for further research that may require dates of known level of accuracy, we offer a list of ASJP time depths for nearly all the world's recognized language families and for many subfamilies. The greater the degree of linguistic differentiation within a stock, the greater is the period of time that must be assumed for the development of such differentiations.
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