Showing papers by "Williams College published in 1989"

The eyewitness suggestibility effect and memory for source.

Abstract: We examined the possibility that eyewitness suggestibility reflects failures of the processes by which people normally discriminate between memories derived from different sources. To test this hypothesis, misled and control subjects were tested either with a yes/no recognition test or with a "source monitoring" test designed to orient subjects to attend to information about the sources of their memories. The results demonstrate that suggestibility effects obtained with a recognition test can be eliminated by orienting subjects toward thinking about the sources of their memories while taking the test. Our findings indicate that although misled subjects are capable of identifying the source of their memories of misleading suggestions, they nonetheless sometimes misidentify them as memories derived from the original event. The extent to which such errors reflect genuine memory confusions (produced, for example, by lax judgment criteria) or conscious misattributions (perhaps due to demand characteristics) remains to be specified.

Contractionary Devaluation in Developing Countries: An Analytical Overview

Abstract: The growing literature on whether devaluation has contractionary effects on output in developing countries is evaluated. The paper explores links between the exchange rate and real output within a unified, fairly general analytical framework that incorporates several of the developing country features cited in the literature. The analysis suggests that many of the arguments on both sides of the debate about contractionary devaluation require modification, that some potential effects have been ignored, and that the direction of the impact effects of devaluation on real output is ambiguous on analytical grounds.

Disrupted eyelid conditioning in a patient with damage to cerebellar afferents.

Abstract: A 54-year-old woman with damage to cerebellar circuitry resulting from a cerebrovascular accident underwent classical conditioning of the eye-blink response to a tone conditioned stimulus and an air-puff unconditioned stimulus. In contrast to 5 age-matched controls who readily acquired the conditioned response (CR), emitting a mean of 56.7 CRs over 70 trials, the patient emitted only 6 CRs in 100 trials and never emitted 2 consecutive CRs. There were no differences in spontaneous blink rate, sensitivity to the air puff, or sensitivity to the tone between the experimental subject and the control subjects. That conditioning of the eye-blink response is disrupted in a human with damage to cerebellar circuitry is consistent with an accumulating body of literature indicating that the cerebellum is the essential site of plasticity for classically conditioned somatic responses.

Acquisition of the classically conditioned eyeblink response in humans over the life span.

Abstract: Human subjects ranging in age from 18 to 85 years underwent classical conditioning of the eyeblink response to a tone conditioned stimulus (CS) and an air-puff unconditioned stimulus (UCS). There was a decline in percentage of conditioned responses with age. This decline was most noticeable in subjects over age 50. These conditioning deficits were not due to age-related changes in sensitivity to the tone CS or the air-puff UCS, nor could the conditioning deficits be attributed to an age-related decline in general cognitive abilities or to changes in spontaneous blink rates. The results are discussed in terms of using the classically conditioned eyeblink in humans in conjunction with the classically conditioned nictitating membrane response in rabbits as a model system for studying the neurobiology of age-related conditioning deficits.

Improved Method for HPLC Analysis of Polyamines, Agmatine and Aromatic Monoamines in Plant Tissue

Abstract: The high performance liquid chromatographic (HPLC) method of Flores and Galston (1982 Plant Physiol 69: 701) for the separation and quantitation of benzoylated polyamines in plant tissues has been widely adopted by other workers. However, due to previously unrecognized problems associated with the derivatization of agmatine, this important intermediate in plant polyamine metabolism cannot be quantitated using this method. Also, two polyamines, putrescine and diaminopropane, also are not well resolved using this method. A simple modification of the original HPLC procedure greatly improves the separation and quantitation of these amines, and further allows the simulation analysis of phenethylamine and tyramine, which are major monoamine constituents of tobacco and other plant tissues. We have used this modified HPLC method to characterize amine titers in suspension cultured carrot (Daucas carota L.) cells and tobacco (Nicotiana tabacum L.) leaf tissues.

Eyewitness accuracy and confidence: within- versus between-subjects correlations.

Abstract: Previous researchers using between-subjects comparisons have found eyewitness confidence and accuracy to be only negligibly correlated. In this study, we examined the predictive power of confidence in within-subject terms. Ninety-six subjects answered, and made confidence ratings for, a series of questions about a crime they witnessed. The average between-subjects and within-subject accuracyconfidence correlations were comparably low: r=.14(p<.001) and r = .17 (p < .001), respectively. Confidence is neither a useful predictor of the accuracy of a particular witness nor of the accuracy of particular statements made by the same witness. Another possible predictor of accuracy, response latency, correlated only negligibly with accuracy (r = -.09 within subjects), but more strongly with confidence (r = —.27 within subjects). This pattern was obtained for both between-subjects and within-subject comparisons. The theoretical and practical implications of these results are discussed. Common sense suggests that the confidence an eyewitness expresses is a good indicator of the accuracy of the testimony. This intuition appears to be widely held, with 56% of jurors (Brigham & Bothwell, 1983), 76% of undergraduates (Deffenbacher & Loftus, 1982), 73% of police officers, 75% of prosecuting attorneys, and 40% of defense attorneys (Brigham & Wolfskiel, 1983) believing that eyewitness confidence and accuracy are positively correlated. Even the United States Supreme Court, in the case of Neil v. Biggers (1972), specified eyewitness confidence as an important predictor of identification accuracy and later reaffirmed this standard in Manson v. Brathwaite (1976). Despite intuition and the Court's assertions, a considerable amount of psychological research indicates that eyewitness confidence is not a reliable predictor of accuracy. Wells & Murray (1984) report that in 18 of the 31 studies they reviewed, accuracy and confidence were not significantly correlated. Even in those studies for which a significant relation was obtained, con

Value‐Guided Attributions: Maintaining the Moral Self‐Image and the Diabolical Enemy‐Image

Abstract: Previous research suggests that people subscribe to ethnocentric “mirror images” of their own country and enemy countries—one's own country is believed moral, whereas one's enemy is believed diabolical. The present research examined the role of value-guided attributions in maintaining those images, whereby the actions of one's own country are attributed to altruistic motives but the identical actions taken by an enemy are attributed to self-serving motives. In two experiments, American students made value-guided attributions consistent with the moral self-image and the diabolical enemy-image. In a third experiment, by contrast, Canadian subjects attributed Soviet and American actions to the same motives, with the exception that only the United States was perceived as engaging in positive actions for self-serving reasons.

Direct versus indirect tests of memory for source: judgments of modality.

Abstract: We studied the relation between performance on direct versus indirect tests of memory for modality. Subjects read or heard words in a mixed list and then were tested by visual perceptual identification (the indirect test) and direct report of items as read, heard, or new. There was a dependent relation between perceptual identification performance and modality judgments, in accord with the hypothesis that subjects base their judgments of modality on relative perceptual fluency. In Experiment 2, we attempted to change the degree of dependence by providing subjects with an alternative basis for modality judgments. Subjects given a mnemonic to encode modality exhibited less dependence between perceptual identification performance and modality judgments than did subjects who encoded modality incidentally. The relation between direct and indirect tests of memory for source characteristics depends on the basis used for each. Language: en

Competence-specific induction of the Bacillus subtilis RecA protein analog: evidence for dual regulation of a recombination protein.

Abstract: The development of competence in Bacillus subtilis is accompanied by the transcriptional activation of DNA damage-inducible (din) operons and other SOS-like responses. We report here that B. subtilis Rec protein (the analog of Escherichia coli RecA), a DNA damage-inducible protein, is substantially induced when cells differentiate to a state of competence. We quantitated the induction of B. subtilis Rec protein and the B. subtilis din-22 operon (representative of all known B. subtilis din operons) during competence development in Rec+ and DNA repair-deficient strains. We present two lines of evidence that Rec protein induction in competent cells is controlled by a competence-specific mechanism that is distinct from the SOS-like regulation that controls Rec induction following DNA damage: (i) Rec protein was significantly induced in rec mutants (recA1 and recE4) that are highly deficient in Rec induction by DNA damage, and (ii) Rec protein induction during competence development was greater than maximum Rec induction by DNA damage. On the other hand, our results suggest that the din-22 operon is induced by the same (SOS-like) mechanism both during competence development and after DNA damage.

Effects of paddle impeller geometry on power input and mass transfer in small‐scale animal cell culture vessels

Abstract: Process scaleup for stirred-tank animal cell cultures such as suspension and microcarrier cultures often begins at the bench scale in small spinner vessels. In order to initiate process development under the proper conditions, it is essential to know the physical conditions under which the cells are grown. In this article, power inputs and surface oxygen transfer rates to culture medium in 500-mL Corning spinner vessels were determined as a function of the impeller geometry, impeller height, and agitation speed. The results obtained indicate that power dissipation dependency differs from literature correlations and may compromise scale up at constant power input from these vessels. These results are of general utility to researchers using small-scale vessels.

The reversed eyewitness suggestibility effect

Abstract: The standard temporal order of events used in studies of eyewitness suggestibility was reversed: Misled subjects were given verbal suggestions about a visual scene before witnessing it. As in the standard procedure, the subjects were later tested on memory of the visual scene. A suggestibility effect was obtained with this reversed procedure, even though the verbal information could not “update” the target memory because no memory of the visual scene existed when the misleading suggestions were given.

Devaluation Crises and the Macroeconomic Consequences of Postponed Adjustment in Developing Countries

Abstract: This paper develops our analytical model to explore the relationship between the dynamics of macroeconomic adjustment and the timing of the implementation of an adjustment program featuring an official devaluation. The effects of postponing adjustment depend on the source of the original shock, In the case of fiscal expansion, postponement implies a larger eventual official devaluation and greater deviations of macroeconomic variables from their steady-state values. For adverse terms of trade shocks, postponement does not affect the size of the eventual official devaluation, but does magnify the amount of post-devaluation overshooting by key macroeconomic variables.

Tempestites recorded as variable Pentamerus layers in the Lower Silurian of southern Norway

Abstract: The brachiopod Pentamerus oblongus is especially abundant in the Lower Silurian RytterAker Formation, which occurs widely throughout the Oslo region in southern Norway. Alternating thin limestones and shales typically occur in a shallowing-upward sequence ending in a massive grainstone often rich in tabulate corals and stromatoporoids. In the lower beds, colonization by pentamerid populations was enhanched by prior emplacement of an orthotetacean shell pavement over the clastic sea bed. Individual Pentamerus size decreases with increasing disturbance of populations or their fragmentation as lag deposits nearer the stratigraphic level of the massive grainstone. The frequency of specific storm events and the changing depth to the sea bed may be indexed according to the average size of pentamerid shells in a given population and the degree to which the population is disturbed. Preservation of prominent growth lines (assumed to be annual) suggests storms stirred the sea bed in deeper waters on an 8-10 year cycle. In shallower waters, storms more regularly disturbed the sea bed every 2-3 years. These data corroborate the interpretation that the Pentamerus community inhabited marine waters below fair-weather wave base, but still within reach of storm wave base.

Compensatory mutations demonstrate that P8 and P6 are RNA secondary structure elements important for processing of a group I intron.

Abstract: Compensatory mutations have been constructed which demonstrate that P8 and P6, two of nine proposed base-pairing interactions characteristic of group I introns, exist within the folded structure of the Tetrahymena thermophila rRNA intervening sequence, and that these secondary structure elements are important for splicing in E. coli and self-splicing in vitro. Two-base mutations in the 5' and 3' segments of P8 are predicted to disrupt P8 and a strong splicing-defective phenotype is observed in each case. A compensatory four-base mutation in P8 is predicted to restore pairing, and results in the restoration of splicing activity to nearly wild type levels. Thus, we conclude that P8 exists and is essential for splicing. In contrast to the strong phenotypes generally exhibited by mutations which disrupt RNA secondary structure, a two-base mutation in L8, the loop between P8[5'] and P8[3'], results in only a slight decrease in splicing activity. We also tested P6, a pairing which is proposed to consist of only two base-pairs in this intron. A two-base mutation in P6[3'] reduces splicing activity to a greater extent than does a two-base mutation in P6[5']. Comparison of the activities of these mutants and a compensatory P6 four-base mutant support the existence of P6, and suggest that the P6 pairing may be particularly important in the exon ligation step of splicing.

Size-minimizing rectifiable currents

Abstract: 1. Introduct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 2. On the existence and regularity of size minimizers . . . . . . . . . . . . . . . . . . . 336 3. Isoperimetric inequalities and size bounds . . . . . . . . . . . . . . . . . . . . . . 345 4. Bernstein theorems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348

Where guesses come from: Evolutionary epistemology and the anomaly of guided variation

Abstract: This paper considers a central objection to evolutionary epistemology. The objection is that biological and epistemic development are not analogous, since while biological variation is blind, epistemic variation is not. The generation of hypotheses, unlike the generation of genotypes, is not random. We argue that this objection is misguided and show how the central analogy of evolutionary epistemology can be preserved. The core of our reply is that much epistemic variation is indeed directed by heuristics, but these heuristics are analogous to biological preadaptations which account for the evolution of complex organs. We also argue that many of these heuristics or “epistemic preadaptations” are not innate but were themselves generatedby a process of blind variation and selective retention.

Imperfectly rational choice: Rationality as the result of a costly activity

Abstract: In identifying characteristics of people and of their choices that determine their degree of rationality — the nature and incidence of imperfect rationality — this paper suggests that there are often observable criteria by which to judge the applicability of the rational choice model to a particular market or choice situation. Clearer understanding will cut both ways, bringing more of non-economic behavior into the productive domain of rational choice analysis while at the same time showing economic, and non-economic, behavior that is badly modeled by the assumption of rational decision makers.

The Hierarchy of Shanghai Prostitution, 1870-1949:

Abstract: Shanghai has been called "the key to modern China" (Murphey, 1953) because of its rapid expansion in the nineteenth and twentieth centuries, its importance as an industrial and commercial center, its extensive exposure to foreign economic and cultural influences, and its role as a hotbed of the radical politics that eventually shaped the Chinese revolution. Yet although recent scholarship has done a great deal to illuminate various aspects of Shanghai's modern growth, large parts of its history remain hidden from view, among them the history of women's experience outside the industrial sphere. By some estimates numbering 100,000 in the 1930s, prostitutes made up arguably the single most numerous of all female groups living and working in the city. Although less visible and more diverse than the ranks of Shanghai cotton-mill workers, they were no less crucial to the city's development. Their labor helped to support their families, promoted the development of commercial and service establishments, and lined the pockets of the police and the powerful underworld gangs that controlled much of the urban economy. If

Individual variation in winter foraging of black-capped chickadees

Abstract: Wintering black-capped chickadees (Paridae: Parus atricapillus) in northwestern Massachusetts showed a high degree of individual variation in foraging behavior. After accounting for the effects of different habitats and weather conditions, individual differences comprised 6–17% of the total observed variation in four measures of foraging location and rate of feeding. Differences between age and sex groups were not significant and explained comparatively little variation (0.0–1.4%). The chickadees did not fall into a few distinct behavioral categories but instead showed continuous variation on all measures of foraging behavior. It appeared that some variation among individuals was a consequence of behavioral convergence within social groups, since birds that were observed together were more similar in their foraging than expected by chance, after taking habitat differences into account. Our results therefore do not support the interpretation that individual variation in feeding behavior serves to reduce exploitation competition within social groups.